Mass balance and elimination mechanism of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during the kraft pulping process.

Papermaking raw materials are usually digested by NaOH and NaS solution. The fate of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during the kraft pulping process is still poorly known. In this study, a comprehensive investigation was conducted on the variation in PCDD/Fs in the kraft pulping section of 3 modern non-wood pulp mills adopting elemental chlorine-free (ECF) bleaching technology.

Mechanistic aspects of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) formation from chlorine bleaching of non-wood pulp.

Chlorine bleaching of non-wood pulp can produce and release polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) into environment. In this study, a series of chlorination experiments were conducted to explore the source, formation pathway and formation kinetics of ClDD/Fs during the chlorine bleaching of wheat straw pulp. The C isotope-labeling experiment verified that PCDD/Fs could not be formed from the chlorination of phenols in pulp.