The Study On Preparation And Properties Of Wheat Straw Esterification Modified Oil Spill Adsorbent

Once oil spills in water systems,it will do harms to the health of human and marine life.Therefore,it is urgent to develop effective remediation methods for oil spills.One of the most economical and efficient means to remove spilled oil on land or in water is the use of sorbents that have low cost,high-efficiency and no secondary pollution.In this paper,wheat straw?RWS?was selected as raw material to prepare the oil-spill adsorbent by esterification.Wheat straw?RWS?was successfully modified by esterification with saturated fatty acids in dimethyl sulfoxide?DMSO?without additional catalysts.The effects of reaction temperature,reaction time,and the content of saturated fatty acids were investigated.In addition,characterizations of the pretreated wheat straw?PWS?and esterified wheat straw?EWS?were performed by Fourier transform infrared spectroscopy?FT-IR?,X-ray diffraction?XRD?,scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?,and contact angle analysis?CA?methods.And oil-absorption capacity,selectivity,adsorption kinetics,oil-retention ability and recyclability of PWS and EWS were discussed.1?RWS was pretreated with toluene-ethanol,1.3%NaClO₂ and 10%NaOH,respectively and the components of RWS and PWS were analyzed.The main components of RWS and PWS as follows:RWS:cellulose 40.43%,hemicellulose 36.21%,lignin 12.89%;PWS:cellulose 78.06%,hemicellulose 9.61%,lignin 5.25%.In comparison with RWS,pretreatment is very effective in the removal of hemicellulose and lignin.Characterizations of RWS and PWS were performed by FT-IR,XRD,SEM and CA.FT-IR spectroscopy demonstrated that the cellulose fiber was extracted from RWS by pretreatment;XRD analysis showed that the crystallinity of PWS is larger than RWS;SEM and CA demonstrated that the PWS has poor effect of oil selectivity.2?PWS was modified by esterification with five linear chain saturated fatty acids?n-butyric acid,lauric acid,palmitic acid,stearic acid and arachidic acid?in dimethyl sulfoxide?DMSO?without additional catalysts.By comparing the oil absorption of EWS with five kinds of linear chain saturated fatty acids,the oil absorption of wheat straw modified by esterification with palmitic acid?EWS1?was higher than others.The characterization of EWS1 was performed by FT-IR,XRD,XPS and CA.The results of FT-IR and XPS indicated that the esterification reaction was carried out smoothly;XRD analysis showed that the crystallinity of EWS1 is smaller than PWS.And EWS1 could achieve a water contact angle of about 131.6°and an oil contact angle of 0°,demonstrating hydrophobic and lipophilic properties in the usual sense.In addition,oil-absorption capacity,and selectivity of PWS and EWS were discussed.The selectivity of five EWSs showed that EWS1 has many advantages of high adsorption efficiency and good effect of oil selectivity.3?Palmitic acid and 2-hexyldecanoic acid are isomers,respectively is linear and branched chain saturated fatty acids.PWS was modified by esterification with2-hexyldecanoic acid?EWS2?in DMSO without additional catalysts.The optimum conditions were confirmed by single factor experiments:reaction time,3 h;reaction temperature,90?;and 2-hexyldecanoic acid content,7 g.The oil absorption of EWS2 for diesel fuel is 26.41 g/g,which is higher than that of EWS1?24.31 g/g?and PWS?15.98 g/g?.In addition,characterization of the EWS2 was performed by FT-IR,XRD,SEM and CA.And the oil-absorption capacity,selectivity,adsorption kinetics,oil-retention ability and recyclability of EWS2 were discussed.