Adsorption of copper from synthetic wastewater using water hyacinth roots and stems modified with chitosan

Abstract

The purpose of this research was to study the copper adsorption in synthetic wastewater using roots and stems of water hyacinth modified with chitosan which is important in increasing the surface area and having functional groups that can bind heavy metal ions. The surface area of the adsorbent was studied by using the Langmuir isotherm of methylene blue adsorption.
The morphology and functional groups of the adsorbent were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the surface area of chitosan-modified stems water hyacinth was the highest, followed by unmodified stems, unmodified roots, and modified roots, with values of 350.1, 283.3, 281.2, and 116.3 m²/g, respectively. These results corresponded with the pore size of the adsorbents obtained from scanning electron microscopy.Finally, the copper adsorption in syntactic wastewater was studied using a batch adsorption method. The results revealed that the chitosan-modified stems water hyacinth showed the highest adsorption capacity of 44.82 mg/g, followed by unmodified stems, unmodified roots, and modified roots, with adsorption capacities of 20.99, 17.07, and 14.25 mg/g, respectively. The copper adsorption on roots fits to monolayer Langmuir model while stems follow the Freundlich isotherm, indicating multilayer adsorption. In conclusion, the modification of the stem adsorbent with chitosan improved the copper adsorption capacity.