Journal articles: 'Diffusion - Organic Dyes'

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Smilek, Jiří, Michal Kalina, Marcela Laštůvková, Irena Türkeová, Petr Sedlacek, and Martina Klučáková. "Reactivity-Mapping Tool Based on Diffusion Techniques for Characterization of Biocolloids." Materials Science Forum 851 (April 2016): 130–34. http://dx.doi.org/10.4028/www.scientific.net/msf.851.130.

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The universal reactivity-mapping tool was developed for characterization and study on barrier properties of selected biopolymers. The reactivity of biocolloids (humic acids) was studied by both diffusion techniques (break-through diffusion technique and non-stationary diffusion). The rate of reactivity of humic acids was compared by the interactions with basic cationic organic dye (Methylene Blue) because of the positive interactions among anionic supramolecular humic acids and cationic organic dyes were expected. The reactivity and barrier properties of biocolloids were compared by determination of fundamental diffusion parameters such as effective diffusion coefficient, sorption capacity, break-through time (the time needed for penetration of chosen organic dye through hydrogel porous barrier) or the concentration of organic dye on the interface hydrogel-solution. The original combination of simple diffusion experiments of suitable diffusion probe (organic dye) with the advantages of hydrogel porous media (simple preparation of hydrogels, the diffusion is undisturbed by convection, etc.) provides very valuable information about the reactivity of chosen biocolloids.

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Klučáková, Martina. "Effect of Chitosan as Active Bio-colloidal Constituent on the Diffusion of Dyes in Agarose Hydrogel." Gels 9, no. 5 (May 9, 2023): 395. http://dx.doi.org/10.3390/gels9050395.

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Agarose hydrogel was enriched by chitosan as an active substance for the interactions with dyes. Direct blue 1, Sirius red F3B, and Reactive blue 49 were chosen as representative dyes for the study of the effect of their interaction with chitosan on their diffusion in hydrogel. Effective diffusion coefficients were determined and compared with the value obtained for pure agarose hydrogel. Simultaneously, sorption experiments were realized. The sorption ability of enriched hydrogel was several times higher in comparison with pure agarose hydrogel. Determined diffusion coefficients decreased with the addition of chitosan. Their values included the effects of hydrogel pore structure and interactions between chitosan and dyes. Diffusion experiments were realized at pH 3, 7, and 11. The effect of pH on the diffusivity of dyes in pure agarose hydrogel was negligible. Effective diffusion coefficients obtained for hydrogels enriched by chitosan increased gradually with increasing pH value. Electrostatic interactions between amino group of chitosan and sulfonic group of dyes resulted in the formation of zones with a sharp boundary between coloured and transparent hydrogel (mainly at lower pH values). A concentration jump was observed at a given distance from the interface between hydrogel and the donor dye solution.

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Chenyakin, Yuri, Dagny A. Ullmann, Erin Evoy, Lindsay Renbaum-Wolff, Saeid Kamal, and Allan K. Bertram. "Diffusion coefficients of organic molecules in sucrose–water solutions and comparison with Stokes–Einstein predictions." Atmospheric Chemistry and Physics 17, no. 3 (February 15, 2017): 2423–35. http://dx.doi.org/10.5194/acp-17-2423-2017.

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Abstract. The diffusion coefficients of organic species in secondary organic aerosol (SOA) particles are needed to predict the growth and reactivity of these particles in the atmosphere. Previously, viscosity measurements, along with the Stokes–Einstein relation, have been used to estimate the diffusion rates of organics within SOA particles or proxies of SOA particles. To test the Stokes–Einstein relation, we have measured the diffusion coefficients of three fluorescent organic dyes (fluorescein, rhodamine 6G and calcein) within sucrose–water solutions with varying water activity. Sucrose–water solutions were used as a proxy for SOA material found in the atmosphere. Diffusion coefficients were measured using fluorescence recovery after photobleaching. For the three dyes studied, the diffusion coefficients vary by 4–5 orders of magnitude as the water activity varied from 0.38 to 0.80, illustrating the sensitivity of the diffusion coefficients to the water content in the matrix. At the lowest water activity studied (0.38), the average diffusion coefficients were 1.9 × 10−13, 1.5 × 10−14 and 7.7 × 10−14 cm2 s−1 for fluorescein, rhodamine 6G and calcein, respectively. The measured diffusion coefficients were compared with predictions made using literature viscosities and the Stokes–Einstein relation. We found that at water activity ≥ 0.6 (which corresponds to a viscosity of ≤ 360 Pa s and Tg∕T ≤ 0.81), predicted diffusion rates agreed with measured diffusion rates within the experimental uncertainty (Tg represents the glass transition temperature and T is the temperature of the measurements). When the water activity was 0.38 (which corresponds to a viscosity of 3.3 × 106 Pa s and a Tg∕T of 0.94), the Stokes–Einstein relation underpredicted the diffusion coefficients of fluorescein, rhodamine 6G and calcein by a factor of 118 (minimum of 10 and maximum of 977), a factor of 17 (minimum of 3 and maximum of 104) and a factor of 70 (minimum of 8 and maximum of 494), respectively. This disagreement is significantly smaller than the disagreement observed when comparing measured and predicted diffusion coefficients of water in sucrose–water mixtures.

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Dey, Shantanu, Ujjwal Mandal, Supratik Sen Mojumdar, Amit Kumar Mandal, and Kankan Bhattacharyya. "Diffusion of Organic Dyes in Immobilized and Free Catanionic Vesicles." Journal of Physical Chemistry B 114, no. 47 (December 2, 2010): 15506–11. http://dx.doi.org/10.1021/jp1068347.

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Chernomorova, Maria A., Natali S. Khrabrova, Vladimir A. Zhinzhilo, and Igor E. Uflyand. "The Use of Copper Terephthalate for the Determination and Separation of Organic Dyes via Solid-Phase Extraction with Spectrophotometric Detection." Applied Sciences 13, no. 5 (February 27, 2023): 3063. http://dx.doi.org/10.3390/app13053063.

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In this work, a metal–organic framework (MOF), copper benzene dicarboxylate (Cu-MOF), was tested for the adsorptive recovery of organic dyes (Sunset Yellow FCF, Tartrazine, Orange II, and Methyl Orange) from aqueous solutions. Studies were also carried out to determine the effects of various parameters, and isothermal and kinetic models were proposed. The adsorption capacity of Cu-MOF was much higher than that of activated carbon. The experimental data are best described by the Langmuir isotherm model (R2 > 0.997) and show the ability of Cu-MOF to adsorb 435 mg/g of the dye under optimal conditions. The study of the kinetics of the dye adsorption process followed a pseudo-second-order kinetic model indicating the coexistence of physical and chemisorption, with diffusion within the particles being the rate-limiting step. Thermodynamic studies were also carried out, and they led to the conclusion that the adsorption of the dye was a feasible, spontaneous, and exothermic process (−25.53 kJ mol−1). The high organic dye recovery shows that Cu-MOF can be used as an efficient and reusable adsorbent for the extraction of dyes from aqueous solutions. These studies may lead to economic interest in this adsorbent material for environmental purposes.

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Kadolkar, Prajakta S., Shivaraj A. Patil, Manjunath N. Wari, and Sanjeev R. Inamdar. "Rotational diffusion dynamics of Alexa flour dyes in aqueous organic environment." Journal of Molecular Liquids 312 (August 2020): 113452. http://dx.doi.org/10.1016/j.molliq.2020.113452.

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BALAKRISHNAN, JEYAGOWRI, and YAMUNA RANGAIYA THIAGARAJAN. "CHARACTERIZATION AND POTENTIAL SUITABILITY OF SIMAROUBA GLAUCA SEED SHELL LIGNOCELLULOSIC BIOMASS AS ADSORBENT OF BASIC DYES FROM AQUEOUS SOLUTIONS." Cellulose Chemistry and Technology 55, no. 5-6 (June 30, 2021): 705–22. http://dx.doi.org/10.35812/cellulosechemtechnol.2021.55.60.

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The present study investigates the potential of Simarouba glauca seed shell powder as a cost-effective adsorbent for the removal of the cationic dyes Malachite green (MG), Methylene blue (MB) and Rhodamine B (RB) from aqueous solutions. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD), as well as by Brunauer–Emmett–Teller (BET) and elemental (CHNS) analyses. Batch mode adsorption studies were carried out varying the experimental conditions, such as initial dye concentration and contact time, adsorbent dose, pH and particle size, in order to assess the adsorbent capacity for the removal of cationic dyes from wastewater. The experimental data were analysed using the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms. The data fitted well the Langmuir model for the dyes studied. Kinetic data were analysed using the pseudo-first order, pseudo-second order, intraparticle diffusion and Boyd models. The experimental results showed that the pseudo-second order model fitted well.

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Dollendorf, Christian, Susanne Katharina Kreth, Soo Whan Choi, and Helmut Ritter. "Polymerization of novel methacrylated anthraquinone dyes." Beilstein Journal of Organic Chemistry 9 (February 28, 2013): 453–59. http://dx.doi.org/10.3762/bjoc.9.48.

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A new series of polymerizable methacrylated anthraquinone dyes has been synthesized by nucleophilic aromatic substitution reactions and subsequent methacrylation. Thereby, green 5,8-bis(4-(2-methacryloxyethyl)phenylamino)-1,4-dihydroxyanthraquinone (2), blue 1,4-bis(4-((2-methacryloxyethyl)oxy)phenylamino)anthraquinone (6) and red 1-((2-methacryloxy-1,1-dimethylethyl)amino)anthraquinone (12), as well as 1-((1,3-dimethacryloxy-2-methylpropan-2-yl)amino)anthraquinone (15) were obtained. By mixing of these brilliant dyes in different ratios and concentrations, a broad color spectrum can be generated. After methacrylation, the monomeric dyes can be covalently emplaced into several copolymers. Due to two polymerizable functionalities, they can act as cross-linking agents. Thus, diffusion out of the polymer can be avoided, which increases the physiological compatibility and makes the dyes promising compounds for medical applications, such as iris implants.

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Mandake, Manoj B., Santosh Walke, Makarand Naniwadikar, Ganesh Patil, and Sandhya D. Jadhav. "Experimental Investigations of the Removal of Methylene Blue from Waste Water using Agricultural Adsorbant." Int. J. of Membrane Science and Technology 10, no. 1 (January 20, 2023): 1–7. http://dx.doi.org/10.15379/2410-1869.2023.10.01.01.

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Abstract: The colored organic or inorganic chemical compounds which can impart colour to other substance are the Dyes which did significant applications in the most industrial sectors like the textile industry, leather industry, paper industry, plastic, foodstuff industry etc, to impart color to their products. Due to the large volume of dye use in these businesses, a significant quantity of wastewater containing colored organics is generated. Because of insufficient dye-fiber fixation, during the dyeing process, half of the dye is lost in the wastewater. Peanut and rice husk are used to absorb MB from water. Initial Methylene Blue concentration, Peanut and Rice Husk dose, and pH were monitored and compared to current adsorbents to identify the optimal removal conditions. The equilibrium amount of MB adsorbed at time t (min) for rice husk and peanut hull are obtained as 5.1 and 5.19 mg/g respectively. As part of the research, an intra-particle diffusion model was implemented to regulate the mass transfer model's rate-controlling step mechanism.

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10

Russo, Mattia, Kirsty E. McGhee, Tersilla Virgili, David G. Lidzey, Giulio Cerullo, and Margherita Maiuri. "Dephasing Processes in the Molecular Dye Lumogen-F Orange Characterized by Two-Dimensional Electronic Spectroscopy." Molecules 27, no. 20 (October 20, 2022): 7095. http://dx.doi.org/10.3390/molecules27207095.

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Molecular dyes are finding more and more applications in photonics and quantum technologies, such as polaritonic optical microcavities, organic quantum batteries and single-photon emitters for quantum sensing and metrology. For all these applications, it is of crucial importance to characterize the dephasing mechanisms. In this work we use two-dimensional electronic spectroscopy (2DES) to study the temperature dependent dephasing processes in the prototypical organic dye Lumogen-F orange. We model the 2DES maps using the Bloch equations for a two-level system and obtain a dephasing time T2 = 53 fs at room temperature, which increases to T2 = 94 fs at 86 K. Furthermore, spectral diffusion processes are observed and modeled by a combination of underdamped and overdamped Brownian oscillators. Our results provide useful design parameters for advanced optoelectronic and photonic devices incorporating dye molecules.

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ERTAN, BENGÜ. "COMPARISON OF STINGING NETTLE ADSORPTION PERFORMANCE TOWARDS ANIONIC AND CATIONIC DYES." Cellulose Chemistry and Technology 55, no. 9-10 (December 3, 2021): 1131–42. http://dx.doi.org/10.35812/cellulosechemtechnol.2021.55.97.

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Stinging nettle was used as lignocellulosic adsorbent for the removal of cationic dye – malachite green (MG), and anionic dye – Congo red (CR), from aqueous solution, without any chemical pretreatment. The adsorption equilibrium data fitted well with the Langmuir model for the adsorption of both dyes, with the calculated maximum adsorption capacity of 270.27 mgg-1 and 172.14 mgg-1 for MG and CR, respectively. The adsorption process was controlled by the pseudo-second-order model in the adsorption of MG and by the pseudo-first-order model in the adsorption of CR. The thermodynamics modelling displayed that the process was spontaneous and endothermic. The π–π electron–donor interaction, hydrogen bonds and pore diffusion may also be effective, besides electrostatic interaction between the adsorbate and the adsorbent in the mechanism of MG and CR uptake.

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Trihutomo, Prihanto, Marji Marji, Muchammad Harly, Bambang Adi Wahyudi, and Muhammad Bustomi Radja. "The effect of Clathrin protein addition on increasing the number of electrons in organic Dye-Sensitized Solar Cell (DSSC)." EUREKA: Physics and Engineering, no. 2 (March 31, 2022): 15–27. http://dx.doi.org/10.21303/2461-4262.2022.001957.

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Dye-Sensitized Solar Cell (DSSC) is a solar cell that uses dyes to convert sunlight into electricity, which has a wide absorption spectrum, is inexpensive and environmentally friendly. Visible light sensitive dyes are used in Dye-Sensitized Solar Cell (DSSC) types to generate electricity. Natural sensitive dyes that are commonly used in DSSC are chlorophyll derived from plants. Chlorophyll is a source of electrons which will be excited when exposed to light, resulting in an electric current in the DSSC. The most basic problem in Dye-Sensitized Solar Cell (DSSC) is that the number of electrons produced is still lower than that of silicon solar cells. This is due to the high recombination process of free electrons due to limited diffusion of electrons trapped at the boundary between TiO2 particles caused by less than optimal contact between particles. Clathrin is a protein that plays an important role in the formation of the vesicle layer which is responsible for the transport of molecules in cells. As a protein that plays an important role in the cell transport system, Clathrin can bind to ions in order to transport cells. This study has proven that the addition of Clathrin protein to the DSSC layer can increase the number of electrons generated in the DSSC. The method used in this study was to vary the addition of Clathrin content to TiO2, namely the Clathrin concentration of 0 %, 25 %, 50 % and 75 %. The results showed that increasing the Clathrin content would increase the electric current and the number of electrons generated by the DSSC, namely the 75 % Clathrin content with an electric current of 5,247 mA and the number of electrons was 3.28x1016

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13

Mandake, Manoj B., Santosh Walke, Makarand Naniwadikar, Ganesh Patil, and Sandhya D. Jadhav. "Experimental Investigations of the Removal of Methylene Blue from Waste Water using Agricultural Adsorbant." International Journal of Membrane Science and Technology 10, no. 1 (January 20, 2023): 1–7. http://dx.doi.org/10.15379/ijmst.v10i1.1069.

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Abstract: The colored organic or inorganic chemical compounds which can impart colour to other substance are the Dyes which did significant applications in the most industrial sectors like the textile industry, leather industry, paper industry, plastic, foodstuff industry etc, to impart color to their products. Due to the large volume of dye use in these businesses, a significant quantity of wastewater containing colored organics is generated. Because of insufficient dye-fiber fixation, during the dyeing process, half of the dye is lost in the wastewater. Peanut and rice husk are used to absorb MB from water. Initial Methylene Blue concentration, Peanut and Rice Husk dose, and pH were monitored and compared to current adsorbents to identify the optimal removal conditions. The equilibrium amount of MB adsorbed at time t (min) for rice husk and peanut hull are obtained as 5.1 and 5.19 mg/g respectively. As part of the research, an intra-particle diffusion model was implemented to regulate the mass transfer model's rate-controlling step mechanism. Keywords: Waste Water, Methylene Blue, Peanut Hull, Rice Husk, Adsorption.

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14

Ścieżyńska, Dominika, Dominika Bury, Michał Jakubczak, Jan Bogacki, Agnieszka Jastrzębska, and Piotr Marcinowski. "Application of Micron-Sized Zero-Valent Iron (ZVI) for Decomposition of Industrial Amaranth Dyes." Materials 16, no. 4 (February 11, 2023): 1523. http://dx.doi.org/10.3390/ma16041523.

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Dyes are highly toxic and persistent in the environment. Their presence in water causes environmental and social problems. Dyes must be effectively removed from the water. A UV/ZVI/H2O2 process was applied to decompose two organic dyes, AM E123 and AM ACID. A commercial ZVI product, Ferox Flow, was used, and its properties were determined using SEM and XRF. The zeta potential, surface area, and optical properties of ZVI were also determined. The efficiency of dye removal in optimal conditions was 85.5% and 80.85% for AM E123 and AM ACID, respectively. Complete decolorization was observed in all samples. The decomposition of both dyes occurred according to a modified pseudo-second-order reaction and there was a statistically significant correlation between the TOC decrease, pH, and process time. The catalyst was observed to have high stability, and this was not affected by the performance of the treatment process even after the third cycle, as confirmed by the results of the catalyst surface analysis and iron diffusion test. Slight differences in process efficiency were observed after each cycle. The need for only a small amount of catalyst to decompose AM E123 and AM ACID, coupled with the ability to reuse the catalyst without the need for prior preparation, may reduce catalyst purchase costs.

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Ouettar, Lamia, El-Khamssa Guechi, Oualid Hamdaoui, Nadia Fertikh, Fethi Saoudi, and Abudulaziz Alghyamah. "Biosorption of Triphenyl Methane Dyes (Malachite Green and Crystal Violet) from Aqueous Media by Alfa (Stipa tenacissima L.) Leaf Powder." Molecules 28, no. 8 (April 8, 2023): 3313. http://dx.doi.org/10.3390/molecules28083313.

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This study includes the characterization and exploitation of an abundant agricultural waste in Algeria, Alfa (Stipa tenacissima L.) leaf powder (ALP) as a biosorbent for the removal of hazardous triphenylmethane dyes, malachite green (basic green 4) and crystal violet (basic violet 3), from aqueous media under various operating conditions in batch mode. The effect of experimental parameters such as initial dye concentration (10–40 mg/L), contact time (0–300 min), biosorbent dose (2.5–5.5 g/L), initial pH (2–8), temperature (298–328 K), and ionic strength on dye sorption was investigated. The results of both dyes show that the increase in initial concentration, contact time, temperature, and initial pH of solution leads to an increase in biosorbed quantity, unlike the effect of ionic strength. The biosorption kinetics for triphenylmethane dyes on ALP was analyzed by pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models proposed by the Weber–Morris equation. Equilibrium sorption data were analyzed by six isotherms, namely the Langmuir, Freundlich, Harkins–Jura, Flory–Huggins, Elovich, and Kiselev isotherms. The thermodynamic parameters were evaluated for both dyes. The thermodynamic results suggest that both dyes’ biosorption is a typical physical process, spontaneous and endothermic in nature.

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Ong, Pin Jin, Siok Wei Tay, and Liang Hong. "Removal of water-soluble dyes by conjugated organic skeletons through drainflow-diffusion filtration." Journal of Environmental Chemical Engineering 6, no. 4 (August 2018): 4612–22. http://dx.doi.org/10.1016/j.jece.2018.07.011.

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Pronkin, Pavel G., and Alexander S. Tatikolov. "Photonics of Trimethine Cyanine Dyes as Probes for Biomolecules." Molecules 27, no. 19 (September 27, 2022): 6367. http://dx.doi.org/10.3390/molecules27196367.

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Cyanine dyes are widely used as fluorescent probes in biophysics and medical biochemistry due to their unique photophysical and photochemical properties (their photonics). This review is focused on a subclass of the most widespread and studied cyanine dyes—trimethine cyanines, which can serve as potential probes for biomolecules. The works devoted to the study of the noncovalent interaction of trimethine cyanine dyes with biomolecules and changing the properties of these dyes upon the interaction are reviewed. In addition to the spectral-fluorescent properties, elementary photochemical properties of trimethine cyanines are considered, including: photoisomerization and back isomerization of the photoisomer, generation and decay of the triplet state, and its quenching by oxygen and other quenchers. The influence of DNA and other nucleic acids, proteins, and other biomolecules on these properties is covered. The interaction of a monomer dye molecule with a biomolecule usually leads to a fluorescence growth, damping of photoisomerization (if any), and an increase in intersystem crossing to the triplet state. Sometimes aggregation of dye molecules on biomolecules is observed. Quenching of the dye triplet state in a complex with biomolecules by molecular oxygen usually occurs with a rate constant much lower than the diffusion limit with allowance for the spin-statistical factor 1/9. The practical application of trimethine cyanines in biophysics and (medical) biochemistry is also considered. In conclusion, the prospects for further studies on the cyanine dye–biomolecule system and the development of new effective dye probes (including probes of a new type) for biomolecules are discussed.

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Patra, Satyajit, Kotni Santhosh, Ashok Pabbathi, and Anunay Samanta. "Diffusion of organic dyes in bovine serum albumin solution studied by fluorescence correlation spectroscopy." RSC Advances 2, no. 14 (2012): 6079. http://dx.doi.org/10.1039/c2ra20633a.

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Heger, Richard, Natalia Zinkovska, Monika Trudicova, Martin Kadlec, Miloslav Pekar, and Jiri Smilek. "Lecithin as an Effective Modifier of the Transport Properties of Variously Crosslinked Hydrogels." Gels 9, no. 5 (April 27, 2023): 367. http://dx.doi.org/10.3390/gels9050367.

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Transport properties are one of the most crucial assets of hydrogel samples, influencing their main application potential, i.e., as drug carriers. Depending on the type of drug or the application itself, it is very important to be able to control these transport properties in an appropriate manner. This study seeks to modify these properties by adding amphiphiles, specifically lecithin. Through its self-assembly, lecithin modifies the inner structure of the hydrogel, which affects its properties, especially the transport ones. In the proposed paper, these properties are studied mainly using various probes (organic dyes) to effectively simulate drugs in simple release diffusion experiments controlled by UV-Vis spectrophotometry. Scanning electron microscopy was used to help characterize the diffusion systems. The effects of lecithin and its concentrations, as well as the effects of variously charged model drugs, were discussed. Lecithin decreases the values of the diffusion coefficient independently of the dye used and the type of crosslinking. The ability to influence transport properties is better observed in xerogel samples. The results, complementing previously published conclusions, showed that lecithin can alter a hydrogel’s structure and therefore its transport properties.

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Birkić, Anamaria, Davor Valinger, Ana Jurinjak Tušek, Tamara Jurina, Jasenka Gajdoš Kljusurić, and Maja Benković. "Evaluation of the Adsorption and Desorption Dynamics of Beet Juice Red Dye on Alginate Microbeads." Gels 8, no. 1 (December 24, 2021): 13. http://dx.doi.org/10.3390/gels8010013.

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The use of alginate microcapsules has often been mentioned as one of the ways to remove dyes from waste solvents, water and materials from the food industry. In addition, alginate can be used as a wall material for the microencapsulation of food dyes and their further application in the food industry. The aims of this study were to: (i) determine the effect of the alginate concentration (1, 2, 3 and 4%) on the ability of the adsorption and desorption of natural beetroot red dye and (ii) evaluate the kinetic parameters of the adsorption and desorption process, as well as the factors affecting and limiting those processes. According to the obtained results, the viscosity of alginate solutions increased with an increase in the alginate concentration. Based on k2 values (the pseudo-second order kinetic rate constant), when a more concentrated solution of alginate was used in the adsorption process, the beads adsorbed a smaller amount of dye. Furthermore, based on the values for n derived from the Korsmeyer–Peppas model, the dye release rates (k) were higher for beads made with lower alginate concentrations, and this release was governed by a pseudo-Fickian diffusion mechanism (n values ranged from 0.2709 to 0.3053).

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Wawrzkiewicz, Monika, Beata Podkościelna, and Przemysław Podkościelny. "Application of Functionalized DVB-co-GMA Polymeric Microspheres in the Enhanced Sorption Process of Hazardous Dyes from Dyeing Baths." Molecules 25, no. 22 (November 11, 2020): 5247. http://dx.doi.org/10.3390/molecules25225247.

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Intensive development of many industries, including textile, paper, plastic or food, generate huge amounts of wastewaters containing not only toxic dyes but also harmful auxiliaries such as salts, acid, bases, surfactants, oxidants, heavy metal ions. The search for effective pollutant adsorbents is a huge challenge for scientists. Synthesis of divinylbenzene copolymer with glycidyl methacrylate functionalized with triethylenetetramine (DVB-co-GMA-TETA) resin was performed and the obtained microspheres were evaluated as a potential adsorbent for acid dye removal from dyeing effluents. The sorption capacities were equal to 142.4 mg/g for C.I. Acid Green 16 (AG16), 172 mg/g for C.I. Acid Violet 1 (AV1) and 216.3 mg/g for C.I. Acid Red 18 (AR18). Non-linear fitting of the Freundlich isotherm to experimental data was confirmed rather than the Langmuir, Temkin and Dubinin-Radushkevich. The kinetic studies revealed that intraparticle diffusion is the rate-limiting step during dye adsorption. Auxiliaries such as Na2SO4 (5–25 g/L), CH3COOH (0.25–1.5 g/L) and anionic surfactant (0.1–0.5 g/L) present in the dyeing baths enhance the dye adsorption by the resin in most cases. Regeneration of DVB-co-GMA-TETA is possible using 1 M NaCl-50% v/v CH3OH.

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DAOUD, LOUBNA, and SADJIA BENNOUR. "PREPARATION OF BIODEGRADABLE CARBOXYMETHYL CELLULOSEBASED HYDROGELS AND THEIR DUAL APPLICATION IN FERTILIZER CONTROLLED RELEASE AND CATIONIC DYE REMOVAL." Cellulose Chemistry and Technology 56, no. 5-6 (June 21, 2022): 667–80. http://dx.doi.org/10.35812/cellulosechemtechnol.2022.56.59.

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"Contamination of the environment by agrochemicals and organic dyes has become a serious issue. In the current study, bioadsorbents based on carboxymethyl cellulose have been synthesized by performing graft copolymerization of crosslinked poly(acrylamide-co-maleic acid) chains onto carboxymethyl cellulose. The synthesized hydrogels were characterized by FTIR, XRD, SEM and TGA. The swelling properties showed that the hydrogels exhibited thermo- and pH-responsive behavior. The incorporation of fertilizer (ammonium nitrate) into the hydrogel at the time of synthesis was carried out. The fertilizer release mechanism followed the Fickian transport model. The toxic cationic dye (methylene blue) removal study was carried out in dye contaminated aqueous solution at neutral pH. The adsorption kinetics fitted well with the pseudo-second order model. The mechanism of the adsorption process was determined from the intra-particle diffusion model. The aim of this work has been to predict the possibility of using the prepared hydrogels in agriculture and wastewater treatment."

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Rajeshkumar, S., M. Vanaja, and Arunachalam Kalirajan. "Degradation of Toxic Dye Using Phytomediated Copper Nanoparticles and Its Free-Radical Scavenging Potential and Antimicrobial Activity against Environmental Pathogens." Bioinorganic Chemistry and Applications 2021 (December 3, 2021): 1–10. http://dx.doi.org/10.1155/2021/1222908.

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The present investigation deals with the green synthesis of copper nanoparticles in an ecofriendly manner using leaf extract of Andrographis paniculata. Green-synthesized copper nanoparticles were studied for their antibacterial, antioxidant, and catalytic activity. The leaves were powdered and extracted with water and added to copper sulphate solution. The reduction of copper ions to nanoparticles was preliminarily identified by the color change of the reaction mixture. The synthesized nanoparticle was characterized by using a UV-Vis Spectrophotometer at a different wavelength with different time intervals. Functional groups available on the surface of the nanoparticle were identified by Fourier transform infrared spectroscopy (FTIR). Surface roughness was characterized by atomic force microscopy (AFM). X-ray diffraction (XRD) analysis showed six distinct intense peaks indicating the crystalline nature of synthesized copper nanoparticles (CuNPs). A scanning electron microscope (SEM) demonstrated polydispersed nanoparticles formed in the reaction process. The antibacterial activity of the nanoparticles was evaluated by an agar well diffusion assay against pathogenic bacteria. The antioxidant activity showed the excellent reduction of DPPH free radicals by nanoparticles. These results confirmed that copper nanoparticles serve as an alternative therapeutic agent over conventional drugs. Moreover, copper nanoparticles were also used to study the effect on the dye degradation process of methyl red and eosin dyes. Copper nanoparticles effectively remove the dyes with high efficiency up to 92% and 95% of methyl red and eosin dye, respectively.

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Jin, Wen Jie, Ying Liu, Han Xue, and Fan Chao Zeng. "Research on Adsorption and Discolor of Dyes on the New Wastewater Purifying Agent Named Granulated Fly Ash." Advanced Materials Research 518-523 (May 2012): 801–6. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.801.

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The new purifying agent named granulated fly ash was used to absorb the organic dyes-ethylene blue, direct red 12B and reactive brilliant orange X-GN in solution in this paper. The effects of dosage, temperature and pH on adsorption and discolor were separately studied. In addition, the adsorption model was also analyzed. Experiment results showed that adsorption isotherm models of ethylene blue and direct red 12B on the new agent conformed to Freundlich equation, and reactive brilliant orange X-GN conformed to Langmuir equation; The adsorption kinetics models of ethylene blue, direct red 12B and reactive brilliant orange X-GN on the new agent conformed to pseudo-secondary kinetic equation, liquid film diffusion was the main control step for adsorption of the three dyes.

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Pang, Xiu-yan, and Fei Gong. "Study on the Adsorption Kinetics of Acid Red 3B on Expanded Graphite." E-Journal of Chemistry 5, no. 4 (2008): 802–9. http://dx.doi.org/10.1155/2008/786025.

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Expanded graphite (EG) is a kind of important adsorbent for organic compound such as oil and dyes. We have investigated the adsorption kinetics characteristics of this adsorbent for dye. EG was prepared with 50 mesh crude graphite through chemical oxidation intercalation of potassium permanganate and vitriol, and dye of acid red 3B was used as model sorbate. We have studied the adsorption kinetic models and rate-limiting step of the process. Adsorption rate and activation energy of the adsorption process were calculated. Kinetic studies show that the kinetic data are well described by the pseudo second-order kinetic model. The equilibrium adsorbance increases with the increase of the initial acid red 3B concentration. Initial adsorption rate increases with the increase of the initial dye concentration and temperature. Adsorption process of acid red 3B on EG has small activation energy. Internal diffusion appears to be the rate-limiting step for the adsorption process.

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Sánchez-Ochoa, F., Gregorio H. Cocoletzi, and G. Canto. "Trapping and diffusion of organic dyes inside of palygorskite clay: The ancient Maya Blue pigment." Microporous and Mesoporous Materials 249 (September 2017): 111–17. http://dx.doi.org/10.1016/j.micromeso.2017.04.060.

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Warren, Brian C. H., and Richard E. Pattle. "Determination and correlation of diffusion coefficients of some dyes in organic solvents of high viscosity." Journal of Applied Chemistry and Biotechnology 27, no. 4 (May 29, 2007): 533–38. http://dx.doi.org/10.1002/jctb.5020270406.

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Mkrtchyan, E. S., E. A. Neskoromnaya, I. V. Burakova, O. A. Ananyeva, N. A. Revyakina, A. V. Babkin, T. S. Kuznetsova, D. A. Kurnosov, and A. E. Burakov. "Comparative Analysis of the Adsorption Kinetics of the Methylene Blue Dye on Graphene Aerogel and Activated Coconut Carbon." Advanced Materials & Technologies, no. 4(20) (2020): 021–28. http://dx.doi.org/10.17277/amt.2020.04.pp.021-028.

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The comparative adsorption capacity of graphene aerogel and activated coconut carbon in the process of removing the main cationic synthetic dye, methylene blue (MB), from aqueous solutions with an initial concentration of 150 mg/l was investigated. The characteristics of the new material have been determined using scanning electron microscopy, thermogravimetry, and Raman spectroscopy. The values of the adsorption capacity of graphene aerogel – 420 mg/g and activated carbon – 205 mg/g were established. The saturation time in the presence of graphene aerogel was 7 min. The experimental data were processed using kinetic models – pseudo-first and pseudo-second order, Elovich and intraparticle diffusion. According to the results obtained, graphene aerogel is a promising sorption material in the extraction of molecular organic pollutants, namely, synthetic dyes, demonstrating a high efficiency of the target pollutant removal.

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Zheng, Yifan, Jingjing Wang, Yedan Wang, Huan Zhou, Zhiying Pu, Qian Yang, and Wanzhen Huang. "The Combination of MoS2/WO3 and Its Adsorption Properties of Methylene Blue at Low Temperatures." Molecules 25, no. 1 (December 18, 2019): 2. http://dx.doi.org/10.3390/molecules25010002.

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It was found previously that neither monomer MoS2 nor WO3 is an ideal material for the adsorption of organic dyes, while MoS2/WO3 composites synthesized by a two-step hydrothermal method have outstanding adsorption effects. In this work, the chemical state of each element was found to be changed after combination by X-ray photoelectron spectroscopy analysis, which lead to their differences in adsorption performance. Moreover, the adsorption test of methylene blue on MoS2/WO3 composites was carried out under a series of temperatures, showing that the prepared composites also had appreciable adsorption rates at lower temperatures. The adsorption process could be well described by the Freundlich isothermal model and the pseudo-second order model. In addition, the particle-internal diffusion model simulation revealed that the internal diffusion of the particles played an important role in the whole adsorption process.

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K. Ramakrishnan, Rohith, Vinod V. T. Padil, Stanisław Wacławek, Miroslav Černík, and Rajender S. Varma. "Eco-Friendly and Economic, Adsorptive Removal of Cationic and Anionic Dyes by Bio-Based Karaya Gum—Chitosan Sponge." Polymers 13, no. 2 (January 13, 2021): 251. http://dx.doi.org/10.3390/polym13020251.

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A novel, lightweight (8 mg/cm3), conjugate sponge of karaya gum (Kg) and chitosan (Ch) has been synthesized with very high porosity (~98%) and chemical stability, as a pH-responsive adsorbent material for the removal of anionic and cationic dyes from aqueous solutions. Experimental results showed that Kg-Ch conjugate sponge has good adsorption capacity for anionic dye methyl orange (MO: 32.81 mg/g) and cationic dye methylene blue (MB: 32.62 mg/g). The optimized Kg:Ch composition grants access to the free and pH-dependent ionizable functional groups on the surface of the sponge for the adsorption of dyes. The studies on the adsorption process as a function of pH, adsorbate concentration, adsorbent dose, and contact time indicated that the adsorption capacity of MB was decreased with increasing pH from 5 to 10 and external mass transfer together with intra-particle diffusion. The adsorption isotherm of the anionic dye MO was found to correlate with the Langmuir model (R2 = 0.99) while the adsorption of the cationic MB onto the sponge was better described by the Freundlich model (R2 = 0.99). Kinetic regression results specified that the adsorption kinetics were well represented by the pseudo-second-order model. The H-bonding, as well as electrostatic interaction between the polymers and the adsorption interactions of dyes onto Kg-Ch sponge from aqueous solutions, were investigated using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and the highly wrinkled porous morphology was visualized in depth by field-emission scanning electron microscopy (FE-SEM) analysis. Moreover, the samples could be reused without loss of contaminant removal capacity over six successive adsorption-desorption cycles. The hierarchical three-dimensional sponge-like structure of Kg has not been reported yet and this novel Kg-Ch sponge functions as a promising candidate for the uninterrupted application of organic pollutant removal from water.

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Ghosh, Shirsendu, Amit Kumar Mandal, Atanu Kumar Das, Tridib Mondal, and Kankan Bhattacharyya. "Diffusion of organic dyes in a niosome immobilized on a glass surface using fluorescence correlation spectroscopy." Physical Chemistry Chemical Physics 14, no. 27 (2012): 9749. http://dx.doi.org/10.1039/c2cp41212h.

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Chakravorty, K. K. "Ultraviolet defined selective in‐diffusion of organic dyes in polyimide for applications in optical interconnection technology." Applied Physics Letters 61, no. 10 (September 7, 1992): 1163–65. http://dx.doi.org/10.1063/1.107633.

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Coetzee, Louis-Charl Cloete, Adedapo Sunday Adeyinka, and Nomampondo Magwa. "A Theoretical Evaluation of the Efficiencies of Metal-Free 1,3,4-Oxadiazole Dye-Sensitized Solar Cells: Insights from Electron–Hole Separation Distance Analysis." Energies 15, no. 13 (July 5, 2022): 4913. http://dx.doi.org/10.3390/en15134913.

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Herein, some novel metal-free 1,3,4-oxadiazole compounds O1–O7 were evaluated for their photovoltaic properties using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations to determine if they can serve as metal-free organic dyes in the use of dye-sensitized solar cells (DSSCs). To understand the trends in the relative efficiencies of the investigated compounds as dyes in DSSCs, their electron contributions, hole contributions, and electron–hole overlaps for each respective atom and fragment within the molecule were analyzed with a particular focus on the electron densities on the anchoring segments. As transition density matrices (TDM) provide details about the departure of each electron from its corresponding hole during excitations, which results in charge transfer (CT), the charge separation distance (Δr) between the electron and its corresponding hole was studied, in addition to the degree of electron–hole overlap (Λ). The latter, single-point excitation energy of each electron, the percentage electron contribution to the anchoring segments of each compound, the incident-photon-conversion-efficiency (IPCE), charge recombination, light harvesting efficiency (LHE), electron injection (Φinj), and charge collection efficiency (ncollect) were then compared to Δr to determine whether the expected relationships hold. Moreover, parameters such as diffusion constant (Dπ) and electron lifetime (t), amongst others, were also used to describe electron excitation processes. Since IPCE is the key parameter in determining the efficiency, O3 was found to be the best dye due to its highest value.

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Zhang, Yingzhe, Yudao Chen, Juan Li, Wei Li, Ding Chen, and Qingdong Qin. "Formation of Cu2O Solid Solution via High-Frequency Electromagnetic Field-Assisted Ball Milling: The Reaction Mechanism." Materials 13, no. 3 (January 30, 2020): 618. http://dx.doi.org/10.3390/ma13030618.

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The contamination of environmental water with organic pollutants poses significant challenges for society, and much effort has been directed toward the development of catalysts and methods that can decompose these pollutants. While effort has been directed toward the fabrication of Cu2O catalysts by ball milling, this technique can involve long preparation times and provide low yields. In this study, we synthesized a solid solution of Cu2O in 22 h by high-frequency electric-field-assisted ball milling below 40 °C in only one step under aqueous conditions. We investigated the catalytic activities of the produced Cu2O solid solution in the microwave-assisted degradation of dyes, namely rhodamine B, phenol red and methyl orange. The prepared Cu2O solid solution was very catalytically active and completely degraded the above-mentioned dyes within 2 min. The one-dimensional diffusion model and the phase boundary (planar) model were found to describe the kinetics well. Synergism between ball milling and the high-frequency electromagnetic field plays a key role in the preparation of Cu2O solid solution nanoparticles. Ball milling facilitates the relaxation of the Cu2O lattice and high-frequency electromagnetic radiation accelerates the diffusion of Fe atoms into the Cu2O crystal along the (111) crystal plane, quickly leading to the formation of a Cu2O solid solution.

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Goossens, Karel, Mira Prior, Victor Pacheco, Dieter Willbold, Klaus Müllen, Jörg Enderlein, Johan Hofkens, and Ingo Gregor. "Accurate Diffusion Coefficients of Organosoluble Reference Dyes in Organic Media Measured by Dual-Focus Fluorescence Correlation Spectroscopy." ACS Nano 9, no. 7 (July 17, 2015): 7360–73. http://dx.doi.org/10.1021/acsnano.5b02371.

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Hori, Teruo, Noriaki Kamon, Hiroshi Kojima, Rolf M. Rohner, and Heinrich Zollinger. "Structure correlation between diffusion coefficients of simple organic compounds and of anionic and cationic dyes in water." Journal of the Society of Dyers and Colourists 103, no. 7-8 (October 22, 2008): 265–70. http://dx.doi.org/10.1111/j.1478-4408.1987.tb01119.x.

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Ghosh, Subhadip, Ujjwal Mandal, Aniruddha Adhikari, and Kankan Bhattacharyya. "Study of Diffusion of Organic Dyes in a Triblock Copolymer Micelle and Gel by Fluorescence Correlation Spectroscopy." Chemistry - An Asian Journal 4, no. 6 (June 2, 2009): 948–54. http://dx.doi.org/10.1002/asia.200800377.

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Policiano Almeida, Carlos Alberto, Tânia Marina Palhano Zanela, Clodoaldo Machado, Juan Antônio Altamirano Flores, Luiz Fernando Scheibe, Nicholas P. Hankins, and Nito Angelo Debacher. "Removal of methylene blue by adsorption on aluminosilicate waste: equilibrium, kinetic and thermodynamic parameters." Water Science and Technology 74, no. 10 (September 12, 2016): 2437–45. http://dx.doi.org/10.2166/wst.2016.408.

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An aluminosilicate waste (AW) was investigated as adsorbent for methylene blue (MB) dye. AW was characterized by petrography, X-ray diffractometry, X-ray fluorescence, scanning electron microscopy, thermogravimetry and zeta potential measurements. It was found that AW contains kaolinite, and other minor components such as quartz, muscovite, smectite, siderite, pyrite and organic compounds. The chemical composition of AW is mainly SiO2 (49%) and Al2O3 (23%) and it has negative superficial charge above pH 1.73. Adsorption of MB dye was studied in a batch system under different conditions of initial dye concentration, contact time and temperature. The isothermal data from batch experiments were fitted to Langmuir and Freundlich equations, with a better fit shown by the Langmuir isotherm equation. Also, pseudo-first-order, pseudo-second-order and intraparticle diffusion models were considered to evaluate the rate parameters. The experimental data fitted the pseudo-first-order kinetic model best. Thermodynamic parameters were calculated, showing the adsorption to be an endothermic yet spontaneous process, with the activation energy of +37.8 kJ mol–1. The results indicate that AW adsorbs MB efficiently, and can be employed as a low-cost alternative in wastewater treatment for the removal of cationic dyes.

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Mac Van, Hung, and Tuan Vu Anh. "Preparation of MoS2 nano-corals by hydrothermal method for adsorption of tartrazine in the aqueous medium." Vietnam Journal of Catalysis and Adsorption 9, no. 4 (December 31, 2020): 93–99. http://dx.doi.org/10.51316/jca.2020.076.

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Corals-like molybdenum disulfide (MoS2) have been successfully synthesized via the hydrothermal method. The as-prepared MoS2 material with a high surface area of 83.9 m2.g-1 was used for the removal of tartrazine from an aqueous solution. The effects of parameters including contact time, MoS2 dosage, and solution pH on adsorption capacity were studied. The optimal dosage of MoS2 for removing tartrazine was 0.08 g and the removal efficiency of tartrazine reached 81.5 % for 100 min of adsorption. The adsorption kinetics studies were carried out using pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The results showed that the pseudo-second-kinetic model better described the adsorption kinetics of tartrazine on MoS2 and film diffusion was the rate-limiting step. In addition, the adsorption capacity of MoS2 was also performed with various organic dyes such as nile blue, janus green B, and congo red.

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Yamamoto, Johtaro, and Akira Sasaki. "Fluorescence Correlation Spectroscopy Measurement Based on Fiber Optics for Biological Materials." Applied Sciences 11, no. 15 (July 22, 2021): 6744. http://dx.doi.org/10.3390/app11156744.

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A robust fluorescence correlation spectroscopy system called fiber-optic based fluorescence correlation spectroscopy (FB-FCS) was developed; this system enables the measurement of diffusion dynamics and concentration of fluorescent molecules based on the principle of fluorescence correlation spectroscopy without any mechanical adjustment of the experimental setup. The system consisted of fiber optics and a water-immersion objective lens. The hydrodynamic diameters and concentrations of organic fluorescent dyes and fluorescently labeled proteins were successfully measured. Because of the fiber-optic-based setup, the FB-FCS system is compact and inexpensive. We expect FB-FCS to be suitable for use in laboratories, medical diagnosis, and environmental measurements.

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Wiśniewska, Małgorzata, Stanisław Chibowski, Monika Wawrzkiewicz, Magda Onyszko, and Viktor Bogatyrov. "C.I. Basic Red 46 Removal from Sewage by Carbon and Silica Based Composite: Equilibrium, Kinetic and Electrokinetic Studies." Molecules 27, no. 3 (February 3, 2022): 1043. http://dx.doi.org/10.3390/molecules27031043.

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The worldwide production of colored products and intermediates is increasing year on year. The consequence of this is an increase in the number of liquid effluents containing toxic dyes entering the aquatic environment. Therefore, it is extremely important to dispose of them. One of the techniques for the elimination of environmentally harmful dyes is adsorption. The main purpose of this study was to explore the possibility of using a carbon and silica (C/SiO2)-based composite for the removal of the azo dye C.I. Basic Red 46 (BR46). The adsorption capacity of C/SiO2 was found to be temperature dependent and increased from 41.90 mg/g to 176.10 mg/g with a temperature rise from 293 K to 333 K in accordance with the endothermic process. The Langmuir isotherm model seems to be the better one for the description of experimental data rather than Freundlich or Dubinin–Radushkevich. The free energy (ΔGo) confirmed the spontaneous nature of BR46 adsorption by C/SiO2. Kinetic parameters revealed that BR46 uptake followed the pseudo-second-order equation; however, the external diffusion plays a significant role. Surfactants of cationic, anionic and non-ionic type influenced BR46 retention by C/SiO2. The electrokinetic results (solid surface charge density and zeta potential) indicated that the adsorption of cationic dye and surfactant influences the structure of the electrical double layer formed at the solid–liquid interface.

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Ali, Rehab, Zahwa Elsagan, and Sara AbdElhafez. "Lignin from Agro-Industrial Waste to an Efficient Magnetic Adsorbent for Hazardous Crystal Violet Removal." Molecules 27, no. 6 (March 11, 2022): 1831. http://dx.doi.org/10.3390/molecules27061831.

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The presence of cationic dyes, even in a tiny amount, is harmful to aquatic life and pollutes the environment. Therefore, it is essential to remove these hazardous dyes to protect the life of marine creatures from these pollutants. In this research, crystal violet (CV) dye elimination was performed using a lignin copper ferrite (LCF) adsorbent. The adsorbent was synthesized and characterized using FTIR, Raman, SEM, EDX with mapping, and VSM, which proved the successful formation of magnetic LCF. Adsorption experiments were performed using different effective parameters. The highest adsorption potential (97%) was executed at mild operating conditions, with a 5 min contact time at room temperature and pH 8. The adsorption kinetic study utilized four kinetic models: first-order, second-order, intraparticle diffusion, and Elovich. The results revealed that the adsorption process complies with the pseudo-first-order with a maximum adsorption capacity of 34.129 mg/g, proving that the adsorption process mechanism is a physical adsorption process. Three isotherm models, Langmuir, Freundlich, and Temkin, were examined. The adsorption mechanism of CV onto LCF was also followed by the Langmuir and Freundlich models. The thermodynamic parameters were examined and revealed that the adsorption onto LCF was an exothermic process. It was proposed that the adsorption process is a spontaneous exothermic process. LCF appears to forcefully remove toxic CV dye from textile wastewater.

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Sasmal, Dibyendu Kumar, Amit Kumar Mandal, Tridib Mondal, and Kankan Bhattacharyya. "Diffusion of Organic Dyes in Ionic Liquid and Giant Micron Sized Ionic Liquid Mixed Micelle: Fluorescence Correlation Spectroscopy." Journal of Physical Chemistry B 115, no. 24 (June 23, 2011): 7781–87. http://dx.doi.org/10.1021/jp202090x.

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Xavier, A., D. Usha, J. Gandhi Rajan, and M. Malarvizhi. "Studies on the Removal of Malachite Green Dyes by Adsorption onto Activated Carbons – A Comparative Study." Materials Science Forum 671 (January 2011): 165–86. http://dx.doi.org/10.4028/www.scientific.net/msf.671.165.

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Malachite Green is an organic compound that is used as a dyestuff for the materials like silk, leather and paper. As a part of removal of malachite green dye from textile and leather industrial wastes, using activated carbon as adsorbents namely, commercial activated carbon (CAC), rose apple carbon (RAC), coconut shell carbon (CSC) and saw dust carbon (SDC). The percentage of malachite green adsorbed increases with decrease in initial concentration and particle size of adsorbent and increased with increase in contact time, temperature and dose of adsorbent. The pH is highly sensitive for dye adsorption process. The adsorption process followed first order kinetics and the adsorption data with Freundlich and Langmuir isotherm models. The first order kinetic equations like Natarajan Khalaf, Lagergren, Bhattacharya and Venkobhachar and intra particle diffusion were found to be applicable. A comparative account of the adsorption capacity of various carbons has been made. These activated carbons are alternative to commercial AC for the removal dyes in General and MG is particular. These results are reported highly efficient and effective and low cost adsorbent for the MG. The thermodynamics parameters are also studied and it obeys spontaneous process. The results are confirmed by before and after adsorption process with the help of the following instrumental techniques viz., FT-IR, UV-Visible Spectrophotometer and SEM photos.

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Byers, Gary W. "Diffusion of dyes in polycarbonate. A new measurement technique and correlation with shadow areas." Macromolecules 26, no. 16 (August 1993): 4242–48. http://dx.doi.org/10.1021/ma00068a026.

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Choy, KKH, JF Porter, and G. McKay. "Film-surface diffusion during the adsorption of acid dyes onto activated carbon." Journal of Chemical Technology & Biotechnology 79, no. 11 (October 8, 2004): 1181–88. http://dx.doi.org/10.1002/jctb.1101.

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Prakash, J., S. Vedanayaki, and K. Karthick. "Removal of Methylene Blue Dye using Carbon Derived from Bulb of Zephyranthes citrina: Adsorption and Kinetic Studies." Asian Journal of Chemistry 32, no. 6 (2020): 1352–60. http://dx.doi.org/10.14233/ajchem.2020.22562.

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The studies open up an innovative approach and investigate porous, efficient raw carbon from Zephyranthes citrina bulb, which was used as an adsorbent to remove organic dyes. The well-dried and finely powdered Zephyranthes citrina bulb was carbonized at 900 ºC. The carbonized crude Z. citrina sample was characterized by FT-IR, UV-visible, scanning electron microscopy (SEM), BET, X-ray diffraction (XRD) techniques and their adsorption potential to remove the basic methylene blue dye from an aqueous sample. Adsorption studies comprise both adsorption isotherm and kinetic methods. The processes were carried out with diverse adsorbate concentrations and adsorbent quantities at various time intervals in the batch process. Kinetic models of Lagergren first order, pseudo-second order and intra particle diffusion were used to assess the kinetics and adsorption mechanism. The results revealed that the adsorption process follows the first order kinetic model of Lagergren. The BET isotherm model confirmed that it has an excellent adsorption capacity in an adsorption process. Based on the results obtained, the maximum removal (81%) of dye was achieved in a solution containing 50 mg of 50 mL dye at 3 h for methylene blue. The results indicated that the bulb of Zephyranthes citrina carbon is a proficient adsorption material and is also used as a cost effective alternative that can adsorb dye from an aqueous solution without activation treatment.

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Zghal, Sabrine, Ilyes Jedidi, Marc Cretin, Sophie Cerneaux, and Makki Abdelmouleh. "Adsorptive Removal of Rhodamine B Dye Using Carbon Graphite/CNT Composites as Adsorbents: Kinetics, Isotherms and Thermodynamic Study." Materials 16, no. 3 (January 22, 2023): 1015. http://dx.doi.org/10.3390/ma16031015.

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The study of the adsorption efficiency of new carbon/CNT composites was undertaken to remove a cationic dye, Rhodamine B (RhB), from dye-contaminated wastewater. Indeed, we investigated the effect of different experimental parameters such as time, initial concentration of dye and temperature on the adsorption of RhB by the carbon composites (KS44-0 and KS44-20). The results showed that the adsorption uptake increased with the initial concentration and solution temperature while maintaining a relatively constant pH. The presence of the carbon nanotubes provided more active sites for dye removal and improved the adsorption behavior of Rhodamine B dye. The analysis of the experimental data was conducted using model equations, such as Langmuir, Freundlich and Temkin isotherms. As regards the Freundlich isotherm model, it was the best fit for the equilibrium data obtained from the experiments. The applicability of the pseudo-second-order equation could be explained assuming that the overall adsorption rate is limited by the rate of adsorbate transport that occurs on the pore surfaces of adsorbents. Furthermore, the intraparticle diffusion and Bangham models were used to investigate the diffusion mechanism of RhB absorption onto carbon composites. They showed that multiple adsorption stages occurred simultaneously via pore surface diffusion. Concerning the thermodynamic parameters (∆G°, ∆H°, and ∆S°), they were calculated and explained in the mean of the chemical structure of the adsorbate. Negative standard Gibbs free energy change values (ΔG°ads) at all temperatures suggested that the adsorption process was spontaneous, and the positive values of the standard enthalpy change of adsorption (∆H°ads) revealed the reaction to be endothermic. The values of standard enthalpy (ΔH°ads) and activation energy (Ea) indicated that the adsorption process corresponds to physical sorption. The mechanisms for the removal of Rhodamine B dye from wastewater using carbon composite were predicted. RhB is a planar molecule that is readily adsorbed, in which adsorbed molecules are bound by hydrophobic or other weak interactions due to the π-π interactions between the dyes’ aromatic backbones and the hexagonal skeleton of graphite and carbon nanotubes. Thus, the graphite carbon/carbon nanotube composite is believed to play a major role in organic pollutant reduction.

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Shahrin, Ensan Waatriah E. S., Nur Alimatul Hakimah Narudin, Nurulizzatul Ningsheh M. Shahri, Sera Budi Verinda, Muhammad Nur, Jonathan Hobley, and Anwar Usman. "Adsorption Behavior and Dynamic Interactions of Anionic Acid Blue 25 on Agricultural Waste." Molecules 27, no. 5 (March 6, 2022): 1718. http://dx.doi.org/10.3390/molecules27051718.

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In this study, adsorption characteristics of a negatively charged dye, Acid Blue 25 (AB25), on pomelo pith (PP) was studied by varying the adsorption parameters, with the aim of evaluating the adsorption mechanism and establishing the role of hydrogen bonding interactions of AB25 on agricultural wastes. The kinetics, intraparticle diffusion, mechanism, and thermodynamics of the AB25 adsorption were systematically evaluated and analyzed by pseudo-first-order and pseudo-second-order kinetic models, the Weber–Morris intraparticle and Boyd mass transfer models, the Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherm models, and the Van’t Hoff equation. It was found that AB25 adsorption followed pseudo-second-order kinetics, governed by a two-step pore-volume intraparticle diffusion of external mass transfer of AB25 onto the PP surface. The adsorption process occurred spontaneously. The adsorption mechanism could be explained by the Langmuir isotherm model, and the maximum adsorption capacity was estimated to be 26.9 mg g−1, which is comparable to many reported adsorbents derived from agricultural wastes. Changes in the vibrational spectra of the adsorbent before and after dye adsorption suggested that AB25 molecules are bound to the PP surface via electrostatic and hydrogen bonding interactions. The results demonstrated that the use of pomelo pith, similar to other agricultural wastes, would provide a basis to design a simple energy-saving, sustainable, and cost-effective approach to remove negatively charged synthetic dyes from wastewater.

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Cibulic, Violeta, Lidija Stamenkovic, Nebojsa Veljkovic, and Novica Staletovic. "Dynamics of the process of colour adsorption from waste waters after dyeing textile fibres on natural zeolites." Chemical Industry 67, no. 1 (2013): 41–49. http://dx.doi.org/10.2298/hemind120209049c.

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This study analyses the process of purifying waste waters from textile fibre dyeing by adsorption of colour on natural zeolites from ?Nemetali? mine, Vranjska Banja, Serbia. The process has been analyzed in an adsorption column filled with natural zeolite as the adsorbent. Adsorbents are organic substances, i.e. colour residues from waste waters, left after textile fibres dyeing. The concentration change in waste waters is represented with the parameter of chemical oxygen demand (COD). Two models of diffusion have been considered: diffusion in pores and diffusion in adsorbent phase on solid adsorbent, for different input loads and two zeolite granulations (13 and 35 mm). It was found that the diffusion in zeolite pores that were in adsorbed phase is dominant in this case, which can be explained by large dimensions of used colours? molecules. This is the reason why its adsorption in zeolite micro pores is minimal, and yet it diffuse well in already adsorbed phase on solid adsorbents. Since this process is slower, it will determine the overall rate of colour adsorption from waste waters. Specific equilibrium capacity, specific dynamic capacity, as well as the level of adsorbent utilization were determined by the use of mass transfer zone concept. It has been shown that the adsorption of organic substances from waste waters is satisfactory, and is around 80%. The highest degree of adsorbent utilization is obtained at the lowest flow of 0.167 cm3 s-1, while the lowest degree of utilization of 30%, is obtained at the highest flow of 3.27 cm3 s-1. Input load has significant influence on the degree of column utilization, while higher values of COD0 result in lower degrees of column utilization. Key words: waste waters, natural zeolite, adsorption, colour adsorption, textile dyes

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Journal articles on the topic 'Diffusion - Organic Dyes'

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