Nitration of Wood Cellulose in HNO_3/Organic Solvent Medium

A steam explosion pretreatment at various severities was applied to pure wood cellulose; the influences of steam pretreatment on the morphological structure, the hydrophilic property and viscosity-average molecular weight of cellulose were evaluated. The nitration of steam-exploded cellulose was carried out in the nitrating agent medium （HNOa/organic solvent）. The performance indexes of nitrocellulose, prepared from original and steam exploded samples, were determined by using the polarized optical microscope. The results show that after pretreatment the reactivity of the three hydroxyl groups in anhydroglucose unit of cellulose is improved, and the nitrogen content and the uniformity of NC from steam exploded cellulose observably increas.

Water-Based Processing of Fiberboard of Acrylic Resin Composites Reinforced With Cellulose Wood Pulp and Cellulose Nanofibrils

Despite the great potential of cellulose wood pulp and cellulose nanofibrils as reinforcing filler in thermoplastics,its use is limited due to its tendency to form agglomerates and due to its high hydrophilic character.Here we describe fiberboard composites with high contents of wood pulp or cellulose nanofibrils,and a resin of poly(styrene-methyl-methacrylate-acrylic acid)used as water-based emulsion.Cellulose wood pulp and cellulose nanofibrils were used directly in the form of water suspensions.The method is based on the flocculation of the polymer emulsion followed by agglomeration of a mixture of the polymer emulsion and cellulose suspension,leading to the co-precipitation of the composite material,which can be easily separated from the water phase.Composites with acrylic polymer/cellulose fibers in the proportions of 75:25,50:50 and 25:75 wt%were prepared.Composites were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA),dynamic mechanical analysis(DMA)and water absorption tests.SEM analysis revealed a very good dispersion of the fibers without evidence of agglomeration,which led to superior mechanical properties.These results showed the effectiveness of the methodology and the potential of cellulose wood pulp and CNF as reinforcement fillers in fiberboard composites and any other high fiber-content materials.

Photoactivation of peroxymonosulfate by wood pulp cellulose biochar/g-C_(3)N_(4)composite for diclofenac degradation:the radical and nonradical pathways

Metal-free photocatalysts have attracted growing concern recently.Herein,the composites combining g-C_(3)N_(4)with wood pulp cellulose biochar(WPBC/g-C_(3)N_(4))were synthesized to effectively activate peroxymonosulfate(PMS)under visible light for the degradation of diclofenac(DCF).The incorporation of WPBC endowed g-C_(3)N_(4)with enhanced visible light absorption,improved charge separation capability,reduced electrical conductivity,and increased photocatalytic and PMS activation capability.Based on quenching tests,electron paramagnetic resonance(EPR),electrochemical analysis and solvent exchange experiments,both radical and nonradical mechanisms were proposed.Radical species including·OH,h^(+),·O_(2)^(-)were identified to contribute to DCF degradation.The 1O2 and electron transfer were the dominant nonradical pathways for DCF degradation.Moreover,the common influencing factors were examined,and DCF concentration was the most influential factor based on principal component analysis.Generally,the composites exhibited good reusability during consecutive runs.Based on HPLC/MS analysis,four intermediates were detected and the possible DCF degradation pathway was proposed.This work provided a potential strategy based on metal-free WPBC/g-C_(3)N_(4)for the photocatalytic activation of PMS to effectively degrade emerging contaminants in wastewater.

Recent progress on green electromagnetic shielding materials based on macro wood and micro cellulose components from natural agricultural and forestry resources

Recent research efforts in the field of electromagnetic interference shielding(EMI)materials have focused on biomass as a green and sustainable resource.More specifically,wood and cellulose nano fiber(CNF)have many advantages,some of which include lightweight,porosity,widespread availability,low cost,and easy processing.These favorable properties have led researchers to consider these types of biomass as an EMI shielding material with great potential.At present,while many excellent published works in EMI shielding materials have investigated wood and CNF,this research area is still new,compared with non-biomass EMI shielding materials.More specifically,there is still a lack of in-depth research and summary on the preparation process,pore structure regulation,component optimization,and other factors affecting the EMI shielding of wood and CNF based EMI shielding materials.Thus,this review paper presents a comprehensive summary of recent research on wood and CNF based EMI shielding materials in recent three years in terms of the preparation methods,material structure design,component synergy,and EMI mechanism,and a forward future perspective for existing problems,challenges,and development trend.The ultimate goal is to provide a comprehensive and informative reference for the further development and exploration of biomass EMI shielding materials.