硫酸鹽紙漿低污染漂白法之研究

Study on Low-Polluting Bleaching Sequences for Sulfate Pulps

蘇裕昌(Yu-Chang Su) ； 葉若鋆(Ruoh-Yun Yeh) ； 陳鴻財(Horng-Tsai Chen)

《台灣林業科學》 14卷2期 (1999/06) Pp. 105-117

https://doi.org/10.7075/TJFS.199906.0105

摘要

本論文建立－低污染漂白流程，以達到低污染減量之要求，提高紙漿漂白性及減低污染負荷，同時尋求解決難漂性紙漿之問題，使漂白漿達到理想之白度及具相當之白度安定性。以傳統漂白流程(C-E1-D1-E2-D2)、部份修飾流程(C/D-E1-D1-E2-D2)、無氯氣漂白流程(Z-E1-D1-E2-D2)、(Z-E1-C/D-E2-D)及全無氯漂白流程(O-Z-E-P-Y)等進行難漂紙漿台灣杉(Taiwania cryptomerioides)及紅柳桉(Shorea albida)之硫酸鹽紙漿之漂白。同時探討各漂白流程紙漿之漂白性，並評估漂白廢液中可吸附性有機氯化物(AOX)進行定量，以為檢討建立低污染漂白流程之依據。在C-E1-D1-E2-D2五段漂白的第一段氯氣漂白以二氧化氯取代部份氯氣的漂白流程中，難漂漿可獲得較好的最終白度（83% ISO以上）及白度安定性（PC值在2.0左右）。白度改善之主因為影響難漂之原因物質，在漂白初期之C/D段已經有部份的除去，因而改善後段的漂白性及漂白漿白度安定性。以臭氧(Z)段取代氯氣(C)段的漂白流程Z-E1-D1-E2-D2及Z-E1-C/D-E2-D，臭氧添加量1%即可達到傳統五段漂白的水準，超過此量則可改善難漂漿的漂白性，但對漂白紙漿的黏度及白度安定性會有影響。全無氯漂白流程O-Z-E-P-Y中以低臭氧消耗量對各紙樣無法漂到理想的白度，將E段改成Eo段可得中白度紙漿。提高臭氧消耗量則可漂白至預期白度值，且漂白漿有良好的白度安定性。各漂白流程廢液中以傳統五段漂白流程有最大的AOX排放量，C/D-E1-D1-E2-D2次之，可減少45% AOX排放量；而以ECF漂白流程之Z-E1-D1-E2-D2可減少傳統漂白流程的80%排放量。

關鍵字

無元素氯漂白流程(ECF) ； 臭氧漂白 ； 難漂紙漿 ； 可吸附性有機鹵化合物(AOX)

並列摘要

This study is to establish a low-pollution sequence to serve the needs of pulp mills in reducing pollution problems of conventional bleaching practices. The bleaching of hard-to-bleach wood species to a satisfactory brightness and brightness stability is also discussed. In this study, the conventional bleaching sequence, such as C-E1-D1-E2-D2, 5-stage bleaching and its modifications, C/D-E1-D1-E2-D2, and certain potential low-polluting sequences are used. Elemental chlorine-free sequence Z-E1-D1-E2-D2 and total chlorine-free sequences such as O-Z-E-P-Y were used to bleach some hard-to-bleach chemical pulps such as pulps from Taiwania cryptomerioides and Shorea albida, respectively. Bleaching ability (chemical dosage, yield, brightness gain), bleached pulp qualities (viscosities, PC number), and bleaching effluent produced are compared. Pulps bleached with a modified bleaching sequences, one which uses chlorine dioxide to substitute for part of the elemental chlorine at the chlorination bleaching stage, resulted in better bleaching ability and brightness stability. The resultant pulps from hard-to-bleach wood species achieved brightness above 83% ISO and a PC number of around 2.0. The improved bleachability of the C/D-E1-D1-E2-D2 sequence was due to the partial removal of the bard-to-bleach pulp substances in the initial stage of the bleaching sequence. We used elemental chlorine-free bleaching sequences Z-E1-D1-E2-D2 or Z-E1-C/D-E2-D which substitute ozone for elemental chlorine in the first bleaching stage. At 1% ozone dosage, we achieved better results compared to those of conventional bleaching. Above this dosage, bleachability is improved, but an ozone charge of more than 1.75% results in a reduction of pulp viscosity. Bleaching of sulfate pulp in the total chlorine-free sequence at low ozone dosages of the O-Z-E-P-Y sequence cannot obtain reasonable brightness; with increasing ozone dosage, high brightness and brightness stability can be achieved. Conventional C-E1-D1-E2-D2 sequences caused the maximum AOX formation; the C/D-E1-D1-E2-D2 sequence, reduced its formation by 45%; and elemental chlorine-free sequences, such as the Z-E1-D1-E2-D2 sequence, showed the least AOX formation, with the reduction of AOX being about 80%.

並列關鍵字

elemental chlorine-free sequence (ECF) ； ozone bleaching ； hard-to-bleach pulp ； adsorbable organic halide (AOX)