Physicochemical evaluation of coconut shell biochar remediation effect on crude oil contaminated soil

The effect of coconut shell biochar on pH, cation exchange capacity (CEC), sesquioxides and residual total petroleum hydrocarbon (TPH) of a crude oil contaminated soil was investigated. Raw coconut shells were carbonized in a muffle furnace at 400 degrees C for 2 hours and chemically activated in sulphuric acid solution for 18 hours to produce coconut shell activated carbon (CSAC). The CSAC and crude oil-contaminated soil from Kaduna Refining and Petrochemical Company had their physicochemical properties determined. Six sets of CSAC- soil mixtures containing 1%, 1.5%, 2%, 2.5%, 3% and 3.5% CSAC content to undergo remediation for 36 days. The pH, cation exchange capacity (CEC) and total petroleum hydrocarbon (TPH) degradation increase with higher CSAC content while sesquioxides composition slightly decreases with CSAC addition. A significant reduction in TPH from (2045 to 447) mg/kg was achieved with peak TPH degradation of 78.14% at 3.5% CSAC content. Therefore, CSAC significantly enhances the adsorption and degradation of petroleum hydrocarbons in the contaminated soil.