马尾松磨石磨木浆的高白度漂白

HIGE BRIGHTNESS BLEACHING OF MASSON PINE GROUNDWOOD

研究中使用了不同的漂剂，包括过氧化氨（Ｈ２Ｏ２）、硼氢化钠（ＮａＢＨ４）连二亚硫酸钠（Ｎａ２Ｓ２Ｏ４）、次氯酸钠（ＮａＣｌＯ）、过乙酸（ＣＨ３ＣＯＯＨ）和臭氧（Ｏ３），以及不同的漂白程序。使用任何单段漂白看来不大可能将马尾松磨石磨木浆漂到７０％白度。采用有丙酮后洗涤的三段漂白，能将初始白度４２．８％的磨石磨木浆漂到８０％以上。浆内有机抽出物的存在被证明是颜色的重要来源，漂后用丙酮洗涤可将它们除去，因而能提高浆白度７～１０度。红外光谱表明，主要发色基团（共轭羰基）被漂剂破坏，这是提高浆白度的主要原因。还发现对羰基的攻击，过乙酸不如过氧化氢和硼氢化物。

Various bleaching agents,including hydrogen peroxide,sodium borohydride,sodium dithionte, sodium hypochlorite, peracetic acid and ozone,and different bleaching sequences were involved in the study. It seemed impossible to bleach masson pine groundwood to 70% brightness with anv sin-gle-stage bleaching.The groundwood with 42.8 % initial brightness could be bl-eached to over 80% brightness by three sequcences with an acetone post-wash-ing, which were 2% NaBH4-4% H2O2,7% CH3COOOH-4% H2O2 and 4% H2O2-2% H2O2.The organic extractives in the pulp was proved to be an mportant source of color.Their removal by acetone washing after bleaching could give an additional brightness increment of 7～10 points.The infra-red spectra showed that the main chromophoric groups (conjugated carbonyl groups) were destroyed by bleaching agents,which was the main reason of brightness incremsent. It was also found that peracetic acid attacked less conju-gated carbonyl groups than peroxide and borohydride.