Mesoporous silica-grafted deep eutectic solvent-based mixed matrix membranes for wastewater treatment: Synthesis and emerging pollutant removal performance

Abstract Nano-enhanced membrane technology and deep eutectic solvents (DESs) have demonstrated effectiveness in addressing emerging environmental pollutants. This research centers on purifying water by removing heavy metals employing membranes enhanced with mesoporous silica and DES. Various DESs, including hexanoic acid, octanoic acid, and decanoic acid, were synthesized using tetrabutylammonium bromide (TBABr) as a base. The study combined a polysulfone-based membrane with mesoporous silica, aiming for efficient indigenous crafting to remove heavy metals. Mesoporous silica was blended with the synthesized DES solution, creating diverse membranes for heavy metal separation. The study characterized these membranes using various techniques such as scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and contact angle measurements. Surface mapping confirmed the integration of silicon-based DES, reducing the membrane surface roughness from 4 to 1.4 nm. By adjusting the carboxylic acid chain length with TBABr and adding mesoporous silica, leaching ratios were reduced from 4.2 to 2.3%. Silica-grafted DES-based membranes exhibited a progressive increase in flux from 2.6 to 26.67 L/m2 h. The synthesized silicon-based membranes demonstrated outstanding performance, achieving rejection rates exceeding 80% for chromium and arsenic, maintaining an impressive 90% flux recovery ratio even at high flux rates. This study will envision the potential of nano-enhanced membrane technology utilizing DES for sustainable water purification and wastewater treatment applications to achieve the sustainable development goal (SDG) of clean water and sanitation (SDG-6).