Amir Rostami

Heavy metal ions in wastewater affect human health and must be removed. This study investigated crosslinked hydrogels of Sodium alginate/Chitosan (80/20) 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 adsorb chromium (Cr) 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 chromium 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 chromium ions adsorption occurred during the first 40 minutes of the 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 chromium ions. The pseudo-second order model is found to be appropriate for expressing the kinetics of chromium ions adsorption by the hydrogel sample based on curve fitting results.