棉短绒浆粕过硫酸氢钾漂白工艺研究及漂白助剂的作用

Research on the Bleaching Process of Cotton Linter Pulp with Potassium Peroxymonosulfate and the effect of Bleaching Additive

关键词:  精制棉  漂白  过硫酸氢钾  活性物种

Key Words:refined cotton  bleach  potassium peroxymonosulfate  active species

摘要:传统含氯漂白工艺会产生难以降解的有机卤化物，对自然环境和人类健康产生危害。无氯漂白技术成为近年研究的热点，本文选用过硫酸氢钾（PMS）作为无氯氧化剂对棉短绒浆粕进行漂白研究。在确定工艺组成的基础上通过单因素实验优化工艺条件，成功制备出白度超过83%且聚合度保持在2200的精制棉。采用多种表征手段对漂白前后的棉短绒浆粕官能团、晶型和形态进行对比分析。结果表明，PMS漂白工艺不仅具有优异的漂白性能且对纤维结构损伤小。电子顺磁共振结果表明，加入漂白助剂PA、PB和SDBS后体系中羟基自由基（?OH）、硫酸根自由基（SO4??）、超氧自由自由基（O2??）和单线态氧（1O2）等活性物种的信号强度升高，漂白效果明显提升。自由基淬灭实验结果表明，漂白过程中影响白度的活性物种主要是超氧自由基（O2??）和单线态氧（1O2），而单线态氧（1O2）对纤维素的降解作用最大。本实验成功开发出一种高效、环保的棉短绒浆粕漂白工艺，不仅提高了产品的白度和聚合度，且废水易处理，为棉短绒浆粕的高效利用提供新途径。

Abstract:In the treatment of cotton linter meal, the traditional chlorine bleaching process may produce non-degradable and carcinogenic substances, such as dioxins and halocarbons, which may put pressure on environmental protection. In this study, an environmental-friendly and high efficiency cotton short staple pulp bleaching process was developed with Potassium peroxymonosulfate (PMS) as the major oxidant, sodium diphosphate (PA), sodium triphosphate (PB) and sodium dodecylbenzene sulfonate (SDBS) as auxiliaries. The dosage of PMS, PA, PB and SDBS were optimized by single-factor experiments with the whiteness and polymerization degree of the product as test parameters as well as the effects of temperature, reaction time and pH during the bleaching process. FTIR, XRD and SEM were performed to measure the functional groups, crystal forms and morphology of cotton short-staple pulp before and after bleaching. The results showed that the PMS bleaching process could effectively remove the colored substance on the cellulose with less damage to the cellulose itself and maintain the degree of polymerization above 2200 when the whiteness reached 83. In addition, the results of EPR analysis and quench experiments showed that superoxide radical (O2??), singlet oxygen (1O2), hydroxyl radical (?OH) and sulfate radical (SO4??) were detected, while the main active species affecting the whiteness of cotton linter pulp during bleaching were O2?? and 1O2, and 1O2 is the most important one damage the polymerization degree. It was also found that the COD of the wastewater in this PMS process was far below that of tradition chlorine process. Thus, a highly efficient and environmental-friendly bleaching method of cotton short fiber pulp was successfully developed.