Hybrid Crosslinked Chitosan-Epichlorohydrin/TiO2 Nanocomposite for Reactive Red 120 Dye Adsorption: Kinetic, Isotherm, Thermodynamic, and Mechanism Study

Hybrid crosslinked chitosan-epichlorohydrin/TiO2 nanocomposite (CTS-ECH/TNC) was synthesized as an inorganic-organic hybrid nanocomposite bioadsorbent for the removal of reactive red 120 (RR120) dye from aqueous environment. Various analytical techniques were utilized to investigate the surface area, surface morphology, martial crystallinity, elemental composition, amino group content, and fundamental functional group of CTS-ECH/TNC. The impact of key adsorption parameters such as adsorbent dosage (0.02-1.2 g), initial RR120 dye concentration (30-400 mg/L), solution pH (3-12), contact time (0-300 min), and temperature (303-323 K) were explored by batch adsorption process. The adsorption data were well illustrated by pseudo-second order (PSO) kinetic and Langmuir isotherm model. The adsorption process was also found to be a spontaneous and endothermic in nature as indicated by thermodynamic study. The maximum adsorption capacity of CTS-ECH/TNC for RR120 dye was recorded to be 210 mg/g at 303 K. Various types of interactions such as electrostatic attraction, n-pi stacking, and H-bonding were responsible for adsorbing RR120 dye molecules on the surface of CTS-ECH/TNC as investigated by tailored adsorption mechanism. Thus, this work introduces CTS-ECH/TNC as promising hybrid biosorbent for the removal of RR120 dye as model of reactive azo dyes from aqueous environment.