P pulp bleaching whit hydrogen peroxide and sodium hypochlorite

In this research, the effect of sodium peroxide and sodium hypochlorite on the chemical-mechanical pulp bleaching (CMP) has been investigated. For this purpose, unbleached CMP pulp was produced from Mazandaran wood and paper mill, and bleaching with hydrogen peroxide and sodium hypochlorite was carried out in two levels of 3 and 4%, during both 60 and 90 minutes in 70°C at 8% consistency. In each treatment, 30 grams of pulp with hydrogen peroxide, sodium silicate, DTPA, sodium hydroxide and sodium hypochlorite for bleaching were prepared. In the following 60 gr/m2 hand sheets were prepared and the optical properties of hand sheets were measured and analyzed based on TAPPI.The results obtained from the review of optical properties of handsheets show that by increasing the bleaching time and the level of chemicals the optical properties was improved. So that the highest brightness and minimum yellowness were observed in the 4% and 90 minutes in bleaching whit hydrogen peroxide. the lowest opacity in the control sample. Resistance properties such as tensile, burst and tear strength of bleached paper were also increased.