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.

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.

Study on TEMPO-Mediated Selective Oxidation of Alkaline Natural Cellulose Pulp and Properties of Its Products

It has been reported that natural cellulose （cellulose I） can not be oxidized by TEMPO - NaOCI - NaBr system, one of TEMPO-mediated selective oxidant systems, but regenerated cellulose （cellulose Ⅱ ） can be completely selectively oxidized. In the present work, natural cellulose pulp was treated with NaOH solution, which concentration is lower than 20 wt%. The alkaline celluloses obtained were oxidized by TEMPO - NaOCI - NaBr system and the factors which influence the selective oxidation reaction rate have been investigated. The structure of the oxidized products has been characterized by Fourier transform-infrared （FTIR）, nuclear magenatic resonace （NMR） and wide angle X-ray diffraction （WAXD） methods, and their adsorption properties for Cu^2＋ and Cd^2＋ in aqueous solutions have been preliminarily examined. The results show that after the alkaline treatment, the primary hydroxyl at C6 position of natural cellulose can be selectively oxidized to carboxyl group in the reaction medium at pH 10.8, the oxidation rate becomes greater with the NaOH concentration and alkaline treatment time increasing. The alkaline treatment has a great effect on the crystal structure of natural cellulose, but the crystal structure of alkaline cellulose keeps almost unchanged after oxidation. The adsorption capacity is enhanced by introducing carboxyl groups into the cellulose macromolecular chains.