จลนศาสตร์และเทอร์โมไดนามิกส์การดูดซับน้ำเสียชุบโลหะโครเมียม (VI) โดยใช้ไคโตซานเชื่อมขวางเรซิน

Abstract

The adsorption of chromium (VI) from electroplating wastewater onto crosslinked chitosan resins as adsorbents was throughly investigated in a batch process. Kinetic and thermodynamic studies were carried out by taking into consideration the effects of contact time, pH and termerature. In the ambient conditions, adsorption capacity of chromium (VI) onto  crosslinked chitosan resins was 1208.4 mg/g for pH 2. Pseudo-first order and pseudo-second order were selected to describe the kinetic model. It was found that the adsorption of chromium (VI) onto crosslinked chitosan resins could be elucidated by pseudo-second order. Kinetic parameters such as the rate constants, equilibrium adsorption capacity, half-adsorption time and mass diffusivity were calculated and discussed. While the mechanism of the adsorption chromium (VI) occur in 2 steps. Thermodynamic parameters,  activation energy (E_a), enthalpy (ΔH⁰), entropy   (ΔS⁰) and free energy   (ΔG⁰) of adsorption were calculated as well. These parameters showed that the adsorption of chromium (VI) onto crosslinked chitosan resins was exothermic and also spontaneous process.