A New Oil Spill Adsorbent from Sulfuric Acid Modified Wheat Straw

Transcription

1 A New Oil Spill Adsorbent from Sulfuric Acid Modified Wheat Straw D. SIDIRAS, I. KONSTANTINOU Department of Industrial Management and Technology University of Piraeus Karaoli & Dimitriou, GR Piraeus GREECE Abstract: This work deals with the chemical modification of wheat straw, a common lignocellulosic agricultural residue, to obtain low cost adsorbents for diminishing an oil-products spill in seawater. The adsorbent was modified by acid hydrolysis, i.e.. N sulfuric acid as a chemical catalyst, in a PARR autoclave at - o C for - min isothermal time period. The oil adsorbency tests were performed, using diesel and crude oil of predetermined quality specifications. Water adsorbency-values for reaction ending temperature at C were found to increase from. g/g to a maximum of. g/g for isothermal reaction time min. At C the maximum was. g/g for the same isothermal reaction time. At and C the water adsorbency was decreasing as low as. g/g for extreme hydrolysis conditions. Diesel adsorbencyvalues for reaction ending temperature at C were found to increase from. g/g to a maximum of. g/g for isothermal reaction time min. At C the maximum was. g/g for isothermal reaction time min. At C the maximum was. g/g for the same isothermal reaction time. At C the maximum was. g/g for isothermal reaction time min. Crude oil adsorbency-values for reaction ending temperature at C were found to increase from. g/g to a maximum of. g/g for isothermal reaction time the same with that in the case of diesel. At C the maximum was. g/g for isothermal reaction time min. At C the maximum was. g/g for isothermal reaction time min. At C the maximum was. g/g for the same isothermal reaction time. Key-Words: adsorbent, acid hydrolysis, lignocellulosic, oil spill, pretreatment, wheat straw. Introduction The oil spills are usually results of transportation and storage activities. Dispersants, skimmers, oilwater separators, booms and adsorbents are used to remove oil from contaminated marine areas and diminish the impact on the affected ecosystems. Adsorbents can be inorganic or organic, synthetic or natural products. Waste biomass as a lignocellulosic agricultural residue or agro-industrial byproducts is a natural organic adsorbent. The chemical modification by autohydrolysis [, ] or acid hydrolysis of this lignocellulosic waste can provide low cost adsorbents with improved qualities for the adsorption of dyes [-] and oil products [-]. Wheat straw is a renewable source for production of energy chemicals. Wheat straw can be used during containment and cleanup of oil spills in aquatic environment. A thin wax layer covers stalks and leaves of cereals. Therefore wheat straw could 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. Wheat straw like the other adsorbing materials is capable of holding oil as the result of 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 []. According to the technical literature, walnut shell [], wheat and barley straw [-], biomass [], raw bagasse [], carbonized pith bagasse [], acetylated sugarcane bagasse [], peat [, ], fatty acid grafted sawdust [] and carbonized fir fibers [] can be used as oil-spill adsorbents. ISBN: ----

2 This work deals with the modification of wheat straw to obtain low cost adsorbents for diminishing an oil-products spill in aquatic environment. The adsorbent was pretreated by acid hydrolysis at - o C for - min with. N sulfuric acid as a chemical catalyst. The oil adsorbency tests were performed, using diesel and crude oil. Materials and Methods. Material Development The wheat straw obtained from Thessaly in Central Greece had a moisture content of.% w/w. It was chopped with hedge shears in small pieces and the fraction with sizes - cm (representing more than % 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.. Acid hydrolysis Process The wheat straw was pretreated using acid hydrolysis; the acid hydrolysis process was performed in a.-l batch reactor PARR. The acid hydrolysis time was - min (not including the preheating time); the hydrolysis reaction was catalyzed by. N sulfuric acid at a liquid-to-solid ratio of :; the liquid phase volume was ml and the solid material dose was g. The acid hydrolysis reaction ending temperature (T in o C) was C, C, C and C, reached after the,, and min preheating time, respectively.. Analytical Techniques Applying the technique proposed by Saeman et al. [], the lignocellulosic materials were quantitatively saccharified 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 ) with an Aminex HPX-H Column, a refractive index detector, and 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- method []. The oil adsorbency test, defined according to the ASTM F- method [], was performed, following the procedure of this standard method, using diesel PPM produced by Hellenic Petroleum S.A. and crude oil. The diesel and crude oil quality specifications are given in Table. Table. Diesel and crude oil quality specifications. Oil type Diesel Crude oil Density (kg/m ) at o C at o C Viscosity (mm /s). at o C Water content (mg/kg) Results and Discussion Cellulose is hydrolyzed to glucose, hemicelluloses are hydrolyzed to xylose and the Klason lignin is not significantly affected by acid hydrolysis. The simulation of the acid hydrolysis process can be performed using a model described in earlier work []. The experimental reaction temperature profiles as a function of acid hydrolysis time are presented in Fig.. The acid hydrolysis solid residue yield 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. The experimental results of the water, diesel and crude oil adsorbency of the untreated and the acid hydrolyzed wheat straw are presented in the following Figures. The water adsorbency-values for reaction ending temperature at C were found to increase from. g/g to a maximum of. g/g for isothermal reaction time min (Fig. ). The diesel adsorbency-values for reaction ending temperature at C were found to increase from. g/g to a maximum of. g/g for isothermal reaction time min (Fig. ). The crude oil adsorbency-values for reaction ending temperature at C were found to increase from. g/g to a maximum of. g/g for isothermal reaction time the same with that in the case of diesel (Fig. ). At C the maximum water adsorbency-value was. g/g for isothermal reaction time min (Fig. ). At the same temperature the maximum diesel adsorbency-value was. g/g for isothermal reaction time min (Fig. ). Moreover, the maximum crude oil adsorbency-value was. g/g for isothermal reaction time min (Fig. ). At and C the water adsorbency was decreasing as low as. g/g ISBN: ----

3 for min isothermal hydrolysis time (Figs. and ). At C the maximum diesel adsorbencyvalue was. g/g for isothermal reaction time min (Fig. ). At the same temperature the maximum crude oil adsorbency-value was. g/g for isothermal reaction time min (Fig. ). At C the maximum diesel adsorbency-value was. g/g for isothermal reaction time min (Fig. ). At the same temperature the maximum crude oil adsorbency-value was. g/g for isothermal reaction time min (Fig. ). The water, diesel and crude oil adsorbency can be given as function of the autohydrolysis time as follows: A i = ait + bit + cit + di () where A is the adsorbency (g/g), t is the autohydrolysis time (min), and i=w, D, C; W is for Water, D is for Diesel and C is for Crude oil. The values of the coefficients of eq. () are given in Table. At the same Table the correlation coefficients are presented. Temperature, T ( o C) oc oc oc oc Fig.. Modified wheat straw water adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Fig.. Modified wheat straw diesel adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Time, t (min) Fig.. Experimental reaction temperature profiles as a function of acid hydrolysis time. Yield, y (% w/w) % % % % % oc oc oc oc % Time, t (min) Fig.. Modified wheat straw crude oil adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Fig.. Wheat straw solid residue yield values as a function of acid hydrolysis time at - o C with. N H SO. ISBN: ----

4 Fig.. Water adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Fig.. Water adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Fig.. Diesel adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Fig.. Diesel adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Fig.. Crude oil adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Fig.. Crude oil adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. ISBN: ----

5 Fig.. Water adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Table. Coefficients of eq. () and correlation coefficients R. T ( o C) i a i b i c i d i R W W W W D D D D C C C C Fig.. Diesel adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Fig.. Crude oil adsorbency vs. the acid hydrolysis time for reaction ending temperatures o C and. N H SO. Conclusion The chemical modification of wheat straw leads to low cost adsorbents for diminishing an oil-products spill in seawater. The straw was modified by acid hydrolysis catalyzed by. N sulfuric acid at - o C for - min isothermal time period. The oil adsorbency tests were performed, using diesel and crude oil of predetermined quality specifications. Water adsorbency-values for reaction ending temperature at C were found to increase from. g/g to a maximum of. g/g for isothermal reaction time min. At C the maximum was. g/g for the same isothermal reaction time. At and C the water adsorbency was decreasing as low as. g/g for extreme hydrolysis conditions. Diesel adsorbencyvalues for reaction ending temperature at C were found to increase from. g/g to a maximum of. g/g for isothermal reaction time min. At C the maximum was. g/g for isothermal reaction time min. At C the maximum was. g/g for the same isothermal reaction time. At C the maximum was. g/g for isothermal reaction time min. Crude oil adsorbency-values for reaction ending temperature at C were found to increase from. g/g to a maximum of. g/g for isothermal reaction time the same with that in the case of diesel. At C the maximum was. g/g for isothermal reaction time min. At C the maximum was. g/g for isothermal reaction time min. At C the maximum was. g/g for the same isothermal reaction time. ISBN: ----

6 Acknowledgments Financial support by the Research Centre of the University of Piraeus is kindly acknowledged. References: [] D. Sidiras, F. Batzias, R. Ranjan, M. Tsapatsis. Simulation and optimization of batch autohydrolysis of wheat straw to monosaccharides and oligosaccharides. Bioresource Technology,,, pp.. [] D. Sidiras. Simulation and Optimisation of Wheat Straw Autohydrolysis to Fermentable Sugars for Bio-ethanol Production, Proc. th European Biomass Conference, Lyon, France,, pp. -. [] 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, (),, pp. -. [] F.A. Batzias, D.K. Sidiras, Dye adsorption by prehydrolysed beech sawdust in batch and fixed-bed systems, Bioresource Technology,,, pp. -. [] 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,,, 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,,, pp. -. [] A. Srinivasan, T. Viraraghavan. Removal of oil by walnut shell media. Bioresource Technology, (),, pp. -. [] D.K. Sidiras, I.G. Konstantinou, T.K.Politi. Autohydrolysis Modified Barley Straw as Low Cost Adsorbent for Oil Spill Cleaning. Proc. th European Biomass Conference, Berlin,, pp. -. [] 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. th International Congress of Chemical and Process Engineering CHISA. Prague, Czech Republic,, No. [] E. Witka-Jezewska, J. Hupka, P. Pieniazek. Investigation of oleophilic nature of straw sorbent conditioned in water. Spill Science & Technology Bulletin, (-),, pp. -. [] E. Khan, W. Virojnagud, T. Ratpukdi. Use of biomass sorbents for oil removal from gas station runoff, Chemosphere, (), pp. -. [] 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, (),, pp. -. [] M. Hussein, A.A. Amer, I. I. Sawsan. Oil spill sorption using carbonized pith bagasse:. Preparation and characterization of carbonized pith bagasse. Journal of Analytical and Applied Pyrolysis, (),, pp. -. [] 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, (),, pp. -. [] 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, (-),, pp. -. [] T. Viraraghavan, G.N. Mathavan. Treatment of oil-in-water emulsions using peat. Oil and Chemical Pollution, (),, pp. -. [] S.S. Banerjee, M.V. Joshi, R.V. Jayaram. Treatment of oil spill by sorption technique using fatty acid grafted sawdust. Chemosphere (),, pp. -. [] M. Inagaki, A. Kawahara, H. Konno. Sorption and recovery of heavy oils using carbonized fir fibers and recycling. Carbon, (),, pp. -. [] J.F. Saeman, Bubl JF, Harris EE., Quantitative saccharification of wood and cellulose. Ind. Eng. Chem. Anal. Ed.,, pp.. [] Tappi Standards. T om- method, Atlanta, Tappi Tests Methods,. [] American Society of Testing and Materials - International, ASTM F -, Standard Test Method for Sorbent Performance of Adsorbents, West Conshohocken,, pp. -. ISBN: ----