Chemical Regeneration of Nickel-Saturated Biochar Derived from Oil Palm Empty Fruit Bunches

Koh, Ai Ling (2024) Chemical Regeneration of Nickel-Saturated Biochar Derived from Oil Palm Empty Fruit Bunches. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Owing to the heavy metal pollution and environmental issue caused by the oil palm empty fruit bunches (OPEFB) waste produced in the cultivation activity, it is necessary to develop a method that can be used to solve both the issues mentioned. Adsorption is one of the techniques that can be applied to remove the heavy metal in the wastewater with the aid of adsorbent where biochar (BC) is a common adsorbent usually produced from biomass which one of the sources is including agricultural waste. By converting the OPEFB into BC, it can resolve the disposal issue and also help in the removal of heavy metal ion from the wastewater. However, the concentration of the heavy metal can be removed by the BC in one adsorption cycle is limited. Thus, a concept of regeneration has been developed to maximize the usage of BC in the adsorption process. Chemical regeneration of BC was studied in this project to determine the suitable chemical reagent in regenerating the spent BC after the adsorption of nickel (II) ions. The BC derived from the OPEFB has an adsorption capacity of 11.2 mg/g where the adsorption efficiency of BC can reach a 95.9%. HCl, HNO3 and H2SO4 used as the desorbing agents has performed a high desorption efficiencies ranging from 96.06% to 98.41% at the optimum concentration. However, there is a drastically drop in the adsorption efficiencies of second adsorption after the rinsing and desorbing process. This situation happened may due to the pH change of the environment of BC which results in the positive surface charge and hence the cationic adsorption is not favourable. Thus, recovery of acid treated BC is carried out by treating the BC with NaOH solution. After treated the BC with 2.0 M NaOH solution, the adsorption efficiencies can be recovered up to 89.95% to 96.77%. It is also found that 0.5 M of H2SO4 is the most suitable reagent to be used with 2.0 M NaOH solution in regeneration of BC as they able to regenerate the BC with a good and stable performance on adsorption and desorption of the Ni (II) ions.