Removal of Petroleum Hydrocarbons in Seawater using A Mixed Adsorbent of Coconut Husks and Shrimp Shells

Abstract: The removal of dissolved petroleum hydrocarbons in seawater was evaluated by using coconut husks and shrimp shells as the adsorbents. The experiments were conducted at a temperature of 30 °C, salinity 30 g/l, pH 8 and dissolved oxygen 6 ppm using the column experiments. The 10 ppm water-soluble fraction (WSF) of the Malaysian crude oil was used for the study. The adsorption kinetic studies were studied by applying the Freundlich Isotherms Equation. The adsorption kinetics of hydrocarbons by coconuts and shrimp shells followed the first order kinetic with Adsorption Capacity (Kf) values of 0.408±0.004, and 0.407±0.006 respectively. The maximum adsorptions of the above adsorbents were 1.81 and 1.57mg hydrocarbons/g respectively. Treatment techniques are attempted to use the above adsorbents for removing hydrocarbon residues in seawater. Both of them possess surprisingly high effectiveness in removing dissolved hydrocarbons in seawater to level below 50 ppb. Both adsorbent exhibits its characteristics and selectivity in adsorbing the aliphatic and aromatic hydrocarbons present in seawater. A combination of coconut husks and shrimp shells is able to reduce the oil in seawater from 10 ppm to 0.0257 ppm. The bioassay study using P. monodon post-larvae as test organism supports the success of this treatment technique.