A novel negatively charged nanofiltration membrane with improved and stable rejection of Cr (VI) and phosphate under different pH conditions

Wu, Yu; Gan, Zhiqiang; Wang, Jia-Rong; Zhao, Yu; Han, Jun; Fang, Li‐Feng; Wei, Xiuzhen; Qiu, Ze-Lin; Zhu, Bao-Ku

doi:10.1016/j.memsci.2021.119756

Cited by 45 publications

(5 citation statements)

References 49 publications

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“…It was reflected by the (much) higher rejection of MgCl 2 than Na 2 SO 4 , which could not be achieved by the typical negatively charged NF membranes. 33,34 Noteworthy is that the control membrane (PA2, prepared with 2.0 wt % PIP and 0.15 wt % TMC) had high rejections of Na 2 SO 4 , MgSO 4 , MgCl 2 , and NaCl, all very likely because the active layer was quite dense. By increasing the sulfuryl chloride percentage in the organic phase, the rejection of Na 2 SO 4 continued to decrease to ∼20% while the rejection of MgCl 2 remained consistently high (> ∼80%), until the weight percentage of sulfuryl chloride was over TMC.…”

Section: Sulfuryl Chloride Blended With Tmc Reducedmentioning

confidence: 99%

Simultaneously Modulating Nanofiltration Membrane Surface Charges and Pore Size in Pursuit of Effective Cation Separation via a Bi-Functional Monomers-Interfered IP Reaction

Wang,

Gao,

Zhang

et al. 2024

ACS EST Eng.

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Reducing the membrane surface negative charge density and properly enlarging the pore size could benefit the selective and efficient separation of divalent cations from monovalent cations desired by many applications (e.g., Li + /Mg 2+ separation) using nanofiltration (NF) by synergistically exploiting the Donnan and steric effects. This study provides a one-step tactic for the preparation of such membranes by simply introducing a small percentage of sulfuryl chloride (SO 2 Cl 2 ) into the organic phase of trimesoyl chloride (TMC). This method is adaptable to the classical interfacial polymerization (IP) technique. The key conditions include a sufficient high concentration of piperazine (PIP) in the aqueous phase (e.g., 2.0 wt %) and a low-to-medium concentration ratio of sulfuryl chloride to TMC. An as-prepared membrane, which manifested a high Li + / Mg 2+ selectivity of 22.2, exhibited a high rejection of MgCl 2 at 92%, a low rejection of Na 2 SO 4 at 34%, and a relatively high water permeance of 11.1 L m −2 h −1 bar −1 . We propose that the sulfuryl chloride monomers mainly played an interferential role rather than largely being incorporated into the polyamide matrix. This was demonstrated by the very low sulfur element composition in the active layer and the substantially enlarged membrane pore size in comparison to that of the control membrane. Adding sulfuryl chloride into the organic phase could allow more PIP monomers to diffuse through the enlarged structure to the superficial surface of the membrane, leaving more unreacted amine groups endowed with positive charges. Moreover, the addition of sulfuryl chloride could greatly change the membrane surface and structural morphologies, and in turn the surface roughness, by increasing the number of large ring-like structures and/or rougher nodules that could cover almost the entire membrane surface. Therefore, this work demonstrated that the membranes fabricated by the novel approach could have practical applications for cation separation.

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Section: Sulfuryl Chloride Blended With Tmc Reducedmentioning

confidence: 99%

Simultaneously Modulating Nanofiltration Membrane Surface Charges and Pore Size in Pursuit of Effective Cation Separation via a Bi-Functional Monomers-Interfered IP Reaction

Wang,

Gao,

Zhang

et al. 2024

ACS EST Eng.

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“…However, the nanoparticles may agglomerate via these hydroxyl groups, reducing their hydrophilicity. [31] It is also possible that when dispersing nanoparticles in the aqueous monomer solution, some nanoparticles were lost during the removal of the excess aqueous monomer solution, thereby reducing the loading of the hydrophilic nanoparticles in the final TFN membranes.…”

Section: Membrane Surface Characterizationmentioning

confidence: 99%

Cellulose nanocrystal addition in thin film nanocomposite membranes: Which monomer solution is preferred?

2023

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Cellulose nanocrystals (CNCs) are biodegradable nanoparticles with a high aspect ratio and abundant surface hydroxyl groups resulting in negatively charged hydrophilic surfaces that make them an ideal candidate to be incorporated in thin‐film nanocomposite (TFN) membranes. In this study, we modified the CNCs via acetylation (ACNCs) to reduce their hydrophilicity and via reaction with L‐cysteine (CysCNCs) to impart them with functionality that promoted their interaction with the trimesoyl chloride organic monomer used in the preparation of the poly(amide) layer of the TFN membranes. These modifications allowed us to question in which monomer solution the nanoparticles should be dispersed. Addition of the unmodified CNCs in either the aqueous or organic monomer solution showed little difference in membrane performance. However, the addition of either the ACNCs or the CysCNCs to the organic monomer solution led to a significant increase in membrane performance in reverse osmosis (RO) and nanofiltration (NF) systems compared to their addition to the aqueous monomer solution. In addition, the CysCNCs exhibited performance very near the upper‐bound line for RO and NF.

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“…In the past decades, some techniques have been applied in Cr(VI) decontamination in wastewater treatment and groundwater remediation, including adsorption [6], membrane process [7], photocatalytic reduction [8], electrochemical methods [9,10], and biological treatment [11]. Compared with these methods, the zero-valent iron-based technologies have garnered lots of attention because of their low cost, environmental friendliness, easy operation, and efficient performance [12,13].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Chromium (VI) Removal by Micron-Scale Zero-Valent Iron Pretreated with Aluminum Chloride under Aerobic Conditions

Long,

Li,

Wan

et al. 2024

Molecules

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Micron-scale zero-valent iron (ZVI)-based material has been applied for hexavalent chromium (Cr(VI)) decontamination in wastewater treatment and groundwater remediation, but the passivation problem has limited its field application. In this study, we combined aluminum chloride solution with ZVI (pcZVI-AlCl3) to enhance Cr(VI) removal behavior under aerobic conditions. The optimal pre-corrosion conditions were found to be 2.5 g/L ZVI, 0.5 mM AlCl3, and a 4 h preconditioning period. Different kinds of techniques were applied to detect the properties of preconditioned ZVI and corrosion products. The 57Fe Mössbauer spectra showed that proportions of ZVI, Fe3O4, and FeOOH in pcZVI-AlCl3 were 49.22%, 34.03%, and 16.76%, respectively. The formation of Al(OH)3 in the corrosion products improved its pHpzc (point of zero charge) for Cr(VI) adsorption. Continuous-flow experiments showed its great potential for Cr(VI) removal in field applications. The ZVI and corrosion products showed a synergistic effect in enhancing electron transfer for Cr(VI) removal. The mechanisms underlying Cr(VI) removal by pcZVI-AlCl3 included adsorption, reduction, and precipitation, and the contribution of adsorption was less. This work provides a new strategy for ZVI pre-corrosion to improve its longevity and enhance Cr(VI) removal.

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A novel negatively charged nanofiltration membrane with improved and stable rejection of Cr (VI) and phosphate under different pH conditions

Cited by 45 publications

References 49 publications

Simultaneously Modulating Nanofiltration Membrane Surface Charges and Pore Size in Pursuit of Effective Cation Separation via a Bi-Functional Monomers-Interfered IP Reaction

Simultaneously Modulating Nanofiltration Membrane Surface Charges and Pore Size in Pursuit of Effective Cation Separation via a Bi-Functional Monomers-Interfered IP Reaction

Cellulose nanocrystal addition in thin film nanocomposite membranes: Which monomer solution is preferred?

Enhanced Chromium (VI) Removal by Micron-Scale Zero-Valent Iron Pretreated with Aluminum Chloride under Aerobic Conditions

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