Homogenous Chemical Modification Of Bagasse And Transformation Of Bagasse Into Bio-Based Materials

Lignocellulosic biomass in the form of plant materials offers the most abundant renewable resource in replacing traditional fossil resources. During the past few decades, much effort has been devoted to increasing the utilization of lignocellulosic biomass to create biofuels, biochemical and a host of other bioproducts to replace fossil-based products. Although a large number of researches have been done on converting lignocellulosic biomass into platform chemicals and energies, researches focused on polymer materials directly from lignocellulosic biomass are scarcely reported. The major challenges for directly converting lignocellulosic biomass into available materials are the complex chemical structure and the narrow processing windows of the resources. Recently, several solvent systems with strong hydrogen-bond-destroying ability, including ionic liquids, DMSO/Li Cl, DMSO/NMI et al. were developed to dissolve lignocellulosic biomass, which providing novel strategies for the utilization of resources. In the present study, the homogenous chemical modification of bagasse was performed and the novel materials were prepared from bagasse by solution processing.Carboxyl groups were attached onto bagasse by the homogenous modification of bagasse with maleic anhydride in ionic liquid 1-butyl-3-methylimidazolium chloride(BMIMCl) without any catalysts. The parameters optimized included maleic anhydride concentration, reaction temperature and reaction time required in the process. The extent of maleation of bagasse was measured by the weight percent gain(WPG), which increased with an increment of maleic anhydride concentration between 1:1 and 5:1(g/g, maleic anhydride/bagasse). It should be noted that WPG decreased at wild conditions, including long reaction duration(>60 min) and high temperature(>110 oC). The results from FT-IR and solid-state CP/MAS 13 C NMR spectroscopies indicated that the maleation of hydroxyl groups in lignin, cellulose and hemicelluloses all occurred. XRD, SEM and TGA/DTG analyses of the native and modified bagasse showed that the cellulose crystalline structure of bagasse was significantly destroyed after dissolution, maleation, and regeneration in BMIMCl. However, the remained cellulose crystalline structure did not change except remarkable decrystallization. The thermal stability of the maleated bagasse decreased at low temperature(lower than 300 oC), and increased at high temperature(above 300 oC) compared with that of native ball-milled bagasse.Homogenous esterification of bagasse with cyclic anhydrides was carried out in ionic liquid 1-allyl-3-methylimidazolium chloride(AMIMCl). The extent of esterification of bagasse was controlled by adjusting the concentration of cyclic anhydrides. The highest WPG for chemical mofidication of bagasse with maleic anhydride, succinic anhydride and phthalic anhydride was 184%, 98.1% and 147%, respectively. FT-IR and solid-state CP/MAS 13 C NMR spectroscopies confirmed the chemical structure of bagasse esters. TGA/DTG studies were performed to understand the thermal behaviors of bagasse upon the homogenous chemical modification with cyclic anhydrides. The results indicated that the thermal stability of bagasse decreased upon homogeneous chemical modification with cyclic anhydrides.Bio-based oil absorption materials were synthesized by homogenous grafted modification of bagasse with acrylic esters in ionic liquid AMIMCl. The extents of grafting efficiency were controlled by ranging the concentration of acrylic esters from 1 m L/g to 4 m L/g. The oil absorption rate of bagasse was remarkably enhanced by grafting modification in AMIMCl. The highest oil absorption rates of the grafted copolymer for mechanical oil, peanut oil and diesel oil were 11.2 g/g, 10.6 g/g and 5.96 g/g, respectively. FT-IR confirmed the chemical structure of the bagasse grafted copolymers. The peak at 1735 cm-1 for C=O absorption, indicated that the graft copolymerizations took place successfully. The effect of the grafted modification on the thermal behaviors on bagasse was studied by TGA/DTG. The result showed that thermal stability of bagasse decreased upon the grafted modification.Lignocellulosic biomass films were prepared directly from bagasse solutions in DMSO/Li Cl without additional film-forming additives by coagulation either in an acetone/water(9/1, v/v) mixture or in water following a freezing treatment. The physicochemical properties of bagasse films were studied by FT-IR, UV/vis, SEM, XRD, and tensile testing. The films were semi-transparent with a yellow color and showed strong abilities in UV light blocking due to the presence of lignin. Relatively high mechanical strength comparable to cellulose-starch-lignin composite films was observed. The physical cross-link and the stress buffer of micropores formed in the freezing treatment resulted in enhanced mechanical strength of the film. The facile and environmentally friendly process creates a new strategy for converting abundant lignocellulosic materials to novel value-added bioproducts.The major challenges for directly converting lignocellulosic biomass into available materials are the complex structure and the narrow processing windows of the resources. In the present study, homogenous chemical modification of bagasse with phthalic anhydride was taken to be an improved strategy to meet the challenges, and bagasse phthalate films were prepared by solution casting. FT-IR and NMR analyses confirmed the chemical structure of bagasse phthalates. HSQC study showed that hydroxyl group at C2, C3, C6 from carbohydrates took part in the reaction. SEM and tensile testing were performed to study the morphologies and mechanical properties of the bagasse phthalate films. The results indicated that bagasse was considerably plasticized and readily dissolved in organic solvents by homogenous chemical modification with phthalic anhydride.Lignocellulosic biomass aerogels with relatively high Brunauer–Emmett–Teller(BET) surface area and pore volume were prepared directly from bagasse solutions in the present study. Bagasse was dissolved in DMSO/Li Cl, treated with cyclic freezing-thawing processes, and regenerated with water. The resulted bagasse hydrogels were solvent-exchanged to t-butanol and subjected to freeze-drying to obtain the lignocellulosic aerogels. The structure of the aerogels was studied with FT-IR, nitrogen absorption, SEM, and XRD. The results showed that the aerogels had sheet-like skeletons interconnected with one another to form three-dimensional networks. The highest BET surface area and total pore volume of the aerogels were 185 m2/g and 0.46 cm3/g, respectively. By adjusting the concentration of bagasse solution in DMSO/Li Cl, the structure of the aerogels could be controlled to some extent.