Treatment of synthetic textile dye effluent using hybrid adsorptive ultrafiltration mixed matrix membranes

Fabrication of crown ether-containing copolymer porous membrane and their enhanced adsorption performance for cationic dyes: Experimental and DFT investigations

Adsorptive separation membranes are widely utilized for the removal of toxic dyeing pollutants from dyeing wastewater. However, developing novel adsorption membranes with large adsorption capacities and enhanced adsorption performance for dyes in actual wastewater poses a significant challenge. This study focuses on the fabrication of crown ether-containing copolymer porous membrane (CRPM) and investigation of the adsorption performance of dyes from aqueous solutions. The morphology structure and pore size distribution revealed that the membrane was endowed with rich micropores and hierarchical porous structures. Three typical cationic dyes (MB, RhB, CV) and an anionic dye (MO) were selected to evaluate the adsorption behavior. The results of adsorption isotherms and kinetics demonstrated that the adsorption data could be well-fitted using the Freundlich and pseudo-first-order kinetic models, the thermodynamic parameters revealed that the adsorption process of dyes on CRPM is a spontaneous endothermic reaction. The membrane exhibited excellent adsorption performance for cationic dyes, with RhB displaying a higher maximum adsorption capacity than previously reported porous membranes. Notably, dynamic adsorption-desorption filtration demonstrated a rapid removal efficiency, with RhB, MB, and CV achieving removal rates of 99.09%, 98.63%, and 99.14% respectively, after five cycles. The filtration volume of the CRPM membrane was 2.4-fold greater than that of a traditional PVDF membrane when applied to actual dyeing wastewater. DFT theoretical calculations were employed to elucidate the adsorption mechanism. These calculations confirmed the significant roles of electrostatic interactions, H-bonds and π-π interactions in facilitating the high-efficiency adsorption of cationic dyes. These findings highlight the potential of the crown ether-containing copolymer as a promising material for adsorption separation membranes in the treatment of dyeing wastewater.

A review on hybrid membrane-adsorption systems for intensified water and wastewater treatment: Process configurations, separation targets, and materials applied

In the era of rapid and conspicuous progress of water treatment technologies, combined adsorption and membrane filtration systems have gained great attention as a novel and efficient method for contaminant removal from aqueous phase. Further development of these techniques for water/wastewater treatment applications will be promising for the recovery of water resources as well as reducing the water tension throughout the world. This review introduces the state-of-the-art on the capabilities of the combined adsorption-membrane filtration systems for water and wastewater treatment applications. Technical information including employed materials, superiorities, operational limitations, process sustainability and upgradeing strategies for two general configurations i.e. hybrid (pre-adsorption and post-adsorption) and integrated (film adsorbents, low pressure membrane-adsorption coupling and membrane-adsorption bioreactors) systems has been surveyed and presented. Having a systematic look at the fundamentals of hybridization/integration of the two well-established and efficient separation methods as well as spotlighting the current status and prospectives of the combination strategies, this work will be valuable to all the interested researchers working on design and development of cutting-edge wastewater/water treatment techniques. This review also draws a clear roadmap for either decision making and choosing the best alternative for a specific target in water treatment or making a plan for further enhancement and scale-up of an available strategy.

A novel synergistic effect of TiO2 and ZnO incorporation in PES-based thin-film nanocomposite nanofiltration membrane for treatment of textile wastewater

A novel synergistic effect of TiO₂ and ZnO incorporation in the PES-based thin-film nanocomposite nanofiltration membranes was developed for the treatment of common effluent treatment plant (CETP) textile wastewater. PES@TiO₂ membranes were developed by phase inversion via the immersion precipitation method followed by the addition of zinc oxide nanoparticles prepared by the rapid microwave-assisted hydrothermal process via interfacial polymerization. p-Phenylenediamine was used as a monomer for the IP process that was coated on the PES@TiO₂ support layer. Various techniques have been applied to characterize the developed thin-film nanocomposite membranes such as Fourier transform infrared (FTIR) microscopy, field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), and contact angle measurement to examine the presence of vibrational modes, surface morphology, the crystal structure of nanoparticles, and hydrophilicity of the membrane, respectively. Membrane properties include porosity, salt rejection, mean pore radius, pure water flux, and industrial effluent rejection efficiency that were studied. The thin-film nanocomposite membrane T5-PES@TiO₂(2%)-ZnO(0.3%) was prepared with a combination of 17 wt% PES, 78 wt% DMF, 3 wt% PVP K30, 2% TiO₂, 2.5 wt% PPD, 0.3 wt% ZnO, and 1.0 wt% TMC that exhibited high water permeability, porosity, higher industrial effluent rejection, and salt rejection efficiency compared to the neat PES membrane.

Photocatalytic membranes: a new perspective for persistent organic pollutants removal

The presence of conventional and emerging pollutants infiltrating into our water bodies is a course of concern as they have seriously threatened water security. Established techniques such as photocatalysis and membrane technology have proven to be promising in removing various persistent organic pollutants (POP) from wastewaters. The emergence of hybrid photocatalytic membrane which incorporates both photocatalysis and membrane technology has shown greater potential in treating POP laden wastewater based on their synergistic effects. This article provides an in-depth review on the roles of both photocatalysis and membrane technology in hybrid photocatalytic membranes for the treatment of POP containing wastewaters. A concise introduction on POP's in terms of examples, their origins and their effect on a multitude of organisms are critically reviewed. The fundamentals of photocatalytic mechanism, current directions in photocatalyst design and their employment to treat POP's are also discussed. Finally, the challenges and future direction in this field are presented.

Emerging Materials to Prepare Mixed Matrix Membranes for Pollutant Removal in Water

Various pollutants of different sizes are directly (e.g., water-borne diseases) and indirectly (e.g., accumulation via trophic transfer) threatening our water health and safety. To cope with this matter, multifaceted approaches are required for advanced wastewater treatment more efficiently. Wastewater treatment using mixed matrix membranes (MMMs) could provide an excellent alternative since it could play two roles in pollutant removal by covering adsorption and size exclusion of water contaminants simultaneously. This paper provides an overview of the research progresses and trends on the emerging materials used to prepare MMMs for pollutant removal from water in the recent five years. The transition of the research trend was investigated, and the most preferred materials to prepare MMMs were weighed up based on the research trend. Various application examples where each emerging material was used have been introduced along with specific mechanisms underlying how the better performance was realized. Lastly, the perspective section addresses how to further improve the removal efficiency of pollutants in an aqueous phase, where we could find a niche to spot new materials to develop environmentally friendly MMMs, and where we could further apply MMMs.