| 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. |