Hamid reza Mehri Iraie; Ali Ghasemian; Hossein Resalati; Ahmad reza Saraeyan; Iman Akbarpour
Abstract
This research was conducted to investigate the bleaching of combined old newspapers (ONP) and old magazines (OMG) deinked pulp using sodium dithionite. The pulp was bleached using 0.5, 0.75, and 1% sodium dithionite and different times of 30, 60 and 90 minutes. The pulps were then refined to 300 ml, ...
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This research was conducted to investigate the bleaching of combined old newspapers (ONP) and old magazines (OMG) deinked pulp using sodium dithionite. The pulp was bleached using 0.5, 0.75, and 1% sodium dithionite and different times of 30, 60 and 90 minutes. The pulps were then refined to 300 ml, CSF freeness and standard handsheets were made from the refined pulps. The optical and mechanical properties of handsheets and the COD of bleaching effluent were measured according to TAPPI standard test methods. The results showed that the brightness of paper was increased significantly with increase in time and sodium dithionite charge. When the charge of bleaching agent increased, the mechanical properties of handsheets and COD load of bleaching effluent were increased and paper bulk and opacity decreased but these changes were not statistically significant. Increasing the bleaching time from 30 to 90 minutes resulted in a significant improvement in tensile, burst and tear indices but the opacity of paper was reduced.
Pulp and paper
Iman Akbarpour; Hossein Resalati
Abstract
This research was accomplished in order to investigate the replacement of organic complex of Glanapone Stab with sodium silicate on optical properties of hardwood CMP pulp bleached by hydrogen peroxide. The highest brightness of 65.5% and the lowest yellowness of 21.6% was attained at silicate-free ...
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This research was accomplished in order to investigate the replacement of organic complex of Glanapone Stab with sodium silicate on optical properties of hardwood CMP pulp bleached by hydrogen peroxide. The highest brightness of 65.5% and the lowest yellowness of 21.6% was attained at silicate-free followed by replacement of 0.7% and 1.5% Glanapone. But the highest opacity 98.2% was gained using 0.5% glanapone. The brightness of paper increased to 68.1% and the yellowness decreased to 20.8. by adding of glanapone consumption from 0.4% to 0.5% in blended with 0.7% sodium silicate. At higher levels than 0.5% glanapone, the brightness of paper decreased and the yellowness increased. Using Higher levels of 1 and 1.5% glanapone in blended with 0.7% sodium silicate resulted the highest opacity 97.9% and 98%, respectively. Increasing of peroxide usage up to 5% at two different states of silicate-free and silicate-containing with glanapone resulted in the paper with higher brightness and lower yellowness and opacity. CMP pulps bleached at 120 minutes resulted the highest brightness of 71.1% and the lowest yellowness of 18.3% at silicate-containing state with glanapone. Maximum opacity of 98.3% and 98% were shown at bleaching time 30 minutes at two states silicate-free and silicate-containing state with glanapone, respectively. In this research with regard to optical properties in relation to paper produced from CMP pulp bleaching at two states silicate-free and silicate-containing with glanapone,it can be said that possibility of producing the paper with similar optical properties or even better using 0.7% or 1.5% at silicate-free is in compared to conventional hydrogen peroxide bleaching. Also, we could produce the paper with higher brightness along with lower yellowness and similar opacity followed by bleaching time of 120 minutes and hydrogen peroxide 5% in combination of 0.7% sodium silicate with 0.5% glanapone in compared to higher consumed values of sodium silicate.
