乙醇-水介质改善竹材化机浆H2O2漂白性能

Improving Hydrogen Peroxide Bleaching Efficiency of Bamboo Chemi-mechanical Pulp in Alcohol Aqueous Medium

关键词:  竹材  化机浆  过氧化氢  乙醇  漂白

Key Words:bamboo  chemo-mechanical pulp  hydrogen peroxide  alcohol  bleaching

摘要:采用乙醇-水溶液作为过氧化氢（H₂O₂）漂白过程中的介质，以提高H₂O₂漂白效率、突破水介质漂白竹材化机浆时的白度增限（白度71%）。结果表明，水介质漂白时，H₂O₂用量15%时仅能将竹浆漂白至69.2%的白度，乙醇-水介质（乙醇质量分数50%）漂白仅需用量9%的H₂O₂即可达到相同白度，节省H₂O₂用量40%；随着H₂O₂用量的增加，乙醇-水介质漂白浆与水介质漂白浆的白度差值随之增加; H₂O₂用量15%时，白度为77.4%，比水介质漂白浆白度增加8.2个百分点；H₂O₂用量25%时，白度为81.7%，比水介质漂白浆白度增加10.3个百分点。紫外可见光吸收光谱（UV-Vis）分析显示，达到同一白度目标值时，乙醇-水介质H₂O₂漂白时，H₂O₂对木素发色结构中370～385 nm处与苯环共轭的α-羰基结构、苯环连接的γ-醛基结构以及400～500 nm处醌型结构破坏作用加强，纸浆的漂白稳定性好。

Abstract:To improve hydrogen peroxide bleaching efficiency and break “brightness ceiling” of bamboo chemi-mechanical pulp（CMP）， tests of an improved hydrogen peroxide bleaching procedure for bamboo chemi-mechanical pulps were performed with inclusion of ethanol in the bleaching medium （IEBM）.Compared with a conventional bleaching method， the CMP was bleached to brightness of 69.2% when the dosage of H₂O₂ was 15%， with the IEBM method the CMP was bleached to the same brightness when the H₂O₂ dosage was 9%， bleaching with the IEBM method reduced H₂O₂ consumption by approximately 40%.At the usage level of 15% H₂O₂， the CMP could be bleached to the brightness of 77.4% with the IEBM method， increased by 8.2 percentage points compared with the conventional method.Further more， the bleached brightness differences between IEBM and conventional method increased dosage level of H₂O₂ increased， it could reach up to 10.3 percentage points, when the CMP was bleached to the brightness of 81.7% at the dosage of 25% H₂O₂ increased.UV-Vis spectrophotometry showed that， for the same brightness， bleached pulps with IEBM method had better bleaching stability than the bleached pulps of conventional method， the main reason was the improved destruction of chromatic structures of the α-carbonyl group conjugated with benzene ring and γ-aldehyde group connected with benzene ring that absorb light in the region of 370～385 nm， and also the improved destruction of quinoid structure that absorb light in the region of 400～500 nm.