Smart Janus membrane for on-demand separation of oil, bacteria, dye, and metal ions from complex wastewater

Removal of Fe(III)/Al(III)/Mg(II) by phosphonic group functionalized resin in wet-process phosphoric acid: Mechanism and intrinsic selectivity

The removal of iron ions (Fe(III)), aluminum ions (Al(III)), and magnesium ions (Mg(II)) in phosphoric acid (H₃PO₄) solution is vital for the production of H₃PO₄ and supply of phosphate fertilizer. However, the mechanism and intrinsic selectivity for removal of Fe(III), Al(III), and Mg(II) from wet-process phosphoric acid (WPA) by phosphonic group (-PO₃H₂) functionalized MTS9500 are still unclear. In this work, the removal mechanisms were determined via combined analysis of FT-IR, XPS, molecular dynamics (MD), and quantum chemistry (QC) simulations based on density functional theory (DFT). The metal-removal kinetics and isotherms were further studied to confirm the removal mechanisms. The results indicate that Fe(III), Al(III), and Mg(II) interact with the -PO₃H₂ functional groups in MTS9500 resin with sorption energies of -126.22 kJ·mol^-1, -42.82 kJ·mol^-1, and -12.94 kJ·mol^-1, respectively. Moreover, the intrinsic selectivities of the resin for Fe(III), Al(III), and Mg(II) removal were quantified by the selectivity coefficient (S_i/j). The S_{Fe(III)/Al(III)}, S_{Fe(III)/Mg(II)} and S_{Al(III)/Mg(II)} are 18.2, 55.1 and 3.02, respectively. This work replenishes sorption theory that can be used in the recycling of electronic waste treatment acid, sewage treatments, hydrometallurgy, and purification of WPA in industry.

Modified poly(vinylidene fluoride) nanomembranes for dye removal from water - A review

Water contamination due to soluble synthetic dyes has serious concerns. Membrane-based wastewater treatments are emerging as a preferred choice for removing dyes from water. Poly(vinylidene fluoride) (PVDF)-based nanomembranes have gained much popularity due to their favorable features. This review explores the application of PVDF-based nanomembranes in synthetic dye removal through various treatments. Different fabrication methods to obtain high performance PVDF-based nanomembranes were discussed under surface coating and blending methods. Studies related to use of PVDF-based nanomembranes in adsorption, filtration, catalysis (oxidant activation, ozonation, Fenton process and photocatalysis) and membrane distillation have been elaborately discussed. Nanomaterials including metal compounds, metals, (synthetic/bio)polymers, metal organic frameworks, carbon materials and their composites were incorporated in PVDF membrane to enhance its performance. The advantages and limitations of incorporating nanomaterials in PVDF-based membranes have been highlighted. The influence of nanomaterials on the surface features, mechanical strength, hydrophilicity, crystallinity and catalytic ability of PVDF membrane was discussed. The conclusion of this literature review was given along with future research.

Superhydrophilic quaternized calcium alginate based aerogel membrane for oil-water separation and removal of bacteria and dyes

In recent years, frequent oil spills and increasing industrial wastewater discharge have caused serious water pollution problems. In addition, there are often microbial and dye pollutants in oil-containing wastewater. The development of materials that can simultaneously treat these three pollutants is very important for the safe treatment and recovery of wastewater. In this work, a modified calcium alginate-based aerogel membrane (CTW) was prepared through sol spraying, Ca²⁺ crosslinking and freeze drying by using tetrabutylammonium hydroxide (TBA) quaternary ammonium salt modified sodium alginate (SA) as raw material and waterborne polyurethane (WPU) as adhesive. The results show that CTW membrane has super hydrophilic and underwater super-oleophobic properties, and can realize the separation oil-water emulsions under gravity, with the separation efficiency of >99 %. CTW membrane can also remove bacteria and dye such as Congo red from water by filtration, with removal rates of 100 % and 99 % respectively. The filtration results of mixed wastewater show that CTW membrane can realize one-step separation of oil, bacteria and dye in wastewater, and can also be recycled, having potential application prospect.

Special Superwetting Materials from Bioinspired to Intelligent Surface for On-Demand Oil/Water Separation: A Comprehensive Review

Since superwetting surfaces have emerged, on-demand oil/water separation materials serve as a new direction for meeting practical needs. This new separation mode uses a single porous material to allow oil-removing and water-removing to be achieved alternately. In this review, the fundamentals of wettability are systematically summarized in oil/water separation. Most importantly, the two states, bioinspired surface and intelligent surface, are summarized for on-demand oil/water separation. Specifically, bioinspired surfaces include micro/nanostructures, bioinspired chemistry, Janus-featured surfaces, and dual-superlyophobic surfaces that these superwetting materials can possess asymmetric wettability in one structure system or opposite underliquid wettability by prewetting. Furthermore, an intelligent surface can be adopted by various triggers such as pH, thermal and photo stimuli, etc., to control wettability for switchable oil/water separation reversibly, expressing a thought beyond nature to realize innovative oil/water separation by external stimuli. Remarkably, this review also discusses the advantages of all the materials mentioned above, expanding the separation scope from the on-demand oil/water mixtures to the multiphase immiscible liquid-liquid mixtures. Finally, the prospects of on-demand oil/water separation materials are also concluded.

Advances in Asymmetric Wettable Janus Materials for Oil–Water Separation

The frequent occurrence of crude oil spills and the indiscriminate discharge of oily wastewater have caused serious environmental pollution. The existing separation methods have some defects and are not suitable for complex oil–water emulsions. Therefore, the efficient separation of complex oil–water emulsions has been of great interest to researchers. Asymmetric wettable Janus materials, which can efficiently separate complex oil–water emulsions, have attracted widespread attention. This comprehensive review systematically summarizes the research progress of asymmetric wettable Janus materials for oil–water separation in the last decade, and introduces, in detail, the preparation methods of them. Specifically, the latest research results of two-dimensional Janus materials, three-dimensional Janus materials, smart responsive Janus materials, and environmentally friendly Janus materials for oil–water separation are elaborated. Finally, ongoing challenges and outlook for the future research of asymmetric wettable Janus materials are presented.