Characterization of Physicochemical Properties and Process Design for Oil Removal using Ceiba pentandra (L.) Gaertn. as a Natural Sorbent

• Main Author: Ur Rahmah, Anisa
• Format: Thesis
• Language: English
• Published: 2009
• Online Access: http://utpedia.utp.edu.my/3007/1/MSc_Thesis-_Anisa_Ur_Rahmah.pdf; http://utpedia.utp.edu.my/3007/

Ceiba pentandra (L.) Gaertn (Kapok) is a natural sorbent that exhibits excellent hydrophobic-oleophilic characteristics. The physicochemical properties of kapok fibre as oil sorbent were characterized. The effect of packing density and the experimental oil types on the oil sorption characteristics of kapok were studied in a batch system. Oil sorption capacity, percentage of dynamic oil retention, oil entrapment stability, packing height reduction, saturation time and kapok reusability were evaluated. Continuous packed-bed column was developed to examine the optimum conditions, in terms of flow rates and packing density for the diesel-water filtration. Chloroform and alkali treatment were employed to investigate the stability of hollow structure and waxy layer on the kapok surface and their roles in oil sorption. Based on SEM, OM and FTIR analyses, kapok fibre was shown to be a lignocellulosic material with hydrophobic waxy coating that covered the hollow structures. The waxy coatings enhance the oil penetration inside the kapok structure and the presence of the hollow structure provide ample interstitial network for oil entrapment. Higher packing density showed lower sorption capacity, but higher percentage of dynamic oil retention, with 1% of oil drained out from the test cell at 0.08 g/cm3. The percentage of dynamic oil retention was in the decreasing order of: used engine oil, new engine oil and Diesel. At higher packing density and higher oil viscosities, kapok exhibited higher saturation but lower bed height reduction. Using diesel oil as the experimental liquid, only 30% of oil sorption capacity reduction was observed even after fifteen cycles of reuse at 0.04 g/cm3 packing density. Oil entrapment inside the packing was stable even after 30 min of shaking inside a horizontal shaker, with more than 90% of diesel and used-engine oil retained inside the assembly of 0.08 g/cm3 kapok. A packed-bed column was constructed to study the performance of kapok filter for oily water filtration. Statistical analyses suggest that none of the factors significantly affected the percentage of COD reduction, but the interaction between packing density and flow rate significantly affected the percentage of turbidity reduction. However, about 99% COD reductions were observed for all kapok filters at vi different packing densities and flow rate. About 97% turbidity reduction was observed for kapok at 0.08 g/cm3 and 0.5 L/h flow rate. The excellent turbidity reduction could be due to the stronger interaction of kapok with oil which can break down oil-water emulsion. After 8 hours of chloroform and alkali treatment, kapok fibres had lower oil sorption capacity, with 2.1 % and 26.3 % reduction, as compared to the raw kapok. SEM image analyses, in comparison to untreated kapok, showed no major structural difference after chloroform treatment, but major structural disruption to flattened-like structure was observed with alkali treatment. These results imply that kapok fibre had stable hollow structure and wax layer attachment on the kapok surface, and it takes extreme conditions as that employed with alkali treatment to make any significant changes. Based on these, the Malaysian kapok indeed has shown great potential as oil sorbent, in terms of high sorption and retention capacity, structural stability, high reusability and high COD and turbidity reduction capability.