The low-cost composite film was prepared by incorporating chitosan, berry soap fruit extract (rarasaponin), and bentonite as the raw materials. The produced chitosan/rarasaponin/bentonite (CRB) composite exhibits outstanding adsorption capability toward copper metal ions (Cu(II)). A series of static adsorption experiments were carried out to determine the isotherm and kinetic properties of CRB composite in the adsorption process. The adsorption equilibrium shows a good fit with the Langmuir isotherm model; the CRB composite has maximum uptake of Cu (II) of 412.70 mg/g; the kinetic adsorption data exhibit a good fit with the pseudo-second-order model. The thermodynamic parameters, ΔH°, ΔG°, and ΔS°, obtained from the isotherm data indicate that the uptake of copper ions by CRB composite is more favored at low temperatures. This study shows that physicochemical modified adsorbent, namely CRB composite, can remove Cu (II) better than pristine adsorbent of AAB and chitosan. The CRB composite also shows potential reusability.
Keywords: Adsorption; Ca-bentonite; Chitosan; Copper ions; Heavy metals; Isotherms; Kinetics; Rarasaponin; Thermodynamics.