With the utilization of used newspaper into the paper making industry, bleaching has been an area of concern to obtain a balance between desired brightness and the amount of treatment it requires. Motivation of this study was to optimize bleaching of recycled newsprint fibers in terms of five variables namely hydrogen peroxide charge, amount of sodium hydroxide employed, pulp consistency, bleaching temperature, and bleaching time. Experimental work was conducted in the laboratory to simulate bleaching plant and it was found that higher peroxide charge is better for improvement in brightness, but it is uneconomical to increase peroxide charge indefinitely. The amount of hydrogen peroxide is added so that the residual peroxide at the end of the reaction is not less than 10% of the initially added peroxide. Sodium hydroxide provides alkalinity which is very important for making the fibers flexible and softening of ink particles but it also contributes to pulp yellowing if residual hydrogen peroxide contents are lesser than the minimum required value. So, for 16 kg t⁻¹ of hydrogen peroxide, 6 kg t⁻¹ of sodium hydroxide prevented the brightness reversion in this study. Higher pulp consistency is better but unavailability of very high consistency pulp mixer in the industry is a limiting factor for higher than 30% pulp consistency. Temperature and time are quite interrelated and, with the given bleaching conditions, a temperature of 95 C with 10 min residence time was found to be optimum for this study. It was also observed that multiple pre-washings increase brightness and save bleaching chemicals.

随着废报纸在造纸工业中的应用，漂白已成为一个令人关注的领域，以在所需的亮度和所需的处理量之间取得平衡。本研究的动机是在五个变量方面优化再生新闻纸纤维的漂白，即过氧化氢电荷、使用的氢氧化钠量、纸浆稠度、漂白温度和漂白时间。在实验室进行了模拟漂白厂的实验工作，发现较高的过氧化物加入量对提高白度更好，但无限期增加过氧化物加入量是不经济的。过氧化氢的加入量应使反应结束时残留的过氧化物不少于最初加入的过氧化物的10%。氢氧化钠提供碱性，这对于使纤维变得柔韧和软化油墨颗粒非常重要，但如果残留的过氧化氢含量低于最低要求值，它也会导致纸浆变黄。因此，对于 16 kg t^-1过氧化氢、6 kg t ^-1氢氧化钠防止了本研究中的亮度回复。纸浆浓度越高越好，但行业中无法使用非常高浓度的纸浆搅拌机是纸浆浓度高于 30% 的限制因素。温度和时间是非常相关的，在给定的漂白条件下，95 摄氏度的温度和 10 分钟的停留时间被认为是本研究的最佳温度。还观察到多次预洗可增加亮度并节省漂白化学品。