Chemical Regeneration of Activated Carbon after Absorption of Ni(II)

Cho, Kin Hau (2018) Chemical Regeneration of Activated Carbon after Absorption of Ni(II). Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Recently, chemical regeneration of activated carbon (AC) has been gaining attention as high-cost granular AC and AC fibers can be reused with minimum manpower and energy cost. In this study, chemical regeneration of activated carbon after adsorption of Ni(II) was conducted. Ni(II) adsorption was carried out by varying parameters such as AC dosage, contact time and initial [NiSO4.6H2O], while types of desorbing agents and their concentrations were determined and optimized for Ni(II) desorption. For effective recovery of Ni(II) adsorption and desorption efficiencies, optimization on [NaOH] was done. The optimum values for 100% Ni(II) adsorption efficiency obtained for AC dosage, contact time, and [NiSO4.6H2O] were 5g, 24 hours and 0.01M respectively. Effective Ni(II) desorption efficiency of 80% - 100% was obtained by using HCl and H2SO4 as the desorbing agents at 3% concentration after 10 minutes contact time. After desorption and washing processes, Ni(II) adsorption and desorption efficiencies of AC had decreased by 50% - 100% due to the retained HCl and H2SO4 in the porous structure of AC, which led to the formation of positive surface charge of AC that had induced electrostatic repulsion to Ni(II) ions. The spent AC was washed with NaOH for 24 hours after desorption procedure to neutralize the acid retained in the AC. The recovery of Ni(II) adsorption and desorption efficiencies of AC increased with the increment of [NaOH]. 100% of Ni(II) adsorption efficiency and 70-100% of Ni(II) desorption efficiency could be recovered after washing with 1% NaOH, indicating that AC had been successfully regenerated with recovered adsorption and desorption capabilities.