Adsorption Isotherm and Thermodynamic Profile of Hexavalent Chromium onto Lumbang (Aleurites moluccana) Activated Carbon Chitosan Composite Crosslinked with Epichlorohydrin

摘要

Adsorption isotherm and thermodynamic profile of hexavalent chromium onto lumbang ( Aleurites moluccana ) activated carbon chitosan composite crosslinked with epichlorohydrin were studied. The optimum conditions were identified at pH 3, contact time of 75 min, adsorbent dose of 3 g/L, initial concentration of 60 ppm, and 30oC temperature resulted to a removal efficiency of 93%. The composite has a round and elliptical adsorption sites, contains –OH and –NH₂ functional groups, and has increased stability with epichlorohydrin crosslinking. The adsorption process is best characterized by the Langmuir isotherm suggesting a monolayer adsorption nature of Cr(VI). The adsorption kinetics obeyed the pseudo-second order model and the adsorption process is exothermic. The investigated adsorption phenomenon described a chemisorption process, with 21.32 kJ mol-1 mean free energy, due to the functional groups identified and the high porosity of the adsorbent surfaces.