Characteristics of uncondensed lignin reactions in soda cooking of wheat straw were studied. Mild and intense cooking conditions were used to get the pulp sample in which lignin was dissolved physically and the pulp s...Characteristics of uncondensed lignin reactions in soda cooking of wheat straw were studied. Mild and intense cooking conditions were used to get the pulp sample in which lignin was dissolved physically and the pulp sample in which lignin was dissolved chemically respectively. The pulp samples were analyzed by phenolic group determination, alkaline nitrobenzene oxidation and ozonation method. The results indicated that around 90% of lignin in wheat straw is alkali-soluble at the mild conditions, is basically dissolved physically without chemical change. The phenolic group content was not changed greatly, the nitrobenzene oxidation yield only changed slightly during the mild cooking. The phenolic group content was increased obviously and uncondensed lignin content was decreased very much when the intense cooking conditions were applied and the delignification was over 90%. The lignin structure was changed greatly during this period.展开更多
A novel electrode design for the in situ generation of ozone in the reaction zone of a tubular reactor is described in this work.The ozone generator uses a porous inner electrode tube in the corona discharge assembly,...A novel electrode design for the in situ generation of ozone in the reaction zone of a tubular reactor is described in this work.The ozone generator uses a porous inner electrode tube in the corona discharge assembly,and the ozone generated around the outer periphery of the porous tube diffuses into the tubular reactor and reacts with the contaminants in the fluid that is being treated.A mathematical model that includes absorption and second order reaction in the film is developed to describe ozonation kinetics of a contaminant dye in the tubular reactor.The model describes the experimental data for dye decolorization,oxidation byproducts,dissolved ozone,and ozone gas concentrations well.Model analysis indicates that the fast dye decolorization reaction occurs partly in the liquid film and partly in the bulk fluid.The model can be used in the selection of appropriate gas-liquid contactors for efficient oxidation of contaminants in effluents.展开更多
文摘Characteristics of uncondensed lignin reactions in soda cooking of wheat straw were studied. Mild and intense cooking conditions were used to get the pulp sample in which lignin was dissolved physically and the pulp sample in which lignin was dissolved chemically respectively. The pulp samples were analyzed by phenolic group determination, alkaline nitrobenzene oxidation and ozonation method. The results indicated that around 90% of lignin in wheat straw is alkali-soluble at the mild conditions, is basically dissolved physically without chemical change. The phenolic group content was not changed greatly, the nitrobenzene oxidation yield only changed slightly during the mild cooking. The phenolic group content was increased obviously and uncondensed lignin content was decreased very much when the intense cooking conditions were applied and the delignification was over 90%. The lignin structure was changed greatly during this period.
基金Supported in part by a research grant(BES-0209343) from the U.S.National Science Foundation
文摘A novel electrode design for the in situ generation of ozone in the reaction zone of a tubular reactor is described in this work.The ozone generator uses a porous inner electrode tube in the corona discharge assembly,and the ozone generated around the outer periphery of the porous tube diffuses into the tubular reactor and reacts with the contaminants in the fluid that is being treated.A mathematical model that includes absorption and second order reaction in the film is developed to describe ozonation kinetics of a contaminant dye in the tubular reactor.The model describes the experimental data for dye decolorization,oxidation byproducts,dissolved ozone,and ozone gas concentrations well.Model analysis indicates that the fast dye decolorization reaction occurs partly in the liquid film and partly in the bulk fluid.The model can be used in the selection of appropriate gas-liquid contactors for efficient oxidation of contaminants in effluents.
