Use of formamidine sulfunic acid as pre-bleaching reagent during the pulping of colored office paper

It is necessarytomakeeffectiverecyclingof wastepaperduetodecliningforestresources. However, some papers are easy to recycle, deink or bleach, while others create problems. For example dye colored office papers cause serious problem in pulping stage. Even if a small amount of colored waste paper fibers are mixed with colorless fibers, the dyestuff separated from the colored paper fiber will also stain other fibers. These dyestuff do not interact physically with the fibers, they are absorbed on the fibers and can not be removed by phase separation methods such as flotation or washing deinking.Such papers need to stripped their colors at the pulper(pre-bleaching) and bleaching tower (post-bleaching).For this reason, in this study, the possibility of FAS utilization instead of peroxide for pre-bleaching of colored office paper in the stage of pulping has been investigated.In the study, colored office papers mixed to colorless office paper as 1:4 ratio. FAS was added as 0.25%, 0.50%, 0.75%, 1.00% and 2.00% into pulper.In addition, the effects of FAS bleaching on different colors were also examined.Reduction ability of colors with FAS were listed as yellow, red, green and blue according to L*a*b*, ΔE andreflectance – absorbancespectrum at 220-900nm wavelenght. The color difference (ΔE) of mix colored office paper (brown) fibers were calculated as 34.54 with 2% FAS.In the study, the tensile and tear indexes of the test papers were also determined and a small decrease in the strength properties was observed.As a result of the study, the optimum FAS rate was determined as 1%.It has been observed that pretreatment with FAS, which is a strong reducing agent instead of weak oxidative hydrogen peroxide, during the pulping of office colored papers by the thesis work, gives effective results in color stripping.