Preparation,Characterization And Adsorption Properties Of Acetylated Wheat Straw

Environmental pollution which caused by the various types of oil severely affected the survival of marine life and human economic activities.The modification of natural organic materials oil adsorption treatment is one of the most effective oi l-cont ami nat ed wat er t reat m ent m et hods.Thi s s t ud y i nves ti gat ed t he transesterification process of preparing a modified wheat straw fiber adsorbent material,and the adsorption characteristics of the modified wheat straw fiber in oil/water mixture.FT-IR,XRD was used to characterize the acetylation of adsorbent.1.The main component of pretreated wheat straw as follows: lignin 4.07 %,hemicellulose 8.93 %,cellulose 79.7 %.Characterization of the wheat straw cellulose(WSC)and pretreated wheat straw was performed by FT-IR,XRD.FT-IR spectrum demonstrated that the cellulose fibers were extracted from the straw fibers by pretreatment.XRD analysis showed that the crystalline form has not changed.However,the crystallinity of the pretreated fiber is larger than that of the untreated fibers.2.The extent of acetylation was measured by weight percent gain(WPG),which increased with the extent of reaction time and temperature.According to WPG and oil sorption capacity of the acetylated cellulose fibers for pure oil and oil slick,the optimum acetylated condition for cellulose fibers is reaction time 2 h,the reaction temperature 90 oC and DBU / IPA ratio of 0.3(v/v).The oil adsorptivity of the acetylated cellulose fibers(AWCF)at the optimum prepared condition was 26.73,25.83g/g for diesel oil,oil slick,respectively.The oil adsorptivity of AWCF for oil slick was smaller than that for pure oil.The new emerging absorption peaks in FT-IR spectra indicated that hydrophobic groups had been grafted to the surface of pretreatment straw.XRD analysis showed that the crystallinity of AWCF was smaller than that of the pretreated fibers.3.The effects of sorbent dose(0.1 g to 0.5 g),initial oil amount(5 g to 30 g),adsorption temperature and the sorption time were also studied.The two materials(WSC,AWCF)had a better adsorptivity at high initial oil amount or in small dosage while significantly decreased with the increasement of temperature.Additionally,the oil could be seperated from sorbent by vacuum filtration,meaning that the AWCF was recirculated.The results of the adsorption kinetic experiment showed that more than 94.5 % of the diesel oil was absorbed by the acetylated cellulose fibers within the first 10 min and the adsorption kinetic was consistent with the simulated-second-order model,where the rate constant was 1.5554 g/(g?min)and 0.0439 g/(g?min)with equilibrium absorbance of 5.53 g/g,25.83 g/g,respectively.The Freundlich isotherm equation could describe the adsorption isotherms of WSC and AWCF,and the adsorption isotherms of AWCF could also be characterized by Langmuir isotherm equation.