查看更多>>摘要：The synergistic effect of radicals and non-radical pathways has attracted much attention for pollutant removal in complex water environments. A novel B-doped CUO/CU2O composite material (B-Cu_xO) was synthesized to activate PMS for the degradation of bisphenol A (BPA). XPS and FT-IR proved that B was doped into the Cu_xO which changed the proportion of Cu(II) and Cu(I). As a result, the cycle of Cu(II)/Cu(I) was promoted and the kinetic degradation rate of BPA increased by 12 times. The radicals quenching experiments and EPR verified the effects of radicals (·OH and SO_4~-) and non-radical (~1O2) pathways in the pollution degradation processes. The results show that B doping accelerated the Cu(II)/Cu(I) cycle, and at the same time realized the synergistic effect of radicals and non-radical. The PMS/B-Cu_xO system exhibited consistent performance in a wide pH range of 5-11. The toxicity evaluation of the transformation products among BPA solutions was studied. This study provided a novel method for accelerating the catalysis of radicals and non-radical synergy.
查看更多>>摘要：Spent copper indium gallium selenide (CIGS) materials are considered a viable resource for the recovery of Cu, In, Ga, and Se. The oxidative roasting-leaching-extraction separation scheme for the recovery of these valuable metals is proposed. Spent CIGS materials were first roasted to transform Cu, In, and Ga from selenides to oxides and volatilize Se. Hydrochloric acid was then used to leach the oxides. The optimum leaching conditions are as follows: acid concentration of 4 mol/L, temperature of 80 °C, leaching time of 3 h, and liquid-solid ratio of 10 mL/g. The leaching rates of Cu, In, and Ga were 99.98%, 93.40%, and 96.86%, respectively. Finally, In and Ga were sequentially extracted from the solution by P204. Through solvent extraction, the extraction rate of In can reach 99.92%, that of Ga can exceed 99.34%, and Cu is hardly extracted. Meanwhile, using hydrochloric acid as the stripping agent, the stripping rates of In and Ga were 99.90% and 99.93%, respectively. Results suggest that the efficient recovery and separation of Cu, In, and Ga in spent CIGS materials can be achieved.
Evgeny E. TereshatovJonathan D. BurnsAmy L. Vonder Haar
10页
查看更多>>摘要：A detailed study of At and Bi extraction from nitric acid media into conventional solvents, namely 1-octanol and methyl anthranilate, has been performed. The analysis includes a mathematical modeling which allows the fitting of experimental data and determination of extraction constants of the two above mentioned elements. Also, this approach helped to estimate a stability constant of a weak AtO(NO3) complex along with thermodynamic constants describing the redox process of At species in the acidic solution and formation of an adduct of Bi in the presence of methyl anthranilate. The results of the fitting have been used to calculate corresponding separation factors of Bi and At as well. Moreover, a computational study has been performed to evaluate At interaction with the above mentioned solvents.
查看更多>>摘要：The complexity and heterogeneous existence of water pollutants ensures that development of possible large-scale water remediation technologies encompasses mimicking real water compositions. Naproxen (NPX) photo-catalytic degradation in the presence of brilliant black and different electrolytes was tested, under visible light irradiation, with rare earth metals (Ce, Er, Gd, and Sm) doped graphic carbon nitride (CN) prepared via one pot solid state method. The materials were characterized with FESEM, TEM, XRD, PL, XPS, BET, UV-vis DRS, TGA, FTIR, and electrochemical techniques. Doping increased the Urbach energy compared to pristine graphitic carbon nitride due to observed shift in absorption towards the visible range of the electromagnetic spectrum, and there was proposed interaction of dopants and CN which decreased photoexcited electrons and holes recombination. The highest degradation efficiency of 92.9% was obtained at 1% loading of Ce, Er, Gd, and Sm metals in CN (1RECN) under visible light irradiation which was ascribed to Z-scheme formation, enhanced visible light absorption and superoxide anion radical's involvement as the major species based on radical trapping experiments. The 1RECN photocatalyst demonstrated remarkable stability with a 3.4 % efficiency reduction after six photocatalytic degradation cycles. The effective and efficient separation and migration of photoexcited electron-hole pairs resulted in their high photodegradation activity compared to other synthesized composites and pristine CN. The fabricated composites provided an interesting perspective for a highly stable multi-elemental doped CN photocatalysts that could be employed for large scale remediation of different classes of organic pollutants.
查看更多>>摘要：Fermentation of residues or side streams can be used to produce valuable products, such as carboxylic acids Reactive solvent extraction is widely studied as isolation method for lactic acid from fermentation broths. Here we investigate the reactive extraction of lactic acid from sweet sorghum silage press juice using different extractants, modifiers, and diluents. Besides a high extraction efficiency, a low crud formation with this highly complex raw material is targeted. Depending on the solvent phase composition, an extraction efficiency of up to 41.1 % was reached using DOA/ALIQ:l-octanol:n-nonane. The crud layer was highly influenced by the applied diluent and amounted to 2.6-42.3 vol% of the total mixture volume. The back-extraction experiments showed that up to 98.2 % of lactic acid were recovered. Summarizing, the results show that reactive solvent extraction of lactic acid is applicable to highly complex process streams, and crud formation can be reduced by adjusting the solvent phase composition.
查看更多>>摘要：This paper reports two new series of benzimidazole functionalized polyimides and ionic polyimides for highly selective membranes with great potential for natural gas sweetening. It has been demonstrated that both the -NH groups in the benzimidazole moieties and the corresponding ionic groups after JV-quaternization tighten the microporous structure and restrict polymer chain mobility through hydrogen bonding and electrostatic interaction. The BET surface areas and d-spacing values decrease with benzimidazole molar content or the degree of ionizadon. Consequently, a linear correlation between C02 permeability coefficients with benzimidazole molar content or degree of ionization was observed due to the decrease of CO2 diffusivity, and the monotonic increase of CO2/CH4 selectivities is ascribed to the increase of both diffusivity selectivity and solubility selectivity. The benzimidazole-based copolyimide and the ionic copolyimide membranes exhibited high CO2/CH4 selectivity under high-pressure mixed-gas conditions. In particular, the copolyimide PI-0.75 membrane displayed a mixed-gas CO2 permeability of 27 Barrer and CO2/CH4 selectivity of 47 at 20 bar total pressure. The performance was much higher than those of the state-of-the-art commercial cellulose triacetate membranes for natural gas upgrading. The facile polymer synthesis and microporosity tunability, as well as the excellent mixed-gas separation performance, render the copolyimide membranes in this study promising towards economic membrane-mediated natural gas upgrading.
查看更多>>摘要：During sustainable high-value utilization of coal-based solid wastes, a kind of characteristic silicon-rich lye (SRL) generated, and its comprehensive recovery and recycling remains an important subject. Through a simple and facile strategy of mild caustic-crystallization method, SRL was favorably utilized through calcium silicate hydrate (C - S - H) synthesis with silicon conversion efficiency over 97.33%. The micro-morphology of C - S - H presented a typical ''honeybee hive''-like porous structure with numerous exchangeable activity cations and combination sites in the silicate chain structure. The amorphous C - S - H products possessed marvelous recovery abilities for typical heavy metals as Cu (II), Zn (II), and Cr (III) in industrial wastewater with recovery efficiency all above 99.6% in quite a short period. The recovery mechanism of C - S - H toward heavy metals was revealed as calcium ions exchange and interlayer structure combination with SiO4 and AlO4 tetrahedron through the analysis of characterization technologies and DFT simulation calculation. C - S - H synthesized in SRL contributes to achieving valuable resources conversion and recycling for guiding sustainable development of coal-based solid waste comprehensive utilization.
查看更多>>摘要：Absorption and separation by aqueous amines is seen today as a mature technology for CO2 capture at large scale. However, it still suffers from some drawbacks, especially the high energy required for the regeneration of the solvent. In this sense, water-free and water-lean solvents are attractive alternatives to replace them due to their potential in reducing this regeneration energy; however, systematic studies on the effect of the co-solvent on the required thermodynamic properties to optimize the separation process are still missing. In this work, we use the polar soft-SAFT equation of state for modeling CO2 chemisorption in a range of aqueous, water-free, and water-lean solvents, formulated using glycol co-solvents. In addition to accurately capturing the CO2 solubility in these solvents, the model allows to isolate the effect of a given organic diluent, and its ratio with water, on CO2 solubility, degree of speciation, and enthalpy of absorption. We find that ethylene glycol is a promising co-solvent, as the reduction in CO2 solubility is minimized, while exhibiting the largest decrease in enthalpy of absorption than other water-lean and water-free solvents, irrespective of the employed amine. This is the first study in which the effect of the co-solvent has been systematically evaluated at post-combustion capture conditions, helping in the rational design of novel solvents for CO2 capture.
查看更多>>摘要：There is an increasing global attention toward hydrogen as a green energy carrier, primarily because of the environmental concerns associated with global wanning issues. It is expected that the produced hydrogen from various sources may be injected to the natural gas grid for economical transportation and use. One interesting option is to evaluate technologies for extracting the hydrogen from the natural gas pipeline for applications using high purity hydrogen. However, natural gas is a complex mixture including CH4, C2H6, CO2, N2 and trace amounts of C3-C6 hydrocarbons. This function requires a natural gas/hydrogen separation technology which must not only operate with low capital and energy cost, but must also provide hydrogen of sufficient purity. The goal of current work therefore was to take a mixture of hydrogen/natural gas of representative concentrations and produce high purity hydrogen using a bespoke pressure swing adsorption (PSA) cycle. A six-bed PSA system with 12 steps was developed and simulated in Aspen Adsorption software to this end. A three-layered adsorption column was designed to capture different groups of components of the mixture selectively within each layer. Informed by measured and literature equilibrium isotherm data, silica gel was chosen as the pre-layer to remove heavy hydrocarbon components and most of the CO2; activated carbon in the main-layer to mainly adsorb methane, and LiLSX zeolite in the top-layer to remove trace nitrogen which had eluted from the earlier layers, for obtaining pure hydrogen product. High purity hydrogen product (>99%) with high recovery (>85%) was achieved with the PSA system for different hydrogen concentrations (5-30%) in the 30 bar feed stream. We also compared the PSA system against an electrolyzer generating hydrogen onsite. Our analysis suggests that the PSA competes favorably, even at a low hydrogen recovery of 40% in cases where the PSA plant is built at a pressure reduction station.
查看更多>>摘要：The degradation of organic pollutants by hydrodynamic cavitation (HC) has become a potential research direction. HC reactor has the advantages of simple structure, easy operation, and low maintenance costs. The combination of HC and other advanced oxidation processes (AOPs) can greatly improve the degradation rate and energy efficiency, reduce the consumption of chemicals and save cost. HC technology was used to degrade tetracycline hydrochloride (TC), the effects of reactor type, geometric parameters, and operation conditions on the degradation were investigated. The results indicated that under the optimal inlet pressure of each reactor, the degradation performance of OP3 was the best, and the degradation rate was 44.9%. After combined HC reaction with 0.10 g/L Na2S2O8 for 2 h, the degradation rate was 92.2%. The synergistic index of HC + 0.050 g/L and HC + 0.10 g/L Na2S2O8 was 1.56 and 4.41, respectively. The synergistic index of HC + 0.047 g/L O3 process was 1.60, and the degradation rate reached 95.5% after 80 min. The degradation intermediates were analyzed by UV-Vis absorption spectrum and LC-MS, and the degradation pathway and mechanism were proposed.
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