Research On The Nano-materials Preparation Of The Sugarcane Bagasse Based On The P-toluene Sulfonic Acid Pretreatment

With the environmental problem increasingly serious and the environmental protection policies increasingly strict,the people's extensive attention was attracted by degradable biomass materials.The nanolignocellulose with excellent mechanical properties,environment friendly,renewability,and good biocompatibility,was one of the unqiure biomass nanomaterial which had been applied in the field of pulp and paper,materials,food,dairy,and medicine.Taken the practical value of sugarcane,the low-level utilization raito and utilization value of the waste bagasse from sugar industry.The development of sugarcane bagasse refine technology and the promote the cleaner production level were very important to the high value utilization of bagasse.The lignin-containing cellulose nanofibril(LCNF)was parpered from the waste bagasse mechanical treatment after the recyclable solid organic acid(p-toluene sulfonic acid,p-TsOH) pretreatment under low temperature.The acid assisted dissolved lignin nanoparticles(LNP) were prepared from the pretreatment filtrate.The carbon quantum dots(CQDs) were prepared from the monosaccharide in the diluted filtrate after LNP separation.The cleaner production of the nanomaterial preparation from sugarcane bagasse and the full utilization of sugarcane bagasse were achieved.Furthormore,the application of LCNF and cellulose nanocrystals(CNC) in Pickering emulsion were systematic studied.Which provided a new sight and strong support to the cleaner production,the control technology,and the application of bagasse nanomaterials.(1)The effects of a fully recyclable p-TsOH on the decomposition of agriculture waste sugarcane bagasse were systemic studied.The hydrolysis kinetics parameters of the lignin and xylan were calculated.The three major factors(p-TsOH concentration,the hydrolysis temperature,and time)of the hydrolysis process were evaluated.The experience formulas of lignin and xylan in residue were fitted.The thermal stability of residue and the components of the hydrolysate were studied.The red CQDs were parpered through the one-pot hydrothermal method from the monosaccharide in diluted hydrolysate.The results showed that the cellulose component was well retained,the hemicellulose component was complete hydrolyzed,and part of lignin was removed after p-Ts OH pretreatment.The p-TsOH concentration had the most important effect on the lignin decomposition,while the reaction temperature and hydrolysis time had the most impact on the xylan degradation.The surface groups and allomorph of residue were steadied.Thermal stability of residue was increased with the hydrolysis condition increased.The red CQDs were succeed parperated from diluted hydrolysate.(2)The properties of the acid assisted dissolve lignin separated through dilution,precipitation,and low speed centrifugation from hydrolysate were systemic studied.The three LNPs were successed separated through high-speed centrifugation from the acid assisted dissolve lignin.The resultes shown that the diameter of lignin separated was 0.1?m to several micronmeters which were consisted of the spherical LNP.The three obtained LNP suspensions were stable.The average diameters of three circula LNP were 29 nm,34 nm,and 34 nm,and thickness were 5.6 nm,5.1 nm,and 2.4 nm,respectively.The thermal stability of lignin was increased with the the hydrolysis condition increased.The average molecular weight(M_n) and the weight average molecular weight(M_w)of the three lignin were quite small and the three lignin had the wide distribution.All three lignin had the H,G,and S type unit which take G-type and S-type as major.The ?-O-4 lignkage had the highest chemical bonding percentage,followed by ?-5 and 5-5 lignkages.The S/G ratio was decreased with the p-Ts OH concentration increased during the hydrolysis.The three lignin were probably coming from middle lamella.(3)The three different LCNF suspensions were produced from the bagasse pretreatment residues after fibrillation and homogenization.The results shown that the three LCNF suspension were stable and the thicknesses of three LCNF were 32 nm,30 nm,and 25 nm.The widths were 79 nm,78 nm,and 68 nm,respectively.Thermal stability of LCNF was steady and the crystal structure were kept cellulose I type.The surface of three LCNF were hydrophilic.The surface lignin content and water contact angle of LCNF were both decreased with the p-TsOH concentration increased during the hydrolysis.The UVB block property of LCNF film was fantastic,and the UVA block property of usual sun-proof materials was achieved when the basis weight above 50 g/m~2.High Yang's modulus of LCNF thin films were achieved which had the ability to partly replace macromolecule polymers.(4)The three Pickering emulsion stabilized by three LCNF were prepared and the stabilization mechanism of LCNF was studied.The effects of oil-water ratio,p H value,and Na Cl concentration on the stability of emulsion droplet were systematically studied.The coordination stabilization mechanism of CNC and LCNF were discussed.The results were found that the oil-in-water Pickering emulsions were obtained by all three LCNF.The low emulsifying capacity of LCNF-40 under low pH value,while better emulsifying capacity was achieved at neutral or higher p H value.The lower emulsifying capacity of LCNF-40was observed owing to the surface charge blocked by the electrolyte.The highest lignin content of LCNF-40 had the best emulsifying capacity,followed by LCNF-50 and LCNF-60.The route of partily lignin kept in the material during the preparation process that can adjust the surface properties of LCNF which benefits the emulsifying capacity.The LCNF was mostly dispersed on the interface of droplets which packaged to compact LCNF layer and the continuous phase that the three-dimensional network structure was formed.The gel-like Pickering emulsion was achieved when the LCNF concentration above 0.1wt%.The CNC was preferred to pack on the interface of droplets,while LCNF-40 was preferred to form three-dimensional network structure,the two structures coordination stabilized emulsion droplets together.The addition of CNC was good for emulsion droplets properties stabilized by LCNF-40.