查看更多>>摘要：The energy-efficiency of the traditional distillation-based processes are low, which results in waste of resources and environmental pollution. Therefore, a sustainable extractive distillation (ED) process should be developed to reduce energy consumption and CO2 emissions while improve the energy efficiency. In this work, a systematic approach is developed for the first time, for the separation of ternary azeotropic mixture containing Tetrahydrofuran (THF)/Ethyl acetate (EtAC)/Water via the combination of side-stream distillation and vapor recompression heat pump techniques. Firstly, the conceptual design of the various intensified schemes such as single (or double) side-stream(s) ED configurations are developed. Subsequently, the developed configurations were optimized using mesh adaptive direct search algorithm to obtain the optimal operating conditions of the established processes. Vapor recompression heat pump technique is used to further reduce the energy consumption. The sustainability of the various established configurations is assessed via the comparison of total annual cost (TAC), CO2 emissions, energy consumption, and thermodynamic efficiency. Overall, it was revealed that the TAC, CO2 emissions, and energy-consumption for the integrated vapor recompression assisted side-stream ED process were reduced by 33%, 49%, and 38%, respectively, relative to the conventional triple column ED. Likewise, the thermodynamic efficiency was improved by 52%.
查看更多>>摘要：One of the most successful methods for reducing membrane fouling in filtration and separation applications is zwitterionic surface modification. Herein, poly[(2-methacryloyloxyethyl phosphorylcholine)-co-(glycidyl methacrylate)] (poly(MPC-co-GMA)) was synthesized as a zwitterionic polymer and grafted onto the polysulfbne (PSF) microfilter membrane using polydopamine chemistry. The stepwise modifications and formation of the zwitterionic PgEDgMG membrane were established by analyzing chemical structure, surface morphology, charge, and wetting properties. The antifouling properties were established by bovine serum albumin (BSA) protein adsorption as low as 3.71 ± 0.78 μg cm~(-2), fluorescence imaging, and in-situ BSA adsorption via zeta potential measurements. After zwitterionization, the in-air and underwater oil wetting tests demonstrate the formation of superhydrophilic and superoleophobic membranes, which are critical for oil-water separation. Finally, the prepared membranes were evaluated in batch and continuous mode for soybean and silicone oil-water emulsion separation. The modified membrane demonstrated nearly complete oil rejection (>99%) and flux recovery up to 99% after a continuous 10-cycle operation along with retention of initial flux during continuous filtration for 12 h. Overall, the combination of polydopamine and poly(MPC-co-GMA) created a robust zwitterionic antifouling surface which induces superhydrophilic character and can be used for long-term water purification and sep-aration applications.
查看更多>>摘要：Recently developed porous materials known as metal-organic frameworks (MOFs) are useful platforms for separating a wide range of contaminants from water. MOFs, which are presently being investigated for water treatment, have effectively separated various contaminants from freshwater. A thin-film composite (TFC) membrane made of GO@CuBTC incorporated polyvinylidene fluoride (PVDF) membrane was investigated in this study for its ability to perform pervaporative desalination of synthetic saltwater. Using phase inversion, we successfully synthesize highly stable, selective, and reproducible GO@CUBTC integrated PVDF membranes for saltwater desalination. The field-emission scanning electron microscopy with Energy Dispersive X-Ray (FESEM-EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), membrane thickness and porosity, water uptake, and contact angle was used to characterize the resulting MOF and membranes. The pervaporative desalination performance was studied as a function of GO@CUBTC loading, feed composition (0 g IT~(-1) to 35 g L~(-1) NaCl), and feed temperature (55 to 75 °C). The experimental data found that the 2% GO@CuBTC/PVDF has the highest water flux of 36.79 ± 0.3 L m~(-2)h~(-1) with the salt rejection of >99.68 ± 0.048% among all five membranes with performance stability of 260 h. The experimental results indicate that GO modified CuBTC could be an important material for the preparation of hydrophilic pervaporative desalination membranes.
查看更多>>摘要：In this work, a novel sulfur-functionalized alkynyl carbon materials (SACMs) were synthesized by mechanochemical reaction of CaC2 and CS2 with rich sulfur and alkynyl functional groups, as well as high porosity and surface area. Their sulfur content varies from 4.1 % to 39.8 %, depending on the stoichiometric ratio of the reactants used. The SACM-2 exhibits extremely high mercury uptake capacity (500 mg·Hg · g~(-1) at ca. 2 μg· g~(-1) of equilibrium Hg(II) concentration), being one of the best adsorbents, and it showed favorable recyclability after 5 cycles. The adsorption behavior follows the Freundlich and the pseudo second-order kinetic model, respectively. The SACM-2 was examined for aqueous phase adsorption of mercury, cadmium, lead, and copper ions. Its affinity for neat heavy metals was in the order of Hg(II) >Cd (II) >Pb(II) >Cu(II). The high-efficiency adsorption of Hg(II) was mainly attributed to the sulfur and alkynyl functional groups as well as their synergestic effect for specific soft acid-soft base interaction between adsorbent and the heavy metal ions. Overall, our work not only reports a promising material for removal of heavy metals-containing wastewater, but inspires the value-added utilization of CS2 in preparing other highly sulfureted materials.
查看更多>>摘要：Cu~I-functionalized materials are highly promising for diverse applications. Unfortunately, the poor oxidation resistance of Cu~I limits their practical applications. Due to the co-presence of moisture and oxygen, Cu~I is easily oxidized to Cu~(II), resulting in loss of activity. Herein, we have tailored a superhydrophobic micro environment to stabilize Cu~I against oxidation by coordinating octadecylphosphonic acid (OPA) onto metal nodes on the surface of metal-organic frameworks. As a proof of concept, MIL-101(Cr) was employed as support to introduce Cu~I active sites, producing Cu~IM. By grafting OPA onto metal nodes on the surface, the original hydrophilic surface turns to be superhydrophobic, which hinders the access of moisture to Cu~I, thus stabilizing Cu~I despite the aerobic conditions. The OPA-grafted material, Cu~IM-OPA, shows constant Cu~I content under the atmosphere for a month, while only 4% Cu~I is retained in Cu~IM after a week. After exposure for a month, Cu~IM-OPA can remove 0.232 mmol/g thiophene, which is evidently superior to CurM (0.015 mmol/g) in spite of the similar initial uptakes. Notably, Cu~IM-OPA shows intriguing adsorptive desulfurization from hydrated fuel without loss in four cycles, whereas only 4% capacity is retained in Cu~IM.
查看更多>>摘要：Algal/polyethyleneimine composite beads (ALPEI) have been successfully functionalized by grafting phosphonate (ALPEI-P), quaternary ammonium groups (ALPEI-Q), and by dual moieties (ALPEI-PQ). The materials are characterized by a wide diversity of analytical methods: SEM and SEM-EDX, TGA, BET, FTIR and XPS, elemental analysis and titration (detailed discussion in Supplementary Information). FTIR and XPS analyses show contributions of quaternary ammonium, hydroxyl, and phosphonate groups in tungstate binding (which may involve polynuclear species, depending on the pH). The synergistic effects of phosphonate and quaternary ammonium moieties contribute to strongly increase W(VI) sorption capacity up to 1.8 mmol W g~(-1) (i.e., 4-times compared with pristine beads), at pH 5. The strong increase of sorption properties with temperature (2.45 mmol W g~(-1) at T: 50 °C) demonstrates the endothermic nature of metal binding, which is spontaneous (and characterized by positive entropy change). The Langmuir Dual Site equation successfully fits sorption isotherm for functionalized sorbents (bearing phosphonate and phosphonate/quaternary ammonium groups in addition to proper reactive groups of pristine beads) contrary to the isotherms for raw beads (fitted by Langmuir equation). The pseudo-first order rate equation fits kinetics (equilibrium reached within ≈60 min). The bi-functional sorbent show's marked preference for W(VI) against base and alkali-earth metals (especially at pH close to 3.5). These properties are confirmed in the treatment of raffinate solutions (after ore leaching and solvent extraction): despite the complexity of the effluent, ALPEI-PQ reveals highly efficient for W(VI) recovery and separation. The sorbent can be used as a polishing treatment for enhancing the recovery of strategic metals. Sorbed tungstate is readily desorbed from the sorbent using 0.2 M NH4Cl solution. The sorbent is efficiently recycled for at least 5 cycles (complete desorption, loss in sorption performance less than 4% at the fifth cycle).
查看更多>>摘要：Herein, lanthanum/aluminum engineered bentonite (LAB) was developed for efficient phosphate separation from aqueous media. LAB-1 (La/Al = 1) exhibited highest adsorption capacity among all samples, and batch experiments indicated that LAB-1 could maintain efficient phosphate uptake (>90%) within the interference of competing anions (Cl~-, NO3~-, HCO3- and SO4~(2-)). Acidic condition (pH 3-6) was beneficial to phosphate capturing, and the maximum experimental capacity of LAB-1 was detected as ~ 93.61 mg P/g. Kinetic modelling with the preferred fitness of pseudo-second-order model revealed the chemisorption nature of phosphate uptake process, while isotherm test suggested multilayer adsorption of phosphate on heterogeneous LAB-1 surface. Adsorption thermodynamics uncovered the spontaneous and endothermic feature of phosphate loading on LAB-1, and phosphate loading contributed to increased randomness of engineered surface. Characterization analysis demonstrated the growth of crystalline lanthanum carbonate hydrate on LAB-1, while phosphate uptake converted it to LaPO4·0.5H2O crystal. However, amorphous Al hydroxide and Al-P complex after adsorption were supposed. Detailed investigation demonstrated the joint involvement of La and Al sites and the formation of metal-P complex through ligand exchange.
查看更多>>摘要：Spent fuel reprocessing is the main part of the closed recycling of nuclear fuel. The efficient capture of radioactive iodine in spent fuel reprocessing remains a major issue for the safe utilization of nuclear energy. To possibly substitute the silver-containing zeolites of high cost, copper-doped porous silica including microporous silicalite-1 zeolite (denoted as Cu-S-1) and mesoporous SBA-15 (denoted as Cu-SBA-15) different from those of copper-exchanged ones previously reported were investigated for iodine adsorption at moderate temperature. The influence of pore diameter on iodine adsorption was emphatically discussed. Because of the nanosized pore structure, Cu-S-1 and Cu-SBA-15 exhibited high iodine adsorption capacities of 501 mg g~(-1) and 59 mg g~(-1), respectively. The iodine adsorption capacity of Cu-S-1 was higher than those of the silver-containing ones reported up to now. Moreover, it was revealed that the microporous structure was more beneficial to adsorb iodine than the mesoporous structure. These copper-doped silica zeolites provide the possibility for the application of iodine adsorption in practical postprocessing conditions.
查看更多>>摘要：Construction of S-scheme heterojunctions that efficiently separate photogenerated electrons and holes is an emerging strategy for the development of high-efficiency performance photocatalysts for the photodegradation of organic pollutants. In this study, S-scheme WO3/BiOBr heterojunction nanoflowers enriched with oxygen vacancies (Vo) were synthesized for the first time via a one-pot hydrothermal method without the addition of surfactants. The XPS characterization of the WO3/BiOBr-Vo indicated the formation of internal electric field at the WO3/BiOBr interface, which facilitated charge separation and charge transfer. The superior ability of WO3/BiOBr-Vo to separate photoinduced electron-hole pairs was confirmed by photoluminescence and photocurrent responses. As a result, the optimal 25WO3/BiOBr-Vo photocatalyst decomposed 100% tetracycline after 50 min of visible light irradiation while pure BiOBr-Vo and WO 3 decomposed less than 90% and 40% of tetracycline, respectively. The EPR analysis and free radicals trapping experiments found that the ·O2~- was the main active species in the photocatalytic mechanism. The oxygen vacancies provided readily accessible reaction sites for the conversion of O2 to ·O2~-. Toxicity assessment revealed that the aquatic toxicity of tetracycline was efficiently reduced after photodegradation. This study demonstrated a promising method for the development of high-performance photocatalysts based on band structure optimization and crystal defect engineering.
查看更多>>摘要：Lithium-aluminum layered double hydroxides (Li-Al LDHs) are a unique group of LDHs and their applications have attracted wide attention. Herein, Li-Al LDH was prepared using the hydrothermal method and was then used to activate peroxymonosulfates (PMS) for degrading sulfamethoxazole (SMX). It was found that 0.4 g/L catalysts, 1.57 mM PMS, and pH = 11.00 were the optimal conditions for the degradation process of the Li-Al LDH/PMS system at 30 °C. Under these conditions, the degradation rate of 80 mg/L SMX could reach 98.2% within 130 min. Meanwhile, the catalyst also showed superior stability and recoverability. After five cycles, the degradation rate of SMX was still higher than 95.3%. Based on free radical scavenging experiments and electron spin resonance results, both the radical and nonradical pathways synergistically completed the degradation in the Li-Al LDH/PMS system, with the nonfree radical (singlet oxygen) playing the predominant role. A reasonable degradation pathway was also proposed based on the detection of intermediates in the degradation process. The Li-Al LDH/PMS system, as expected, has great potential for efficient wastewater catalytic treatment.
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