Oil is one of the important energy resources in the modern world and must be transported across the globe via oceans and inland transport. Kapok fiber or scientifically named as Ceiba pentandra (L.) Gaertn is a natural sorbent that has the possibility as a filter material to separate the immiscible liquids such as oil-in-water mixture. Various modifications have been proposed to improve the oil sorption properties of kapok fibers, including surface modification and chemical modification.
This research project evaluates and compares the performance of different types of kapok fibers in the application of residual oil removal from palm oil mill effluent (POME) and diesel oil representing oil pollution for oil spill cleanup. Three types of kapok fibers, namely raw kapok fiber, sodium hydroxide treated kapok fiber and surface modified kapok fiber, are evaluated for their sorption properties and compared. In addition, the effectiveness of residual oil removal using the kapok fibers would be evaluated in a continuous packed bed column, where the effect of packing densities on chemical oxygen demand (COD) reduction and pH changes would be evaluated.
INTRODUCTION
- Background study
- Problem Statement
- Objectives
- Scope of Study
For example, oil spill skimmer, oil dispersant, oil gelling agent and oil adsorbent have been used for oil spill cleanup until now (Wang.J., 2012). In the treatment of palm oil mill effluents (POME), several methods have been used for efficient and effective treatment methods, including adsorption, flocculation, coagulation and solvent extraction (Ahmad et al., 2005; Hameed et al., 2003). Various natural sorbents have been studied and have been used in the application of residue removal from POME, including chitosan, bentonite and activated carbon (Ahmad et al., 2005).
However, the disposal of processing waste, which is the palm oil mill effluent (POME), poses a major problem with an estimated 54 million tonnes of POME being produced in 2011. Realizing the potential pollution that can arise from this effluent, the Malaysian Department of Environment (DOE) has already set the maximum allowable limit for oil and grease level at 50 mg/l during the discharge or disposal of POME (Hameed et al., 2003). The comparative study on the sorption of different kapok fibers will be studied in both batch and continuous study.
LITERATURE REVIEW
Sorbent Materials for residual oil removal
Naturally abundant or widely available as waste by-product of industrial processes - Can be low cost - Can serve to protect wildlife at extraction sites. Difficult to control, can be spread by wind - Difficult to retrieve - Oil and sorbent mixture can be difficult to pump - Disposal of oil sorbent mixture more limited than oil alone. Based on oil uptake of 30-40 g oil/g sorbent (Table 2), cotton, wool, milkweeds and kapok show high performance as oil sorbent compared to other natural organic sorbents.
Kapok as natural sorbent
Modification on kapok fibers
Strong alkali caused the de-esterification of kapok fibers. Morphological analysis - Trivial fibers, broken hole, shallow dimple observed. In another review, Wang et al. 2012) investigated a surface modification on kapok fiber, known as superhydrophobic, which was prepared by incorporating silica nanoparticles on kapok fiber using the sol-gel method. As a result, the oil/water selectivity was improved and the oil sorption capacity increased.
This study concludes that the prepared fiber is promising as a candidate for organic oil sorbent replacement and is applied in large-scale residual oil removal. Recently, another chemical modification studied by Wang et al. 2013) in the Journal of Chemical Environmental Science investigate the acetylation of kapok fibers using two. Shows small groove on fiber surface and open lumen hole - Shows creation of rough surface useful for oil adhesion.
METHODOLOGY
- Research Methodology and Project Activities
- Experimental Procedure/ Approach
- Kapok fibers preparation
- Characterization of kapok fibers
- Investigation on Oils Sorption characteristics of kapok fiber
- Data analysis and report
- Key Milestone
- Project Gant Chart
Surface Modified Kapok Fiber (SMKF) .. 1) Raw kapok fibers are cut into a small shape using cutting tools. In a batch study, the passing weight of the oil bath will be recorded every minute for 30 minutes. The average value of the final mass of the oil bath will be calculated and the sorption capacity will be calculated using the following equation.
The performance of kapok fibers in a continuous packed bed column is evaluated based on the biological chemical oxygen demand (COD) and pH change. The COD value and pH of the oil-water mixture would be measured before and after the sorption studies. We would then calculate the COD reduction and pH change and evaluate the sorption efficiency of each kapok fiber studied.
RESULTS AND DISCUSSION
Characterization of kapok fibers
As illustrated in Figure 8, the spectra of both raw and sodium hydroxide-treated kapok fibers show a similar pattern. Moreover, the disappearance of the absorption band at 1231.85 cm-1 in the sodium hydroxide-treated kapok fiber suggested the complete removal of hemicellulose materials compared to lignin (Mwaikambo et al., 2002). From the FT-IR results, it is clear that there were several differences between the raw kapok fiber and the sodium hydroxide-treated kapok fiber due to some reactions occurring during the alkalization.
As a comparison, the absorbent capacities of surface modified kapok fiber show the highest value compared to kapok fiber treated with raw kapok and sodium hydroxide for both palm oil and petroleum. This shows that the surface modified kapok fiber has the best oil absorption performance compared to raw kapok fibers and sodium hydroxide treated kapok fibers. The higher sorption capacity of raw kapok fiber (RKF) compared to sodium hydroxide treated kapok fiber (SKF) is a result of wax removal from the kapok surface as suggested by Abdullah et al.
Compared to the kapok fibers used, the sodium hydroxide-treated kapok fiber shows the best performance in retaining the oil in the kapok assembly, compared to raw kapok fiber and surface-modified kapok fiber for both types of experimental oil, respectively. The reduction in organic content in the effluent after each treatment cycle is due to the trapping of the residual oil in the kapok fiber assembly. This proved the high selectivity of the kapok fiber for the oil compared to water.
The entrapment of oil on the surface of kapok fibers is clearly observed during the treatment processes, as shown in Figure 16. In addition, the surface-modified kapok fibers show the best oil sorption performance of both types of test oil. This suggests that surface-modified kapok fiber is an effective method to improve the sorption capacity of raw kapok fiber.
Effect of packing density on fiber sorption capacity and dynamic oil retention time AF) Raw kapok fiber with crude palm oil.
Properties of experimental oils
Treatment using kapok fibers as sorbent material
- Effect of packing density on fibers sorption capacity and
- Continuous packed bed column oil treatment
The higher sorption capacity would contribute to the high performance of the residual oil and vice versa. Therefore, the color change could suggest that the experimental oil is trapped in the structure and demonstrate the ability of the oil to penetrate into the hollow lumen of the kapok fiber structure. The table data in Table 12 are further analyzed according to Figure 9 below and it is observed that the sorption capacities of surface modified kapok fibers, raw kapok fibers and sodium hydroxide treated kapok fibers show decreasing values as the packing density increases.
Meanwhile, the sorption capacity values of palm oil show a higher result compared to diesel oil. The decreasing order of the sorption capacities of the kapok fibers as the packing density increases could be the result of the more compact configuration of the kapok assembly in the cell due to the higher packing density. This would make the experimental oil more difficult to absorb compared to loosely packed kapok fibers.
This was supported by Lim, T., (2007) who reported that the interactions and van der Waals forces between the oils and the wax on the kapok fiber initiated the absorption mechanism of oil in the hollow lumen. It was further supported by Wang et al. 2012), who described that the alkalization can change the fine structure of kapok fibers, where the hollow lumen to store the oils disappears partially or completely, and the detrimental effect on the tube structure is prominent. In addition, the surface-modified kapok fiber exhibits a better performance compared to the raw kapok fiber, which is concluded due to the incorporation of the silica nano particles on the surface of the fiber.
This SMKF was concluded to have little similarity to superhydrophobic kapok fiber prepared by Wang et al. In according to Wang et al. 2012), in addition to the rougher surface, the superhydrophobic modified kapok fiber also contributes to reducing the surface energy, which affects the oil affinity. The ability of the kapok fibers to retain the remaining oil in its structure is also one of the important parameters to evaluate the performance of the kapok fibers as a sorbent material.
This was due to the fact that the high loosely packed kapok fiber caused higher percentages of oil to drip from the cell.
CONCLUSION AND RECOMMENDATION
Conclusion
The results would indicate that the Malaysian kapok fiber has excellent properties as an oil absorbing material and stable. Meanwhile, the simple setup of the apparatus to evaluate the performance of the kapok fiber in continuous operation proved the high selectivity of the kapok fiber towards the oil rather than water. More than 99% of COD reductions are observed for all cap types and at different packing densities and flow rates.
This experiment depicted the significant interaction of the packing density and flow rate in changing the pH where the highest packing density with the lower flow rate resulted in the highest pH incremental value.
Recommendation
Desalination , 88. 5) Ahmad, A. L. Sumathi, S. & Hameed, B. 2005, "Adsorption of residue oil from palm oil effluent using powder and flake chitosan: Equlibrium and kinetic studies," Water Research, 2484. Retrieved April , 2013, from Office of Response and Restoration, National Ocean Service: http://incidentnews.noaa.gov. Evaluation of kapok (Ceiba pentandra (L.) Gaertn.) as a natural hydrophobic-oleophilic fibrous hollow sorbent for oil spill cleanup.
Evaluation of the hydrophobicity/oleophilicity of kapok and its performance in filtering oily water: Comparison of raw and solvent-treated fibers. Retrieved April 17, 2013, from Mother Nature Network: http://www.mnn.com/earth-matters/wilderness-resources/stories/the-13-largest-oil-spills-in-history. Retrieved April 13, 2013, from Technical Information Document: http://www.itopf.com/information- services/publications/documents/TIP8UseofSorbentMaterialsinOilSpillResponse.
