Influence of Chemical Pretreatment on the Dissolved Organics in Poplar Alkaline Peroxide Mechanical Pulping Effluent

The components of the effluent from the chemical pretreatment of poplar alkaline peroxide mechanical pulp(APMP) were analyzed in this study. The main dissolved organics were low-molecular weight(LMW) lignin, oligosaccharides, and monosaccharides. The lignin and sugar concentrations in the effluent obtained using different chemical pretreatment conditions and chemical dosages were analyzed using ultraviolet(UV) spectroscopy. This analysis provided a theoretical basis for the subsequent treatment and utilization of APMP effluent. The experimental results showed that the dosages of Na OH, H_2O_2, and Na_2 SiO_3 in the chemical pretreatment process affected the lignin and sugar concentrations in the effluent and that different chemicals had differing degrees of influence. The degree of influence exhibited the following order: Na OH>H_2O_2>Na_2SiO_3. More specifically, the dosages of Na OH and H_2O_2 had stronger influences on the lignin and sugar concentrations than that of Na_2 SiO_3. Indeed, the Na_2 SiO_3 dosage hardly affected the lignin and sugar concentrations in the effluent, but Na_2 SiO_3 could stabilize the chemical pretreatment system and improve the reactive efficiency of Na OH and H_2O_2. The pretreatment temperature and time also affected the organic components, and the influence of the temperature was stronger than that of time.

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

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, BMIMC1）, 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（AEaapp ） for ATRP of MMA in BMIMC1 was 16.6 kJ/mol which is much lower than that in diphenyl ether.