The raw material of coconut pith (CP) was supplied by T&H Coconut Fiber Sdn. Bhd. (Johor, Malaysia). This sample was kept in a desiccator for characterizations and further used as char precursor. The deionized water produced by the Purite Water System model Select Analyst HP40 (U.K) was used to prepare all solutions, while the double-distilled water was used for
glassware washing and cleaning.