Mohsen Abbasi

Heavy metal ions in wastewater affect human health and must be removed. This study investigated crosslinked hydrogels of PVA/CS and its single nanofiller as well as hybrid nanocomposites containing carbon nanotubes and graphene in different ratios (3 to 1, 1 to 1, and 1 to 3) in order to absorb Cu ions. Scanning electron microscope (SEM) images showed good dispersion and distribution of both nanofillers. As a result of preventing nanofiller aggregation in hybrid samples, a very large specific surface area is created, which results in synergistic thermal stability and copper absorption for hybrid samples containing a 3:1 ratio of graphene and carbon nanotubes. According to the thermogravimetry analysis (TGA), cross-linking the hydrogel and adding nanofillers significantly improved its thermal stability. The maximum amount of copper ions adsorption occurred during the first 80 minutes of the batch adsorption process. For graphene-containing nanofiller samples, it shows significant adsorption, which can be attributed to graphene's high specific surface area and its ability to adsorb copper ions. The pseudo-second order model is found to be appropriate for expressing the kinetics of copper ion adsorption by the hydrogel sample based on curve fitting results.