Graphene oxide modified CuBTC incorporated PVDF membranes for saltwater desalination via pervaporation

Shear-aligned graphene oxide nanosheets incorporated PVDF composite membranes for selective dye rejection with high water flux

Membrane technology is crucial in addressing water pollution challenges, particularly in removing dyes from wastewater. This study presents a novel approach to fabricating shear-aligned graphene oxide (GO) nanosheets incorporated polyvinylidene fluoride (PVDF) membranes for achieving exceptional dye rejection efficiency while maintaining high water flux. The membranes were prepared by dispersing graphene oxide within a PVDF matrix and subsequent subjection to shear alignment techniques. Shear and flow-induced alignment were explored to achieve precise and controlled alignment of graphene oxide flakes within the PVDF matrix. The resulting membranes exhibited enhanced structural integrity and optimized molecular packing of PVDF and GO, enabling them to selectively reject dyes while allowing efficient water permeation. The fabricated membranes were extensively characterized using appropriate testing methods. The results demonstrated that the shear-aligned GO sheets infused PVDF composite membranes exhibited outstanding dye rejection (96-99%) performance, surpassing conventional membranes while maintaining high water flux. This innovative membrane fabrication approach holds significant promise for advanced water treatment applications, offering a sustainable solution for selective dye removal and efficient water purification.

Liquid- liquid (Cyclohexanone: Cyclohexanol) separation using augmented tight nanofiltration membrane: A sustainable approach

Organic solvent nanofiltration (OSN) is an incipient technology in the field of organic liquid-liquid separation. The incomplete separations and complexity involved in these, forces many organic liquids to be released as effluents and the adverse effects of these on environment is enormous and irreparable. The work prominences on the complete separation of industrially significant cyclohexanone: cyclohexanol (keto-alcohol oil) and heptane: toluene mixtures. The separations of these above-mentioned organic liquid mixtures were carried out using the fabricated Lewis acid modified graphitic carbon nitride (Cu2O@g-C3N4) incorporated polyvinylidene difluoride (PVDF) composite membranes. These fabricated membranes showed a separation factor of 18.16 and flux of 1.62 Lm-2h-1 for cyclohexanone: cyclohexanol mixture and separation of heptane and toluene mixture (with heptane flux of 1.52 Lm-2h-1) showed a separation factor of 9.9. The selectivity and productivity are based on the polarity and size of the organic liquids. The role of Cu2O@g-C3N4 is influencing the pore size distribution, increased divergence from solubility parameters, polarity, solvent uptake and porosity of the composite membranes. The developed composite membranes are thus envisioned to be apt for a wide range of liquid-liquid separations due to its implicit nature.

Efficient Dye Extraction from Wastewater Using Indium-MOF-Immobilized Polyvinylidene Fluoride Membranes with Selective Filtration for Enhanced Remediation

Industrial activities have led to releasing harmful substances into the environment, necessitating the elimination of these toxic compounds from wastewater. Organic dyes, commonly found in industrial effluents, pose a threat to ecosystems and human health. Conventional treatment methods often suffer from limitations such as high cost and poor efficiency. Metal-organic frameworks (MOFs) have emerged as promising materials for selective separation, including membrane filtration (MF). Mixed-matrix membranes (MMMs) combining MOFs with polymers offer improved filtration properties. In this study, MMMs were fabricated by incorporating synthesized In-MOF with a polyvinylidene fluoride (PVDF) polymer (In-MOF@PVDF MMMs) using the nonsolvent-induced phase separation process. The MMMs were evaluated for the MF of various organic dyes, achieving notable removal efficiencies. The membrane containing 20% In-MOF (M4) demonstrated exceptional performance, removing 99% of the methylene blue (MB) dye. Additionally, membrane M4 effectively filtered Azure A (AZA), Azure B (AZB), and toluidine blue O (TOLO) with a removal efficiency of 99%. However, for Rhodamine B (RHB) and methyl orange (MO), the removal efficiencies were slightly lower at 74 and 39%, respectively. Further, these membranes are utilized in selective dye filtration in the MB+/RHB+ and MB+/MO- systems, where the selectivity was found for MB. The isothermal and DFT studies revealed the membrane's behavior with dye mixtures, while water stability and regeneration studies confirmed its durability. Thus, these findings highlight the potential of In-MOF@PVDF MMMs for effective and selective dye removal in wastewater treatment applications.

One-step uranium extraction and brine desalination via adsorptive pervaporation by graphene-oxide scaffold membranes

The ocean reserves nearly four billion tons of uranium, providing an inexhaustible supply of nuclear energy if the limits of ultralow U(VI) concentration (3.3 µg·L^-1) are addressed. Membrane technology is promising to make this happen by simultaneous U(VI) concentration and extraction. Herein, we report a pioneering adsorption-pervaporation membrane for efficient enrichment and capture of U(VI) along with clean water production. A bifunctional poly(dopamine-ethylenediamine) and graphene oxide 2D scaffold membrane was developed and further crosslinked by glutaraldehyde, capable of recovering over 70% U(VI) and water from simulated seawater brine, which validates the feasibility of one-step water recovery, brine concentration, and uranium extraction from seawater brine. Moreover, compared with other membranes and adsorbents, this membrane exhibits fast pervaporation desalination (flux: 153.3 kg·m^-2·h^-1, rejection: >99.99%) and excellent uranium capture properties of 228.6 mg·m^-2 benefiting from plentiful functional groups provided by embedded poly(dopamine-ethylenediamine). This study aims to provide a strategy for recovering critical elements from the ocean.

Graphene based composite membranes for environmental toxicology remediation, critical approach towards environmental management

Graphene-based composite membranes, as laminated, stacked, and assembled architectures of graphene, have surpassed other conventional membranes with their advanced and preeminent structural specialization and potential use in a wide range of sustainable and environmental applications. The characteristic membrane features such as distinct laminar morphology, tailored physicochemical properties, as well as extraordinary molecular properties have fascinated scientists. Due to remarkable mechanical properties, these membranes can be easily fabricated. Recent progress has been achieved by graphene and its derivatives-based membranes to purify water and gases for environmental remediation. This review explained the latest and groundbreaking advances in chemical design, fabrication, and application of graphene-based membranes. Special attention is paid to the recent developments on graphene-based composites into membranes with various forms: free-standing, layered, and graphene-based nanocomposite membranes. Furthermore, a unique approach on environmental management with as-fabricated membranes is provided by discussing the effect of physicochemical properties. Consequently, their full-scale use for environmental management, water purification, gas purification, and biological treatments will pave the way for their promising features and realize their future prospects.

PVDF/MOFs mixed matrix ultrafiltration membrane for efficient water treatment

Polyvinylidene fluoride (PVDF), with excellent mechanical strength, thermal stability and chemical corrosion resistance, has become an excellent material for separation membranes fabrication. However, the high hydrophobicity of PVDF membrane surface normally leads a decreased water permeability and serious membrane pollution, which ultimately result in low operational efficiency, short lifespan of membrane, high operation cost and other problems. Metal-organic frameworks (MOFs), have been widely applied for membrane modification due to its large specific surface area, large porosity and adjustable pore size. Currently, numerous MOFs have been synthesized and used to adjust the membrane separation properties. In this study, MIL-53(Al) were blended with PVDF casting solution to prepare ultrafiltration (UF) membrane through a phase separation technique. The optimal separation performance was achieved by varying the concentration of MIL-53(Al). The surface properties and microstructures of the as-prepared membranes with different MIL-53(Al) loading revealed that the incorporation of MIL-53(Al) enhanced the membrane hydrophilicity and increased the porosity and average pore size of the membrane. The optimal membrane decorated with 5 wt% MIL-53(Al) possessed a pure water permeability up to 43.60 L m-2 h-1 bar-1, while maintaining higher rejections towards BSA (82.09%). Meanwhile, the prepared MIL-53(Al)/LiCl@PVDF membranes exhibited an excellent antifouling performance.