Mechanocatalytic Solvent-free Modification Of Sugarcane Bagasse

Lignocellulosic biomass is the most abundant renewable resources on the earth.Lignocellulosic biomass has attracted a lot attention because of a variety of advantages,including low cost,renewable and biodegradable,to fossil resources.However,lignocellulosic biomass has poor material properties,which limited further expansion of its applications.Chemical modification is an improved way to overcome above shortcomings.Lignocellulosic biomass suffers from the drawbacks of complex cell wall structure,which makes it resistant to chemical reagents and leading to low reaction efficiency of heterogeneous system.In the past few years,there are increasing interests towards homogerous system of biomass modification.However,DMSO based solvents are hazardows and difficult to recover.Although ionic liquids are green solvents,they are far away from industrial available due to the high cost.In this study,solvent-free esterification of sugarcane bagasse(SCB)under ball-milled treatment was performed,which will improve modification efficiency with simplier process and lower cost than traditional modification system.Esterification of SCB with acetic anhydride(AA),propionic anhydride(PA)and butyric anhydride(BA)performed by ball-milling was researched.The effects of reaction conditions on weight percent gain(WPG)and the degree of substitution(DS)of sample were investigated.A similar trend between DS and WPG was observed.The crystalline structure has been destroyed by ball milling.With the AA/SCB dosage of 27:1 mmol/g,the maximum DS of SCB ester was 8.9 mmol/g.With the PA/SCB dosage of 23:1 mmol/g,the SCB ester with the highest WPG of 33.6% was obtained.X-ray diffraction(XRD)and scanning electron microscopy(SEM)results indicated that prolonging reaction time could destroy the crystalline structure.The thermal stability of SCB increased after the mechnocatalytic esterification.Adsorption materials of dyeing wasterwater was prepared by the esterification of SCB with succinic anhydride(SA).The effects of SA dosage,Py dosage and ball-milling time on WPG and DS were investigated.With the SA dosage of 10:1 mmol/g,the SCB ester with WPG and DS of 60.2% and 10.1 mmol/g,respectively.XRD results indicated that the crastalline index(CrI)values decreased with the increasing reaction time.SEM and adoption results indicated SCB was cut into fractions during ball-milling which resulted in the adoption time to methylene blue increased from 14 h to 6 h.After mechanocatalytic esterification between SA and SCB,the adoption amount increased from 91.2% to 96.9% which resulted from the introduction of carboxyl.The thermal stability of SCB decreased after modification.Ring-opening graft polymerization of ε-caprolactone(ε-CL)onto SCB was researched.The effects of ε-CL dosage,DMAP dosage and ball-milling time on grafting degree and grafting efficiency were investigated.With the ε-CL/SCB dosage of 26:1 mmol/g,the molar ration of DMAP to ε-CL of 1:1,the grafting degree and grafting efficiency of SCB-graft-poly(ε-caprolactone)(SCB-g-PCL)were 85.1% and 95.7%,respectively.XRD results indicated that the CrI of samples decreased after mechanocatalytic ring-opening graft polymerization.The thermal stability of SCB-g-PCL is higher than native SCB,but still lower than that of pure PCL.