Development of a New Oil Spill Adsorbent from Autohydrolysis Modified Lignocellulosic Waste Material

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1 Development of a New Oil Spill Adsorbent from Autohydrolysis Modified Lignocellulosic Waste Material D. SIDIRAS a, F. BATZIAS a, I. KONSTANTINOU a, M. TSAPATSIS b a Department of Industrial Management and Technology University of Piraeus 8 Karaoli & Dimitriou, GR 1853 Piraeus GREECE sidiras@unipi.gr b Department of Chemical Engineering and Materials Science University of Minnesota 1 Washington Avenue SE, Minneapolis, Minnesota 5555, USA tsapa1@umn.edu Abstract: This work deals with the chemical modification of a widely found lignocellulosic agricultural residue (wheat straw) to obtain low cost adsorbents for diminishing an oil-products spill in seawater. The lignocellulosic adsorbent was modified by autohydrolysis, i.e. pure water as a chemical, in a PARR autoclave at 1- o C for -5 min. The oil adsorbency tests were performed, using diesel and crude oil spills (of predetermined quality specifications) in seawater. Diesel and crude oil adsorbency-values were found to increase up to a maximum by intensifying the autohydrolysis conditions (time and reaction-ending temperature). Optimal modification conditions were found at o C for autohydrolysis time 1 min giving diesel adsorbency-value up to.5 g/g and crude oil adsorbency-value up to.91 g/g. The relative diesel adsorbency-value (RDA) was 71% and the relative crude oil adsorbency-value (RCOA) was 7% at these conditions. Key-Words: adsorbent, autohydrolysis, lignocellulosic, oil spill, pretreatment, waste, wheat straw. 1 Introduction The oil spills in seawater are usually results of exploration or transportation or storage activities. Dispersants, skimmers, oil-water separators, booms and sorbents are used to remove oil from contaminated marine areas and diminish the impact on the affected ecosystems. Adsorbents can be inorganic mineral or organic synthetic or organic natural products like waste biomass coming from lignocellulosic agricultural residues or agroindustrial byproducts. The modification of such wastes can provide low cost adsorbents with improved qualities for the adsorption of dyes, heavy metals and oil products [1-9]. Wheat straw is a renewable material for production of cellulose, glucose, bioethanol and other chemicals. Wheat straw is often used during containment and clean up of oil spills. A thin wax layer covering stalks and leaves of cereals is composed of esters, long chain fatty acids and monohydroxy alcohols, therefore wheat straw should favorably adsorb hydrophobic liquids. Waxes are insoluble in water, thus the coating on external surfaces of stems, leaves, flowers, fruits and seeds protects them from excessive water evaporation or outer moisture. Waxes also protect plants from microorganisms and mechanical damage. Wax coating aids the process of crop ripening by preventing stalks from becoming moist again. Wheat straw like the other sorbing material is capable of holding oil as the result of two processes: adsorption and absorption. The adsorption capacity depends primarily on the chemical structure of straw tissue that has direct contact with oil. The absorption capacity is a function of the structure of the straw stalks in the bundles, distances between them, the diameter and cross-sections of each stalk and leaf. Due to high oil adsorption by wheat straw, oil is mostly held due to capillary of straw tissue and interior part of stalk, as well as to the existence of oil bridges between stalks. Wheat straw adsorption capacity varies for many researches due to different apparent densities of wheat straw and ways of its adsorbent form. The absorption of oil depends on surface properties of wheat straw [1]. ISBN:

2 The corresponding technical literature shows that biomass [11], raw bagasse [1], carbonized pith bagasse [13], acetylated sugarcane bagasse [1], peat [15, 1], fatty acid grafted sawdust [17] and carbonized fir fibers [18] can be used as a sorbents for oil-spills. The present work deals with the modification of wheat straw to obtain low cost adsorbents for diminishing an oil-products spill in seawater. The adsorbent was pretreated by autohydrolysis, in a PARR autoclave at 1- o C for -5 min. The oil adsorbency tests were performed, using diesel and crude oil spills in seawater. Materials and Methods.1 Material Development The wheat straw obtained from Thessaly in Central Greece had a moisture content of 8.75% w/w. It was chopped with hedge shears in small pieces and the fraction with sizes 1 - cm (representing more than 95% of the raw total wheat straw) was collected by sieving. This fraction was chosen because it is more suitable for scale up of the process. The composition is presented in Table 1. Table 1. Composition of wheat straw. Component % w/w Cellulose 3.7 Hemicelluloses.5 Xylose 19,3 Arabinose,7 Acetyl groups,5 Klason lignin 1.8 Ash.7 Extractives. Other components Autohydrolysis Process The wheat straw was pretreated by autohydrolysis; the autohydrolysis process was performed in a 3.75-L batch reactor PARR 83. The hydrolysis time was -5 min (not including the preheating time); the reaction was catalyzed by the organic acids produced by the wheat straw itself during autohydrolysis at a liquid-to-solid ratio of :1; the liquid phase volume was ml and the solid material dose was 1 g. The autohydrolysis reaction ending temperature (T in o C) was 1 C, 18 C, C and C, reached after the, 7, and 8 min preheating time, respectively..3 Analytical Techniques Following the technique proposed by Saeman et al. [19], the lignocellulosic materials were quantitatively hydrolyzed to glucose, xylose and arabinose in nearly quantitative yields. The filtrates from the quantitative saccharification, as well as those from the autoclave, were analyzed for their content of glucose, xylose, and arabinose using high-performance liquid chromatography (HPLC, Agilent 1) with an Aminex HPX-87H Column, a refractive index detector, and 5 mm HSO in water as the mobile phase. Glucose, xylose and arabinose were produced via quantitative saccharification of the solid residue in each one of the twenty-four experiments. Cellulose was estimated as glucan, and hemicelluloses were estimated as xylan and arabinan. Based on these results the cellulose and hemicelluloses content of the adsorbents were estimated. Finally, the acidinsoluble lignin (Klason lignin) was determined according to the Tappi T om-88 method []. The scanning electron microscope (SEM) used herein was a JEOL JSM-7F Field Emission Scanning Electron Microscopy. The SEM tests were carried out on samples which were Pt coated (5 nm). The magnifications were 75, 75 and 5, respectively. The oil adsorbency test, defined according to the ASTM F7- method [1], was performed, following the procedure of this standard method, using diesel 1 PPM produced by Hellenic Petroleum S.A. (the density of diesel at 15 o C was 835 kg/m 3 and the viscosity at o C was 3.7 mm /s) and crude oil (the density of crude oil at 15 o C was 8 kg/m 3 ). 3 Results and Discussion Cellulose is hydrolyzed to glucose, hemicelluloses are hydrolyzed to xylose and the Klason lignin is not significantly affected by autohydrolysis. The simulation of the autohydrolysis process can be performed using a model described in earlier work []. The experimental reaction temperature profiles as a function of autohydrolysis time are presented in Fig. 1. The autohydrolysis solid residue yield (SRY) of the wheat straw (dry weight of product % w/w of the original dry material) is presented in Fig. as a function of reaction time. ISBN:

The SEM micrographs for autohydrolyzed (1 o C, min+ min preheating period) wheat straw are shown in Fig. 3.

, 5 and the diesel adsorbency, the adsorbency and the relative diesel adsorbency (RDA) are presented vs. the autohydrolysis time, assuming that diesel oil spill is formed in seawater. In Figs.

1, 11 and 1 the crude oil adsorbency, the adsorbency and the relative crude oil adsorbency (RCOA) are presented vs. the autohydrolysis time, assuming that crude oil spill is formed in seawater.

3 The SEM micrographs for autohydrolyzed (1 o C, min+ min preheating period) wheat straw are shown in Fig. 3. The experimental results of the diesel and crude oil adsorbency of the untreated and the autohydrolyzed wheat straw are shown in the following diagrams. In Figs., 5 and the diesel adsorbency, the adsorbency and the relative diesel adsorbency (RDA) are presented vs. the autohydrolysis time, assuming that diesel oil spill is formed in seawater. In Figs. 7, 8 and 9 the diesel adsorbency, the adsorbency and the relative diesel adsorbency (RDA) are presented vs. the (1-SRY). In Figs. 1, 11 and 1 the crude oil adsorbency, the adsorbency and the relative crude oil adsorbency (RCOA) are presented vs. the autohydrolysis time, assuming that crude oil spill is formed in seawater. In Figs. 13, 1 and 15 the crude oil adsorbency, the adsorbency and the relative crude oil adsorbency (RCOA) are presented vs. the (1-SRY). (a) (b) Fig. 1. Experimental reaction temperature profiles as a function of autohydrolysis time. (c) Fig. 3. SEM micrographs for autohydrolyzed (1 o C, min+ min preheating period) wheat straw. Fig.. Experimental values for the solid residue yield (SRY) as a function of autohydrolysis time at 1- o C. ISBN:

4 Diesel Adsorbency (g/g) Autohydrolysis Time, t (min) 1oC 18oC oc oc Diesel Adsorbency (g/g) % 1% % 3% % 5% % 7% 1-SRY (% w/w) Fig.. Diesel adsorbency vs. the autohydrolysis time for reaction ending temperatures 1- o C (Diesel oil spill in seawater). Fig. 7. Diesel adsorbency vs. the (1-SRY) for reaction ending temperatures 1- o C (Diesel oil spill in seawater). Adsorbency (g/g) Autohydrolysis Time, t (min) 1oC 18oC oc oc Fig. 5. Adsorbency vs. the autohydrolysis time for reaction ending temperatures 1- o C (Diesel oil spill in seawater). Relative Diesel Adsorbency (%) 9% 8% 7% % 5% % 3% Autohydrolysis Time, t (min) 1oC 18oC oc oc Fig.. Relative Diesel Adsorbency (RDA) vs. the autohydrolysis time for reaction ending temperatures 1- o C (Diesel oil spill in seawater). Adsorbency (g/g) % 1% % 3% % 5% % 7% 1-SRY (% w/w) Fig. 8. Adsorbency vs. the (1-SRY) for reaction ending temperatures 1- o C (Diesel oil spill in seawater). Relative Diesel Adsorbency (%) 9% 85% 8% 75% 7% 5% % 55% 5% % 1% % 3% % 5% % 7% 1-SRY (% w/w) Fig. 9. Relative Diesel Adsorbency (RDA) vs. the (1-SRY) for reaction ending temperatures 1- o C (Diesel oil spill in seawater). ISBN:

5 Fig. 1. Crude oil adsorbency vs. the autohydrolysis time for reaction ending temperatures 1- o C (Crude oil spill in seawater). Fig. 13. Crude oil adsorbency vs. the (1-SRY) (Crude oil spill in seawater). Fig. 11. Adsorbency vs. the autohydrolysis time for reaction ending temperatures 1- o C (Crude oil spill in seawater). Fig. 1. Adsorbency vs. the (1-SRY) (Crude oil spill in seawater). Fig. 1. Relative Crude Oil Adsorbency (RCOA) vs. the autohydrolysis time for reaction ending temperatures 1- o C (Crude oil spill in seawater). Fig. 15. Relative Crude Oil Adsorbency (RCOA) vs. the (1-SRY) (Crude oil spill in seawater). Conclusion The modified wheat straw can be used as low cost adsorbent for diminishing an oil-products spill in seawater. The adsorbent was autohydrolyzed at 1- o C for -5 min. The oil adsorbency tests were performed, using diesel and crude oil spills in seawater. Diesel and crude oil adsorbency-values were found to increase up to a maximum by ISBN:

6 intensifying the autohydrolysis time and temperature conditions. Optimal autohydrolysis conditions were found at o C for time 1 min giving diesel adsorbency-values up to.5 g/g and crude oil adsorbency-values up to.91 g/g, while the RDA value was 71% and the RCOA value was 7%. 5 Acknowledgments Financial support by the Research Centre of the University of Piraeus is kindly acknowledged. References: [1] A. Srinivasan, T. Viraraghavan. Removal of oil by walnut shell media. Bioresource Technology, 99(17), 8, pp [] D. Sidiras, F. Batzias, R. Ranjan, M. Tsapatsis. Simulation and optimization of batch autohydrolysis of wheat straw to monosaccharides and oligosaccharides. Bioresource Technology, 1, 11, pp [3] D. Sidiras, F. Batzias, E. Schroeder, R. Ranjan, M. Tsapatsis. Dye adsorption on autohydrolyzed pine sawdust in batch and fixed-bed systems. Chemical Engineering Journal, 171(3), 11, pp [] F.A. Batzias, D.K. Sidiras, Dye adsorption by prehydrolysed beech sawdust in batch and fixed-bed systems, Bioresource Technology, 98, 7, pp [5] F. Batzias, D. Sidiras, E. Schroeder, C. Weber, Simulation of dye adsorption on hydrolyzed wheat straw in batch and fixed-bed systems, Chemical Engineering Journal, 18, 9, pp [] F.A. Batzias, D.K. Sidiras, Simulation of methylene blue adsorption by salts-treated beech sawdust in batch and fixed-bed systems, Journal of Hazardous Materials, 19, 7, pp [7] D.K. Sidiras, I.G. Konstantinou, T.K.Politi. Autohydrolysis Modified Barley Straw as Low Cost Adsorbent for Oil Spill Cleaning. Proc. 19 th European Biomass Conference, Berlin, 11, pp [8] F.A. Batzias, I.G. Konstantinou, N.L. Vallaj, D.K Sidiras, Diminishing an oil-products spill in seawater by using modified lignocellulosic residues as low cost adsorbents. Proc. 19 th International Congress of Chemical and Process Engineering CHISA 1. Prague, Czech Republic, 1, No [9] D. Sidiras. Simulation and Optimisation of Wheat Straw Autohydrolysis to Fermentable Sugars for Bio-ethanol Production, Proc. 18 th European Biomass Conference, Lyon, France, 1, pp [1] E. Witka-Jezewska, J. Hupka, P. Pieniazek. Investigation of oleophilic nature of straw sorbent conditioned in water. Spill Science & Technology Bulletin, 8(5-), 3, pp [11] E. Khan, W. Virojnagud, T. Ratpukdi. Use of biomass sorbents for oil removal from gas station runoff, Chemosphere, 57(7), pp [1] A.E-A. Said, A.G. Ludwick, H.A. Aglan. Usefulness of raw bagasse for oil absorption: A comparison of raw and acylated bagasse and their components. Bioresource Technology, 1(7), 9, pp [13] M. Hussein, A.A. Amer, I. I. Sawsan. Oil spill sorption using carbonized pith bagasse: 1. Preparation and characterization of carbonized pith bagasse. Journal of Analytical and Applied Pyrolysis, 8(), 8, pp [1] X. F. Sun, R. C. Sun, J. X. Sun. Acetylation of sugarcane bagasse using NBS as a catalyst under mild reaction conditions for the production of oil sorption-active materials. Bioresource Technology, 95(3),, pp [15] S. Suni, A.L. Kosunen, M. Hautala, A. Pasila, M. Romantschuk. Use of a by-product of peat excavation, cotton grass fibre, as a sorbent for oil-spills. Marine Pollution Bulletin, 9(11-1),, pp [1] T. Viraraghavan, G.N. Mathavan. Treatment of oil-in-water emulsions using peat. Oil and Chemical Pollution, (), 1988, pp [17] S.S. Banerjee, M.V. Joshi, R.V. Jayaram. Treatment of oil spill by sorption technique using fatty acid grafted sawdust. Chemosphere (),, pp [18] M. Inagaki, A. Kawahara, H. Konno. Sorption and recovery of heavy oils using carbonized fir fibers and recycling. Carbon, (1),, pp [19] J.F. Saeman, Bubl JF, Harris EE., Quantitative saccharification of wood and cellulose. Ind. Eng. Chem. Anal. Ed. 17, 195, pp. 35. [] Tappi Standards. T om-88 method, Atlanta, Tappi Tests Methods, [1] American Society of Testing and Materials - International, ASTM F 7-, Standard Test Method for Sorbent Performance of Adsorbents, West Conshohocken,, pp ISBN:

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