Zhan Huai-yu

Regulation of Superoxide Anion Radical During the Oxygen Delignification Process

Abstract In this study, the superoxide anion radicals were generated by the auto-oxidation of 1,2,3-trihydroxybenzene and determined by UV spectrophotometry, and the reaction was found to be facilitated by anthraquinone-2-sulfonic acid sodium salt. The bamboo kraft pulps were treated by the 1,2,3-trihydroxybenzene auto-oxidation method or the 1,2,3-trihydroxybenzene auto-oxidation combined with anthraquinone-2-sulfonic acid sodium salt to show the effect of the superoxide anion radicals during the oxygen delignification of bamboo kraft pulp and the enhancing affect of anthraquinone compounds as an additive on delignification. The results indicated that the superoxide anion radicals could react with lignin and remove it from pulp with negligible damage on cellulose, and the an-thraquinone-2-sulfonic acid sodium salt could facilitate the generation of superoxide anion radical to enhance delignification of pulps. The oxygen delignification selectivity could be improved using the 1,2,3-trihydroxybenzene auto-oxidation system combined with anthraquinone-2-sulfonic acid sodium salt.

Study on wet-laid nonwoven separator of lithium-ion battery

In this paper, a new kind of wet-laid nonwoven material composed of highly fibrillated PPTA (para-phenylene terephthalamide) pulp is used in the preparation of a lithium-ion battery separator. Because the PPTA pulp is composed of fibrils and micro-fibrils, which are mostly less than 1 µm in diameter, the pore size of the separator could be well controlled to less than 1 µm. The effects of PPTA pulp on the pore structure of the separator, thermo-stability, electrochemical property and mechanical properties are researched. The results show that with the increase of PPTA pulp dosage, the pore size of separator is decreased. In addition, this type of separator shows excellent thermal stability. The strength retention of the nonwoven separator is 45% after it is stored at 180°C for 10 minutes, but the polyolefin membrane is completely molten under the same conditions.

Kinetics of Atom Transfer Radical Polymerization of Methyl Methacrylate Initiated by Cellulose Chloroacetate in BMIMCl

The kinetics of atom transfer radical polymerization(ATRP) of methyl methacrylate(MMA) initiated by cellulose based macroinitator, cellulose chloroacetate, performed in ionic liquid(1-N-butyl-3-methylimidazolium chloride, BMIMCl), dimethyl sulfoxide(DMSO) and dimethyl formamide(DMF) were respectively studied in detail. The polymerizations were carried out under homogeneous conditions with CuBr as catalyst and 2,2′-bipyridine(bpy) as ligand. The dependences of the rate of polymerization on solvent, temperature, monomer/initiator ratio and catalyst/ligand ratio were presented. Plots of ln([M]0/[M]t) vs. time and molecular weight vs. conversion showed a linear dependence, indicating a constant number of propagating species throughout the polymerization as well as a negligible contribution of termination or transfer reactions. On the basis of an Arrhenius plot, the apparent energy of activation(ΔEaapp) for ATRP of MMA in BMIMCl was 16.6 kJ/mol which is much lower than that in diphenyl ether.

Pentachlorophenol (PCP) degradation microorganism community structure under microaeration condition

The comparison of pentachlorophenol (PCP) degradation was conducted under micro-aeration and anaerobic condition with three series of batch experiment, results of which indicated that during micro-aeration condition co-immobilized of anaerobic granular sludge and isolated aerobic bacterial species could enhance the efficiency of PCP reduction through the synergism of aerobes and anaerobes reductive dechlorination and exchange of metabolites within the co-immobilized granular sludge. While during anaerobic condition, there was no great difference in the three series. The specific activities experiment further confirmed that strict anaerobes were not affected over the presence of micro aeration environment. Microorganism community construction of co-immobilized anaerobic granular sludge and the mixed isolated aerobic community was also deduced. By the efficient cooperation of aerobes and anaerobes, the high efficiency removal rate of PCP was implemented.

Solid-Phase Preparation and Characterization of Chitosan

Chitosan was prepared with stressing method by blending chitin and solid alkali in a single-screw extruder at given temperature and characterized by potentiometric titration, gel permeation chromatography (GPC), infrared spectrum (IR) and carbon-13 magnetic resonance sperctroscopy (13C NMR). Chitosan with a deacetylation degree (DD) of 76.1% was obtained at a mass ratio 0.2:1:1 for H2O/chitin/NaOH at 160°C for 12 min. Compared to conventional solution method(usually 1: 10 for chitin/NaOH), the alkali assumption greatly decreased. Molecular weight of chitosan obtained by solid-phase method (S3,Mw 1.54×105) was lower than that obtained by suspension method (Y2,Mw 3.34 ×105). During deacetylation, molecular weight decreased with high reaction temperature and long reaction time but remained same at different initial ratios of NaOH/chitin. It might be concluded that degradation of chitosan was caused by breakout of the main chain of the oxidized chitosan catalyzed by alkali during the deactylation. IR and13C NMR showed that structures of chitosans prepared by solid-phase method were not changed.