DESALINATION
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2022
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IF 11.211
Songchen Xie,Ngie Hing Wong,Jaka Sunarso,Qiang Guo,Chunguang Hou,Zhiguang Pang,Yuelian Peng
Mineral scaling is one of the major challenges for membrane distillation in concentrating high-salinity brine. This work first investigated the characteristic of CaSO 4 scaling, then explored different cleaning reagents to evaluate their efficiencies and mechanisms. By analyzing the SEM and EDX mapping images, the CaSO 4 scaling process could be divided into surface and pore scaling stages. Three cleaning solutions, i.e., commercial detergent (20 %), EDTA-4Na (0.05 M), and MgCl 2 (0.8 M), were chosen for their high CaSO 4 solubility (0.7 g CaSO 4 per 100 g H 2 O). At the surface scaling stage, three cleaning solutions exhibited excellent removal of CaSO 4 scaling with approximately similar 96 % cleaning efficiencies. However, at the pore scaling stage, only the commercial detergent showed high efficiency (89 %). Such high cleaning efficiency was mainly attributed to the detergent's high total dissolved solids (salinity), low pH, and high diffusion rate (5.46 μm cm −1 min −1 ) across the membrane. Moreover, periodic cleaning at the surface scaling stage with the commercial detergent followed by drying throughout a 43.5 h continuous concentration test on an actual RO brine could restore the PTFE membrane performance completely, giving 90 % of the total water recovery . This work provides new insights into the cleaning mechanism for gypsum scaling in a hydrophobic porous membrane.
研究领域:
环境科学
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材料科学
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产品关联
DOI
高影响因子
WATER RESEARCH
·
2021
·
IF 11.236
Dachao Lin,Langming Bai,Daliang Xu,Han Zhang,Tiecheng Guo,Guibai Li,Heng Liang
The aim of this study was to evaluate the effects of oxidation on humic-acid-enhanced gypsum scaling in different nanofiltration phases, including the short-term membrane flux behaviors and the long-term ones. On the basic of correlation analysis between the changing physicochemical properties of feed solution and membrane fouling, the inner mechanisms were revealed from aspects of bulk crystallization (interaction between humic acid and inorganic ions) and surface crystallization (compositions and morphologies of surface crystallization). Furthermore, the reliability of applicating differential log-transformed absorbance spectroscopy for predicting membrane fouling was also systematically evaluated. There was an upward trend in short-term membrane fouling with increasing dosage of NaClO, while long-term membrane fouling decreased after an initial increase. During short-term filtration, the enhanced combination between inorganic ions and the humic acid with stronger density of carboxyl groups, which was generated more easily under stronger oxidation conditions, favored the earlier appearance of flux decline. During long-term filtration, the size of bulk crystallization depended on the total content of carboxyl groups in feed solution. Both of them increased firstly and then decreased with increasing oxidation. The terminal fouling layer resistance also shared a similar tendency with them, because the deposition of bulk crystallization on membranes and the formation of dense scaling layer were the direct reasons for the long-term membrane fouling. Furthermore, the differential log-transformed absorbance spectroscopy was proven to be an efficient approach to predict short-term membrane fouling, especially in the wavelength range of 260 to 280 nm. This research could not only provide guidance on alleviating oxidation-enhanced membrane fouling in nanofiltration but also propose an efficient way to predict the membrane fouling which was influenced by the interaction between organic matters and inorganic ions.
研究领域:
环境科学
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化学工程
✓ 已验证
DOI
高影响因子
WATER RESEARCH
·
2025
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IF 12.4
Jinjin Jia,Daliang Xu,Jiaxuan Yang,Dachao Lin,Longfeng Hu,Wenxing Jin,Jinlong Wang,Weijia Gong,Guibai Li,Heng Liang
Residual aluminum (Al) is a growing pollutant in nanofiltration (NF) membrane-based drinking water treatment. To investigate the impact of distinct Al species fouling layers on gypsum scaling during NF, gypsum scaling tests were conducted on bare and three Al-conditioned (AlCl 3 -, Al 13 , and Al 30 -) membranes. The morphology of gypsum, the role of Al species on Ca 2+ adsorption during gypsum scaling, and the interactions between gypsum crystals and Al-conditioned membranes were investigated. Results indicated that Al-conditioned membranes had lower flux decline than the bare membrane, with the order of AlCl 3 -
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
Journal of Water Process Engineering
·
2023
·
IF 7
Xinyuan Yi,Haowei Wu,Xin He,Bin Xu,Tongchun Wang,Yulin Tang
Aluminum (Al) coagulants are widely and frequently applied to coagulation pretreatment before nanofiltration . However, the excess coagulants and residual natural organic matters (NOMs) might affect the gypsum scaling during nanofiltration process. This study investigated the nanofiltration membrane fouling process under Al coagulants and specific NOMs, including humic acids (HA), bovine serum protein (BSA), and sodium alginate (SA) in a dual-system. The flux and the particle size decreased significantly when both above were present. The gypsum crystallization on the membrane surface was enhanced, while the bulk crystallization was weakened. Zeta potential and the NICA-Donnan model showed that Al coagulants competed with Ca 2+ to bind HA weakening the bulk crystallization of gypsum. Meanwhile, Al coagulants decreased the salt rejection rate. Interestingly, the BSA and SA alleviated the flux decrease. Furthermore, the characterization of the fouled membrane showed that the concentration of Ca 2+ and SO 4 2− on the membrane surface increased further in the presence of Al coagulants, the grain size reached 582.0 nm when both HA and Al were present, larger than the control group and when they were present in the feed solution alone. Finally, the modified Hermia model was introduced to analyze the mechanism of the interaction between Al coagulants and NOMs. It is suggested that the control of Al coagulants and HA is necessary for the coagulation pretreatment before nanofiltration.
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
SCIENCE OF THE TOTAL ENVIRONMENT
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2019
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IF 5.589
Dachao Lin,Zhongsen Yan,Xiaobin Tang,Jinlong Wang,Heng Liang,Guibai Li
Nanofiltration is routinely applied as an advanced water treatment technology after conventional water treatment. However, the residual coagulant after coagulation process may affect the nanofiltration process and to our best of knowledge, few studies focused on this phenomenon. To address such issues, ferric and aluminum ions were adopted as the model coagulant, and the influences of coagulant concentrations, coagulant conditioning time and fouling strategies on gypsum scaling were systematically investigated. The results indicated that coagulant conditioned on the membrane surface could improve membrane flux, enhance scaling, and increase the conductivity of permeate. The contents of coagulant accumulated on the membrane surface gradually increased with its increasing concentration in feed solution and extending conditioning time, resulting in severer scaling and flux decline. Interestingly, the formation of heterogeneous scaling layer will contribute to membrane fouling alleviation and prevent the further flux decline regardless of the ongoing increase of coagulant concentrations in the feed water as well as on the membrane surface. As a result, a critical value of coagulant concentrations in the feed water was obtained in present conditions. Furthermore, it's found that successive fouling strategy could lead to less gypsum scaling but severer flux decline, compared to simultaneous fouling strategy. Both the scaling quantity and scaling morphologies conferred significant influence on the flux decline. It is suggested that the concentrations of coagulant should be strictly controlled prior to nanofiltration process, especially with practical relevance for the applications of it in treating the water rich in calcium ions and sulfate anions.
研究领域:
环境科学
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水处理工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2022
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IF 10.53
Di Xu,Zhigao Zhu,Guangming Tan,Xiangyang Xue,Jiansheng Li
Scaling in membrane distillation (MD) is inevitable in concentrating hypersaline wastewaters. Although adding antiscalants in hypersaline brines can effectively mitigate membrane scaling, the effectiveness and underlying mechanisms in preventing scaling on differently wettable membrane surfaces with different functional-group antiscalants have rarely been reported. Herein, the hydrophobic, superhydrophobic and Janus membranes with ultrathin scale inhibition layer were elaborately designed to elucidate the efficiencies of functional groups of antiscalants in preventing gypsum scaling on differently wettable membrane surfaces. The results show that the superhydrophobic and Janus membranes are the most effective in retardation of membrane scaling in the presence of a single antiscalant with carboxyl or amino functional groups, respectively. Besides, the performance of the superhydrophobic membrane can be further improved while the Janus membrane was continuously declined as amino and carboxyl-functional-group antiscalants were simultaneously added to the feed gypsum solution. A set of characterization analyses revealed that the significant improvement in membrane gypsum scaling resistance is ascribed to the obstruction of scale precursors to nucleation. Meanwhile, the physicochemical characteristics of antiscalants also contribute to reducing the salt deposited on the MD membrane surface in the supersaturated brine. This work provides new insight into the structure design of membrane and antiscalants tailored to MD for concentrating hypersaline brines with high water recovery and robust salts rejection efficiency.
研究领域:
环境工程
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膜科学
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水处理
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2019
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IF 7.015
Wei Yu,Di Song,Aimin Li,Hu Yang
The mitigation of gypsum scaling on reverse osmosis (RO) membrane using carboxymethyl cellulose (CMC) as a green antiscalant was investigated in this study. Static test was conducted to pre-evaluate the inhibition performance and mechanism against gypsum scale using optical microscope and X-ray diffraction (XRD) as auxiliary analysis methods. The antiscaling effects in the RO system were investigated by flux change measurement and membrane surface observation. Results from the static test and RO operation indicated that a suitable degree of carboxymethyl substitution and an appropriate dose were both necessary for CMC to achieve satisfactory inhibition performance. Analysis from optical microscope and XRD showed obvious changes in crystal size and surface morphology of gypsum scales using CMC as antiscalant, which indicated that the effects of chelation, dispersion, and lattice distortion were all involved. In the RO operation, permeate fluxes in the presence of CMC remain relatively constant in gypsum-dominated solution compared with the sharp flux drop in the blank test. Coexisting anions, such as CO 3 2− and PO 4 3− , nearly had no influence on the antiscaling effect of CMC in the RO operation. Direct observation of RO membrane surface under scanning electron microscopy indicated that only a thin layer that contained few deposits was found when CMC was used. However, a thick crystal layer completely covered the membrane surface for the antiscalant-free test. Thus, CMC is an efficient and environmentally friendly antiscalant with remarkable potentials for membrane fouling control in RO operation.
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
DESALINATION
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2024
·
IF 8.3
Jinjin Jia,Jinlong Wang,Dachao Lin,Jing Zhao,Hesong Wang,Longfeng Hu,Jiaxuan Yang,Han Zhang,Guibai Li,Heng Liang
Membrane scaling severely hinders practical application of nanofiltration (NF) for brackish water treatment. However, the contributions of residual aluminum ( Al ), especially various species with differing polymerization degrees and sizes, to gypsum scaling remain unclear. Herein, the complex interactions between three Al species (AlCl 3 , Al 13 and Al 30 ) and gypsum scaling were investigated, including surface and bulk crystallization processes. Results demonstrated that Al species adhering to the membrane surface promoted surface crystallization and altered crystal morphology. Notably, the Al 13 species induced the formation of dense, complete rosette crystals causing the most severe flux decline. For bulk crystallization, Al 30 was the primary species to promote nucleation. This promotion resulted from two factors: a lower nucleation energy barrier and the promoted aggregation of small crystals. Furthermore, molecular dynamics (MD) simulations revealed that the inhibition of nucleation due to the competition between Al species and calcium ions at nucleation sites was negligible compared to the strong promotion effect. These findings demonstrated that PACl exhibit higher scaling potential during NF than monomeric Al coagulants. Ultimately, the competition between surface and bulk crystallization determined the final membrane flux decline. This study offers valuable insights into the mechanisms of NF scaling caused by residual Al and guides mitigation strategies.
研究领域:
环境科学
·
水处理
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膜技术
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Ruijun Zhang,Wenqian Zhu,Jiayu Tian,Shanshan Gao,Bart Van der Bruggen
Reverse osmosis is an effective seawater desalination way extending the available sources of fresh water, but challenged by the gypsum scaling. Herein, D (+)-glucosamine (DGA) was rationally selected and utilized to prepare a novel polyesteramide (PEA) NF membrane that can reject SO 4 2− but release Ca 2+ . Then it was employed in the pretreatment of seawater reverse osmosis to spatially isolate SO 4 2− and Ca 2+ , thus removing the “foundation” for forming gypsum. Compared to the referenced NF270, the optimized sample denoted as DGA-PEA-NF has a looser structure with stronger negative charge, as well as a higher resistance to both organic fouling and chlorine attack. During the pretreatment of seawater, both the water permeability and SO4 2− /Ca 2+ selectivity of the DGA-PEA-NF membrane were much higher than those of NF270; the seawater permeance and SO 4 2− /Ca 2+ selectivity of DGA-PEA-NF were 10.25 L m −2 ·h −1 ·bar −1 and 7.62, respectively, while those of NF270 were only 5.11 L m −2 ·h −1 ·bar −1 and 2.08. Consequently, the DGA-PEA-NF membrane effectively reduced the gypsum scaling both in NF and RO stages rather than just transferring the fouling problem forwards to NF stage. The implementation of this research is expected to provide guidance for a targeted fabrication of NF membranes, as well as support for the sustainable development of seawater desalination.
研究领域:
材料科学
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环境工程
·
水处理
✓ 已验证
产品关联
DOI
高影响因子
DESALINATION
·
2024
·
IF 8.3
Yin-Shuang Hu,Shuo-Chun Ke,Yu-Xi Huang
Membrane fouling and scaling are two critical challenges in membrane distillation (MD). The traditional superhydrophobic anti-scaling strategy is contradictory to the hydrophilic anti-fouling coating, creating a crucial challenge to combine these two properties into one material. In this study, glutamic acid (GA) was grafted on a polyvinylidene fluoride (PVDF) membrane surface to achieve fouling and scaling resistance simultaneously. The hydrophilic GA modification endowed the membrane with a larger underwater oil contact angle without affecting the surface morphology. The direct contact MD (DCMD) tests demonstrated that the GA-modified membrane had excellent oil fouling resistance due to the formation of a hydration layer by the GA molecules. In addition, the surface carboxyl groups offered plenty of coordination sites for metal ions, such as calcium ions. The surface coordination of calcium resulted in a lower free calcium concentration on the membrane surface, thereby postponing the scale nucleation and preventing the scales from intruding into the membrane matrix. The scaling tests also showed that the gypsum scales grown on the modified membrane were smaller than those on the pristine PVDF membrane. Besides, membrane cross-section analyses revealed that no scale intrusion was observed in the GA-modified membrane. Long-term stability tests and practical application with ethylene plant spent caustic further confirmed the promising application potential of the membrane. These results demonstrated that anti-fouling and anti-scaling properties can be integrated using the GA modification. This study provides a new surface modification strategy for designing and fabricating a robust anti-fouling and anti-scaling MD membrane.
研究领域:
材料科学
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化学工程
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ENVIRONMENTAL MANAGEMENT
·
2024
·
IF 8
Yahui Li,Yanan Dong,Shangqing Chen,Yingqiu Wu,Junfeng Wang,Yi Nie
Nanofiltration (NF) has been proven to be with great potential for the separation of morpholines with molecular weight less than 200 Da in refining reverse osmosis concentrate (ROC), but its application is significantly restricted by the membrane fouling , which can reduce the rejection and service time. To enable the long-term operation stability of nanofiltration, this work focuses on the fouling behavior of each substance in the hydrosaline organic solution on nanofiltration membrane, aiming to give insight into the fouling mechanism. To this end, in this work, the effects of salts (i.e NaCl and Na 2 SO 4 ), organic substances (including N-(2-hydroxypropyl)morpholine(NMH) and 4-morpholineacetate(MHA)) and representative divalent ions (Ca 2+ and Mg 2+ ) on the performance and physicochemical properties of DK membrane were systematically investigated. The results show that both salts and organics can induce DK membrane swelling, leading to an increase of the mean effective pore size. After the filtration of Na 2 SO 4 –NaCl–H 2 O, the mean pore size increased by 0.002 nm, resulting in the decrease of the removal ratio of NMH and MHA for 3.82% and 13.10%, respectively. With static adsorption of NMH and MHA, the mean pore size of DK membrane increased by 0.005 and 0.003 nm. The swelling slowed the entrance of more organic molecules into membrane pores. Among them, MHA led to the terrible irreversible pore blocking. As the concentration of Ca 2+ increased, gypsum scaling was formed on the membrane surface. During this process, NMH and MHA played different roles, i.e. NMH accelerated the CaSO 4 crystallization while MHA inhibited. As a conclusion, the fouling behavior of substances in the high saline organic wastewater on DK membrane were systematically revealed with the fouling mechanisms proposed, which could provide an insightful guidance for membrane fouling control and cleaning in the treatment of high salinity and organic wastewater.
研究领域:
环境工程
·
水处理
·
膜技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
DESALINATION
·
2022
·
IF 11.211
Bing Zhang,Jing Shen,Heli Tang,Yu Shen,Jiansheng Li,Zhigao Zhu
Membrane distillation (MD) that can sustainably recover freshwater until salt crystallization is a potential candidate for hypersaline wastewater treatment. However, a huge challenge for MD is membrane scaling, which sharply decreases membrane flux and salts rejection efficiency. This study reported an ion-nucleating competition cooperated with commercial antiscalants to mitigate membrane scaling. Results showed that the superhydrophobic PVDF (SH-PVDF) membrane could effectively delay the gypsum nucleation on the slippery membrane surface owing to the increased membrane surface roughness, but scaling inevitably occurs on the membrane surface in the supersaturated condition. Introducing the foreign ions such as one-component Na + or Mg 2+ and two-component Na + /Mg 2+ mixture can improve the gypsum solubility and delay gypsum nucleation for mitigating membrane scaling. Besides, the synergistic combination of commercial antiscalant and ion-nucleating competition is extraordinarily effective in retarding membrane scaling and preventing membrane pore wetting, achieving a high-water recovery of ~85 % and robust salt rejection of ~100 %. The mechanisms of ion-nucleating competition cooperated with antiscalants were also discussed with the help of characterizations. This work provided a novel ion-nucleating competition in collaboration with antiscalants for hypersaline wastewater management, which is important for MD to be applied in near-zero liquid discharge (ZLD).
研究领域:
环境工程
·
水处理
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膜技术
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海水淡化
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废水管理
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）