SEPARATION SCIENCE AND TECHNOLOGY
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2013
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IF 1.164
Jiahui Shao,Shu Qin,Wenxi Li,Yiliang He
Simultaneous recovery of nickel and cobalt from aqueous solutions by complexation-ultrafiltration process with polyethylenimine (PEI) was studied. Experiments were performed as a function of polymer/metal ratio (P/M), solution pH, and ionic strength. Effects of concentration time on metal rejection and membrane flux were also studied. At optimum experimental conditions of pH 6.0 and P/M 5.0, the nickel removal efficiency reaches at 99.9% and cobalt removal efficiency goes to 96.4%. Both nickel and cobalt removal efficiencies decreased as the adding salt concentration increases. During 12 h of the ultrafiltration process, the decline of membrane flux was less than 16% and the removal efficiencies for both nickel and cobalt were kept almost constant. Diafiltration was further performed to regenerate PEI. The removal efficiencies for both metals using recycled PEI were found to be close to those with the original PEI. Results from the two-step process of complexation-UF and decomplexation-UF separation showed that it could be a promising method for simultaneous recovery of nickel and cobalt from aqueous solutions.
研究领域:
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
Water
·
2019
·Vol. 11
·期 1
·90
·
IF 2.524
Fan Bu,Baoyu Gao,Qinyan Yue,Caiyu Liu,Wenyu Wang,Xue Shen
Ultra-filtration technology has been increasingly used in drinking water treatment due to improvements in membrane performance and lowering of costs. However, membrane fouling is the main limitation in the application of ultra-filtration technology. In this study, we investigated the impact of four different pre-treatments: Coagulation, adsorption, coagulation followed by adsorption (C-A), and simultaneous coagulation and adsorption (C+A), on membrane fouling and natural organic matter removal efficiency. The results showed that adsorption process required a large amount of adsorbent and formed a dense cake layer on the membrane surface leading to severe membrane fouling. Compared to adsorption alone, the coagulation and C-A processes decreased the transmembrane pressure by 4.9 kPa. It was due to less accumulation of particles on the membrane surface. As for water quality, the C-A ultra-filtration process achieved the highest removal efficiencies of natural organic matter and disinfection by-product precursors. Therefore, the addition of adsorbent after coagulation is a potentially important approach for alleviating ultra-filtration membrane fouling and enhancing treatment performance.Keywords:water treatment;ultra-filtration;coagulation;adsorption;membrane fouling
研究领域:
环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2012
·
IF 0.826
Jianxian ZENG,Xiahui SUN,Lifeng ZHENG,Qincheng HE,Shu LI
Polyquaternium-6 (PQ6) as the water-soluble polymer was used for complexing the anion forms of tungsten (VI) before ultrafiltration. Tungsten (VI)-PQ6 complex was retained by polysulfone hollow fiber ultrafiltration membrane in the complexation-ultrafiltration process. Effects of various operating parameters such as polymer metal ratio(PMR), pH and chloride ion concentration on permeate flux ( J ) and tungsten rejection coefficient ( R ) were investigated. The integration of four experiments including concentration, decomplexation, diafiltration and reuse of regenerated polymer was carried out. In the process of concentration, J declines slowly and R is about 1 at PMR of 3 and pH of 7. Tungsten concentration in the retentate increases linearly with volume concentration factor. Tungsten is concentrated efficiently with the membrane. The concentrated retentate was used further for the decomplexation. It takes about 6 min to reach the decomplexation equilibrium at chloride ion concentration of 50 mgL −1 . The decomplexation percentage of tungsten (VI)-PQ6 complex reaches 56.1%. In the diafiltration process, tungsten (VI) can be extracted effectively by using 50 mgL −1 chloride ion solution, and the purification of the regenerated PQ6 is acceptably satisfactory. The regenerated PQ6 was used to bind tungsten (VI) at various pH values. The binding capacity of the regenerated PQ6 is close to that of fresh PQ6, and the recovery percentage of binding capacity is higher than 90%.
研究领域:
化学工程
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Luolu Zhou,Meng Chen,Hu Yang,Zhen-liang Xu
This study introduces a novel ultrafiltration (UF) membrane, called NFFM, which utilizes a nanofiber (NF) layer as an integral filler during the phase inversion process. The photoactive NFFM was prepared using photoactive PAN-C 3 N 4 (PCN) NF, which is made using C 3 N 4 nanosheets as a visible light responsive photocatalyst with a loading ratio of up to 20%. NFFM membranes made using PAN NF, hydrophilic modified PAN-C 3 N 4 (HPC) NF as filler, and PAN-C 3 N 4 blend membrane were also prepared for comparison. NFFMs showed special morphologies, such as porous surfaces, selective layer located at the internal interface in cross-section, diverse pore sizes and pore size distribution , which are different from that of the traditional blend membrane made with the same ratio of components. Because the dissolving of NF layer into the casting solution changes the composition, polymer distribution, and property of the casting solution, thus change the membrane property. Thickness, composition and surface states of NF Layer can influence its dissolution process. Membrane filled with PCN NF (NFFM-PCN) showed a smaller pore size than membrane filled with HPC (NFFM-HPC), due to the low solubility of HPC. Moreover, a longer contacting time can cause the casting solution penetrate into the surface of the HPC layer, leading to a smooth surface. Finally, dye rejection and photoactivity test showed that NFFM-PCN showed better dye rejection property and photoactivity than other membranes, despite the lower photoactivity of C 3 N 4 due to the coverage effect of PAN. Overall, this primitive study provides a new method for preparing a new type of membrane for some potential applications.
研究领域:
材料科学
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环境工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Water Process Engineering
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2023
·
IF 7
Zhiwei Zhou,Chunjiao Liu,Liping Tian,Huiping Wang,Yanling Yang,Xiaobo Wang,Xiaoxiang Cheng
Moderate chemical pre-oxidation of coagulation to remove algae without breakage of the algae cells and release of algal organic matter has been well reported, while little was known about moderate pre-photocatalysis followed by coagulation on the ultrafiltration performance and membrane fouling control during algae-laden water treatment . Herein, three pretreatment methods (photocatalysis, coagulation and moderate pre-photocatalysis-enhanced coagulation (PC)) were investigated to reduce membrane fouling during ultrafiltration of algae-laden water. Moderate photocatalysis by a composite of Bi 2 O 3 -TiO 2 /PAC (Bi-doped TiO 2 nano-composites supported by powdered activated carbon) not only avoided algae cell breakage and controlled the release of intracellular organic matter, but also halved the aluminum sulphate (AS) coagulant dosage, since Bi 2 O 3 -TiO 2 /PAC acted as both a photocatalyst and flocculation core. Under optimal conditions (1.2 g/L Bi 2 O 3 -TiO 2 /PAC irradiated under visible light for 20 min and 0.1 mM AS), the removal of OD 680 , DOC and UV 254 were 83.8 %, 60.3 % and 77.3 % respectively. Moderate photocatalysis degraded medium and high molecular weight organics (biopolymers, humic substances and building blocks) to low MW acidic and neutral organics, resulting in effective removals of humic substances and microbial metabolites typically present in algal-derived pollutant. Following PC pre-treatment with ultrafiltration, 87.5 % increase in the final specific flux, 96.1 % reduction in irreversible resistance, and a change in the fouling mechanism from cake layer blockage to intermediate blockage. In addition, the zeta potential was reduced and the interaction force between pollutant-pollutant/membrane became a repulsive force. This work demonstrates the potential benefits of moderate pre-photocatalysis-enhanced coagulation to remove algal contaminants and mitigate ultrafiltration membrane fouling.
研究领域:
环境科学
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水处理工程
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产品关联
DOI
高影响因子
Journal of Water Process Engineering
·
2024
·
IF 6.3
Yiwen Wang,Shuanglin Gui,Qinliang Jiang,Pei Han,Hong Wang,Jianping Deng,Tao Chen,Jianxin Li
As the rare earth industry develops and energy efficiency improves, high-salinity rare earth smelting wastewater poses a significant environmental concern. This study applied integrated ultrafiltration (UF) - nanofiltration (NF) membrane technology to treat high-salt rare earth smelting wastewater (Ca 2 ⁺: 10.75 g/L, COD: 3.5 g/L, turbidity: 1.36 NTU) for salt removal and recovery. The effects of UF pretreatment were explored, and the operating parameters for NF were optimized, with the performance of various commercial NF membranes being evaluated. Membrane fouling conditions were also investigated to determine appropriate cleaning methods. The experimental results demonstrate that the UF-NF integrated process is effective in actual wastewater treatment. The calcium ion content in the permeate was reduced from 10.75 g/L in the feed solution to 0.96 g/L, achieving a removal rate of 91.1 %, which meets reuse water standards. Trace amounts of organic molecules in the water, such as 2-Ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507), were also effectively removed. The removal rates for COD and TOC were notably high at 97.7 % and 98.3 %, respectively. Acid washing, alkaline washing, and water washing were employed to clean the membranes, all of which achieved flux recovery rates exceeding 95.0 %. In summary, the integrated UF-NF process demonstrated outstanding performance in salt recovery/separation of different valence salts from rare earth smelting wastewater. Its excellent operational stability and high flux recovery rates highlight its strong industrial applicability. The exceptional treatment efficacy it displays provides a feasible technological pathway for resource recovery and water recycling in practical applications.
研究领域:
环境工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Water Quality Research Journal
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2024
·
IF 2.4
Yao Tangchun,Chen Yichao,Wu Wenting,Jin Binbin,Xiao Hua,Wang Qing,Wang Ao,Xu Hang
In this study, we utilized direct ultrafiltration (UF) and integrated microflocculation–ultrafiltration (MF–UF) processes to treat raw water from four distinct sources, covering both dry and heavy rainfall periods. We assessed the effectiveness of microflocculation (MF) as a pretreatment to enhance treatment efficiency under complex water conditions, focusing on its role in mitigating membrane fouling. The results demonstrated the superior adaptability of UF membranes when combined with MF pretreatment, particularly in managing high turbidity during heavy rainfall, a challenge for standalone UF processes in meeting regulatory standards. This integrated approach notably improved UV254 removal efficiency from approximately 60–80%. Additionally, excitation–emission matrix spectroscopy revealed that while the MF–UF process is effective in removing dissolved organic matter (DOM), it faces limitations with high DOM concentrations in raw water. Comparative analysis of membrane flux between the two methods showed that MF pretreatment reduces filtration time, enhances flux rates, and significantly decreases membrane fouling. Finally, scanning electron microscopy further provided insights into the structure and morphology of UF membrane surface filter cakes, illustrating how MF pretreatment contributes to the sustained efficiency of membrane flux. The different water quality conditions were studied. The MF–UF process was studied in realistic conditions. Organic matter and hard particulate matter were studied. Elucidating mechanisms to the MF–UF membrane flux efficiency.
研究领域:
环境科学
·
水处理工程
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产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Xueting Zhao,Youyou Lan,Kai Yang,Ruoxi Wang,Lijuan Cheng,Congjie Gao
This study proposes a novel strategy to fabricate antifouling UF membrane with integrated zwitterionic and TiO 2 functionality via in situ mixed-charge copolymerization and TiO 2 mineralization. The mixing of positively and negatively charged monomers at the molecular level endows membrane surface with balanced mixed-charge zwitterionic functionality, and the in situ TiO 2 mineralization endows membrane surface with well-dispersed TiO 2 nanoparticles. Thanks to the unique hydrophilicity of mixed-charges and TiO 2 , the obtained PVDF/P(MAA-TA)-TiO 2 membrane shows greatly enhanced surface hydrophilicity. The outstanding hydrophilicity of the PVDF/P(MAA-TA)-TiO 2 membrane significantly improves permeability and protein rejection compared to that of the unmodified PVDF membrane. What's more, the PVDF/P(MAA-TA)-TiO 2 membrane exhibits excellent antifouling capability against protein with flux recovery rate and fouling removal efficiency about 100%. Results of detailed fouling analysis indicate that both surface fouling and pore fouling were limited on the PVDF/P(MAA-TA)-TiO 2 membrane. The antifouling performance is mainly attributed to the synergistic hydrophilicity of mixed-charges and TiO 2 , and meanwhile the decrease in the surface electronegativity and pore size also plays a role. Results of this study provide a facile and scalable method for designing antifouling UF membrane, and highlight the promising potential of mixed-charges and TiO 2 synergy for manipulating hydrophilic and antifouling modification of UF membranes.
研究领域:
材料科学
·
环境工程
✓ 已验证
DOI
高影响因子
MARINE CHEMISTRY
·
2019
·
IF 2.713
Yuxi Lu,Xuelu Gao,Chen-Tung Arthur Chen
In this study, a method was developed for the desalination and pre-concentration of three colloidal trace metals in seawater , namely Cd, Cu and Pb, using diethylammonium diethyldithiocarbamate and ammonium 1-pyrrolidine dithiocarbamate as chelates. Seawater samples were first treated with cross-flow ultrafiltration (CFUF) for the separation of the colloidal matter of different molecular weights , i.e. 1–3 kDa, 3–10 kDa and 10 kDa-0.22 μm. Then, after acid digestion , the organic chelates and the extracting agent chloroform were added at pH = 3.8. Finally, the organic phase was back extracted, and the target metals in all samples were measured using inductively coupled plasma mass spectrometry (ICP-MS) with low detection limits in the range of 0.13–1.18 pmol L −1 . The extraction efficiencies for the three metals were in the range of 92.2%–100.3% with an enrichment factor of 40, and their mass recoveries in the studied colloidal fractions were in the range of 83.1%–103.5%. The developed method has been successfully applied for the analysis of seawater samples collected from the sites off the south coast of North Yellow Sea in Shandong Peninsula , China. For the first time, the distribution of colloidal Cd, Cu and Pb in different molecular weights in this area is reported. The results obtained from real samples demonstrate that the developed method is simple, efficient and convenient for routine analysis with low detection limit.
研究领域:
海洋化学
·
分析化学
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产品关联
DOI
高影响因子
International Journal of Environmental Research and Public Health
·
2019
·Vol. 16
·期 23
·4659
·
IF 2.468
Zhen Shen,Wei Chen,Hang Xu,Wen Yang,Qing Kong,Ao Wang,Mingmei Ding,Juan Shang
Membrane fouling is still a critical issue for the application of ultrafiltration, which has been widely used in water treatment due to its efficiency and simplicity. In order to improve the antifouling property, a new 2D material MXene was used to fabricate composite ultrafiltration membrane with the approach of in situ embedment during the phase inversion process in this study. Scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), water contact angle, bovine serum albumin rejection and porosity measurements were utilized to characterize the prepared membranes. Due to the hydrophilicity of the MXene, the composite membranes obtained higher hydrophilicity, confirmed by the decreased water contact angle. All the modified membranes had a high bovine serum albumin rejection above 90% while that of the pristine polysulfone membrane was 77.48%. The flux recovery ratio and the reversible fouling ratio of the membranes were also improved along with the increasing content of the MXene. Furthermore, the highest flux recovery ratio could also reach 76.1%. These indicated the good antifouling properties of MXene composite membranes. The enhanced water permeability and protein rejection and excellent antifouling properties make MXene a promising material for antifouling membrane modification.Keywords:MXene (Ti3C2Tx);polysulfone;hydrophilicity;ultrafiltration membrane;antifouling
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Lei Wu,Menghan Liu,Yuting Chen,Ming Li,Tingting Yin,Cong Ma,Wei Fan
UF is widely used as a wastewater treatment and recycling technology. However, membrane fouling is still an important factor affecting the wide application. In this study, APIm with positive amino group was adsorbed to the surface of the carboxylated polyacrylonitrile (PAN) membrane by electrostatic force to reduce the fouling of sodium alginate (SA) caused by Ca 2+ . The results show that 1 v/v% APIm was selected as the optimal dosage, accompanied by the highest water flux of 330.5 L·m -2 h −1 bar −1 and bovine serum albumin (BSA) rejection rate of 91.0 %. When the concentration of Ca 2+ was increased to 10 mM, the Ca 2+ catch amount increased to 48.25 mg/cm 2 . The main anti-fouling mechanism was that APIm captured a certain amount of Ca 2+ in situ, destroyed the complex structure of sodium alginate (SA) and Ca 2+ . Then the fouling layer was easy to be removed by physical cleaning. At the concentration of 10 mM Ca 2+ , the membrane flux recovery rate of 1 v/v% APIm membrane was increased to 80.1 %. This study demonstrates a fouling control strategy for in-situ removal of Ca 2+ bound SA fouling, providing a new approach for the future development of UF membrane.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Membranes
·
2024
·Vol. 14
·期 6
·125
·
IF 3.3
Qingao Li,Lixin Xie,Shichang Xu,Wen Zhang
The removal of dissolved organic matter (DOM) from seawater before the reverse osmosis (RO) processes is crucial for alleviating organic fouling of RO membranes. However, research is still insufficiently developed in the comparison of the effectiveness of integrating coagulation with ultrafiltration (UF) or sand filtration (SF) in the pretreatment stage of seawater reverse osmosis (SWRO) for the removal of DOM. In this study, we investigated the effect of pretreatment technologies on RO fouling caused by DOM in seawater, including the integration of coagulation and sand filtration (C-S pretreatment) and the integration of coagulation and ultrafiltration (C-U pretreatment). Both integrated pretreatments achieved comparable DOM removal rates (70.2% for C-U and 69.6% for C-S), and C-S exhibited enhanced removal of UV-absorbing compounds. Although C-U was more proficient in reducing the silt density index (below 2) compared to C-S (above 3) and improved the elimination of humic acid-like organics, it left a higher proportion of tyrosine-protein-like organics, soluble microbial by-product-like organics, and finer organics in the effluent, leading to the formation of a dense cake layer on RO membrane and a higher flux decline. Therefore, suitable technologies should be selected according to specific water conditions to efficiently mitigate RO membrane fouling.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）