Studies on Adsorption Characteristics of Corn Cobs Activated Carbon for the Removal of Oil and Grease from Oil Refinery Desalter Effluent in a Downflow Fixed Bed Adsorption Equipment

Abstract

The discharge of oil and grease (O&G) containing effluent without treatment may contaminate the aquatic environs and freshwater. The removal of O&G from simulated refinery desalter effluent (SRDE) by activated carbon (AC) originated from chemical activation/carbonization of corn cobs (CCs) was investigated through fixed-bed column studies. The corn cobs activated carbon (CCAC) was characterized to determine its physicochemical properties, and the functional groups presently active on it partaking in the column adsorption process. The CCAC size (150, 300 and 600 µm), initial adsorbate concentration (200, 300 and 400 mg/L), and bed height (100, 200 and 300 mm) were varied to observe their influence on the adsorption of O&G and breakthrough time (τ) at a constant flow rate of 10.5 mL/min in a 10 mm diameter column of length: 60 mm. The removal of O&G from SRDE was inspected using the Bohart-Adams (B-A) and Yoon-and-Nelson (Y-N) kinetic models. Breakthrough time and %O&G removal decreased with increasing CCAC particle size and feed concentration and improved with rising bed height (BH). The void fractions (ε) at BHs of 100, 200 and 300 mm were 0.0247, 0.0124 and 0.0082, respectively. The ideal residence time (tR ) was 4.49 min. The B-A model yielded the highest degree of fit to the data than the Y-N model with R2 within 0.8217 and 0.9771. This means that the B-A model can be used to predict the breakthrough curve of any desired values for the present study. This work also revealed that CCs could be packed in a fixed-bed column for O&G reduction from refinery desalter effluent.