Study On Steam Explosion Pretreatment Of Wheat Straw And Preparation Of Hydrogel By Steam Explosion Liquid

The preparation of hydrogel by the steam explosion liquid of wheat straw not only reduces environmental pollution and improves the high value utilization of agricultural waste,but also enriches the research system of hydrogel.Because of the structural characteristics of wheat straw,it is necessary to pretreat to destroy the complex recalcitrance deconstruction for the biorefinery.Steam explosion is a physical and chemical pretreatment method with low energy consumption,less pollution and effective separation of components.The hemicellulose of wheat straw can be degraded into soluble sugar by pretreatment.And the steam explosion liquid that separated from residue by filtration is to prepare hydrogel.The main influencing factors of steam explosion are pressure and retention time.The results of experiment showed that it is obvious when the pressure was 1.8 MPa,and retention time was 6 min on retain more cellulose and removal most hemicellulose,the recovery of cellulose and lignin are 80.5%and 53.0%,and the hemicellulose removal content was 88.2%.Fourier Transform Infrared(FI-IR)spectroscopy,X-ray diffracti on(XRD),thermogravimetric analysis(TGA)and scanning electron microscopy(SEM)were used to analyze the residues and steam explosion liquid of the condition of pressure was 1.8 MPa and retention time was 6 min.It’s showed that glucose.xylose,arabinose,glucan,xylan,polyarabinose,formic acid,acetic acid,levulinic acid,furfural and 5-hydroxymethyl furfural(5-HMF)were the main component of steam explosion liquid,and their concentrations were 0.2 mg/mL,3.7 mg/mL,0.8 mg/mL,2.4 mg/mL,10.1 ng/mL,0.6 mg/mL,3.7 mg/mL,2.1 mg/mL,0.4 mg/mL,0.5 mg/mL,0.9 mg/mL respectively.It is also showed that the structure and shape of material with pretreatment of steam explosion changed significantly.The material could be used as raw in paper industry or other mater-ials for research.Add Initiator ammonium persulfate/anhydrous sodium sulfite,Monomer acrylamide(AM)and acrylic acid(AA),Crosslinking agent N,N-methylene bisacrylamide(MBA)to the steam explosion liquid,making the reaction system form hydrogels by free radical polymerization.Using the Box-Behnken model of response surface methodology to optimize the preparation conditions of hydrogels,and taking the swelling rate of hydrogels as the response value.And the software of Design-Expert can help us get the date and desired graphics.The center points of experimental conditions were steam explosion liquid 5.0 g,initiator 70.0 mg,monomer acrylamide 250.0 mg,monomer acrylic acid 750.0 mg and crosslinking agent 12.5 mg.The results of experiment showed that the optimum technological conditions were steam explosion liquid 5.0 g,initiator 74.7 mg,monomer acrylamide 333.3 mg5 monomer acrylic acid 576.5 mg and crosslinking agent 10.06 mg,and the swelling rate of hydrogel that predicted was 259.0 g/g.The actual swelling rate was 243.9 g/g.The experimental method of hydrogel preparation is not only simple to operate,but also can save time.And the hydrogel has good water retention.It can be used in the water-retaining and slow-release materials of crops.So as to improve the distribution of soil moisture,the living environment of crops,and the viability of crops.And The hydrogels can be recycled to eliminate the influence of secondary pollution.