Oily Wastewater Treatment Using Modified Rice Husks as a Cost-Effective Adsorbent

Abstract

In oilfields and refineries, large quantities of oily wastewater are discharged into the rivers which cause major pollution to the environment. The removal of oil content may be attained successfully by using cost-effective adsorbents such as agricultural wastes that are readily available in a large amount in nature. This study deals with the oil content removal of oily wastewater by rice husks as adsorbents and investigates their adsorption capacity at different experimental conditions in batch mode. In batch experiments, the influence of pH value, agitation speed, contact time and the adsorbent dose at constant temperature 25℃ and 1.18-2 (mm) particle sizes were studied for the determination of the optimum operating conditions for oil content removal. The potential of rice husks particles was suitable and the removal efficiency of oil content by this adsorbent was reached 99.28 % at 25℃ within the optimum conditions (i.e. pH=4, 200 rpm as agitation speed and 3g/100mL as adsorbent dose). After 150 minutes of continuous agitating, the adsorption equilibrium was reached as well the maximum adsorption capacity was 5.06484 (mg/g) for the dosage 0.5g/100mL. Equilibrium isotherms were also studied and the experimental data were fitted with three isotherm models. The adsorption isotherm study suggested that the favourable and best-fitted adsorption method was with the Langmuir model. Also, the kinetic experimental data have been examined by using four models and it was observed that the kinetics of oil content adsorption onto rice husks followed the pseudo-second-order model. © 2023 American Institute of Physics Inc.. All rights reserved.