Hydrogels from non-woody lignocellulosic biomass for toxic metal uptake from wastewater: a brief overview

Innovative and environmentally sound materials are essential for wastewater remediation to ensure sustainability and drinking water quality. Hydrogels formed from cellulose alone or combined with hemicelluloses and lignin are an excellent choice. They are the primary components of lignocellulosic biomass, whose main source is wood. However, the dependence on wood as a source of lignocellulosic macromolecules is challenging since the trees’ growth requires years and continuous surveillance against deforestation. Therefore, the aim of this Overview was oriented towards non-woody biomass (NWB) to produce hydrogel sorbents, focusing on their potential application in wastewater treatment by removing heavy metals. Papers reporting the use of NWB, such as wheat and tobacco straw, sugarcane bagasse, and recycled cotton fabrics, were considered. The Overview assessed the deconstruction of the NWB, cellulose dissolution, hydrogel formation, and mechanism of heavy metals sorption. The hydrogels from NWB, primarily formed through radical polymerization, are rich in hydroxyl groups, which leads to efficient crosslinking and high sorption capacities. Further investigation on functionalization and novel approaches to creating hydrogels from NWB may enhance the sustainability side of hydrogel formation and its potential for removing heavy metals, offering a promising solution to wastewater treatment.