Removal of crystal violet in aqueous solution by activated carbon from the pericarp of rubber fruit and bagasse: kinetics, thermodynamics and adsorption studies

Activated carbons prepared from the pericarp of rubber fruit (PrAC) or from bagasse (BAC) were compared with a commercial activated carbon (CAC) in an adsorption and desorption study of crystal violet in aqueous solution. The adsorbents were characterized by scanning electron microscopy, as well as for specific surface and pore size distribution from Brunauer-Emmett-Teller, Fourier-transform infrared spectroscopy, and the point of zero charge (pH pzc ). The effects of adsorbent dosage, contact time, initial concentration of crystal violet, pH, and temperature were studied. The Langmuir adsorption isotherm fit well, and the calculated maximum adsorption capacities (q m ) were 896.7, 432.66, and 351.12 mg g -1 at 60C and pH 5.0 for CAC, PrAC, and BAC, respectively. The desorption study confirmed that PrAC, BAC, and CAC can be regenerated. The adsorption of crystal violet by PrAC, BAC, or CAC was endothermic and spontaneous. The heats of adsorption (H/kJ mol -1 = 18.43 for PrAC, 16.49 for BAC, and 30.82 for CAC) confirmed physisorption as adsorption mechanism. The maximum desorption percentages of crystal violet solution were 67. 08, 46.32, and 40.64 for CAC, PrAC, and BAC at pH 2.03, indicating that PrAC and BAC can be reused in an economic treatment process.