Newly developed polymer nanocomposite of chitosan-citrate/ZrO2 nanoparticles for safranin O dye adsorption: Physiochemical properties and response surface methodology

Abstract

In this work, crosslinked chitosan-citrate/ZrO2 (CS-CIT/ZrO2) nanocomposite was straightforwardly synthesized in two steps: first, chitosan biopolymer (CS) was functionalized with a zirconia inorganic nanomaterial (zirconium dioxide, ZrO2), and then, citrate (CIT) was used in an ionic cross-linking procedure. This new nanocomposite's physicochemical characteristics have been fully investigated using methods including FTIR, CHN–O, BET, pHpzc, XRD, and FESEM-EDX. Using the response surface methodology approach, the removal of cationic dye (Safranin O, SO) from an aqueous solution by CS-CIT/ZrO2 was thoroughly investigated with concerning adsorption factors (pH (4–10), duration (10–90 min), and CS-CIT/ZrO2 dosage (0.02–0.08 g)). Freundlich isotherm demonstrates the equilibrium behavior of SO by CS-CIT/ZrO2. The optimal conditions for achieving the maximum removal of SO (70.7 %) were found to be at pH 10.0, with a dosage of CS-CIT/ZrO2 of 0.05 g/L, and a time of 90 min, depending on the desirability function. A pseudo-first-order model characterized the kinetics data of SO adsorption by CS-CIT/ZrO2 in an adequate manner. CS-CIT/ZrO2 has a remarkable adsorption capacity of 280.14 mg/g. The effective adsorption of SO on the positively charged CS-CIT/ZrO2 is responsible for the electrostatic interactions between the SO cation and the negatively charged CS-CIT/ZrO2, along with the H-bond and n-π interactions. According to this work, CS-CIT/ZrO2 has great promise as a superior bioadsorbent for adsorption of synthesized cationic dyes from polluted water.