Description:
Pinus radiata sapwood stakes were treated with ellagic acid and tetraguanidinium, tetracholine and tetrakis-benzyltrimethylammonium ellagates. The effect of these treatments upon moisture movement and uptake was investigated by wick action. Given that chemical reactions within the wood substrate between nutrients and treatment solutions may alter the properties of the wood with regard to moisture movement, the presence of Cu2+ in the system was also examined. Water-soluble ellagates reduced water loss by 25-35 %, but had no effect upon water uptake. Ellagic acid in N-methylpyrrolidone significantly reduced both water loss and moisture uptake. The effect of Cu2+ upon moisture movement and uptake in the treated stakes was negligible.
Description:
Oxidation-reduction reactions between carbohydrates, lignin and quinone additives in Pinus radiata soda pulping liquors have been investigated. A reduction peak at -0.72 V (Vs SCE) was observed using differential pulse polarography when Pinus radiata wood is heated in alkaline solution in the presence of oxygen, and has been shown to result from the oxidation of lignin structures. The results of this study indicate that the electroactive species present in Pinus radiata soda pulping liquors is an oxidation product, resulting from the formation of phenoxy radicals and /or quinone methides. Although reduction potentials for anthraquinone, carbohydrates and the electroactive lignin structure fit the general redox mechanism propsed for accelerated delignification, the species observed by polarography in this study has been shown not to be involved in the main pulping reactions due to its low concentration.
Description:
Oxidation-reduction reactions between carbohydrates, lignin and quinone additives in Pinus radiata soda pulping liquors have been investigated. A reduction peak at -0.72 V (Vs SCE) was observed using differential pulse polarography when Pinus radiata wood is heated in alkaline solution in the presence of oxygen, and has been shown to result from the oxidation of lignin structures. The results of this study indicate that the electroactive species present in Pinus radiata soda pulping liquors is an oxidation product, resulting from the formation of phenoxy radicals and /or quinone methides. Although reduction potentials for anthraquinone, carbohydrates and the electroactive lignin structure fit the general redox mechanism propsed for accelerated delignification, the species observed by polarography in this study has been shown not to be involved in the main pulping reactions due to its low concentration.