Zeitschriftenartikel: „Ca-bentonite“

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Ma, Yu Xin, Feng Mei Shi und Miao Nan Wu. „Removal of Fluoride from Aqueous Solution by Using Ca-Bentonite and H-Bentonite“. Advanced Materials Research 391-392 (Dezember 2011): 1417–22. http://dx.doi.org/10.4028/www.scientific.net/amr.391-392.1417.

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Removal of fluoride from aqueous solution by using Ca-bentonite and H-bentonite (acid-treated bentonite) was studied by batch equilibrium method. The fluoride sorption capacity of Ca-bentonite increases with the fluoride concentration increase or the pH-value decrease. H-bentonite has better affinity to fluoride than Ca-bentonite. H-bentonite can be used effectively for fluoride removal as a low cost adsorbent. The adsorption type of H-bentonite is ion exchange and the adsorption type of Ca-bentonite can be explained by ion exchange and physical adsorption.

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Yang, Yu-Ling, Krishna R. Reddy, Yan-Jun Du und Ri-Dong Fan. „Sodium hexametaphosphate (SHMP)-amended calcium bentonite for slurry trench cutoff walls: workability and microstructure characteristics“. Canadian Geotechnical Journal 55, Nr. 4 (April 2018): 528–37. http://dx.doi.org/10.1139/cgj-2017-0291.

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This study aims to investigate workability and microstructural characteristics of sodium hexametaphosphate (SHMP)-treated calcium bentonite (Ca-bentonite) as a potential material for soil–bentonite slurry trench cutoff walls. First, a series of Marsh viscosity, filtrate loss, density, and pH experiments are performed on bentonite – tap water slurries containing Ca-bentonite amended with 0%–8% SHMP dosages. Subsequently, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and zeta potential tests are conducted to explore microstructural characteristics that control the mechanisms of SHMP treatment. The results indicate that the workability of the slurry is significantly improved with SHMP addition. The SEM, XRD, and zeta potential analyses show that SHMP-amended Ca-bentonite possesses a more dispersed structure and higher negative zeta potential relative to the unamended Ca-bentonite. The mechanisms of SHMP amendment are identified to be exchange of bivalent calcium cations in Ca-bentonite by monovalent sodium cations in the SHMP, sorption of the SHMP anions that give the clay system a steric stabilization and increased negative surface charge density, and sequestration of the bivalent calcium cations on the Ca-bentonite. Overall, the SHMP treatment is effective in making the Ca-bentonite slurry amenable for use in the soil–bentonite slurry trench wall construction.

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Xue, Tian Li, Shao Jian Ma, Lin Ling Jiang, Xu Yuan Zhang und Wei Mo. „Study on Physicochemical Properties and Application Prospect of Several Typical Bentonite“. Applied Mechanics and Materials 333-335 (Juli 2013): 2015–18. http://dx.doi.org/10.4028/www.scientific.net/amm.333-335.2015.

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Four kinds of bentonite samples were studied in this paper. Mainly discussing the particle size distribution, mineral composition and physicochemical properties of bentonite, the aim was to provide a useful reference for the efficient development and utilization of bentonite resources. The results indicated that NM-bent., HB-bent. and EZ-bent. were Ca (Mg)-bentonite while XZJ-bent. was Na-bentonite. The physicochemical properties of bentonite mainly depended on interlayer cations. Many properties indexes of Na-bentonite were better than that of Ca (Mg)-bentonite. Some properties indexes showed a poor reproducibility when tested by standard methods. The natural Na-bentonite has excellent properties and extensive application prospects while Ca (Mg)-bentonite needed for further processing to meet the demand of the application field.

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Hariani, Poedji Loekitowati, Fatma Fatma, Fahma Riyanti und Hesti Ratnasari. „ADSORPTION OF PHENOL POLLUTANTS FROM AQUEOUS SOLUTION USING Ca-BENTONITE/CHITOSAN COMPOSITE“. Jurnal Manusia dan Lingkungan 22, Nr. 2 (31.07.2015): 233. http://dx.doi.org/10.22146/jml.18747.

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Phenolic compounds areorganic pollutants that are toxic and carcinogenic.The presence of phenol in the environmentcan be adverse to humanand the environmentalsystem. One methodthat iseffective toreduce thephenolisadsorption. In this study, the adsorption of phenol in aqueous solution using Ca-bentonite/chitosan composite was investigated. Chitosan is the deacetylation product of chitin from shrimp waste. Characterization of Ca-bentonite/chitosan composite was done by using Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy-Energy Dispersive X Ray Spectroscopy (SEM-EDX). Batch adsorption studies were performed to evaluate the effects of some parameters such as initial concentration of phenol, composite weight, pH and contact time. The results showed that FTIR spectra of Ca-bentonite/chitosan composite presented the characteristic of peak of Ca-bentonite and chitosan that confirmed the successful synthesis of composite. The SEM-EDX characterizationresultsshowedCa-bentonite surfacecoverage by chitosanand the presence ofcarbonandnitrogenelementsinCa-bentonite/chitosancompositeindicated that chitosan had bonded with bentonite. The optimum condition of adsorption of Ca-bentonite/chitosan to phenol was obtained at 125 mg.L-1 of concentration in which the weight of composite was 1.0 g, the pH of solution was 7, the contact time was 30 minutes, and the capacity of adsorption was 12.496 mg.g-1.

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Zhang, Yuanbo, Tao Jiang, Liyong Chen und Guanghui Li. „Study on Sodium Modification of Inferior Ca-Based Bentonite by Suspension Method“. ISRN Materials Science 2011 (14.09.2011): 1–6. http://dx.doi.org/10.5402/2011/953132.

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Hunyuan Ca-based bentonite is one of large-type bentonite deposits in China, the reserve of which is more than 0.15 billion tons. However, they are not completely utilized in the pellet production. Process mineralogy investigation shows that the bentonite is a kind of typical Ca-bentonite (Ca-Bent). The sodium modification of the sample is studied by suspension method in this study. Results present the alkali coefficient K of modified Na-bentonite that is increased from 0.34 to 1.33, and the 2HWA, dilation, and colloid index are, respectively, increased to 601%, 32.4 mL/g and 87.6 mL/(3 g) under optimal conditions of Na2CO3 dosage 3.0%, pulp density 20%, sodium temperature 55°C, and sodium time 0.5 h. The XRD patterns show that d(001) of the sample bentonite is reduced from 1.5539 nm down to 1.2467 nm, and 2θ(001) of the sample bentonite is increased from 5.6875° to 7.0907°, indicating that the sample Ca-Bent is effectively modified into Na-Bent.

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Lee, Jae Owan, Jin Gyu Lim, Il Mo Kang und Sangki Kwon. „Swelling pressures of compacted Ca-bentonite“. Engineering Geology 129-130 (März 2012): 20–26. http://dx.doi.org/10.1016/j.enggeo.2012.01.005.

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7

Wan, Yong, Dongdong Guo, Xinminnan Hui, Lei Liu und Yuan Yao. „Studies on Hydration Swelling and Bound Water Type of Sodium- and Polymer-Modified Calcium Bentonite“. Advances in Polymer Technology 2020 (09.10.2020): 1–11. http://dx.doi.org/10.1155/2020/9361795.

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Modified calcium bentonite (Ca-bentonite) is extensively used in engineered barrier systems (EBSs) for municipal and industrial disposal sites due to its high swelling potential and low hydraulic conductivity. However, few studies have focused on the micromechanism of hydration and swelling under the effect of inorganic chemical solution. In this study, free swell index (FSI) and the type and content of modified Ca-bentonite bound water under the inorganic chemical solution were quantitatively studied by using the free swell test and nuclear magnetic resonance (NMR). According to the results, modification of sodium and polymer significantly increases the FSI of Ca-bentonite, bringing it close to that of natural sodium bentonite. In addition, the chemical stability of polymer-modified bentonite is significantly higher than that of sodium-modified bentonite but less than that of natural Na-bentonite. The FSI of modified Ca-bentonite decreases with the increase of cation valence and ionic strength. T2 distribution curves of the two types of modified bentonite are three-peak curves. With the increase of ionic strength, the content of total water and permeated hydrated water (accounting for 69%–95%) in bentonite decreases gradually, whereas the surface hydration water (accounting for 2%–31%) and free water content (accounting for 0–15%) increase. A uniform linear relationship exists between the FSI and corresponding total peak area of NMR (independent of ion valence, concentration, and bentonite type). Furthermore, a linear relationship exists between the FSI of the same type of bentonite and the T2 relaxation time. Research results can provide data and theoretical basis for quantitative analysis and mechanism of the hydration swelling of bentonite.

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Wijaya, Karna, Ani Setyo Pratiwi, Sri Sudiono und Emi Nurahmi. „STUDY OF THERMAL AND ACID STABILITY OF BENTONITE CLAY“. Indonesian Journal of Chemistry 2, Nr. 1 (05.06.2010): 22–29. http://dx.doi.org/10.22146/ijc.21929.

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The thermal and acid stability of the bentonite clays (Na- and Ca-bentonite) have been tested. The thermal stability testing has been carried out by heating 5 gram of the clays for five hours at 200, 300 and 500 °C respectively, meanwhile acid stability testing was performed by immersing 5 gram clays into 100 mL sulphuric acid 1M, 2M and 3M for 24 hours. The tested clays, then were characterized by means of X-Ray difractometry and IR-spectroscopy methods. The characterization results showed that upon heating, both Ca- and Na-bentonites indicated same thermal stability. However, upon acid treatment, Na-bentonite was found relatively stabiler and more resistance then Ca-bentonite. Keywords: bentonite, clay, thermal stability, acid stability.

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Zhang, Bing Bing, Ming Yue Miao, Jing Bai, Guang Jin Yuan, Yan Yan Jia, Zhe Xiang Han, Zhi Guo Zhao und Hai Quan Su. „Researches on Purification and Sodium-Modification of Ca-Bentonite by Tri-Roller Grinder“. Advanced Materials Research 962-965 (Juni 2014): 809–13. http://dx.doi.org/10.4028/www.scientific.net/amr.962-965.809.

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To fully evaluate the usability of a raw Ca-bentonite source and to deeply understand the property of bentonite mineral are critical for applications of these special layered materials. Due to sodium bentonites have several advantages over calcium bentonites, especially in expansibility, cation exchange capacity, cohesive force, dispersibility, and thermostability, sodium-modification of Ca-bentonite is regarded as a top priority of effective utilization of abundant Ca-bentonite source in China. In present work, the purified Na-montmorillonite was synthesized by purification and sodium-modification of a raw Ca-bentonite source (Liaoning, China) by tri-roller grinder. Important influencing factor rolling times in purification and sodium modification process was investigated. Mineral compositions, microscopic morphology, and thermal stability were characterized by using different techniques. The crystalline phases and compositions were identified by X-ray powder diffraction (XRD). The morphology and structure were evaluated by scanning electron microscopy (SEM). The thermal properties were investigated using differential thermal gravity analysis (DTG) and differential thermal analysis (DTA) analysis.

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Baborová, Lucie, Eva Viglašová und Dušan Vopálka. „Comparison of Sr Transport in Compacted Homoionous Na and Ca Bentonite Using a Planar Source Method Evaluated at Ideal and Non-Ideal Boundary Condition“. Water 13, Nr. 11 (28.05.2021): 1520. http://dx.doi.org/10.3390/w13111520.

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With the aim to determine the influence of dominant interlayer cation on the sorption and diffusion properties of bentonite, diffusion experiments with Sr on the compacted homoionous Ca- and Na-forms of Czech natural Mg/Ca bentonite using the planar source method were performed. The bentonite was compacted to 1400 kg·m−3, and diffusion experiments lasted 1, 3 or 5 days. Two methods of apparent diffusion coefficient Da determination based on the analytical solution of diffusion equation for ideal boundary conditions in a linear form were compared and applied. The determined Da value for Ca-bentonite was 1.36 times higher than that for Na-bentonite sample. Values of Kd were determined in independent batch sorption experiments and were extrapolated for the conditions of compacted bentonite. In spite of this treatment, the use of Kd values determined by batch sorption experiments on a loose material for the determination of effective diffusion coefficient De values from planar source diffusion experiments proved to be inconsistent with the standard Fickian description of diffusion taking into account only the pore diffusion in compacted bentonite. Discrepancies between Kd and De values were measured in independent experiments, and those that resulted from the evaluation of planar source diffusion experiments could be well explained by the phenomenon of surface diffusion. The obtained values of surface diffusion coefficients Ds were similar for both studied systems, and the predicted value of total effective diffusion coefficient De(tot) describing Sr transport in the Na-bentonite was four times higher than in the Ca-bentonite.

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Doula, M., A. Ioannou, A. Dimirkou und J. Mitsios. „Potassium sorption by calcium‐bentonite (Ca‐b)“. Communications in Soil Science and Plant Analysis 25, Nr. 9-10 (Juni 1994): 1387–400. http://dx.doi.org/10.1080/00103629409369122.

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12

Özdamar, Ş., Ö. I. Ece, B. Uz, F. Boylu, H. Ü. Ercan und G. Yanik. „Element mobility during the formation of the Uzunisa-Ordu bentonite, NE Turkey, and potential applications“. Clay Minerals 49, Nr. 5 (Dezember 2014): 609–33. http://dx.doi.org/10.1180/claymin.2014.049.5.01.

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AbstractDacitic andesitic calc-alkaline lavas and their pyroclastic rocks of Upper Cretaceous age are widespread in the Ordu area, eastern Black Sea Coast of Turkey. Ca-bentonite and Ca/Nabentonite deposits with significant economic potential formed in the broader region. The mineralogy and geochemistry of these deposits were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and chemical analyses. The parent rocks (PR) and bentonite samples were analysed for the major and trace element contents, including rare-earth elements, to understand the effect of differential alterations on element mobility. The bentonites contain mainly di-octahedral Ca-montmorillonite with minor amounts of illite, quartz, calcite, dolomite and feldspar. Primary K-feldspar and plagioclase phenocrysts were altered in the bentonite horizons, and were completely leached at greater depth. For this reason, the higher quality bentonites are found at deeper zones. Bentonite horizons are characterized by relatively high loss on ignition (LOI: 9.8–20.8%) and MgO content (3–5%) and low K2O (<0.5%) and Na2O (<2%) contents compared with the least altered parent rocks. Silicon, Ca, Mg, Mn and P are markedly enriched whereas Fe, Na, K and Ti are depleted in the bentonite samples. The chondrite-normalized rare earth element (REE) patterns show identical trends characterized by strong light rare earth element (LREE) enrichment in both the PR and bentonite samples. The LREE contents are higher than those of their heavy counterparts (HREE) in the samples. Alteration of the PR to bentonite is associated with intense chemical leaching and subsequent removal of K and Na in open-system conditions.

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13

Daniels, Katherine A., Jon F. Harrington, Antoni E. Milodowski, Simon J. Kemp, Ian Mounteney und Patrik Sellin. „Gel Formation at the Front of Expanding Calcium Bentonites“. Minerals 11, Nr. 2 (20.02.2021): 215. http://dx.doi.org/10.3390/min11020215.

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The removal of potentially harmful radioactive waste from the anthroposphere will require disposal in geological repositories, the designs of which often favour the inclusion of a clay backfill or engineered barrier around the waste. Bentonite is often proposed as this engineered barrier and understanding its long-term performance and behaviour is vital in establishing the safety case for its usage. There are many different compositions of bentonite that exist and much research has focussed on the properties and behaviour of both sodium (Na) and calcium (Ca) bentonites. This study focusses on the results of a swelling test on Bulgarian Ca bentonite that showed an unusual gel formation at the expanding front, unobserved in previous tests of this type using the sodium bentonite MX80. The Bulgarian Ca bentonite was able to swell to completely fill an internal void space over the duration of the test, with a thin gel layer present on one end of the sample. The properties of the gel, along with the rest of the bulk sample, have been investigated using ESEM, EXDA and XRD analyses and the formation mechanism has been attributed to the migration of nanoparticulate smectite through a more silica-rich matrix of the bentonite substrate. The migration of smectite clay out of the bulk of the sample has important implications for bentonite erosion where this engineered barrier interacts with flowing groundwater in repository host rocks.

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Morawong, Duangsamorn, Atchana Wongchaisuwat und Ladda Meesuk. „A Sulfide Ion Sensor from Commercial Bentonite“. Advanced Materials Research 894 (Februar 2014): 412–15. http://dx.doi.org/10.4028/www.scientific.net/amr.894.412.

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Bentonite is a synonymous term of montmorillonite which is a clay mineral consisting of 2 : 1 aluminosilicate layered structure. In this work, a commercial bentonite was used to prepare an intercalation compound [Ca (2,2-bipyridine)3]2+in the interlayer space, by solid-solid reaction, which formation was confirmed by the expansion of the interlayer space of bentonite from 1.5 to 1.8 nm, by powder X-Ray Diffraction technique. The intercalation compound [Ca (2,2-bipyridine)3]2+-bentonite was then used as a sensor to assemble a potentiometric electrode. The electrode gave best response to sulfide ion in terms of Nernstian slope. Precision of measurement, reproducibility and percent recovery were also studied. The electrode could be used to measure sulfide ion in real water samples and gave satisfactory results.

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Fu, Yong. „The Forming Mechanism of a New Oil-Mineral Aggregate“. Advanced Materials Research 211-212 (Februar 2011): 1176–81. http://dx.doi.org/10.4028/www.scientific.net/amr.211-212.1176.

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A new Oil-Mineral Aggregate with bentonite and calsium hydroxide and sawdust has been done. Through several dozens of experiments, the coagulation efficiency with bentonite and Ca(OH)2 and sawdust is 94.53%. The functions of bentonite are coagulation, adsorption and emulsification. Calsium hydroxide is a good coagulant-mate, and strengthen the coagulating function of bentonite. It can be used as the source of calcium ions, which can strongly adsorb on both bentonite and oil droplets, and is helpful for the coagulation between bentonite and oil droplets. Sawdust is also very important in the OMA, its fouctions are buoyant, bridge-made and adsorbant.

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Ding, Shu Li, Dan Dan Hou, Bo Hui Xu und Yu Zhuang Sun. „Adsorption of Pb²⁺, Cu²⁺ and Cr³⁺ on Yongnian Bentonite“. Advanced Materials Research 1056 (Oktober 2014): 16–19. http://dx.doi.org/10.4028/www.scientific.net/amr.1056.16.

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The Bentonite from Yongnian is Ca-Bentonite, Montmorillonite Content 52%, Colloidal Value 57ml/15g, Eca2+/CEC 53.60%. the Adsorption Characteristics of Pb2+, Cu2+ and Cr3+ onto Bentonite under Conditions of Constant Temperature and Ph have been Studied. the Results Show that the Adsorption Capacities of Heavy Metal Ions onto Bentonite from Yongnian Follow the Order of Pb2+> Cu2+> Cr3+. it is Found that the Adsorption Process of Bentonite Accords with the Langmuir Isotherm Model. the Maximum Adsorption of 3 Kinds of Metal Ions onto Bentonite is in Order of Cr3+>Cu2+>Pb2+.

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Wang, Rong, Yingying Chu und Mengjun Chen. „Adsorption Kinetics of 137Cs+/90Sr2+ on Ca-Bentonite“. Water Environment Research 89, Nr. 9 (01.09.2017): 791–97. http://dx.doi.org/10.2175/106143017x14902968254593.

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18

Doula, M., A. Dimirkou und A. Ioannou. „Potassium sorption by ca‐bentonite—commonly used isotherms“. Communications in Soil Science and Plant Analysis 27, Nr. 5-8 (März 1996): 1107–23. http://dx.doi.org/10.1080/00103629609369620.

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19

Choi, J. W., und D. W. Oscarson. „Diffusive transport through compacted Na- and Ca-bentonite“. Journal of Contaminant Hydrology 22, Nr. 3-4 (April 1996): 189–202. http://dx.doi.org/10.1016/0169-7722(95)00081-x.

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20

Wang, Quan, Ronghua Li, Hanzhen Cai, Mukesh Kumar Awasthi, Zengqiang Zhang, Jim Jian Wang, Amjad Ali und Mahar Amanullah. „Improving pig manure composting efficiency employing Ca-bentonite“. Ecological Engineering 87 (Februar 2016): 157–61. http://dx.doi.org/10.1016/j.ecoleng.2015.11.032.

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21

Liu, Xiao Dong, Xian Jun Lu, Jun Qiu, Zhi Ming Wang und Peng Wu. „Purification of Low Grade Ca-Bentonite for Iron Ore Pellets“. Advanced Materials Research 454 (Januar 2012): 237–41. http://dx.doi.org/10.4028/www.scientific.net/amr.454.237.

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According to the bentonites properties and mineral composition, three bentonites with 32-36% montmorillonite content(MC) from Laiyang, Shandong, China, are purified for utilizing low grade bentonite sufficiently. Research shows that the purification is effective by separating –325 mesh products from raw bentonite after soaking, stirring and rubbing in water. Firstly, the three bentonites are combined into one and soaked in water for 24h with the ratio of liquid and solid 15:1, and then, the bentonite is purified using –325 mesh sieve after stirring and rubbing in water for 1h with pulp density of 26%. Methylene blue index(MBI) of the product is 22.52g/100g, swell index(SI) is 5.5mL/2g, water absorption(WA) is 184.3%, water content(Wa.C) is 9.7%, and the indexes meet the stantard of three grade Ca-bentonite(TGCB)applying to iron ore pellets.

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Haerudin, Hery, Nino Rinaldi und Adel Fisli. „CHARACTERIZATION OF MODIFIED BENTONITE USING ALUMINUM POLYCATION“. Indonesian Journal of Chemistry 2, Nr. 3 (09.06.2010): 173–76. http://dx.doi.org/10.22146/ijc.21913.

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The modification of bentonite by pillarization using aluminum polycation type Keggin [Al13O4(OH)24(H2O)12]7+ has been carried out, by exchange of cation from interlayer with aluminum polycation. The amount of aluminum polycation, which was used for the pillaring of bentonite was varied, i.e. 5 mmol/gram, 10 mmol/gram, and 20 mmol/gram of bentonite. After drying, the pillared bentonite was calcined at 400 oC for 6 hour with temperature rate of 5 oC/min. The cationic exchange capacity (CEC) of starting bentonite was 98.3 meq/100 gram. The concentration ratio of Al/Si increased from 0.27 to 0.34 for pillared bentonite and of Ca/Si was decreased from 0.06 to 0.006 for pillared bentonite. The basal space for pillared bentonit increased significantly from 7.30 Å to about 18 Å . The measured specific surface area (by BET) of pillared bentonite was also increased significantly from 46 m2/g to about 162 m2/g. It was concluded that bentonite has been pillared by aluminum polication successfully. Keywords: aluminum polycation, bentonite

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Dakovic, Aleksandra, Tanja Raonic, Srdjan Matijasevic, Magdalena Tomasevic-Canovic und Ana Radosavljevic-Mihajlovic. „Influence of the type of exchangeable cation on the electrolytic conductivity of bentonite suspensions“. Chemical Industry 57, Nr. 5 (2003): 215–18. http://dx.doi.org/10.2298/hemind0305215d.

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The electrolytic conductivity of bentonite aqueous suspensions was investigated. The starting material (Ca-Mont) was exchanged with sodium ions, using an ion exchange column. The sodium form of bentonite (Na-Mont) was used to obtain organobentonites. The electrolytic conductivity of the starting material, Na-Mont and organobentonites was studied for different suspension concentration. The highest value of the electrolytic conductivity was obtained for Na-Mont, while the organic cation in the bentonite structure decreased the electrolytic conductivity.

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Doula, M., A. Ioannou und A. Dimirkou. „Thermodynamics of potassium exchange in calcium bentonite (Ca‐b)“. Communications in Soil Science and Plant Analysis 26, Nr. 9-10 (Mai 1995): 1535–45. http://dx.doi.org/10.1080/00103629509369389.

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25

Zhang, Hanbing, Zhangfa Tong, Tengyou Wei und Yankui Tang. „Sorption characteristics of Pb(II) on alkaline Ca-bentonite“. Applied Clay Science 65-66 (September 2012): 21–23. http://dx.doi.org/10.1016/j.clay.2012.06.010.

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Huang, Yan-fang, Yuan-bo Zhang, Gui-hong Han, Tao Jiang, Guang-hui Li, Yong-bin Yang, Bin Xu und Yu-feng Guo. „Sodium-modification of Ca-based bentonite via semidry process“. Journal of Central South University of Technology 17, Nr. 6 (Dezember 2010): 1201–6. http://dx.doi.org/10.1007/s11771-010-0619-9.

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27

Markou, Giorgos, Vassilis J. Inglezakis, Dimitris Mitrogiannis, Ilias Efthimiopoulos, Maria Psychoyou, Petros Koutsovitis, Koenraad Muylaert und Ioannis Baziotis. „Sorption mechanism(s) of orthophosphate onto Ca(OH)2pretreated bentonite“. RSC Advances 6, Nr. 27 (2016): 22295–305. http://dx.doi.org/10.1039/c5ra27638a.

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Shu, Ming Yong, Hai Ying Yin und Guang Hui Liu. „Influences of Bentonite Modification Methods on the Physical and Chemical Properties of Bentonite“. Advanced Materials Research 482-484 (Februar 2012): 2096–102. http://dx.doi.org/10.4028/www.scientific.net/amr.482-484.2096.

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The current study focuses on the artificial modification of natural bentonite using pulping sodium, stacking sodium, extrusion sodium, wheel rolling sodium, and microwave sodium treatments. The effects of these methods on the physical and chemical properties of bentonite are investigated. The results indicate that the wheel rolling sodium treatment, which features the effects of extrusion and kneading, facilitated maximum separation and sodium treatment of Ca2+and Mg2+in the lattice of bentonite. This method produced highly efficient Ca-bentonite with full modification. When the wheel rolling sodium treatment was performed for 60 min, the modified bentonite exhibited a colloid index of 300 mL/3 g, swelling value of 275 mL/2 g, swelling volume of 94 mL/g, and 2 h water absorption of 755%. The modified bentonite has desirable cohesiveness, dilatability, suspension property, dispersibility, and high physical and chemical performances, which are suitable for use as iron ore concentrate pallet and casting bentonite binders.

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Li, Jian-rong, Li Zhu, Jianfeng Tang, Kun Qin, Gang Li und TsingHai Wang. „Sequestration of naturally abundant seawater calcium and magnesium to enhance the adsorption capacity of bentonite toward environmental phosphate“. RSC Advances 6, Nr. 28 (2016): 23252–59. http://dx.doi.org/10.1039/c6ra01145d.

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Lukić, Igor, und Ivana Horvat. „Moment of Bentonite Addition, Co-Addition of Tannins, and Bentonite Type Affect the Differential Affinity of Pathogenesis-Related Grape Proteins towards Bentonite during Fermentation“. Foods 9, Nr. 11 (25.10.2020): 1534. http://dx.doi.org/10.3390/foods9111534.

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To test the effect of the moment of bentonite addition, co-addition of tannins, and bentonite type on the differential affinity of pathogenesis-related (PR) proteins towards bentonite during grape must fermentation, three separate experiments were set up. PR proteins in the obtained wines were analyzed by reverse phase and size exclusion high-performance liquid chromatography (HPLC). The most significant reduction of bentonite dose and PR protein concentration was achieved by applying bentonite in the last third of fermentation. Particular thaumatin-like proteins (TLP) and proteins with lower molecular mass in general were more affected than others, while TLPs were more affected than chitinases. Exogenous enological tannins interacted with particular PR proteins, mostly TLPs, and lowered the total bentonite dose required. The combined application of tannins and bentonite in fermentation removed more PR proteins than bentonite alone, but did not achieve a synergistic effect in reducing the bentonite dose. Various bentonite types, including two Na-activated bentonites, an activated Na bentonite with specifically adsorbed silica, and an active Na-Ca bentonite, exhibited differential affinity towards different PR proteins. The results obtained could be used in developing wine fining protocols which combine treatments with complementary affinity for adsorption and removal of PR proteins, and in this way achieve greater efficiency of bentonite fining by reducing its total dose, which is of significant interest to the wine industry.

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McAdams, Neo E. B., Mark D. Schmitz, Mark A. Kleffner, Jacques Verniers, Thijs R. A. Vandenbroucke, James R. Ebert und Bradley D. Cramer. „A new, high-precision CA-ID-TIMS date for the ‘Kalkberg’ K-bentonite (Judds Falls Bentonite)“. Lethaia 51, Nr. 3 (16.09.2017): 344–56. http://dx.doi.org/10.1111/let.12241.

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Hrenovic, Jasna, Mirela Rozic, Tomislav Ivankovic und Anamarija Farkas. „Biosorption of phosphate from synthetic wastewater by biosolids“. Open Life Sciences 4, Nr. 3 (01.09.2009): 397–403. http://dx.doi.org/10.2478/s11535-009-0030-4.

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AbstractThe aim of this study was to determine the potential of phosphate (P) removal from wastewater by biosolids prepared by the immobilization of P-accumulating bacteria onto organic bentonite. Organic bentonite was prepared by treating bentonite clay with quaternary ammonium salt — cetyltrimetylammonium (CTA) bromide. Cation exchange capacity (CEC) of the bentonite was found to be 179.0 meq/100 g of the dry bentonite. The CTA occupied ca. 175% of the CEC. Modification of bentonite with CTA in amounts higher than 55% of the CEC resulted in the change of zeta potential of particles from negative to positive. Only in reactors containing organic bentonite samples occupied with 3.5 and 28% of the CEC was P efficiently removed from wastewater by combined adsorption and bacterial uptake in the biomass. Organic bentonite samples with higher CTA loadings (from 55 to 175% of the CEC) showed bactericidal effects. To enhance P removal from wastewater in the aerated biological system, biosolids consisting of P-accumulating bacteria and organic bentonite can be used, but special attention should be given to the configuration of sorbed CTA molecules and its potential desorption.

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Daniel S Bath, Jenal M Siregar und M Turmuzi Lubis. „PENGGUNAAN TANAH BENTONIT SEBAGAI ADSORBEN LOGAM Cu“. Jurnal Teknik Kimia USU 1, Nr. 1 (19.09.2012): 1–4. http://dx.doi.org/10.32734/jtk.v1i1.1396.

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Bentonite serve the purpose of substance adsorpsi because swelling ability and cation for exchange. But adsorption ability is limited so that require to be activated by strong acid to higher level adsorption of bentonite. This research use Ca-Bentonit activated by strong acid HCl. Cation Cu analysed by using Spektofometri Serapan Atom (SSA). Result of research indicate that the increasing of HCl concentration and activation time can improve the adsorption capacity of bentonite. Maximum HCl concentration at 1,6 M and maximum activation time at 24 hour. Optimum heavy bentonite at 4 gr of 100 ppm Cu solution and optimum contact time at 2 hour. Result from Cu isoterm adsorption is weight of adsorption have same range with Cu concentration

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Beccari, M., M. Majone, L. Torrisi und M. Petrangeli Papini. „Enhancement of anaerobic treatability of olive oil mill effluents by addition of Ca(OH)2 and bentonite without intermediate solid/liquid separation“. Water Science and Technology 43, Nr. 11 (01.06.2001): 275–82. http://dx.doi.org/10.2166/wst.2001.0692.

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Previous work on the anaerobic treatment of olive oil mill effluents (OME) have shown : (a) lipids, even if more easily degraded than phenols, were potentially capable of inhibiting methanogenesis more strongly; (b) a pretreatment based on addition of Ca(OH)2 and bentonite removed lipids almost quantitatively; (c) preliminary biotreatability tests performed on the pretreated OME showed high bioconversion into methane at very low dilutions ratios, especially when the mixture (OME, Ca(OH)2 and bentonite) was fed to the biological treatment without providing an intermediate phase separation. This paper was directed towards two main aims: (a) to optimize pretreatment : the best results in terms of methane production were obtained by addition of Ca(OH)2 up to pH 6.5 and of 10 g L-1 of bentonite; (b) to evaluate the enhancement of anaerobic treatability of OME pretreated under optimized conditions in a lab-scale continuous methanogenic reactor fed with the substrate without intermediate solid/liquid separation: very satisfactory performances were obtained (at an organic load of 8.2 kg COD m-3 d-1 and at a dilution ratio of 1:1.5 total COD removal was 91%, biogas production was 0.80 g CH4 (as COD)/g tot. COD, lipids removal was 98%, phenols removal was 63%). The results confirm the double role played by bentonite (adsorption of the inhibiting substances and release of the adsorbed biodegradable matter in the methanogenic reactor).

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Jabbar, Fayq Hsan, und Wisam A. Latif. „A Comparative Analysis of Various Types of Modified Bentonite Clays Added to Poly Methyl Butadiene for Nanocomposite Preparation“. NeuroQuantology 19, Nr. 1 (18.02.2021): 67–71. http://dx.doi.org/10.14704/nq.2021.19.1.nq21010.

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New Nano-composite of biopolymers was prepared for this analysis. The natural bentonite clay group forms Na- Bentonite (Na- BTT), K- Bentonite (K- BTt), and Ca- Bentonite (Ca-Btt) has been modified by the addition of synthesized fatty amide (FACO), namely Corn oil (CO). To achieve the modification the clay particles was mixed thoroughly in an aqueous (FACO) solution which increases the separation of the clay layer from 1.25 to 2.75 nm of BTT, 1.17 to 1.34 nm of BTt and 1.14 to 1.31nm of Btt due to the action exchange capacity of Na- BTT which is much greater than the low cation exchange capacity of K- BTt and Ca-Btt, respectively. The improved Na- BTT was then used in the preparation of poly methyl butadiene (PMB) Nano-composite. The modifiers interaction in the clay layer is described by X-ray diffraction (XRD). A conventional approach was used to synthesize the Nano-composite, in which the modified clay (FACO- BTT) was melt mixed with PMB. To classify the Nano-composite XRD, Transmission Electron Microscopy (TEM) and Thermogravimetric have been used. The results of XRD and TEM confirmed Nano-composite growth. In contrast to pure PMB, PMB modified BTT Nano-composite showed higher thermal stability. The use of FACO as a vegetable oil derivative to modify clay would minimize reliance on petroleum based surfactants. Moreover, such Nano-composites are considered environmentally friendly in addition to being renewable resources.

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Yang, Yu-Ling, Krishna R. Reddy, Wen-Jie Zhang, Ri-Dong Fan und Yan-Jun Du. „SHMP-Amended Ca-Bentonite/Sand Backfill Barrier for Containment of Lead Contamination in Groundwater“. International Journal of Environmental Research and Public Health 17, Nr. 1 (06.01.2020): 370. http://dx.doi.org/10.3390/ijerph17010370.

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This study investigated the feasibility of using sodium hexametaphosphate (SHMP)- amended calcium (Ca) bentonite in backfills for slurry trench cutoff walls for the containment of lead (Pb) contamination in groundwater. Backfills composed of 80 wt% sand and 20 wt% either Ca-bentonite or SHMP-amended Ca-bentonite were tested for hydraulic conductivity and sorption properties by conducting laboratory flexible-wall hydraulic conductivity tests and batch isothermal sorption experiments, respectively. The results showed that the SHMP amendment causes a one order of magnitude decrease in hydraulic conductivity of the backfill using tap water (1.9 to 3.0 × 10−10 m/s). Testing using 1000 mg/L Pb solution resulted insignificant variation in hydraulic conductivity of the amended backfill. Moreover, SHMP-amendment induced favorable conditions for increased sorption capacity of the backfill, with 1.5 times higher retardation factor relative to the unamended backfill. The Pb transport modeling through an hypothetical 1-m-thick slurry wall composed of amended backfill revealed 12 to 24 times of longer breakthrough time for Pb migration as compared to results obtained for the same thickness slurry wall with unamended backfill, which is attributed to decrease in seepage velocity combined with increase in retardation factor of the backfill with SHMP amendment. Overall, SHMP is shown to be a promising Ca-bentontie modifier for use in backfill for slurry trench cutoff wall for effective containment of Pb-contaminated groundwater.

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Chen, Xiao Long, Yong Sheng Sun, Yue Xin Han und Bin Zhang. „The Research on the Performance of Asphalt Mastics Modified by Mineral Fillers“. Advanced Materials Research 158 (November 2010): 287–97. http://dx.doi.org/10.4028/www.scientific.net/amr.158.287.

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For a long time, the mineral additive was regarded as inert filler which had no reaction with the asphalt, so does the concrete mix. But some research conducted in the recent year proved that was not the case. In this study, four types of mineral materials (diatomite, kaolin (China Clay), Na-bentonite and Ca-bentonite) were selected out to investigate their effect on the asphalt mastics. The high temperature performance, low temperature performance and the temperature susceptibility of the asphalt mastics were evaluated. The result showed the diatomite rank first of the four minerals. The porous structure, huge specific area, mineralogical surface characteristic and the irregularity might be the reason for its positive effect. The bentonite, especially Na-bentonite is unfavorable to the asphalt modification.

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Lu, A., D. Zhao, J. Li, C. Wang und S. Qin. „Application of vermiculite and limestone to desulphurization and to the removal of dust during briquette combustion“. Mineralogical Magazine 67, Nr. 6 (Dezember 2003): 1243–51. http://dx.doi.org/10.1180/0026461036760162.

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AbstractSmall domestic cooking furnaces are widely used in China. These cooking furnaces release SO2 gas and dust into the atmosphere and cause serious air pollution. Experiments were conducted to investigate the effects of vermiculite, limestone or CaCO3, and combustion temperature and time on desulphurization and dust removal during briquette combustion in small domestic cooking furnaces. Additives used in the coal are vermiculite, CaCO3 and bentonite. Vermiculite is used for its expansion property to improve the contact between CaCO3 and SO2 and to convey O2 into the interior of briquette; CaCO3 is used as a chemical reactant to react with SO2 to form CaSO4; and bentonite is used to develop briquette strength. Expansion of vermiculite develops loose interior structures, such as pores or cracks, inside the briquette, and thus brings enough oxygen for combustion and sulphation reaction. Effective combustion of the original carbon reduces amounts of dust in the fly ash. X-ray diffraction, optical microscopy, and scanning electron microscopy with energy dispersive X-ray analysis show that S exists in the ash only as anhydrite CaSO4, a product of SO2 reacting with CaCO3 and O2. The formation of CaSO4 effectively reduces or eliminates SO2 emission from coal combustion. The major factors controlling S retention are vermiculite, CaCO3 and combustion temperature. The S retention ratio increases with increasing vermiculite amount at 950°C. The S retention ratio also increases with increasing Ca/S molar ratio, and the best Ca/S ratio is 2-3 for most combustion. With 12 g of the original coal, 1 to 2 g of vermiculite, a molar Ca/S ratio of 2.55 by adding CaCO3, and some bentonite, a S retention ratio >65% can be readily achieved. The highest S retention ratio of 97.9% is achieved at 950°C with addition of 2 g of vermiculite, a Ca/S ratio of 2.55 and bentonite.

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Köster, Mathias H., Stefan Hölzl und H. Albert Gilg. „A strontium isotope and trace element geochemical study of dolomite-bearing bentonite deposits in Bavaria (Germany)“. Clay Minerals 52, Nr. 2 (Juni 2017): 161–90. http://dx.doi.org/10.1180/claymin.2017.052.2.01.

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AbstractThe Landshut bentonites that formed from Ca- and Mg-poor rhyolitic tuffs in a fluviatile-lacustrine depositional environment of the Miocene Upper Freshwater Molasse, southern Germany, contain abundant palustrine, pedogenic and groundwater carbonates. Geochemical analyses of dolomites, calcites and smectites from bentonites of various environments by X-ray diffraction, thermal ionization mass spectrometry, inductively coupled plasma-mass spectrometry, and handheld X-ray fluorescence yield new insights into the compositions of fluids and sources of imported components involved in carbonate formation and bentonitization, as well as the timing of bentonite formation. Evaporated, Sr-rich brackish surface water with a molar Mg/Ca ratio of 2–5, derived mostly from the weathering of detrital carbonates, was involved in dolomite and bentonite formation in palustrine and some pedogenic environments. However, Sr-poor groundwater with a molar Mg/Ca ratio of ∼ 1 and a stronger silicate weathering component caused bentonite and calcite formation in strictly pedogenic and groundwater settings. The 87Sr/86Sr and molar Mg/Ca in the smectite interlayers indicate later cation exchange with water having more radiogenic Sr sources and smaller molar Mg/Ca ratios. The Rb-Sr data indicate the common presence of detrital illitic phases in the <0.2 μm fractions of the bentonites. Cogenetic palustrine dolomite and a single smectite residue sample which lacks this detrital illitic phase provide an age constraint for bentonitization at 14.7 ± 4.1 Ma identical to primary ash deposition. Thus a rapid onset of bentonitization of accumulated ash and dolomite formation in evaporation-driven wetland environments is indicated for the genesis of the Landshut bentonites.

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Motoshima, Takayuki, Sachie Iso und Tomoyoshi Nishimura. „Behavior of compacted Ca-bentonite subjected to HMC loading: observations and interpretation“. MATEC Web of Conferences 337 (2021): 04004. http://dx.doi.org/10.1051/matecconf/202133704004.

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This study presents result of HMC experimental test and discussions of chemical effort in Cabentonite. SWCC test, swelling pressure test and unconfined compression test as hydro-mechanical-chemical (HMC) test were applied to Cabentonite-sand mixture. Na-type bentonite has been studied to predict safety and confidence for artificial barrier layer consist of bentonite that many experimental research reports are represented, and can offer technology advanced comprehensive performance due to mathematical simulation models associated to physical parameters on thermal-hydration-mechanical-chemical properties. This study proposed a significant property for calcium bentonite to relate evaluating safety in radioactive waste disposal system, which emphasised much influence of suction and salinity chloride to hydration-mechanical behaviour for Calcium bentonite.

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Kim, Wantae. „Ultrasound-Assisted Removal of Microcrystalline Opal-CT from Ca-Bentonite“. MATERIALS TRANSACTIONS 57, Nr. 12 (2016): 2158–64. http://dx.doi.org/10.2320/matertrans.m2016276.

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Samper, Javier, Zhenxue Dai, Jorge Molinero, M. García-Gutiérrez, T. Missana und M. Mingarro. „Inverse modeling of tracer experiments in FEBEX compacted Ca-bentonite“. Physics and Chemistry of the Earth, Parts A/B/C 31, Nr. 10-14 (Januar 2006): 640–48. http://dx.doi.org/10.1016/j.pce.2006.04.013.

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Liu, Xiao Dong, Xian Jun Lu, Jun Qiu, Zhi Ming Wang und Peng Wu. „Purification of Low Grade Ca-Bentonite for Iron Ore Pellets“. Advanced Materials Research 454 (Januar 2012): 237–41. http://dx.doi.org/10.4028/scientific5/amr.454.237.

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Srour, Rafif K., und Louis M. McDonald. „Effect of cosolvents on Ca-Na exchange onto Wyoming bentonite“. clays and clay minerals 53, Nr. 5 (01.10.2005): 536–47. http://dx.doi.org/10.1346/ccmn.2005.0530510.

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Lian, Lili, Liping Guo und Chunjing Guo. „Adsorption of Congo red from aqueous solutions onto Ca-bentonite“. Journal of Hazardous Materials 161, Nr. 1 (Januar 2009): 126–31. http://dx.doi.org/10.1016/j.jhazmat.2008.03.063.

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Wu, Zhan Sheng, Xi Fang Sun und Chun Li. „Effects of Bentonite Clarificants on Organic Acids Contents in Red Wine during Clarification“. Advanced Materials Research 194-196 (Februar 2011): 802–5. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.802.

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Effects of different bentonite clarificants on the main organic acids contents in wine were investigated during the clarification process. Citric acid (CA) concentration changed slightly during the first day with average elimination ratio (AER) of 0.57%, and tartaric acid (TA), malic acid (MA), lactic acid (LA) and succinic acid (SA) were varied with AER of 12.39%, 9.80%, 7.27% and 6.27%, respectively, while acetic acid (AA) has the biggest AER of 15.42%. The pH and titratable acidity were significantly dependent on the variation of CA and TA. The –OH group in organic acids could be combined with –Si-O or –AlO groups in bentonite surface by hydrogen bond, which could caused the decrease in concentration various organic acids.

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Heikola, T., S. Kumpulainen, U. Vuorinen, L. Kiviranta und P. Korkeakoski. „Influence of alkaline (pH 8.3–12.0) and saline solutions on chemical, mineralogical and physical properties of two different bentonites“. Clay Minerals 48, Nr. 2 (Mai 2013): 309–29. http://dx.doi.org/10.1180/claymin.2013.048.2.12.

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AbstractThe interaction of two different bulk bentonites (Na- and Ca-types) with three types of simulated cement waters (pH 9.7, 11.3 and 12.0) and one saline groundwater simulate (pH 8.3) as a reference, was studied in batch reactors at 25°C. The solution pH was monitored in order to keep the pH as steady as possible by replacing the leaching solution with fresh one when needed. After 554 days, one set of parallel samples was removed from the experiment in order to investigate the possible changes in the bentonite materials.The buffering capacity of bentonite was clearly observed, especially at the beginning of the high-pH experiments, as the pH of the leaching solutions decreased quite dramatically due to interaction with bentonite. The solution chemistry results showed a decrease of Ca content in all leachate samples, but especially in pH 12.0 experiments. Small amounts of silica were released throughout the experiment. Both bentonites in pH 12.0 experiments also released detectable amounts of Al, while in the lower pH experiments the levels were below detection limit. These observations were also supported by chemical analyses of the bentonite materials. Only minor changes were detected in the mineralogy, and they were mainly concentrated on experiments at pH 11.3 and pH 12.0. The measured swelling pressure showed an increase in pH 12.0 experiments. The results obtained in this research may facilitate modelling of bentonite interaction with high-pH solutions.

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Yoon, Seok, WanHyoung Cho, Changsoo Lee und Geon-Young Kim. „Thermal Conductivity of Korean Compacted Bentonite Buffer Materials for a Nuclear Waste Repository“. Energies 11, Nr. 9 (29.08.2018): 2269. http://dx.doi.org/10.3390/en11092269.

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Engineered barrier system (EBS) has been proposed for the disposal of high-level waste (HLW). An EBS is composed of a disposal canister with spent fuel, a buffer material, backfill material, and a near field rock mass. The buffer material is especially essential to guarantee the safe disposal of HLW, and plays the very important role of protecting the waste and canister against any external mechanical impact. The buffer material should also possess high thermal conductivity, to release as much decay heat as possible from the spent fuel. Its thermal conductivity is a crucial property since it determines the temperature retained from the decay heat of the spent fuel. Many studies have investigated the thermal conductivity of bentonite buffer materials and many types of soils. However, there has been little research or overall evaluation of the thermal conductivity of Korean Ca-type bentonite buffer materials. This paper investigated and analyzed the thermal conductivity of Korean Ca-type bentonite buffer materials produced in Gyeongju, and compared the results with various characteristics of Na-type bentonites, such as MX80 and Kunigel. Additionally, this paper suggests various predictive models to predict the thermal conductivity of Korean bentonite buffer materials considering various influential independent variables, and compared these with results for MX80 and Kunigel.

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Lin, Zongkun, Yuru Yang, Zizhan Liang, Lei Zeng und Aiping Zhang. „Preparation of Chitosan/Calcium Alginate/Bentonite Composite Hydrogel and Its Heavy Metal Ions Adsorption Properties“. Polymers 13, Nr. 11 (07.06.2021): 1891. http://dx.doi.org/10.3390/polym13111891.

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In order to avoid the secondary pollution of the toxic residue of chemical crosslinking agent accompanied by chemical hydrogel adsorbent and enhance the adsorption performance of physical hydrogel, chitosan/calcium alginate/bentonite (CTS/CA/BT) composite physical hydrogel was constructed. The formation mechanism and structure of the composite hydrogel were determined by FTIR, XRD and SEM. Adsorption performances of the hydrogel toward Pb2+, Cu2+ and Cd2+ in water under different condition as well as multi-ion competitive sorption were investigated. The adsorption processes were described with the canonical adsorption kinetics and isotherms models. With the utilization of XPS analysis and adsorption thermodynamics analysis, it was found that the adsorptions were spontaneous physico-chemical adsorptions. The results showed that the maximum adsorption capacity of the hydrogel for Pb2+, Cu2+ and Cd2+ reached up to 434.89, 115.30 and 102.38 mg·g−1, respectively, better than those of other physical hydrogels or chitosan/bentonite composite. Moreover, the composite hydrogel improved the collectability of bentonite and showed a good reusability. The modification of bentonite and the formation of hydrogel were completed simultaneously, which greatly simplifies the operation process compared with the prior similar works. These suggest that the CTS/CA/BT composite hydrogel has promising application prospects for removal of heavy metal ions from water.

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Yang, Yuling, Krishna R. Reddy, Hongbin Zhan, Ridong Fan, Songyu Liu, Qiang Xue und Yanjun Du. „Hydraulic conductivity of soil-bentonite backfill comprised of SHMP-amended Ca-bentonite to Cr(VI)-impacted groundwater“. Journal of Contaminant Hydrology 242 (Oktober 2021): 103856. http://dx.doi.org/10.1016/j.jconhyd.2021.103856.

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