Document Type : Research Paper

Authors

• Hamid reza Mehri Iraie ¹
• Ali Ghasemian ²
• Hossein Resalati ³
• Ahmad reza Saraeyan ²
• Iman Akbarpour ⁴

¹ M.Sc Graduate of Pulp and Paper Industries, Gorgan University of Agricultural Sciences and Natural Resources (GUASNR)

² Associate Prof. of Pulp and Paper Technology, GUASNR, Faculty of Wood and Paper Engineering, Dept. of Wood and Paper Industries

³ Prof. of Pulp and Paper Technology, GUASNR, Faculty of Wood and Paper Engineering, Dept. of Wood and Paper Industries

⁴ Ph.D Student of Pulp and Paper Industries, GUASNR, Faculty of Wood and Paper Engineering, Dept. of Wood and Paper Industries

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, 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.

Keywords

• Old newspaper
• Old Magazine
• Deinking
• bleaching
• Sodium Dithionite