Photocatalytic and adsorption performance of MXene@Ag/cryogel composites for sulfamethoxazole and mercury removal from water matrices

Abstract

Water reuse is expected to grow with the increase of freshwater scarcity that is on the rise globally because of climate change. This research has addressed the preparation of an advanced material that can treat both inorganic and organic contaminants from water thanks to the synergy of its different components. Specifically, the advanced material is a novel hybrid filter media composed of a macroporous cryogel and single-layer Ti3C2Tx MXene nanosheets modified with silver nanoparticles (AgNPs). The cryogel was prepared using polyethylenimine and dimethylacrylamide below subfreezing temperatures. Single-layer MXenes produced via etching of Al from Ti3AlC 2 flakes were sorbed to the cryogel. AgNPs were prepared in-situ and deposited onto the MXenes. The composite was studied using SEM-EDS, TEM, XRD, XRF, FT-IR, zeta potential, DRS and it tested with two model substances that are global pollutants of distinct nature: the antibiotic sulfamethoxazole, that results from incomplete wastewater treatment, and Hg2+ from geogenic or industrial emissions. The composite acted as sorbent/photocatalyst and was highly effective towards the degradation of sulfamethoxazole under light irradiation together with adsorption of Hg2+ from waters, including river water. The photocatalytic activity of AgNP was enhanced by the MXene co-catalyst, while the cryogel served as scaffold for MXene@Ag and as Hg adsorbent. The effectiveness of composites reached 97% of degradation of sulfamethoxazole and around 98% of Hg2+ when working at concentrations greater than environmental levels. Hence, the combination of adsorption and photocatalytic properties in water filtration media consisting of MXene@Ag/cryogel composites and opportunity to explore for treating water.