Enhancement of Chromium (VI) Removal by Pre-Treatments of Cocolumber (Cocos nucifera) Sawdust: Vacuum Drying and Plasma Treatments

This study deals with the enhancement of chromium (VI) removal by vacuum drying and plasma pre-treatments of cocolumber (Cocos nucifera) sawdust. For fixed adsorbent dose and pH, the effects of important parameters such as initial adsorbate concentration and contact time are determined. Results show that both pre-treatments increased the adsorption efficiency of the sawdust. The adsorption data also fitted well with both Langmuir and Freundlich isotherm models. For an adsorbent dose of 2.0×10 mg/L, adsorbate 4 concentration of 5.0 mg/L, contact time of 240 minutes and at a pH of 2, the %chromium (VI) removal for the plasma treatments (oxygen, hydrogen and argon) and for the vacuum drying treatment are 81.2%, 73.5%, 66.4% and 58.7%, respectively. These results are higher compared to 33.9% for the untreated sawdust. Therefore, oxygen plasma pre-treatment of cocolumber sawdust is found to be the most efficient treatment for the removal of aqueous chromium (VI).