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首页> 外文会议>TAPPI(Technical Association of the Pulp and Paper Industry) Engineering, Pulping amp; Environmental Conference; 20061105-08; Atlanta,GA(US) >USE OF HYDROCHLORIC ACID OR SULFURIC ACID IN THE PRE-ACIDIFICATION OF PULPS PRIOR TO CHLORINE DIOXIDE DELIGNIFICAT1ON AND MULTISTAGE BLEACHING
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USE OF HYDROCHLORIC ACID OR SULFURIC ACID IN THE PRE-ACIDIFICATION OF PULPS PRIOR TO CHLORINE DIOXIDE DELIGNIFICAT1ON AND MULTISTAGE BLEACHING

机译：在二氧化氯脱除醛和多级漂白之前对纸浆进行预酸化时使用盐酸或硫酸

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Hexauronic acid and Lignin-Carbohydrate Complexes (LCC) that the hexauronic acid (HexAs) associate with are particularly prominent in unbleached hardwood pulps in tropical hardwood pulps like eucalyptus. The influence of LCCs and HexAs on chlorine dioxide delignification and bleaching has raised the awareness of acid pretreatment prior to bleaching of hardwood pulps. When pulps are cooked to low Kappa numbers, they have almost twice the amount of HexAs as conventional pulps. Therefore extended cooked low Kappa number hardwood pulps require rigorous acid treatment prior to chlorine dioxide treatment. If oxygen delignification is practiced prior to multi-stage bleaching, then the pre-treatment conditions would have to be even more rigorous to have enough of an effective bleaching to reach target pulp properties, including final pulp brightness. The employed acid pretreatment conditions, while conducive to the removal of HexAs, also initiate acid hydrolysis of cellulose, resulting in yield and viscosity losses of pulp. Acid hydrolysis of glycosidic bonds, a pH-dependent reaction, in cellulose and hemicelluloses is dictated by the type of acid used, with strong protic acids like sulfuric and hydrochloric reacting differently than acids like acetic acids. If the purpose of pre-acidification is to activate the lignocellulosic structures to enhance the delignification of pulp, then the type of acid used is critical since it would have an impact not only on the delignification of pulps but also on cellulose degradation and its removal. There is one other issue to consider when using a protic acid for pretreatment of pulp: whether the acid will warrant any special materials of construction, (MOC) requirement for its use in the reactor as well as in other auxiliary equipments. In this paper, the two aspects of hydrochloric acid or sulfuric acid use in chlorine dioxide delignification - final pulp properties and reaction with MOC, and the financial consequences of switching from one acid to the other is investigated and detailed.
机译：与六糖醛酸（HexAs）缔合的六糖醛酸和木质素-碳水化合物配合物（LCC）在热带硬木纸浆（如桉树）的未漂白硬木纸浆中尤为突出。 LCC和HexAs对二氧化氯脱木素和漂白的影响提高了人们对硬木浆漂白之前进行酸预处理的认识。当纸浆煮至低Kappa值时，其HexAs含量几乎是传统纸浆的两倍。因此，扩展的低Kappa熟度硬木纸浆在进行二氧化氯处理之前需要进行严格的酸处理。如果在多步漂白之前进行氧气脱木素，则预处理条件将必须更加严格，才能进行足够的有效漂白才能达到目标纸浆性能，包括最终的纸浆白度。所采用的酸预处理条件，尽管有利于除去HexAs，但也引发了纤维素的酸水解，导致纸浆的产率和粘度损失。纤维素和半纤维素中糖苷键的酸水解（pH依赖的反应）取决于所用酸的类型，强质子酸（如硫酸和盐酸）的反应不同于酸（如乙酸）。如果预酸化的目的是激活木质纤维素结构以增强纸浆的脱木质素，则所用酸的类型至关重要，因为酸不仅会影响纸浆的脱木质素，还会影响纤维素的降解及其去除。使用质子酸对纸浆进行预处理时，还需要考虑另一个问题：该酸是否需要任何特殊的结构材料，（MOC）在反应器以及其他辅助设备中的使用要求。本文研究并详细说明了盐酸或硫酸用于二氧化氯脱木素的两个方面-最终纸浆性能和与MOC的反应，以及从一种酸转换为另一种酸的财务后果。

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