查看更多>>摘要：In this work, the technology for absorbing methyl tert-butyl ether (MTBE) with ionic liquids (ILs) is first proposed and systematically investigated from the molecular level to system scale. The imidazolium-based ILs, [BzMIM] [Tf2N] and [AMIM] [Tf2N] are screened from 272 IL species using the COSMO-RS model. The absorption mechanism at the molecular level is explored by combined characterization techniques (i.e. ~1H NMR and FT-IR) with quantum chemical (QC) calculations (i.e. binding energy and weak interaction analyses). The vapour-liquid equilibrium (VLE) of MTBE-IL and MTBE-triethylene glycol (TEG) systems are experimentally determined and predicted through the UNIFAC-Lei model. The results show that the model can well quantitatively predict the VLE of these mixed systems. Moreover, the equilibrium absorption capacities of MTBE in ILs and TEG are measured and the magnitude is in the order of [BzMIM] [Tf2N] > [AMIM] [Tf2N] > TEG. The equilibrium stage and rate-based models on the basis of the UNIFAC-Lei model is established to perform the process design and optimization for MTBE absorption. When achieving the same separation task (i.e., MTBE content in the product gas less than 500 ppm in mole fraction), the mixed absorbent of [AMIM] [Tf2N] + TEG has the lower loss of product gas and the lower energy demands (i.e., heating and cooling energy along with exergy demands) compared with the pure TEG and pure IL processes. This validates that ILs are potential absorbents and IL-based mixed absorbents may be the better strategy for achieving highly efficient absorption of MTBE.
查看更多>>摘要：Metal ions are unavoidable in pulp solution, and they frequently influence the flotation recovery of minerals, such as by activation or depression. In this work, we systematically investigated the adsorption characteristics of Cu~(2+) species on cerussite surfaces and the concomitant effect on sulfidization flotation by micro-flotation experiments and surface analysis. The flotation results indicated that the flotation recovery of cerussite was almost unchanged at low Cu~(2+) concentration in the presence of Na2S, but it decreased at high Cu~(2+) concentration. X-ray photoelectron spectroscopy indicated that CuCO3 species formed on cerussite surface in the presence of Cu~(2+), and Pb-S species and Cu-S species formed after Cu~(2+)-Na2S treatment. Time-of-flight-secondary-ion mass spectrometry indicated that the distribution of lead species narrowed and that of copper species broadened with increasing Cu~(2+) concentration, which demonstrated that Cu~(2+) covered the mineral surfaces and inherent Pb~(2+) was shield. Ultraviolet-visible spectroscopy indicated that the stability of cerussite surface increased with increasing amount of added Na2S. Compared with only Na2S treatment, consumption of xanthate was almost unchanged at low Cu~(2+) concentration, whereas consumption of xanthate considerably increased at high Cu~(2+) concentration, which may be because xanthate was consumed by the residual copper ions in the pulp solution. Zeta potential measurements indicated that Cu~(2+) can chemisorb on cerussite surfaces and increasing the Cu~(2+) concentration facilitates adsorption of copper species, but it inhibits adsorption of Na2S and BX. Therefore, sulfidization flotation of cerussite is not substantially affected by low concentrations of Cu~(2+), but is greatly affected by high concentrations of Cu~(2+).
查看更多>>摘要：Recovery of lithium from Mg-rich salt-lake brines by solvent extraction has been widely studied for high Li~+/ Mg~(2+) selectivity and Li~+ extraction efficiency. In a previous study, a ternary synergistic solvent extraction system consisting of tributyl phosphate (TBP), 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507, denoted as HL) and FeCl3 was developed, in which high Li~+ selectivity and efficient Li~+ stripping simply with water were realized. In this study, to further elucidate the extraction mechanism of the TBP/P507/FeCl3 system and minimize the efforts on the process optimization for Li extraction from Mg-rich salt-lake brines with different component concentrations from different sources, a thermodynamic empirical model based on mass balances and equilibrium equations has been developed. The model parameters were optimized by fitting the calculated data to experimental results. By calculating the distribution of species in the organic phase with the model, it was found that Li~+ primarily existed in the form of [Li(TBP)2][FeCl4], followed by [Li(TBP)][FeCl4]. When Li~+ was stripped with water, Fe~(3+) mainly existed in the form of FeCl2L·HL·2TBP in the organic phase at low O/A ratios but converted to [H(TBP)2] [FeCl4] at high O/A ratios. This thermodynamic model provides a guide for the design of practical process flow.
查看更多>>摘要：Based on the dioctadecyldimethylammonium chloride surfactant, three novel ionic liquids (ILs) involving dio-ctadecyldimethylammonium ([DODMA]~+ cations and N,N-dialkyl-diglycolamide acid (DGA) anions was firstly designed and synthesized for extraction of thorium iOns in nitric acid solution. The integrated extraction and solidification of Th(IV) was developed by formation of self-assembly (SA) solid in two-phase interface. The SA solid was identified by spectroscopic methods including SEM with mapping EDS, XPS, FT-IR and ESI-HRMS. The excellent extraction efficiency was observed for extraction of thorium using [DODMA]+[DGA]'' ionic liquids, more than 99% of Th(IV) were extracted and enriched as SA solid in one-step process. The outstanding selectivity of Th(IV) to Ln(III) and U(VI) was observed, and separation factors were up to 3470 for Th/Eu and more than of 1980 for Th/U, respectively. The proposed strategy not only provides an alternate method for the separation of thorium ions with uranyl ions and lanthanides(III) ions in the nuclear fuel cycle, but also pioneers to develop the self-assembly extraction based on [DODMA]~+ ionic liquids. In view of the similarity of Pu(IV) and Th(IV), the simple integrated strategy may be further expanded for extraction and enrichment of Pu(IV) in nuclear industry.
查看更多>>摘要：Electrically conductive membranes (ECMs) have the potential to conduct and distribute an externally applied potential across the membrane surface, which enable some phenomena at the membrane/water interface, including increase in electrostatic repulsive forces between foulants and the membrane surface, and electrochemical oxidation and reduction of toxic contaminants. The objective of this study was to develop highly stable and conductive polyaniline/multiwall carbon nanotubes (PANI/MWNT) membranes through vacuum filtration assisted layer-by-layer assembly technique coupled with heat treatment, and to demonstrate its application in electrochemical filtration systems to degrade contaminants and reduce membrane fouling. The PANI/MWNT conductive membrane was assembled for ten bilayers through the comprehensive evaluation of surface conductivity, pure water flux, pore size distribution and electrochemical properties. The surface conductivity, pure water flux and average pore size of the membrane were 732.0 S/m, 596.6 L/m~2·bbar and 72.0 nm, respectively. The stability evaluation revealed that the conductive membrane exhibited excellent physical, electrochemical and chemical stability. The degradation rate of methylene blue, methyl orange and phenol can achieve 94.9%, 96.1% and 95.6% under the applied voltage of 2.5 V, much higher than the traditional electrochemical oxidation process. Anti-fouling test conducted with humic acid showed mat the fouling was effectively alleviated and the flux recovery rate increased from 63.3% to 78.0% when a negative bias was applied. This study provides a new insight for the multifunctional application of ECMs and offers a promising enhancement to existing membrane-based water treatment processes.
查看更多>>摘要：A kind of novel catalytic pervaporation membrane was fabricated for the process intensification of the synthesis of ethyl acetate. Firstly, asymmetric PVA pervaporation membranes (AMs) were prepared by non-solvent induced phase separation (NIPS) method, then the asymmetric membranes were modified with 5-sulfosalicylic acid for the grafting of sulfonic acid group to form the asymmetric 5-sulfosalicylic acid - PVA catalytic pervaporation membranes (CMs). For the separation performances of CMs, in the pervaporation of 2 wt% water - ethyl acetate, water flux and separation factor of CMs with the 8 wt% PVA could reach 756.2 g/(m~2·h) and 592.87 respectively. For the catalytic performance of CMs, final acetic acid conversion rate reached 63.5% in the synthesis of ethyl acetate. Furthermore, for the coupling experiments of catalysis with pervaporation, the conversion rate was 20% higher than diat of ordinary catalytic reaction and the CMs showed excellent reusability that the conversion rate still reached 87% after 5 runs.
查看更多>>摘要：With increasing amounts of the discharge of oily wastewater and the ongoing occurrence of oil spills at sea, it is vitally important to achieve efficient and green oil/water separation using an effective and low-energy-consumption technology. Although hydrogel membranes for oil/water mixtures separation have been extensively reported, it is still a challenge to develop hydrogel membranes with superior mechanical properties and resistance to complex environment. In our work, a perforated kelp membrane (PKM) was fabricated through a one-step laser perforating method using natural kelp as a raw material. The obtained membrane is capable of achieving oil/water separation with high flux (>1210.7 L-m~(-2)·h~(-1)) and excellent separation efficiency (>99.8%). In addition, the kelp membrane manifests favorable mechanical performances with a tensile strength of 2.12-3.89 MPa and strain of 117.59-183.00%, when exposed to complex conditions (strongly acidic, alkaline, saline, low temperature, and boiling water). More importantly, kelp membranes are completely degraded under natural condition after 30 days. Therefore, the economy and eco-friendly PKMs with outstanding mechanical properties are expected to provide a promising candidate for oil/water separation.
查看更多>>摘要：Efficient separation of fine-disseminated rhodochrosite is a challenge in the purification of manganese carbonate ore and a key to reduce the discharge of electrolytic manganese slag. The agglomeration behavior of the fine particles is of importance for flotation separation. In this study, we investigated the agglomeration behavior and aggregate properties of rhodochrosite fines co-induced by oleic acid (OA) and shearing using particle size and structure analysis, surface properties measurement, extended DLVO (EDLVO) theoretical calculation and shear fracture model analysis. The results showed that rhodochrosite fines agglomerates obviously with the increasing OA concentration and pH value, and the average particle size reaches the maximum at the initial OA concentration of 1 × 10~(-3) mol/L and pH of 6. The monolayer physical and chemical saturation adsorption of OA cause stronger hydrophobicity of rhodochrosite. Meanwhile, the hydrophobic attractive force between particles is stronger than electrostatic repulsive force, resulting in hydrophobic agglomeration. The moderate stirring rate is conducive to forming larger-sized and denser agglomerates with the critical rate of 500 rpm. However, intensive shearing will cause significant damage to the formed agglomerates. Besides, the volume concentrations of 10-30 μm and 30-45 μm particles increased with the increase of stirring rate after breakage and with a lower value of γ than 0.5, suggesting that the agglomerates breakage is mainly controlled by large-scale fragmentation mechanism. Interestingly, as recovering shearing from the higher rate to the initial rate, a secondary agglomeration is achieved by the regrowth of core (30-45 μm particles) and attach of branches and coadngs (some < 10 μm and 10-30 μm particles) under the synergy of hydrophobic attraction and shearing. However, it did not fully recover back to the original balanced state before fragmentation, which was due to irreversible damage caused by excessive shearing. This research will be beneficial for in-depth understanding of agglomeration mechanisms of rhodochrosite fines and provide a basis for subsequent efficient flotation separation.
查看更多>>摘要：To separate the antitumor drug doxorubicin by polyacrylonitrile (PAN)- polyamide (PA) thin film composite (TFC) membrane, different factors were exploited including adjusting the size of pores, membrane superficial charge, and pH of the medium. For this purpose, copper oxide nanoparticles and silica hydrogel were added to the superficial PA layer and PAN sublayer, respectively, whereby Si_iPAN-CujPA membranes were synthesized. Energy Dispersive X-Ray Spectroscopy (EDS) test confirmed the presence of Cu in the superficial layer and Si in the sublayer. The effect of Si on enhancing the sublayer porosity was proven by scanning electron microscopy (SEM) images, and the impact of Cu on increasing the crosslinking of the superficial layer was demonstrated by attenuated total reflection-fourier transform infrared (ATR-FTIR) test. The results indicated that adding silica hydrogel to the raw SioPAN-CuoPA membrane, through 22% increase in membrane porosity, caused elevation of flux from 12.3 to 27.9 LMH for Si3PAN-Cu_0PA membrane. Meanwhile, the level of rejection and flux recovery of this membrane eventually reached 77 and 58% respectively. Addition of copper oxide nanoparticles to the Si3PAN-Cu0PA membrane, through reducing the size of membrane pores from 6.2 to 4.7 nm, caused the Si3PAN-CU3PA membrane rejection to grow to 86% and flux recovery to 97%. Eventually, upon elevating the pH from 2 to 8, because of shrinkage of the membrane pores according to the Brunauer-Emmett-Teller (BET) analysis, increased superficial charge and zeta potential as well as reduction of the membrane pH_(PZC), the doxorubicin rejection was boosted to 99.4%.
Diego Rodriguez-LlorentePablo NavarroPablo Gutierrez-Sanchez
12页
查看更多>>摘要：The increasing consumption of pharmaceuticals, along with the ineffectiveness of conventional wastewater treatment, has resulted in an increased presence of these pollutants in both drinking water supplies and aquatic environments. The potential adverse health effects and environmental impact of these chemicals are drawing the attention of several bodies around the world. For instance, some antibiotics such as ciprofloxacin, trimethoprim, and sulfamethoxazole have been included in the most recent European Surface Water Watch List under the EU Water Framework Directive (Decision 2020/1161). The present work proposes the use of terpenoids and eutectic solvents, as effective and green solvents with low toxicity, for multicomponent liquid-liquid extraction of ciprofloxacin, trimethoprim, and sulfamethoxazole from ultrapure water and hospital wastewater. The COSMO-RS method was used for a predictive initial solvent screening. Thymol, carvacrol, eutectic solvents (thymol + fatty acids), and conventional solvents (methyl isobutyl ketone and ethyl acetate) were selected to be used in the experiments. The influence of the volumetric S/F ratio, aqueous matrix, and pH was analysed. Conventional solvents show significantiy lower overall extraction yields than those observed for eutectic solvents and terpenoids at any pH and matrix. Carvacrol presented the most favourable conditions, reaching overall extraction yields above 98.0% (98.9% for trimethoprim, 99.5% for ciprofloxacin, and 97.0% for sulfamethoxazole) with hospital wastewater at pH 5.0 and S/F ratio of 1.00. Carvacrol showed a feasible operation in a continuous extraction column at room temperature, providing effective reuse and regeneration processes in this study.
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