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Статті в журналах з теми "PHB solvent extraction"
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Ibrahim, Mohammad H. A., and Alexander Steinbüchel. "Poly(3-Hydroxybutyrate) Production from Glycerol by Zobellella denitrificans MW1 via High-Cell-Density Fed-Batch Fermentation and Simplified Solvent Extraction." Applied and Environmental Microbiology 75, no. 19 (August 7, 2009): 6222–31. http://dx.doi.org/10.1128/aem.01162-09.
Повний текст джерелаАнотація:
ABSTRACT Industrial production of biodegradable polyesters such as polyhydroxyalkanoates is hampered by high production costs, among which the costs for substrates and for downstream processing represent the main obstacles. Inexpensive fermentable raw materials such as crude glycerol, an abundant by-product of the biodiesel industry, have emerged to be promising carbon sources for industrial fermentations. In this study, Zobellella denitrificans MW1, a recently isolated bacterium, was used for the production of poly(3-hydroxybutyrate) (PHB) from glycerol as the sole carbon source. Pilot-scale fermentations (42-liter scale) were conducted to scale up the high PHB accumulation capability of this strain. By fed-batch cultivation, at first a relatively high cell density (29.9 ± 1.3 g/liter) was obtained during only a short fermentation period (24 h). However, the PHB content was relatively low (31.0% ± 4.2% [wt/wt]). Afterwards, much higher concentrations of PHB (up to 54.3 ± 7.9 g/liter) and higher cell densities (up to 81.2 ± 2.5 g/liter) were obtained by further fed-batch optimization in the presence of 20 g/liter NaCl, with optimized feeding of glycerol and ammonia to support both cell growth and polymer accumulation over a period of 50 h. A high specific growth rate (0.422/h) and a short doubling time (1.64 h) were attained. The maximum PHB content obtained was 66.9% ± 7.6% of cell dry weight, and the maximum polymer productivity and substrate yield coefficient were 1.09 ± 0.16 g/liter/h and 0.25 ± 0.04 g PHB/g glycerol, respectively. Furthermore, a simple organic solvent extraction process was employed for PHB recovery during downstream processing: self-flotation of cell debris after extraction of PHB with chloroform allowed a convenient separation of a clear PHB-solvent solution from the cells. Maximum PHB recovery (85.0% ± 0.10% [wt/wt]) was reached after 72 h of extraction with chloroform at 30°C, with a polymer purity of 98.3% ± 1.3%.
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Montiel-Jarillo, Gabriela, Diego A. Morales-Urrea, Edgardo M. Contreras, Alex López-Córdoba, Edwin Yesid Gómez-Pachón, Julián Carrera, and María Eugenia Suárez-Ojeda. "Improvement of the Polyhydroxyalkanoates Recovery from Mixed Microbial Cultures Using Sodium Hypochlorite Pre-Treatment Coupled with Solvent Extraction." Polymers 14, no. 19 (September 21, 2022): 3938. http://dx.doi.org/10.3390/polym14193938.
Повний текст джерелаАнотація:
The use of mixed microbial cultures (MMC) and organic wastes and wastewaters as feed sources is considered an appealing approach to reduce the current polyhydroxyalkanoates (PHAs) production costs. However, this method entails an additional hurdle to the PHAs downstream processing (recovery and purification). In the current work, the effect of a sodium hypochlorite (NaClO) pre-treatment coupled with dimethyl carbonate (DMC) or chloroform (CF) as extraction solvents on the PHAs recovery efficiency (RE) from MMC was evaluated. MMC were harvested from a sequencing batch reactor (SBR) fed with a synthetic prefermented olive mill wastewaster. Two different carbon-sources (acetic acid and acetic/propionic acids) were employed during the batch accumulation of polyhydroxybutyrate (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from MMC. Obtained PHAs were characterized by 1H and 13C nuclear magnetic resonance, gel-permeation chromatography, differential scanning calorimetry, and thermal gravimetric analysis. The results showed that when a NaClO pre-treatment is not added, the use of DMC allows to obtain higher RE of both biopolymers (PHB and PHBV), in comparison with CF. In contrast, the use of CF as extraction solvent required a pre-treatment step to improve the PHB and PHBV recovery. In all cases, RE values were higher for PHBV than for PHB.
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Samrot, Antony V., Sree K. Samanvitha, N. Shobana, Emilin R. Renitta, P. Senthilkumar, Suresh S. Kumar, S. Abirami, et al. "The Synthesis, Characterization and Applications of Polyhydroxyalkanoates (PHAs) and PHA-Based Nanoparticles." Polymers 13, no. 19 (September 27, 2021): 3302. http://dx.doi.org/10.3390/polym13193302.
Повний текст джерелаАнотація:
Polyhydroxyalkanoates (PHAs) are storage granules found in bacteria that are essentially hydroxy fatty acid polyesters. PHA molecules appear in variety of structures, and amongst all types of PHAs, polyhydroxybutyrate (PHB) is used in versatile fields as it is a biodegradable, biocompatible, and ecologically safe thermoplastic. The unique physicochemical characteristics of these PHAs have made them applicable in nanotechnology, tissue engineering, and other biomedical applications. In this review, the optimization, extraction, and characterization of PHAs are described. Their production and application in nanotechnology are also portrayed in this review, and the precise and various production methods of PHA-based nanoparticles, such as emulsion solvent diffusion, nanoprecipitation, and dialysis are discussed. The characterization techniques such as UV-Vis, FTIR, SEM, Zeta Potential, and XRD are also elaborated.
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Rocha, Marisa Cristina Guimarães, Nancy Isabel Alvarez Acevedo, and Carlos Eduardo Nazareth de Oliveira. "Mechanical and Morphological Properties of PHB/Oil-Free Coffee Dregs (OFCD) Composites." Materials Science Forum 1079 (December 26, 2022): 93–102. http://dx.doi.org/10.4028/p-k5hv1o.
Повний текст джерелаАнотація:
Poly(3-hydroxybutyrate) (PHB) and coffee dregs (CDs) are both biodegradable materials. The latter are household wastes with no commercial value that are discarded in landfills mixed with other organic wastes. PHB has properties equivalent to polypropylene (PP), but its prohibitive cost restricts its field of application. The incorporation of this residue in a PHB matrix is a way to obtain materials with a high cost/benefit ratio. The aim of this work was to investigate the effect of adding oil-free coffee dregs (OFCDs) on the mechanical and morphological properties of PHB. Soxhlet extraction using ethanol as a solvent was used to obtain OFCDs. The PHB/OFCD composites were prepared in a twin-screw extruder. Standardized methods were used to evaluate the tensile and flexural properties. The test specimens were obtained by compression molding. Scanning electron microscopy (SEM) was applied to evaluate the morphology of the composites obtained. The data obtained showed that the incorporation of 15 wt.% of OFCD caused no significant differences in the tensile modulus, tensile strength and flexural modulus. The flexural strength decreased with the incorporation of OFCD in the PHB. However, the material obtained was interesting, since it was more attractive in terms of cost and environmental impact. SEM micrographs showed good dispersion of OFCD in PHB when the OFCD content was 5 wt.%. However, when higher levels of residues were incorporated in the PHB, the formation of agglomerates became evident. Poor interfacial adhesion between the filler and matrix was indicated by the cracks and voids revealed in the micrographs. The results obtained indicated that PHB/OFCD composites prepared with 15 wt.% of OFCD particles have potential to be used in the production of PHB materials that require high stiffness, adequate strength, and lower cost, such as sheets and thermoformed products for food, medical, personal care and laboratory applications
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Fiorese, Mônica Lady, Filomena Freitas, Joana Pais, Ana Maria Ramos, Gláucia M. F. de Aragão, and Maria A. M. Reis. "Recovery of polyhydroxybutyrate (PHB) from Cupriavidus necator biomass by solvent extraction with 1,2-propylene carbonate." Engineering in Life Sciences 9, no. 6 (December 2009): 454–61. http://dx.doi.org/10.1002/elsc.200900034.
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B, Viswapriya, Balamurugan V, and Jayaprakash K. "ISOLATION OF SEAWEED ASSOCIATED BACTERIA'S AND THEIR PRODUCTION OF BIOPOLYMER BY SOLID-STATE FERMENTATION." International journal of multidisciplinary advanced scientific research and innovation 1, no. 7 (September 30, 2021): 134–41. http://dx.doi.org/10.53633/ijmasri.2021.1.7.04.
Повний текст джерелаАнотація:
Plastic material is any of a wide range of synthetic or semi-synthetic organic solids that are moldable. Plastics are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, but many are partially natural. Environmental pollution by the disposal of non-degradable conventional plastics is a fast-growing problem worldwide, especially in India. Nowadays, plastics are replacing by other constructional materials like glass, wood, metal in numerous applications. In this study, there has been considerable interest in the development and production of biodegradable polymer to solve the current problem of pollution caused by the continuous use of synthetic polymer from seaweed associated Bactria. . Based on the dry weight of total biopolymer content, the strain SBT 09 showed maximum accumulation and selected for optimizing at different pH, temperature, salinity, carbon, and nitrogen source and the peak time of PHB accumulation. Based on the biochemical tests, the strain SBT 09 was found.The optimum pH, temperature, and salinity were found to be 7, 300C, and 5%. The peak time of PHB accumulation was found to be 36hrs. The best carbon and nitrogen source was found to be sucrose and (NH4)2 HPO4. The selected strain was mass cultured using the optimized media and PHB was extracted by solvent extraction. Keywords: Marine Bacteria, PHB, Biosynthesis, Biopolymer.
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Filippi, Sara, Patrizia Cinelli, Andrea Mezzetta, Pietro Carlozzi, and Maurizia Seggiani. "Extraction of Polyhydroxyalkanoates from Purple Non-Sulfur Bacteria by Non-Chlorinated Solvents." Polymers 13, no. 23 (November 28, 2021): 4163. http://dx.doi.org/10.3390/polym13234163.
Повний текст джерелаАнотація:
In this study, non-chlorinated solvents such as cyclohexanone (CYC) and three ionic liquids, (ILs) (1-ethyl-3-methylimidazolium dimethylphosphate, [EMIM][DMP], 1-ethyl-3-methylimidazolium diethylphosphate, [EMIM][DEP] and 1-ethyl-3-methylimidazolium methylphosphite, [EMIM][MP]) were tested to extract polyhydroxyalkanoates (PHAs) from the purple non-sulfur photosynthetic bacterium (PNSB) Rhodovulumsulfidophilum DSM-1374. The photosynthetic bacterium was cultured in a new generation photobioreactor with 4 L of working volume using a lactate-rich medium. The extracted PHAs were characterized using a thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy, proton nuclear magnetic resonance and gel permeation chromatography. The most promising results were obtained with CYC at 125 °C with an extraction time of above 10 min, obtaining extraction yields higher than 95% and a highly pure poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV) with around 2.7 mol% of hydroxylvalerate (HV). A similar yield and purity were obtained with chloroform (CHL) at 10 °C for 24 h, which was used as the referent solvent Although the three investigated ILs at 60 °C for 4 and 24 h with biomass/IL up to 1/30 (w/w) obtained PHAs strongly contaminated by cellular membrane residues, they were not completely solubilized by the investigated ILs.
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Martínez-Herrera, Raul E., María E. Alemán-Huerta, Verónica Almaguer-Cantú, Walfred Rosas-Flores, Víctor J. Martínez-Gómez, Isela Quintero-Zapata, Gildardo Rivera, and O. Miriam Rutiaga-Quiñones. "Efficient recovery of thermostable polyhydroxybutyrate (PHB) by a rapid and solvent-free extraction protocol assisted by ultrasound." International Journal of Biological Macromolecules 164 (December 2020): 771–82. http://dx.doi.org/10.1016/j.ijbiomac.2020.07.101.
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de Oliveira Schmidt, Vanessa Kristine, Evelise Fonseca dos Santos, Débora de Oliveira, Marco Antônio Záchia Ayub, Karina Cesca, Paulo Roberto Dall Cortivo, Cristiano José de Andrade, and Lilian Raquel Hickert. "Production of Polyhydroxyalkanoates by Bacillus megaterium: Prospecting on Rice Hull and Residual Glycerol Potential." Biomass 2, no. 4 (December 16, 2022): 412–25. http://dx.doi.org/10.3390/biomass2040026.
Повний текст джерелаАнотація:
The production of polyhydroxyalkanoates (PHAs) by Bacillus megaterium using industrial residues, crude glycerol from biodiesel synthesis and rice hull hydrolysate (RHH), as low-cost carbon sources was investigated. The experiments were conducted by shaking flasks at 30 °C and 180 rpm up to 72 h. The extraction of PHA was carried out using sodium hypochlorite to make its recovery more environmentally friendly by avoiding organic solvents (chloroform). The yields of PHA varied depending on the extraction method. A total of 33.3% (w·w−1) (mixing chloroform: sodium hypochlorite) and 52.5% (w·w−1) (sodium hypochlorite only) were obtained using glycerol and glucose as a carbon source, respectively. Preliminary experiments using RHH as a carbon source Indicated a yield of PHA of 11% (w·w−1) (chloroform). The PHA produced had thermal properties, such as transition temperature, similar to the commercial polyhydroxybutyrate (PHB).
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Dunnivant, Frank M., and Alan W. Elzerman. "Determination of Polychlorinated Biphenyls in Sediments, Using Sonication Extraction and Capillary Column Gas Chromatography-Electron Capture Detection with Internal Standard Calibration." Journal of AOAC INTERNATIONAL 71, no. 3 (May 1, 1988): 551–56. http://dx.doi.org/10.1093/jaoac/71.3.551.
Повний текст джерелаАнотація:
Abstract A sonication technique is presented for the extraction of polychlorinated biphenyls (PCBs) from sediments. In addition, a quantitation scheme is described which allows peak-specific and, in many cases, congener-specific determination of PCBs. PCBs are quantitated by capillary column gas chromatography-electron capture detection, with internal standard calibration. Results utilizing sonication extraction were compared with those obtained by Soxhlet and steam distillation extractions of 3 U.S. Environmental Protection Agency (EPA) quality control sediment samples and 3 lake sediments known to be contaminated with PCBs. Environmental lake sediments were extracted wet, with no drying prior to extraction. Recoveries by each technique varied depending on the sediment sample being extracted and degree of chlorination of PCB congeners. With proper selection of extraction solvent, the sonication technique can recover amounts of PCBs equivalent to and sometimes greater than recoveries by the Soxhlet or steam distillation techniques. A 24-h quiescent period in the extraction solvent between 2 sonications improved extraction efficiency for 2 freeze-dried sediments but did not affect results obtained for 3 environmentally contaminated sediments that were extracted without drying. Replacement of Soxhlet extraction with the sonication technique results in reduced sample preparation time, decreased volumes of solvents and sample, and substitution of common laboratory glassware in place of fragile, expensive Soxhlet glassware. Sonication extraction can also improve precision compared with Soxhlet extraction
Дисертації з теми "PHB solvent extraction"
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MONGILI, BEATRICE. "Biotechnological approches for green-based bioplastic production." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2836776.
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Azis, Muhammad Yudhistira. "Analyse des micropolluants organiques dans les sédiments et le biota (Perna viridis et Polymesoda erosa) de la baie de Jakarta et de la lagune de Segara Anakan, Indonésie." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4715.
Повний текст джерелаАнотація:
Les activités anthropiques ainsi que des phénomènes naturels sont à l’origine de risques avérés pour l’environnement. L'Indonésie est un pays archipélagique qui contient de nombreuses îles et régions côtières, où la croissance exponentielle des activités anthropiques a exposé l’environnement indonésien à de graves détériorations au cours des dernières décennies. Cette étude vise à explorer (qualitativement et quantitativement) les niveaux de contamination des sédiment de surface et du biote (P. Viridis, P. erosa,) au travers de deux sites atelier : la baie de Jakarta et la lagune de Segara Anakan (Java, Indonésie).Les méthodes de préparation des échantillon (extraction par solvant puis purification par chromatographie d’adsorption) suivies de l’analyse des extraits par GC/MS/MS ont été développées et qualifiées (linéarité, spécificité, reproductibilité).Les n-alcanes, HAP, PCBs et OCs sont détectés à des teneurs pouvant atteindre respectivement 1935 µg/kgPS, 916 µg/kg PS, 116,49 µg/kg PS, et 16,70 µg/kg PS, dans des sediments et 1739 µg/kg PS des HAPs et 24,79 µg/kg PS des OCs dans le biote. Les hydrocarbures, comme les HAPs sont majoritairement d’origine pétrolière (fuites, transport utilisation) même si la contribution pyrolytique est toujours présente.L’évaluation du risque environnemental a été réalisés pour les HAP, PCBS et et les OCs en utilisant les lignes directrices de la qualité des sédiments (RQS). Ces données peuvent servir de référence de base dans le cadre du programme de gestion intégrée des bassins versants impliquant la biodiversité, l'écologie de l'eau douce, et l'activité économique dans le domaine de cette étudeEnvironmental problems can increase due to anthropogenic activities or natural phenomena. Indonesia is an archipelagic country that consists of many islands and coastal regions, where the growth of anthrophogenic and natural activities has exhibited severe environmental degradation in the past few decades. This study aims to explore (both qualitatively and quantitatively) the extent and sources of organic contaminants, i.e., n-alkanes in surface sediments; PAHs, PCBs and OCs in sediments and mussels, P. viridis from Jakarta Bay, North Jakarta, and P. erosa from the Segara Anakan Lagoon. Each protocol was continued with qualitative and quantitative analysis by GC-QQQ(triple-quadropole)/MS. Matrix interferences have been evaluated with proper samples with suitable yield of extraction and analysis. The n-alkanes, PAHs, PCBs and Organochlorin pesticides are detected in the highest levels in sediments, respectively 1935 µg/kg dw, 916 µg/kg dw, 116,49 µg/kg dw, and 16,70 µg/kg dw. In addition, the highest levels of PAHs (1739 µg/kg dw) and OCs levels (24,79 µg/kg dw) were found in biota. The source of hydrocarbons source, such the PAHs were generalelly petroleum source (transport utilization) although the pyrolytic are still present in sediments and biota. Environmental risk assessment from sediment quality guidelines (SQGs) were used to evaluate the probability risk in marine environments. Besides SQGs, sediments and mussels also in regard to the extent of the PAHs, PCBs and OCs (i.e. pp’-DDE) have been compared to other studies conducted at some polluted sites
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O'Connell, Maureen. "Optimizing Solvent Extraction of PCBs from Soil." Thesis, 2009. http://hdl.handle.net/10012/4529.
Повний текст джерелаАнотація:
Polychlorinated biphenyls (PCBs) are carcinogenic persistent contaminants. Although their manufacturing in North America ceased in the late 1970s, their high heat resistance made their use widespread over their production lifetime. As a result, PCB contamination has occurred globally and in particular has plague brownfield redevelopment in urban environments. The remediation of PCB contaminated soil or sediments has historically been dealt with through the expensive and unsustainable practice of excavation followed by off-site disposal or incineration. One potential technology that has shown some success with on-site remediation of PCB contamination is solvent extraction. Solvent extraction is technically simple; it involves excavating the contaminated soil, placing it in a vessel and adding solvent. The PCBs are extracted by the solvent and the treated soil is returned for use on site. Although successful at removing a large quantity of PCBs from some soils, this technology can be improved upon by extracting additional PCB mass and making the extraction more efficient and suitable for colder climates.
This thesis aimed to identify the factors controlling PCB extraction with solvents in order to optimize PCB extraction as it is applied on different soil types and in various climates. The research investigated the impact of elevated moisture contents (≤ 20% by weight) on solvent extraction efficiency, the effects of low temperatures (<5ºC) on solvent extraction, and developed a kinetic model to represent PCB solvent extraction. As past research has shown, weathered PCB in soil is more difficult to remove. Contaminated field samples from Southern Ontario, Canada were used for this work, rather than synthetically prepared samples.
The impact of elevated moisture contents and low temperature on extraction efficiency was determined through a series of screening experiments using polar and non-polar solvents at both 20ºC and 4ºC. It was hypothesized that improved extractions may be possible with combinations of polar and non-polar solvents. Based on the results of these screening experiments, a factorial experiment was designed using solvent combinations to further assess the role of moisture contents and low temperatures. The role of PCB mass distribution among grain sizes was also evaluated to see if optimization based on grain size separation is possible. Finally, experiments were performed to generate data suitable for the development of a kinetic model that incorporates key factors affecting solvent extraction.
Four suitable solvents for solvent extraction in Ontario were identified through a literature review and these were used for this work: isopropyl alcohol (polar), ethanol (polar), triethylamine (non-polar) and isooctane (non-polar). Triethylamine outperformed isooctane and performed best on its own rather than in combination with polar solvents. An interaction between soil moisture content and choice of polar solvent (isopropyl alcohol versus ethanol) was established: a given polar solvent achieves optimal PCB extraction at a specific moisture content range. Temperature was also identified as significantly influencing PCB extraction. Although it was determined that PCBs were distributed unevenly amongst grain sizes, a simple relationship between grain size and fractional organic carbon or organic content was not found.
A simple two-compartment kinetic model was developed which is suitable for predicting the PCB concentrations extracted up to 24 hours. The model incorporates both temperature and soil to solvent ratio in order to estimate PCB concentration extracted.
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Silva, Carolina Belchior Calado da. "Recuperação de metais preciosos de placas de circuito impresso obsoletas através do processo de extracção por solventes." Master's thesis, 2018. http://hdl.handle.net/10316/86460.
Повний текст джерелаАнотація:
Dissertação de Mestrado Integrado em Engenharia Química apresentada à Faculdade de Ciências e TecnologiaEste trabalho consistiu no desenvolvimento e otimização de uma metodologia hidrometalúrgica para a recuperação de metais presentes nas placas de circuito impresso (PCI) em fim de vida. Inicialmente, as PCI foram sujeitas a um tratamento físico/mecânico que possibilitou a sua fragmentação e consequente redução de tamanho utilizando equipamentos como guilhotinas para o corte e moinhos de lâminas para a redução a tamanhos inferiores a 2 mm.Procedeu-se em seguida à caracterização quantitativa dos metais, onde foram analisados individualmente quatro lotes, cada um com diferentes componentes associados às PCI, sendo que para cada um destes foi feita uma separação granulométrica em duas frações – oversize (> 0,707 mm) e undersize (< 0,707 mm). Verificou-se que o metal presente em maior quantidade é o cobre, sendo que este se encontra maioritariamente na fração oversize, com uma concentração máxima de 50 % (m/m). Os metais preciosos como o ouro e a prata encontram-se em quantidades promissoras na fração undersize, com cerca de 0,4 mgmetal/gresíduo e 0,2 mgmetal/gresíduo, respetivamente. Nesta caracterização química foram testados três métodos de digestão, o que se revelou mais eficiente para a digestão da maioria dos metais básicos (Cu, Fe, Zn, Ni, etc.) foi aquele que utilizou ácido fluorídrico como reagente principal. Quanto à digestão dos metais precisos, o método que se revelou mais adequado foi aquele que usou água-régia e peróxido de hidrogénio. Finalmente foram realizados ensaios de lixiviação para a extração do cobre e do ouro, utilizando dois estágios sequenciais. No primeiro estágio visando a recuperação seletiva do cobre, usaram-se como reagentes uma solução de amónia e peróxido de hidrogénio como agente oxidante, procurando conjugar elevados níveis de eficiência de extração assim como um baixo impacte ambiental. Foram otimizados dois parâmetros operatórios relevantes (razão líquido/sólido e a concentração de reagentes) com recurso a um planeamento fatorial a 3 níveis, tendo-se obtido um rendimento máximo de 100% para a extração do cobre, e uma seletividade de 77 % para uma razão L/S =5 e uma concentração máxima de reagente (72,4% (v/v)). No segundo estágio o objetivo foi a recuperação do ouro, recorrendo a um solvente orgânico (ácido acético) como reagente principal e ácido clorídrico, peróxido de hidrogénio e cloreto de sódio, com tempos de reação na ordem dos segundos/minutos. No entanto, os resultados relativos à extração do ouro foram inconclusivos.
This work consisted in the development and optimization of a hydrometallurgical methodology for the recovery of metals present in end-of-life printed circuit boards (PCB). Initially, the PCB were submitted to a physical / mechanical treatment that allowed their fragmentation and consequent size reduction using equipment such as cutting guillotines and blade mills for its reduction to particle sizes smaller than 2 mm.The quantitative characterization of the metals was then carried out, where four batches, each with different components associated to the PCB, were individually analyzed, and for each of them a particle size separation was performed in two fractions – oversize (>0,0707 mm) and undersize(<0,707 mm). It has been found that the most present metal is copper, which is mostly found in the oversize fraction, with a maximum concentration of 50% (m / m). Precious metals such as gold and silver are also present in promising quantities in the undersize fraction, with about 0.4 mg metal / gresidue and 0.2 mg metal / waste, respectively.. In this chemical characterization, three digestion methods were tested, hydrofluoric acid proved to be the most effective reagent for the digestion of the majority of basic metals (Cu, Fe, Zn, Ni, etc.).As for the digestion of the precious metals, the most suitable method was the one that uses aqua-regia and hydrogen peroxide.Finally, leaching tests were carried out to extract copper and gold using two sequential stages. In the first stage for the selective recovery of copper, a solution of ammonia and hydrogen peroxide was used as the oxidizing agent, aiming to conjugate high levels of extraction efficiency as well as a low environmental impact. Two relevant operative parameters (liquid / solid ratio and reagent concentration) were optimized using factorial planning at 3 levels, yielding an optimal yield of 100% and a selectivity of 77% for a ratio L/S= 5 and a maximum concentration of reagent (72.4% v/v). At the statistical level, the two parameters did not reveal a significant contribution. In the second stage the objective was to recover the gold, using an organic solvent (acetic acid) as the main reactant and hydrochloric acid, hydrogen peroxide and sodium chloride, reaction times in the order of seconds / minutes. However, the gold extraction results were inconclusive.
Книги з теми "PHB solvent extraction"
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Blakemore, Robert John. The determination of change in PCB concentration by GC/MS with Soxhlet extraction: And GC/ECD with automated solvent extraction from Portsmouth Harbour sediment. Portsmouth: University of Portsmouth, School of Pharmacy and Biomedical Sciences, 1999.
Знайти повний текст джерелаЧастини книг з теми "PHB solvent extraction"
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Reilly, T. R., S. Sundaresan, and J. H. Highland. "Cleanup of PCB Contaminated Soils and Sludges by a Solvent Extraction Process: A Case Study." In Studies in Environmental Science, 125–39. Elsevier, 1986. http://dx.doi.org/10.1016/s0166-1116(08)70935-x.
Повний текст джерелаЗвіти організацій з теми "PHB solvent extraction"
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Bloom, G. A., A. J. Lucero, L. J. Koran, and E. N. Turner. PCB extraction from ORNL tank WC-14 using a unique solvent. Office of Scientific and Technical Information (OSTI), September 1995. http://dx.doi.org/10.2172/114030.
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Peters, T., and S. Fink. RESULTS OF ANALYTICAL SAMPLE CROSSCHECKS FOR NEXT GENERATION SOLVENT EXTRACTION SAMPLES ISOPAR L CONCENTRATION AND PH. Office of Scientific and Technical Information (OSTI), September 2011. http://dx.doi.org/10.2172/1026682.
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Schmidt, A. J., G. S. Klinger, and P. R. Bredt. Evaluation of Ion Exchange Materials in K Basin Floor Sludge and Potential Solvents for PCB Extraction from Ion Exchange Materials. Office of Scientific and Technical Information (OSTI), April 1999. http://dx.doi.org/10.2172/5089.
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Schmidt, Andrew J., George S. Klinger, and Paul R. Bredt. Evaulation of Ion Exchange Materials in K Basin Floor Sludge and Potential Solvents for PCB Extractions from Ion Exchange Materials. Office of Scientific and Technical Information (OSTI), April 1999. http://dx.doi.org/10.2172/15010561.
Повний текст джерела
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Peter, J. M., M. G. Gadd, C. Jiang, and J. Reyes. Organic geochemistry and petrology of sedimentary exhalative Pb-Zn and polymetallic hyper-enriched black shale deposits in the Selwyn Basin, Yukon. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328017.
Повний текст джерелаАнотація:
Paleozoic strata of the Selwyn Basin host sedimentary exhalative (SEDEX) Pb-Zn deposits, and age-correlative strata of the Richardson trough host polymetallic hyper-enriched black shale (HEBS) deposits. In both deposit types, organic matter is spatially and temporally associated with mineralization. We investigated the characteristics of organic matter in mineralization and unmineralized host rocks in the XY Central SEDEX deposit in the Howard's Pass district, and the Nick and Peel River HEBS deposits in the Richardson trough using Rock-Eval pyrolysis, organic petrography, and solvent extraction and gas chromatography mass spectrometry (GCMS) analysis of the soluble organic matter (SOM). All samples experienced extremely high thermal maturity (Tmax up to 599°C), indicating they contain low SOM. Rock-Eval parameters S1, S2, HI, and OI values are low. Total organic carbon (TOC) values are low for Nick and Peel River and are generally higher for XY Central. Residual carbon values are universally high. Mineral carbon values are low for deposits studied (one outlier). Pyrobitumen reflectance is mostly below 5.80%. Full-scan GCMS analyses of SOM reveal that most, if not all, high molecular weight hydrocarbons, including biomarkers, have been lost due to thermal cracking and many detected peaks are likely due to contaminants introduced during sampling.
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Naim, Michael, Gary R. Takeoka, Haim D. Rabinowitch, and Ron G. Buttery. Identification of Impact Aroma Compounds in Tomato: Implications to New Hybrids with Improved Acceptance through Sensory, Chemical, Breeding and Agrotechnical Techniques. United States Department of Agriculture, October 2002. http://dx.doi.org/10.32747/2002.7585204.bard.
Повний текст джерелаАнотація:
The tomato, a profitable vegetable crop in both the USA and Israel, has benefited significantly from intensive breeding efforts in both countries, and elsewhere (esp. Holland). : Modem hybrids are highly prolific and resistant to a variety of major pests. They produce attractive, firm fruit for both processing and fresh-marketing. In all cases, however, reduction in flavor and aroma have occurred concomitantly with the increase in yield. Sugars-acids ratio dominate fruit taste, whereas aroma volatiles (potent at minute ppb and ppt levels) contribute to the total characteristic tomato flavor. An increase in sugars (1-2%) contributes significantly to tomato fruit taste. However, because of energy reasons, an increase in fruit sugars is immediately compensated for by a decrease in yield. Our main objectives were to: (a) pinpoint and identify the major impact aroma components of fresh tomato; (b) study the genetic and environmental effects on fruit aroma; (c) determine precursors of appealing (flavors) and repelling (off-flavors) aroma compounds in tomato. Addition of saturated salts blocked all enzymatic activities prior to isolation of volatiles by dynamic and static headspace, using solvent assisted flavor evaporation (SAFE) and solid phase micro-extraction (SPME) from highly favored (FA-612 and FA-624) and less preferred (R 144 and R 175) tomato genotypes. Impact aroma components were determined by gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry (GC- MS) and aroma extract dilution analysis (AEDA). The potent odorant (Z)-1,5-octadien-3-one, was identified for the first time in fresh tomato. From the ca. 400 volatile compounds in the headspace of fresh tomato, the following compounds are proposed to be impact aroma compounds: (Z)-3-hexenal, hexanal, 1-penten-3-one, 2-phenylethanol, (E)-2-hexenal, phenyl acetaldehyde, b-ionone, b-damascenone, 4-hydroxy-2,5-dimethyl-3-(2H)-furanone (FuraneolR), (Z)-l,5-octadien-3-one, methional, 1-octen-3-one, guaiacol, (E,E)- and (E,Z)- 2,4-decadienal and trans- and cis-4,5-EPOXY -(E)-2-decenal. This confirms the initial hypothesis that only a small number of volatiles actually contribute to the sensation of fruit aroma. Tomato matrix significantly affected the volatility of certain impact aroma components and thus led to the conclusion that direct analysis of molecules in the headspace . may best represent access of tomato volatiles to the olfactory receptors. Significant differences in certain odorants were found between preferred and less-preferred cultivars. Higher consumer preference was correlated with higher concentrations of the following odorants: l-penten-3-one, (Z)-3-hexenal, (E,E)- and (E,Z)-2,4-decadienal and especially Furaneol, whereas lower consumer preference was associated with higher concentrations of methional, 3-methylbutyric acid, phenylacetaldehyde, 2-phenylethanol, and 2-isobutylthiazole. Among environmental factors (salinity, N source, growth temperature), temperature had significant effects on the content of selected aroma compounds (e.g., 3-methylbutanal, 1- penten-3-one, hexanal, (Z)-3-hexenal, (E)-2-hexenal, 2-isobutylthiazole, 6-methyl-5-hepten- 2-one, 1-octen-3-one, methional, 2-phenylethanal, phenyl acetaldehyde, and eugenol) in fresh tomatoes. Salt stress (20 mM NaCl) increased the content of odorants such as (Z)-3-hexenal, 2-phenylethanol and 3-methylbutanal in the R-144 cultivar whereas salinity had minor effects on 1-pentene-3-one, 2-isobutylthiazole and b-ionone. This fundamental knowledge obtained by comprehensive investigation, using modem chemical, sensory and agrotechnical methodology will assist future attempts to genetically modify the concentrations of key odorants in fresh tomatoes, and thus keep the tomato production of Israel and the USA competitive on the world market.