The Study For Mg?OH?₂ Used In P Segment OHP Bleaching Of Wheat Straw NaOH-AQ Pulp

In this paper,detailed study for magnesium hydroxide used in hydrogen peroxide bleaching of caustic soda-anthraquinone wheat straw pulp.First,According to mature hydrogen peroxide bleaching process parameters used in softwood,through detailed experimental find the optimum conditions for sodium hydroxide used in hydrogen peroxide bleaching of caustic soda-anthraquinone wheat straw pulp,proved that do not add sodium silicate will not affect the results of bleaching;accurately determine the optimum pH value of hydrogen peroxide bleaching used in sodium hydroxide between 10.5 and 11.O.In this range of pH,can effectively suppress the decomposition of hydrogen peroxide,can well control the reaction rate of hydrogen peroxide,can achieve the highest brightness;verify the amount of magnesium sulfate added can improve the pulp brightness after bleaching,but if added too much will cause the pulp brightness after bleaching to down.Second,after finding the optimum conditions for sodium hydroxide used in hydrogen peroxide bleaching,instead of sodium hydroxide and magnesium sulfate with magnesium hydroxide carried out a series of experimental,and the experimental results are compared.The results show,magnesium hydroxide added will bring about:brightness after bleaching lower,residual hydrogen peroxide higher,pH value lower,bleach filtrate chemical oxygen demand and cationic charge demand significantly reduced,transition metal ions reduced,bulk slightly higher,folding strength significantly higher,breaking length and tear resistance slight changed,yield increase,dirt unchanged.Magnesium hydroxide instead of sodium hydroxide with the biggest advantage is reflected in the clean production and environmental protection,magnesium hydroxide as the alkali source of hydrogen peroxide bleaching makes the lower alkalinity,makes less lignin removal,makes less anion content in pulp,makes less bleaching of organic matter in the waste water,and easier handle.Esle,its makes less fiber loss,yield high,haves good economic benefits.But its shortcomings is that pulp whiteness is slightly lower.Another is difficult to store magnesium hydroxide,transport it is so.Transport it need progressive cavity pump specifically.Magnesium hydroxide and the slurry mixed need to stir,In order to make slurry and magnesium hydroxide mixed uniform.Magnesium hydroxide instead of sodium hydroxide as the alkali source,the bleach effluent residual hydroxide peroxide is too high,through experiment proved,residual hydrogen peroxide in bleaching filtrate still remains bleaching ability,can improve the whiteness of pulp,can be used as the water to wash pulp behind the hypochlorite bleach.All in,magnesium hydroxide applied to hydroxide peroxide bleach of wheat straw pulp is completely feasible,has good economic benefits and environmental benefits.