Synthesis of alumina-based cross-linked chitosan-HPMC biocomposite film: an efficient and user-friendly adsorbent for multipurpose water purification

The need for an eco-friendly biocomposite for multi-purpose water treatment has been gaining more attention in recent times. In this regard, bio-polymeric composite materials could be the most suitable candidate. Herein, a novel alumina-based cross-linked chitosan-hydroxypropyl methyl cellulose (HPMC) biocomposite film (CgHA) has been designed and its superior fluoride and azo dye removal capacity from water/wastewater with a user-friendly adsorption procedure is demonstrated. Its physicochemical characteristics were investigated by XRD, FTIR, FESEM, TGA, DSC, and XPS techniques. Tensile strength, swelling test, and contact angle measurements demonstrated the suitable stability and hydrophilicity of the composite CgHA film. The fluoride adsorption capacity of the CgHA biocomposite was compared with chitosan-alumina (CgA) and HPMC-alumina (HgA) composites and the results showed the highest adsorption capacity of the reported biocomposite to be 125.1 mg g(-1) for CgHA. Also, an enhanced fluoride removal efficiency of 96% from 5 L of real groundwater was achieved with only 0.1 g of CgHA. Again, 82.7% fluoride removal was achieved in highly concentrated fluoride solution (Z100 mg L-1) which established its large-scale potential. Furthermore, the applicability of CgHA in the removal of methyl orange (MO) dye was also demonstrated with textile wastewater, bolstering its superior adsorption capacity. In the end, a novel experimental set up was illustrated for the simultaneous adsorption and separation from the aqueous medium using novel biocomposite. Overall, this study demonstrates a novel, efficient, user-friendly and sustainable biopolymer-based composite as a potential adsorbent for the purification of drinking water as well as industrial wastewater.