Sponge-like zinc oxide nanoparticles loaded xanthan gum/cationic chitosan cryogel: Synthesis, characterization, microbicidal and adsorption of synthetic dye and heavy metal

The current work was designed to prepare a multifunctional cryogel based on zinc oxide nanoparticles (ZnONPs) loaded xanthan gum (XG) and cationic chitosan (CC) using a facile freeze-drying technique. The ZnONPs was prepared by solid state technique using XG as stabilizing agent. The features of the prepared materials were fully investigated. The results demonstrated that the prepared ZnONPs was smaller than 50 nm and has nearly hexagonal shape. The zeta potential (-41.54 mv) affirmed the well stability of the prepared ZnONPs. The ZnONPs loaded XG/CC composite cryogels exhibited porous morphological structures. The FTIR data also affirmed the chemical interaction between XG, CC and ZnONPs. After ensuring the successful preparation of cryogels, their adsorption efficiency toward reactive yellow 145 (RY145) dye and copper ions (Cu2+) was evaluated. The results displayed that the highest removal of RY145 dye (94%) and Cu2+ (93%) was achieved after 1 hr at pH 2 and 5 using 0.5 g/L and 1.0 g/L, respectively, of ZnONPs-4 @XG/CC cryogel. The kinetic, isotherm and thermodynamic studies revealed that the adsorption was favorable, multilayer, spontaneous, endothermic and mainly physisorption for RY145 and chemisorption for Cu2+. The co-existence of RY145 dye and Cu2+ in a solution decreases the adsorption of each other. The ZnONPs-4 @XG/CC cryogel removed color, aluminum, arsenic, boron, barium, iron, and lead from real textile wastewater sample. Moreover, the antimicrobial activities of nanocomposite cryogel (ZnONPs-4 @XG/CC) revealed highest resistance growth rate (R% = 100%) against both S. aureus and E. coli. Based on these obtained findings, the composite based on ZnONPs loaded XG/CC cryogel can be considered as promising material for an efficient wastewater treatment.