Yang Yang,Zhu Xiong,Zhu Wang,Yi Liu,Zijun He,Akun Cao,Li Zhou,Lijing Zhu,Shuaifei Zhao
Carbon nanotube (CNT) based adsorbents have attracted extensive research interest for aqueous pollutants removal. However, such adsorbents face the problems of limited adsorption capacities and costly regeneration. Here, we report a highly adsorptive photo-regenerable CNT based multifunctional membrane with excellent self-cleaning properties via the facile vacuum filtration method, followed by FeOOH in-situ anchoring and silver-amino reaction. Various dyes (Rhodamine B, methylene blue, eosin Y and acid orange 7) and emerging contaminants (bisphenol A, amoxicillin and p-nitrophenol) were tested with the CNT based membrane. Our membrane exhibited superior adsorption performance to dyes among CNT based adsorbents reported in literature. In particular, the CNT based composite membrane displayed even better adsorption performance to cationic dyes. The adsorption capacities of the membrane for Rhodamine B and methylene blue were up to 181 and 247 mg/g, respectively. The membrane also had excellent self-cleaning and photo-regenerable properties after severe organic fouling. Our multifunctional CNT based membrane combined the features of adsorption, membrane separation , and catalytic degradation into one system, showing great promise for dye polluted wastewater purification. This study also offers a new strategy to engineer robust adsorptive, self-cleaning and regenerable membranes for wastewater treatment .
Aijiao Zhou,Kai Yang,Xumeng Wu,Guoqing Liu,Tian C. Zhang,Qin Wang,Fan Luo
Adsorption method has been widely used in the removal of emerging contaminants. However, many adsorbents are puzzled by key obstacles for effective and simple regeneration. In this work, the functionally-designed graphitic carbon nitride (g-C 3 N 4 ) embedded chitosan-polyvinyl alcohol composite (g-C 3 N 4 /CS/PVA) hydrogel beads were synthesized for the adsorptive removal of sulfamethoxazole (SMX) from water, and they could be regenerated by light. The adsorption kinetics, isotherm, thermodynamics, and impacting factors were systematically investigated. And the adsorption capacity of the hydrogel for SMX was relatively stable at pH of 4–8, with the maximum adsorption capacities being 5.8 mg g −1 at pH 5. The main adsorption force may be inferred to the electrostatic interactions between SMX and hydrogel beads, and hydrogen bonds between the amino or hydroxyl groups of the hydrogel and the amino of the SMX. The dominance of electrostatic interactions resulted in SMX adsorption being highly dependent on ionic strength. Being irradiated with an ultraviolet lamp for 5 recycles, the hydrogel beads still kept good adsorption capacity. The regeneration behavior was attributed to the photocatalytic degradation of SMX by g-C 3 N 4 . Namely, photocatalytic oxidation reactivated the adsorption sites and increased the release of adsorbed pollutants with improved desorption performance.
J. Lu,Y.-Y. Qin,Y.-L. Wu,Z. Zhu,M.-N. Chen,Y.-S. Yan,C.-X. Li
Since the in-depth exploration of molecularly imprinted membranes (MIMs), compatibility between high selectivity and superior regeneration has been always the focus. Here we propose, based on biomimetic self-polymerization of dopamine, highly specific, self-cleaning, and interfacial-stable g-C 3 N 4 /Ag 3 PO 4 /PDA-composited molecularly imprinted membranes (C/A/D-MIMs) for enhanced treatment of fit-for-purpose water. Ciprofloxacin (CFX) was selected as a representative target because of its potential toxic effect on the microorganism, which will inevitably weaken the traditional biological-based water treatment. Besides superior antifouling performance, remarkable permselectivity ( β NFX/CFX = 1.65, β EFX/CFX = 1.90, and β OFX/CFX = 2.08) and flux regeneration rate (84.4% after photo-regeneration) could be ascribed to (i) effective formation of molecularly imprinted sites by self-polymerization of dopamine, (ii) synergism of polydopamine in constructing Z-scheme heterojunction configuration, as well as (iii) bio-adhesion of polydopamine in coupling photocatalyst and MIMs. Achievements in the present work will promote the development of highly specific and self-cleaning MIMs with considerable stability and applications in specific and selective separation.
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