Boosting adsorption capacity of methylene blue dye by multiple functional ZnO-g-C3N4/ carboxymethyl chitosan/alginate –grafted polyacrylic acid composite

Abstract The present study has focused on the development of multiple functional (carboxymethyl chitosan/alginate)-grafted polyacrylic acid composite (CMCH/ALG)-g-PAA with graphitic carbon nitride (ZnO-g-C 3 N 4 ) as a high-potential filler in order to satisfy the increasing demands of recycling and separation problem of ZnO-g-C 3 N 4 , which is powdery sorbent and hard to recycle after adsorption and represents a secondary pollution with high-performance in addition to strong π-π stacking interactions between g-C 3 N 4 nanosheets can lead to serious agglomeration and restacking, which reduces g-C 3 N 4 adsorption activity. ZnO-g-C 3 N 4 nanosheets has been generated by traditional thermal condensation method and investigated by TEM, SEM, XRD, and FTIR. The investigation of ZnO-g-C 3 N 4 @ (CMCH/ALG)-g-PAA was done using FTIR, XRD, SEM, and TG. The highest swelling ratios of (CMCH/ALG)-g-PAA were 1697.10% at pH 8.0 and 140.5% in saline solution. Vigot and first order models fit the swelling capacity data. For (CMCH/ALG)-g-PAA with 3% ZnO-g-C 3 N 4 , the maximum adsorption capacity was 24.30 mg/g at adsorbate concentration (0.1 g/L), MB dye concentration (25 mg/L), and pH 8.0. The practical data of adsorption was well being fitted by the Langmuir, Redlich-Peterson, and Sips models indicating complicated adsorption process. Since the Δ G ◦ values are more than − 20 kJ/mol, the adsorption is physisorption. ZnO-g-C 3 N 4 @ (CMCH/ALG)-g-PAA succeeded in effective dye removal from wastewater.