查看更多>>摘要：High efficiency separation is a significant process of the mechanical recycling to manage the mixed waste plastics. However, most of the extant methods can only deal with binary mixtures. In this paper, a novel automatic and continuous separation method based on magneto-Archimedes levitation is proposed to handle multi-plastics. A theoretical model on how the object is levitated above a single square magnet with the aid of paramagnetic media is established. The model revealed that object with different densities would be levitated at different heights. Lighter object would be levitated rapidly to a certain height and then be pushed away slowly. Thereby, the separated plastics could be collected automatically and the continuous separation of the mixtures can be addressed. The separation of polyurethane (PU), polyamide (PA6), and polytetrafluoroethylene (PTFE) demonstrated that the method can deal with multiple plastics with purities over 96.2%. Combined with additional advantages of low cost and no energy consumed in separation process, the method has the potential to be industrialized into an economically-viable and environmentally-friendly mass production procedure.
查看更多>>摘要：Plastic pollution has become one of the most pressing environmental issues. Meanwhile, developing highly efficient adsorbents for uranium removal from the wastewater of its tailings is also of great significance in environmental protection. In this study, wastes of the plastic membrane in daily life were recycled and functionalized to treat uranium pollution in the environment. Membrane adsorbent with amidoxime (AO) group was successfully prepared using recycled plastic membranes through two-step polymerization. A network of nano holes and nanostructured particles were observed on the surface of the AO modified membrane (AO -membrane) adsorbent. The adsorption performances from uranium solution and uranium tailings wastewater were evaluated in batch and column adsorption experiments. AO-membrane exhibited good removal performance in a wide pH range from 2 to 8. After adsorption in uranium tailings wastewater, the equilibrium concentrations of uranium in solution were lower than 50 mu g/L, meeting the national standard of uranium solution discharge (50 mu g/L). AO-membrane could reach adsorption equilibrium within 5 h in uranium tailings wastewater and present uranium removal ratio of nearly 100%. These indicated that this AO-membrane could be used for deep purification of wastewater, especially with low uranium concentration. AO-membrane exhibited a remarkable reuse performance and long service life. During the 10 cycles of adsorption and desorption, AO-membrane exhibited almost 100% uranium removal ratio even after ten adsorption and desorption cycles. This work provides new insights into the technology of waste control by waste.
查看更多>>摘要：Hydrogel microspheres encapsulating molecularly imprinted polymers (MIPs) are promising hybrid sorbents, due to several advantages of high selectivity, fast mass transfer efficiency, and simple collection. Thus, Janus single hole hollow nanoparticles (J-HNPs) with the size of 550 +/- 70 nm were firstly designed by anisotropic emulsion template, and then MIPs were grafted onto their inner surface through electron transfer atom transfer radical polymerization (ARGET ATRP). Then as-prepared J-HNPs-MIPs were loaded into hydrogel microspheres via polymerizable water-in-oil (W/O) emulsion droplets combining gelatin methacryloyl (GMA) as monomers, and then obtained J-HNPs-MIPs@Gel with the mean diameter of 2.0 mu m was applied for effective and selective separation of 2'-deoxyadenosine (dA). Fast adsorption equilibrium of J-HNPs-MIPs@Gel for dA can be achieved within 40 min, thanks to the hydrogel matrix and single-hole hollow structure for enhancing diffusion. The maximum multi-layer adsorption capacity calculated according to the Freundlich model was 10.31 mu mol g(-1) at 298 K. The specific memory to the size, shape and functional groups of dA endowed excellent recognition ability, and 88% of the initial capacity after four consecutive adsorption-desorption cycles was maintained. In addition, J-HNPs-MIPs@Gel was expected to show great potential for the selective enrichment and analysis of target dA molecule in complex biological samples.
查看更多>>摘要：The sustainable utilization of metal resources and the imbalance between supply and demand for metals urgently require the recovery of metals from e-waste, which is considered an "urban mine. " In this study, poly-N-phenylglycine (PNPG) particles were firstly used to capture gold with adsorption capacity (1356.78 mg.g(-1)) and good sensitivity to Au(III) in low-concentration solutions at pH 1. The mechanism of Au(III) adsorption by PNPG mainly involved chemisorption and monolayer adsorption, as evidenced by the well-fitting pseudo-second-order model and Langmuir isotherm model. Electrostatic interactions and redox reactions occurred during adsorption, as characterized by zeta potential, XRD, TEM, FT-IR, and XPS. To solve the problem of removing the adsorbent after adsorption, the PNPG membrane was prepared in advance by vacuum filtration, and corresponding stability test experiments were conducted. SEM characterization revealed that the support layer did not participate in the adsorption process. The PNPG membrane remained active for a minimum of three cycles and could selectively capture Au(III) from uneven-concentration polymetallic solutions. Approximately 80% of the gold in the leaching solution of waste printed circuit boards of computers was selectively recovered using the prepared 2-mg PNPG membrane, proving the practical application of PNPG membranes for the recovery of gold from e-waste.
查看更多>>摘要：Coating a soluble shell material on the surface of nanoscale zero-valent iron (nZVI) particles to eliminate the problems of agglomeration and rapid aqueous corrosion of Fe(0) in groundwater is an effective strategy for longterm maintaining uranium removal efficiency. However, the precise role of controllable shell corrosion on uranium removal mechanism remains unclear. In this study, a homogeneously dispersed Mg(OH)(2) shell coated on nZVI (nZVI@Mg(OH)(2)) prepared by one-step surface precipitation was exploited to investigate the relationship between shell corrosion and uranium removal mechanism. The results confirm that nZVI with uniform coating shell (Mg(OH)(2)/Fe(0) = 1:2, mass ratio) was synthesized by simply mixing magnesium hydroxide with Fe2+ and NaBH4 solution under the flowing stream of N-2 (25 +/- 1 degrees C). The longevity and reactivity release rate of coated nZVI depended upon the initial pH value of the aqueous solution. At initial pH = 5, coated nZVI showed a high reduction activity, its ORP measured was 1.3 times that measured at initial pH = 3, and the duration could be prolonged to more than 4.5 times. The exposed Fe(0) core rapidly elimination U(VI) by synergistic attributed to the adsorptive (44.1%) and reductive (55.9%) processes after the passivation shell was eroded by reaction with H+. The results provide an efficient approach to improve the long-distance transport capacity and controllable release of nZVI, which can maintain its long-term reactivity in groundwater remediation.
查看更多>>摘要：Ethyl acetate (EAC) and isopropanol (IPOH) are important organic chemical raw materials. During the production of ampicillin sodium, there are a large amount of waste water containing EAC and IPOH. In order to separate the dilute solution containing EAC, IPOH, both a four-column extractive distillation process with pre concentration distillation column (PDC) and a three-column extractive distillation process of combining the pre-concentrated column with the extractant recovery column (ERC) are presented. In addition, three intensified processes with the application of heat integration and heat pump are proposed. The feasibility of the proposed processes is evaluated from four aspect: economy, energy consumption, environment, exergy analysis. The results show that these five processes have a good effect of energy saving and cost saving. Especially, the vapor recompressed heat pump assisted CTE process (HP-CTE) process, which is the most energy saving scheme, can reduce 37.80% of total annual cost, 55.43% of energy consumption, 54.46% of CO2 emission, 54.85% of SO2 emission, 54.82% of NOX emission, and 53.17% of exergy destruction, respectively, compared with the proposed four-column process.
查看更多>>摘要：Hydrophilic poly (ethylene-co-vinyl alcohol) (EVOH) was blended with hydrophobic polysulfone (PSF) in the presence of polyethylene glycol (PEG) (20 kDa), which acted as a hydrophilic additive and compatibilizer, to fabricate ultrafiltration (UF) membranes with high porosity and antifouling properties. The polymer blend containing 10 wt% EVOH was selected for optimization using PEG (0 to 24 wt%). After a detailed study, it was concluded that 20 wt% of PEG content was optimal for mixing with PSF/EVOH to increase miscibility. The membranes were characterized using differential scanning calorimetry (DSC) analysis, contact angle, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The effectiveness of PEG as a compatibilizer was observed via no phase separation occurred when the solution was allowed to stand at room temperature for four weeks. It was further confirmed by the appearance of a single T-m peak in DSC. In addition, molecular dynamic simulations illustrated that the PSF/EVOH 90/10 wt% blend had a radial distribution of g(r) = 3.29 angstrom, and g(r) = 2.69 angstrom in the presence of PEG, indicating better miscibility in the presence of PEG. Pure water permeance of blend membrane (85/15 wt%) reached 316 L.m(-2)h(-1) bar(-1), 54% greater than the pristine membrane. Simultaneously, bovine serum albumin (BSA) rejection of up to 97% and permeance recovery ratio of 87% were observed for the PSF/EVOH 90/10 wt% blend membrane, showing improved hydrophilicity and antifouling properties. These findings identify a potential modifier for fabricating low fouling UF membranes for wastewater treatment by blending with EVOH and PEG.
查看更多>>摘要：Ethyl acetate-isopropyl alcohol-water is a common ternary mixture in pharmaceutical and chemical industries, containing multiple binary minimum azeotropes. Highly efficient separation for this mixture is of great significance to reduce environmental risk, recover valuable resource and maintain eco-sustainability. In this work, various enhanced extractive distillation processes using ionic liquid (IL) as entrainer are compared with conventional extractive distillation process (CED) in terms of the reductions of cost, energy and carbon emissions. First of all, ethylene glycol (EG) and 1-ethyl-3-methylimidazolium acetate ([BMIM][OAC]) as the most promising conventional and IL entrainers are screening out through quantum chemistry calculation based on COSMO-SAC model. Secondly, two methods of improving energy efficiency such as differential pressure heat integration and divided-wall column are applied to the CED process. Finally, the resulting six configurations are optimized by simulated annealing algorithm, taking minimum total annual cost (TAC) as goal, and subsequently evaluated from four aspects of TAC, annual capital cost (ACC), annual operating cost (AOC) and CO2 emission. The results show that the new heat-integrated extractive distillation configuration with [BMIM][OAC] as entrainer, known as EDHI-IL is the best solution for ecological efficiency. As compared to the CED process, TAC, ACC, AOC and CO2 emission of this process are reduced by 38.86%, 36.51%, 41.41% and 41.36%, respectively.
查看更多>>摘要：Tailor-made ultrathin and defect-free supported ionic liquid membranes (SILMs) have great potential for CO2 separation. Herein, we developed a highly perm-selective CO2-philic laminated GO supported ionic liquid membrane (GO-SILM) with a thickness of 100 nm, via a reduced pressure-assisted vapor penetration strategy. Specifically, under reduced pressure condition, the IL 1-ethyl-3-methylimidazolium tetrafluomborate ([EMIM] [BF4]) vapor can not only seal the possible defects/pores in GO membrane, but also penetrate into the 2D nanochannels of laminated GO membrane. Based on the favorable interaction between IL and GO nanosheets, IL can be confined within the nanochannels of laminated GO membranes, which favors a fast and selective CO2 transport. Besides, the ultrathin selective layer shortens the transport distance extremely. Benefiting from the aforementioned features, the obtained GO-SILMs display a high CO2 permeance of 56.6 GPU with CO2/CH4 selectivity of 53.5, which is superior to other reported SILMs. The groundbreaking membrane fabrication approach through reduced pressure-assisted IL vapor penetration into GO membrane to seal the non-selective defects is facile, effective and IL-saving, which paves a new way for the development of ultrathin and defect-free SILMs for high-efficient CO2 separation.
查看更多>>摘要：Recently, the preparation of environmentally friendly adsorbent aerogels with reinforced mechanical performance has attracted much attention. As one of the promising environmentally friendly bio-materials, polysaccharide-based aerogels have a high potential for use in environmental engineering, especially for the absorption of water pollutants. However, the poor mechanical properties have seriously restricted their practical applications hence the development of a polysaccharide-based adsorbent with high mechanical properties is a critical challenge. Herein, we successfully fabricated a new kind of kappa-carrageenan/polyacrylamide double network aerogel containing graphene oxide (GO) nanosheets. The aerogel demonstrated excellent compressive strength (25.902 MPa), good toughness, resilience, and shape recovery, simultaneously. This could be mainly explained in terms of synergistic effects of newly formed reversible interactions induced by the formation of interpenetrating network structure, as well as the bridging effect of the GO nanosheets between the networks. Moreover, the adsorption experiments showed that the nanocomposite double network aerogel could effectively remove cationic and anionic dyes (maximum adsorption capacity: methylene blue = 105.18 mg/g, Congo red = 42.95 mg/g). It is hoped that this knowledge can contribute to the development of environmentally friendly adsorbent aerogels with high service life by enhancing their mechanical performances and can expand their applications, especially for the purification of contaminated aqueous media under high hydrostatic and hydrodynamic stresses.
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Elsevier