| 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. |