Selective separation and recovery of Co(Ⅱ)and Ni(Ⅱ)from lithium-ion battery using Cyanex 272 adsorptive membrane

Liquid-liquid solvent extraction,commonly used for high purity Co(Ⅱ)extraction,suffers from drawbacks such as environmental pollution and high cost.To overcome these challenges,a novel Cyanex 272(bis(2,4,4-trimethyl pentyl)phosphinic acid,HCyanex)adsorptive membrane(CAM)was synthesized using the phase inversion method with varied Cyanex 272 loadings(0–52.5%)to extract Co(Ⅱ)from cobalt-nickel mixed sulfate solution.Fourier transform infrared(FTIR)spectrometer,Scanning electron microscopy(SEM),and Energy dispersive X-ray spectroscopy(EDX)of asprepared CAMs confirmed the successful and homogeneous blending of Cyanex 272 with poly(vinylidenefluoride)(PVDF),and increased pore sizes were observed with the addition of Cyanex 272.The highest Co(Ⅱ)removal was achieved by the CAMs containing 33.2%weight percentage of Cyanex 272 to PVDF with a Langmuir sorption capacity of 1.42 mg/g.The extraction process for Co(Ⅱ)and Ni(Ⅱ)by CAMs was sensitive to pH and temperature,with an optimal separation factor of 209.5 at pH 6.8 and 75°C.The adsorption process is endothermic.Additionally,the membrane exhibited excellent stability and durability,maintaining around 98%adsorption capacity after 20 cycles in the recycling process.These findings suggest that the as-prepared CAMs are a promising technology for the separation of Co(Ⅱ)from Ni(Ⅱ)in the recycling process of lithium-ion batteries.

Removal of copper by modified chitosan adsorptive membrane

In this study,a novel adsorptive membrane was prepared from chitosan as the functional polymer and some additive blend solutions by solution casting method.The modified chitosan membrane was characterized by FTIR and its Water Swelling Ratio(WSR).The adsorption of copper ions on the adsorptive membrane was investi-gated in batch experiments.The results obtained from the experiments indicated that the membrane had a good adsorption capacity for copper ions,the optimal ionic strength and pH were 0.1 and 5–6,respectively.Compared with the Langmuir isotherm model,the experimental data were found to be following the Freundlich model.

Role of membrane and compound properties in affecting the rejection of pharmaceuticals by different RO/NF membranes

This study was conducted to assess the merits and limitations of various high-pressure membranes, tight nanofiltration （NF） membranes in particular, for the removal of trace organic compounds （TrOCs）. The performance of a low-pressure reverse osmosis （LPRO） membrane （ESPA1）, a tight NF membrane （NF90） and two loose NF membranes （HL and NF270） was compared for the rejection of 23 different pharmaceuticals （PhACs）. Efforts were also devoted to understand the effect of adsorption on the rejection performance of each membrane. Difference in hydrogen bond formation potential （HFP） was taken into consideration. Results showed that NF90 performed similarly to ESPA1 with mean rejection higher than 95%. NF270 outperformed HL in terms of both water permeability and PhAC rejection higher than 90%. Electrostatic effects were more significant in PhAC rejection by loose NF membranes than tight NF and LPRO membranes. The adverse effect of adsorption on rejection by HL and ESPA1 was more substantial than NF270 and NF90, which could not be simply explained by the difference in membrane surface hydrophobicity, selective layer thickness or pore size. The HL membrane had a lower rejection of PhACs of higher hydrophobicity （log D〉0） and higher HFP （〉0.02）. Nevertheless, the effects of PhAC hydrophobicity and HFP on rejection by ESPA1 could not be discerned. Poor rejection of certain PhACs could generally be explained by aspects of steric hindrance, electrostatic interactions and adsorption. High-pressure membranes like NF90 and NF270 have a high promise in TrOC removal from contaminated water.

Membrane fouling controlled by coagulation/adsorption during direct sewage membrane filtration(DSMF) for organic matter concentration

Unlike the role of the membrane in a membrane bioreactor, which is designed to replace a sediment tank, direct sewage membrane filtration（DSMF）, with the goal of concentrating organic matters, is proposed as a pretreatment process in a novel sewage treatment concept. The concept of membrane-based pretreatment is proposed to divide raw sewage into a concentrated part retaining most organics and a filtered part with less pollutant remaining, so that energy recovery and water reuse, respectively, could be realized by post-treatment. A pilot-scale experiment was carried out to verify the feasibility of coagulant/adsorbent addition for membrane fouling control, which has been the main issue during this DSMF process. The results showed that continuous coagulant addition successfully slowed down the increase in filtration resistance, with the resistance maintained below 1.0 × 1013m^（-1） in the first 70 hr before a jump occurred. Furthermore,the adsorbent addition contributed to retarding the occurrence of the filtration resistance jump, achieving simultaneous fouling control and chemical oxygen demand（COD）concentration improvement. The final concentrated COD amounted to 7500 mg/L after 6 days of operation.

Positively charged microporous ceramic membrane for the removal of Titan Yellow through electrostatic adsorption

To develop a depth filter based on the electrostatic adsorption principle, positively charged microporous ceramic membrane was prepared from a diatomaceous earth ceramic membrane.The internal surface of the highly porous ceramic membrane was coated with uniformly distributed electropositive nano-Y2O3 coating. The dye removal performance was evaluated through pressurized filtration tests using Titan Yellow aqueous solution. It showed that positively charged microporous ceramic membrane exhibited a flow rate of 421 L/（m^2·hr） under the trans-membrane pressure of 0.03 bar. Moreover it could effectively remove Titan Yellow with feed concentration of 10 mg/L between pH 3 to 8. The removal rate increased with the enhancement of the surface charge properties with a maximum rejection of 99.6%. This study provides a new and feasible method of removing organic dyes in wastewater. It is convinced that there will be a broad market for the application of charged ceramic membrane in the field of dye removal or recovery from industry wastewater.

Hierarchically Porous Carbon Membranes Derived from PAN and Their Selective Adsorption of Organic Dyes

Porous carbon membranes were favorably fabricated through the pyrolysis of polyacrylonitrile（PAN） precursors, which were prepared with a template-free technique-thermally induced phase separation. These carbon membranes possess hierarchical pores, including cellular macropores across the whole membranes and much small pores in the matrix as well as on the pore walls. Nitrogen adsorption indicates micropores（1.47 and 1.84 nm） and mesopores（2.21 nm） exist inside the carbon membranes, resulting in their specific surface area as large as 1062 m2/g. The carbon membranes were used to adsorb organic dyes（methyl orange, Congo red, and rhodamine B） from aqueous solutions based on their advantages of hierarchical pore structures and large specific surface area. It is particularly noteworthy that the membranes present a selective adsorption towards methyl orange, whose molecular size（1.2 nm） is smaller than those of Congo red（2.3 nm） and rhodamine B（1.8 nm）. This attractive result can be attributed to the steric structure matching between the molecular size and the pore size, rather than electrostatic attraction. Furthermore, the used carbon membranes can be easily regenerated by hydrochloric acid, and their recovery adsorption ratio maintains above 90% even in the third cycle. This work may provide a new route for carbon-based adsorbents with hierarchical pores via a template-free approach, which could be promisingly applied to selectively remove dye contaminants in aqueous effluents.

Surface/Interfacial design and tailoring of polymeric membranes for liquid-phase separation

Synthetic polymer membranes are widely used in many applications,including,among others,water purification,protein separation,and medicine.However,the use of existing polymer membranes faces major challenges,such as the trade-off between permeability and selectivity,membrane fouling,and poor mechanical strength.To address these problems the authors have focused their research on surface/interfacial tailoring and the structure-property relationship of polymer membranes used in liquid separation systems.Progress has been made as follows:(1)a methodology for membrane surface functionalization and nanofiltration(NF)membrane preparation based on mussel-inspired catecholic chemistry was proposed and established;(2)a class of mechanically robust and environmentally-responsive composite membranes with hydrogel pore-filled in rigid macroporous supports was designed and developed;(3)a methodology for surface tailoring and antifouling modification of polymer membranes based on amphiphilic copolymers was created and the scientific implications for amphiphilic polymer membranes elaborated;(4)an adsorption membrane with both filtration and adsorption functions was designed and developed to achieve rapid removal of trace micropollutants,including heavy metal ions,organic dyes,plasticizer,antibiotics,and others.This mini-review briefly summarizes this work.

The energy-free purification of trace thallium(I)-contaminated potable water using a high-selective filter paper with multi-layered Prussian blue decoration

Thallium is a highly toxic metal,and trace amount of thallium(I)(Tl+)in potable water could cause a severe water crisis,which arouses the exploitation of highly-effective technology for purification of Tl+contaminated water.This report proposes the multi-layered Prussian blue(PB)-decorated composite membranes(PBx@PDA/PEI-FP)based on the aminated filter papers for Tl+uptake.Extensively characterization by Fourier transform infrared spectrometer-attenuated total reflectance,scanning electron microscope,thermogravimetric analysis,X-ray photoelectron spectroscopy and X-ray diffraction were performed to confirm the in situ growth of cubic PB crystals on filter paper membrane surfaces via the aminated layers,and the successful fabrication of multi-layered PB overcoats via the increasing of aminated layers.The effect of PB layers on Tl+removal by PBx@PDA/PEI-FP from simulated drinking water was evaluated as well as the influence of different experimental conditions.A trade-off between PB decoration layer number and PB distribution sizes is existed in Tl+uptake by PBx@PDA/PEI-FP.The double-layered PB2@PDA/PEI-FP membrane showed the maximum sorption capacity,but its Tl+uptake performance was weakened by the acid,coexisting ions(K+and Na+)and powerful operation pressure,during filtrating a large volume of low-concentrated Tl+-containing water.However,the negative effect of coexisting ions on the Tl+uptake could be effectively eliminated in weak alkaline water,and the Tl+removal was increased up to 100%without any pressure driving for PB2@PDA/PEI-FP membrane.Most importantly,PB2@PDA/PEI-FP displayed the high-efficiency and high-selectivity in purifying the Tl+-spiked Pearl River water,in which the residual Tl+in filtrate was less than 2μg·L^(–1) to meet the drinking water standard of United States Environmental Protection Agency.This work provides a feasible avenue to safeguard the drinking water in remote and underdeveloped area via the energy-free operation.