Self-assembly of graphene oxide containing bio-nanocomposite hydrogels for removal of chlorpyrifos and methylene blue.

Developing bio-based nanocomposite hydrogels consisting of a matrix of biopolymers embedded with nanoparticles to treat wastewater is important due to their benefits of eco-friendliness, affordability, and easy accessibility. This study aimed to fabricate a new self-assembled ternary nanocomposite hydrogel based on the polymer skeleton of xanthan gum and chitosan embedded with graphene oxide nanosheets (CTS/XG/GO). Structural characterizations using different techniques confirmed the successful incorporation of GO into the CTS and XG polymer network. A bio-nanocomposite was utilized to adsorb chlorpyrifos (CP) pesticide and methylene blue (MB) dye pollutants from water. The evaluation of the CP and MB adsorption performance by CTS/XG/GO in batch mode was conducted with varying dosages, solution pH, contact time, and initial CP/MB concentration. CP and MB maximum adsorption occurred at pH 7 and saturation equilibrium occurred within 30 min for both. CP and MB adsorption kinetics and isotherms on CTS/XG/GO were governed by pseudo-second-order and Freundlich models, respectively. CP's and MB's maximal adsorption capacities were determined to be 1030 and 1131 mg/g, respectively. As per thermodynamic parameters, CP and MB adsorption occurred spontaneously and exothermically. Moreover, the nanocomposite is reusable five times and removes dye and pesticides with 78.5 % and 77.5 %, respectively. These results confirm CTS/XG/GO's potential as a stable, effective, reusable, and sustainable adsorbent.