Literature Review Emulsified oil in waste water constitutes is a severe problem in the different treatment stages before disposed of in a manner that does not violate environmental criteria. One commonly used technique for remediation of petroleum contaminated water is adsorption. The main objective of this study is to examine the removal of oil from oil–water emulsions by adsorption on bentonite, powdered activated carbon (PAC) and deposited carbon (DC). The results gave evidence of the ability of the adsorbents to adsorb oil and that the adsorptive property of the three adsorbents (bentonite, PAC, and DC) has been influenced by different factors. The effects of contact time, the weight of adsorbents and the concentration of adsorbate on the oil adsorption have been studied. Oil removal percentages increase with increasing contact time and the weight of adsorbents, and decrease with increasing the concentration of adsorbate. Equilibrium studies show that the Freunlich isotherm was the best fit isotherm for oil removal by bentonite, PAC, and DC. The data show higher adsorptive capacities by DC and bentonite compared to the PAC [1].
Figure 1 Application of Langmiur and Freundlich Models [1]
The adsorption of oil on anthracite follows the Freundlich isothermal adsorption law: given initial oil concentrations of 160.5 or 1023.6 mg/L the absorption capacity was 23.8 or 840.0 mg/g. The absorption mechanism consists of two kinds of absorption, a physical process assisted by a chemical one [2]. A micro porous hydrophobic membrane allows the permeation of an oil phase at almost zero pressure and retains the water. The separation of dilute oil-in-water mixtures using flat sheet hydrophobic PVDF membranes has been investigated using an unstirred laboratory scale semi-batch experimental system operated at 40°C. The flat sheet membranes were prepared in the laboratory by an immersion precipitation method and were characterised in terms of a mean pore radius, porosity and breakthrough pressure. The experimental results can be predicted reasonably well using the Hagen–Poiseuille equation at a high vertical velocity and the percentage of oil removed can be achieved as high as 77% under normal experimental conditions [3]. A batch study was conducted to evaluate efficiencies of four types of biomaterials to remove oil from water. The oils used in the study were standard mineral oil, vegetable oil and cutting oil. Two fungal biomasses of Mucor rouxii and Absidia coerulea along with chitosan and walnut shell media were the biomaterials used. The study was carried out with an initial oil concentration of 200 mg/L for 6 h. Nonviable M. rouxii biomass was found to be more effective than A. coerulea biomass in removing oil from water. The study demonstrated that the removal efficiencies by M. rouxii for these oils were in the 77–93% range at a pH of 5.0. The adsorption capacities for standard mineral oil, vegetable oil and cutting oil were 77.2, 92.5, and 84 mg/g of biomass, respectively. The adsorption capacities for various oils exhibited by M. rouxii biomass were less than those of chitosan and walnut shell media [4]. An agricultural by-product, barley straw, was chemically modified by a cationic surfactant, hexadecylpyridinium chloride monohydrate (CPC) and employed as an adsorbent to remove emulsified canola oil from aqueous solution. It was found that addition of CPC created a non-polar layer on barley straw surface thus endowing SMBS with much better adsorption capacity for oil removal from water. The adsorption was found less favourable at high acidic condition and the maximum adsorption capacity was observed at about neutrality. Larger particle size would result in lower adsorption while adsorption temperature would not affect oil adsorption significantly. The kinetic study revealed that equilibrium time was short and the isotherm study indicated that the oil adsorption was fitted well by the Langmuir model. The adsorption capacity determined from the Langmuir isotherm was 576.0 ± 0.3 mg g−1at 25 °C [5]. The study showed that walnut shell media can be used as a sorbent for oil removal. For pure oil medium, sorption capacities of 0.30 g/g, 0.51 g/g and 0.58 g/g were obtained for standard mineral oil [6].
The aim of this study was to highlight the possibility of using recycled wool-based nonwoven material as a sorbent in an oil spill clean-up. This material sorbed higher amounts of base oil SN 150 than diesel or crude oil from the surface of a demineralized or artificial seawater bath. Superficial modification of material with the biopolymer chitosan and low-temperature air plasma led to a slight decrease of sorption capacity. Loose fibers of the same origin as nonwoven material have significantly higher sorption capacities than investigated nonwoven material. White light scanning interferometry analysis of the fibres suggested that roughness of the wool fiber surface has an important role in oil sorption. The laboratory experiments demonstrated that this material is reusable. Recycled wool-based nonwoven material showed good sorption properties and adequate reusability, indicating that a material based on natural fibres could be a viable alternative to commercially available synthetic materials that have poor biodegradability. Recycled wool-based nonwoven material is obviously an efficient sorbent either in water or in oil medium, and it can be a viable alternative to commercially available synthetic materials because of the relatively high oil sorption capacity, reusability, and biodegradability [7]. A new oil adsorption method called adsorption filtration (AF) has been developed. It is a technology where by oil residues can be cleaned from water by running it through a simple filter made from freeze treated, dried, milled and then fragmented plant material. By choosing suitable plants and fragmentation sizes it is possible to produce filters, which pass water but adsorb oil. The aim of this study was to investigate the possibilities of manufacturing oil adsorbing filter materials from reed canary grass (Phalaris arundinacea), flax (Linum usitatissimum L.) or hemp fibre (Cannabis sativa L.). The oil (80 ml) was mixed with de-ionised water (200 ml) and this mixture was filtered through 10 or 20 g adsorption filters. Fine spring harvested hemp fibre (diameter less than 1 mm) and reed canary grass fragments adsorb 2–4 g of oil per gram of adsorption material compared to 1–3 g of water. Adsorption filtration is thus a novel way of gathering spilled oil in shallow coastal waters before the oil reaches the shore [8]. Sponge-like exfoliated vermiculite (EV)/carbon nanotube (CNT) hybrids with different CNT content were prepared by intercalating aligned CNT arrays into natural vermiculite layers for oil adsorption. The intercalated growth of CNT arrays among EV layers of the EV/CNT hybrids was characterized by scanning electron microscopy and transmission electron microscopy. Thermogravimetric analysis under air atmosphere showed that CNT contents of the hybrids varied from 11.4% to 94.8% for different growth
duration. Pore size distributions measured by an ex-situ Hg penetration method showed that large amount of pores can be formed in the hybrids after the intercalation of CNT arrays. N 2 adsorption results showed that the specific surface areas of all hybrids were significantly improved compared with original EV particles. Oil adsorption tests were conducted on a class of organic solvents and oils in baker and the recovery process was carried out in a syringe. It was found that the oil adsorption capacities of the asobtained sponge-like EV/CNT hybrids were significantly improved compared with original EV particles due to the large quantity of pores produced by the intercalated growth of aligned CNT. The highest adsorption capacity of the EV/CNT hybrids was 26.7 g/g for diesel oil when the CNT content reached 91.0%, which also exhibited good recycling performance. Furthermore, the adsorption capacity for diesel oil can be further increased to 70.6 g/g by transforming the EV/CNT hybrids into fluffy EV/CNT cotton through high-speed shearing [9]. Polypropylene oil-absorption fibre (PP-g-BA) was prepared by radiationinduced graft polymerization of butyl acrylate (BA) onto polypropylene (PP) using divinylbenzene (DVB) as cross-linking agent. The original and grafted PP fibres were characterized by Fourier transform infrared (FT-IR) spectrometer and Scanning Electron Microscopy (SEM), and the result indicated that butyl acrylate was successfully grafted onto PP fibre. The factors that influenced the grafting degree of PP were discussed, such as the concentration of monomer and crosslinking agent. When the concentration of DVB was 2% and the concentration of BA was 10%, the maximum grafting degree reached 20.53%. The oil absorption properties of PP and PP-g-BA fibre were investigated and the results showed that the maximum adsorption capacity of PP-g-BA reached 19.74 g/g for toluene and 18.8 g/g for kerosene. Simulating absorption in the oil floating on the surface of water showed that the oil could be absorbed quickly and completely in three minutes. PP-g-BA exhibited quicker adsorption rate and higher adsorption capacity than PP fibre did [10]. Kapok fibers enjoy a low specific gravity, water repellence and a high oil-adsorbing capacity. When they are used as an adsorbent of oils and brought into contact with oils floating on or suspended in water, they provide effective adsorption of the oils. The oil-adsorbing materials made of synthetic high-molecular substances also have the disadvantage that they themselves may cause serious ecological problems if not thorough recovered after use on seas or oceans. To attain the objects described above, the method for the adsorption of oils according to the present invention uses kapok fibers as the oil-adsorbing material which is brought into contact with oils floating on or suspended in water. The kapok fibers have a specific gravity of only 0.04 to 0.05 and repel water and, hence, enjoy high floatability in water. They also abound in an oil-adsorbing capacity. The fibers, therefore, provide effective adsorption of oils which is floating on water or suspended in water. An oil fence or oil fiber which utilizes to advantage the oil-adsorbing
property of kapok fibers may also be produced such as by mixing kapok fibers with some other fibers and suitably shaping the resultant mixed fibers [11].
In this study, kapok fibers have been acetylated for oil spill cleanup in the aqueous environment. Without severe damage to the lumen structures, the kapok fibers were successfully acetylated and the resulting acetylated fibers exhibited a better oil sorption capacity than raw fibers for diesel and soybean oil. Compared with high viscosity soybean oil, low viscosity diesel shows better affinity to the surface of acetylated fibers. Sorption kinetics is fitted well by the pseudo second-order model, and the equilibrium data can be described by the Freundlich isotherm model. The results implied that acetylated kapok fiber can be used as the substitute for nonbiodegradable oil sorption materials [12].
Figure 2 Oil Sorption Capacities of Different Materials [12]
Figure 3 Parameters of Langmuir and Freundlich Models [12]
This study shows kapok fibres has a high sorption capacity than raw fibres and can be well described by Freundlich model than Langmuir model [12]. Dr. Essam Al Zubaidy studied effect of activation of Date Palm Kernel Powder on the remediation process of oil polluted water (DPKPP). Date palm kernels were washed, dried, crushed and activated to be a sorbent for oil remediation. Four types of date palm kernel powder were used; date palm kernels powder (DPKP) without any activation, thermally carbonized DPKP (CDPKP), acid activated carbonized date palm kernel powder (AACDPKP), and ZnCl2 activated carbonized date palm kernel powder (ZnCl2CDPKP). It was found that the type of activation of DPKP had a significant effect on oil sorption capacity. It was found that ZnCl2CDPKP had the highest sorption activity among others while DPKP without activation got the lowest oil sorption capacity. Oil sorption capacities were 3.25 g/g, 4.14 g/g, 4.35 g/g, and 4.48 g/g for DPKP, CDPKP, AACDPKP, and ZnCl2CDPKP respectively. Oil retention and sorbent reusability were studies. The reusability was studied for 10 cycles. The oil sorption capacity was reduced by 19.7-32% of total adsorbed oil. The performance of these sorbents was compared with other biomass materials from other work. [13]
Figure 4 water and oil uptake of different DPKPs in g/g [13]
Figure 5 Amount of Absorbed oil with amount of sorbents using different activation forms of DPKP [13]
Figure 6 Crude oil sorption capacity with mass of sorbent for different types of DPKPs [13]
Figure 7 Oil retention for DPKPs sample in wt% [13]
Figure 8 Reusability of DPKPs with oil sorption capacity [13]
This study used waste bio material for oil removal and it showed that activation method is in favour of oil removal and it showed that activation method is in favour of oil remediation [13].
Bibliography 1- Okiel, Khaled, Mona El-Sayed, and Mohamed Y. El-Kady. "Treatment of Oil–water Emulsions by Adsorption onto Activated Carbon, Bentonite and Deposited Carbon." Egyptian Journal of Petroleum 20.2 (2011): 9-15. 2- Li, Xiaobing, Chunjuan Zhang, and Jiongtian Liu. "Adsorption of Oil from Waste Water by Coal: Characteristics and Mechanism." Mining Science and Technology (China) 20.5 (2010): 778-81. 3- Kong, J., and K. Li. "Oil Removal from Oil-in-water Emulsions Using PVDF Membranes." Separation and Purification Technology 16.1 (1999): 83-93. 4- Srinivasan, Asha, and Thiruvenkatachari Viraraghavan. "Oil Removal from Water Using Biomaterials." Bioresource Technology 101.17 (2010): 6594-600. 5- Ibrahim, Shariff, Shaobin Wang, and Ha Ming Ang. "Removal of Emulsified Oil from Oily Wastewater Using Agricultural Waste Barley Straw."Biochemical Engineering Journal 49.1 (2010): 78-83. 6- Srinivasan, Asha, and Thiruvenkatachari Viraraghavan. "Removal of Oil by Walnut Shell Media." Bioresource Technology 99.17 (2008): 8217-220. 7- Radetić, Maja M., Dragan M. Jocić, Petar M. Jovančić, Zoran Lj. Petrović, and Helga F. Thomas. "Recycled Wool-Based Nonwoven Material as an Oil Sorbent." Environmental Science & Technology 37.5 (2003): 1008-012. 8- Pasila, Antti. "A Biological Oil Adsorption Filter." Marine Pollution Bulletin49.11-12 (2004): 1006-012. 9- Zhao, Meng-Qiang, Jia-Qi Huang, Qiang Zhang, Wei-Liang Luo, and Fei Wei. "Improvement of Oil Adsorption Performance by a Sponge-like Natural Vermiculite-carbon Nanotube Hybrid." Applied Clay Science 53.1 (2011): 1-7. 10- "Synthesis of Butyl Acrylate Grafted Polypropylene Fibre and Its Applications on Oil-adsorption in Floating Water. E-Polymers, 01 Dec. 2009. 11- US Paten No 4061567 A (issued Dec 6, 1977). 12- Jintao Wang, Yian Zheng, Aiqin Wang, "Investigation of Acetylated Kapok Fibers on the Sorption of Oil in Water. “Investigation of Acetylated Kapok Fibers on the Sorption of Oil in Water. 27 June 2012. 13-Zubaidy, Essam Al. "Effect of Activation of Date Palm Kernel Powder on the Remediation Process of Oil Polluted Water." International Journal of Environmental Pollution and Remediation (2012).
