Reduction of oil and COD from produced water by activated carbon, zeolite, and mixed adsorbents in a fixed-bed column
Eman H. Khader, Thamer J. Mohammed, Sana Watheq Adnan
Abstract
ABSTRACT In this work, activated carbon, zeolite, silica gel, and mixed adsorbents (activated carbon and silica gel) were used for adsorption of oil and chemical oxygen demand (COD) from produced water by experiments of adsorption (continuous fixed-bed column). Two types of activated carbon (powdered and granular) were utilized. The effects of operational parameters, such as flow rate (1.25–3.15 mL/min), oil concentration (40–1,000 ppm), and COD concentration (1,350–28,500 ppm), on the performance of the column were studied. Also, two kinetics models (Thomas and Yoon– Nelson models) were applied to predict the breakthrough curve and calculate the distinguishing parameters of the column that are beneficial for a process design. The results reveal that Thomas kinetic model was suitable for the adsorption of oil and COD on all types of adsorbents. Also, the removal of pollutants increased with a decrease in flow rate and concentration. The highest removal of oil and COD were obtained (83.62% and 78.81%) by mixed adsorbents, (72.98% and 69.5%) by powdered activated carbon, (67.8% and 64.74%) by silica gel, (64.87% and 60.94%) by granular activated carbon, (58.58% and 52.49%) by zeolite at a flow rate (1.25 mL/min), adsorbent dose (0.5 g) oil concentration (40 ppm), and COD (1,350 ppm) bed height (2 cm); the highest adsorption capacity was 108.38 mg/g for oil and 96.74 mg/g for COD by mixed adsorbents. As well, the results illustrate that the highest removal of pollutants by mixed adsorbents, and least removal of pollutants by zeolite. Therefore, the results suggest that mixed adsorbents (activated carbon and silica gel) can be an effective adsorbent for the removal of pollutants from produced water.