Synthesis of Chitosan-TiO<sub>2</sub> Nanocomposite for Efficient Cr(VI) Removal from Contaminated Wastewater Sorption Kinetics, Thermodynamics and Mechanism
Noor Sabah Al-Obaidi, Zainab Esmail Sadeq, Zaid H. Mahmoud, Ahmed Najem, Anfal Salam Al-Mahdawi, Farah K. Ali
Abstract
A photolysis method was used to prepare a nanocomposite adsorbent (Chitosan-TiO2) and was tested for Cr(VI) removal from aqueous solution. The produce nanocomposite was investigated using, XRD, BET, FTIR, FESEM-EDX and TEM before and after Cr(VI) adsorption. The XRD results shows prepared anatase phase of TiO2 with 12 nm. According to BET measurements, the surface area of the TiO2/chitosan nanocomposite was lower and archived to 26 m2/g, while the TEM and FESEM images show a uniform distribution of TiO2 throughout the chitosan matrix. Adsorption and kinetic experiments were run in batch system under different conditions of pH, contact time, adsorbent dosage and temperature. Experimental Cr(VI) adsorption equilibrium and kinetics data fitted well to Langmuir model. The calculated Langmuir maximum adsorption capacity (qmax) value of nanocomposite was 488 mg/g. Moreover, the highest quantity of Cr(VI) uptake was achieved of pH = 2 and 45℃ and TiO2 and CS-TiO2 had respective removal efficiencies of 94 and 87.5%. The thermodynamic parameters of Cr(VI) adsorption by nanocomposite affirm the spontaneous and endothermic nature of process. Chromium adsorption mechanism by CS-TiO2 nanocomposite were proposed and discussed.