Optimization Process Variables of Deinked Pulp Bleaching - Improvement of Wet Tensile Strength of Tissue Paper

In this study dispersed deinked pulp (DIP) of Latif Company which includes a mixture of straw printers, mixed office waste (MOW) and mechanical recycle paper was used to investigate the effect of bleaching variables on pulp and paper properties. Six variables of bleaching process including the amount of hydrogen peroxide, sodium hydroxide, and sodium silicate, bleaching time, bleaching temperature and final pH were optimized in order to improve wet and dry tensile index of handsheet. Design Expert software was used for analyzing and modeling. Results in from of the central composite design (CCD) were investigated and response surface methodology (RSM) was modeled and analyzed. Optimized wet and dry tensile were obtained by appling 1.55% hydrogen peroxide, 1.55% sodium hydroxide and 1.55% silicate, 90 minutes bleaching time, 83 0C bleaching temperature, and final pH equal to 8.5. The result showed that bleaching variables affect significantly the optical properties sample as well as mechanical strength of paper, and also dry and wet tensile strengths can be improved by optimization of bleaching condition.