Mg(OH)2 as Alkaline Source in Peroxide Bleaching of Wheat Straw Pulp

The present work sought to make a contribution to the study on application of Mg(OH)(2) in peroxide bleaching of the wheat straw soda-AQ pulp. The results showed that: (1) for an unbleached pulp, when 24-73% of the NaOH was replaced with Mg(OH)(2), a higher brightness and viscosity were achieved comparing to the NaOH as the sole alkaline source. The brightness and viscosity of the bleached pulp at 48% of Mg(OH)(2) replacement were respectively 6.4%ISO and 107 mL.g(-1) higher than those of the NaOH as the sole alkaline source. (2) for a chelated oxygen-delignified pulp, the brightness of bleached pulp at 24% Mg(OH)(2) replacement was considerable to that of the NaOH as the sole alkaline source, and at 48% Mg(OH)(2) replacement 2.8% ISO lower than that of the NaOH as the sole alkaline source. While the viscosity increased consistently with the increase of Mg(OH)(2), and the COD load of bleaching filtrates at 24-48% Mg(OH)(2) replacement was lower 22-31% than that of the NaOH as the sole alkaline source. Therefore, partial substitution of Mg(OH)(2) for NaOH had positive effects on peroxide bleaching of wheat straw soda-AQ pulp.