Functionality of poly(α-hydroxyacrylic acid) as H<inf>2</inf>O <inf>2</inf> stabilising agent

The functional properties of the polymeric hydrogen peroxide stabilising agent, poly(alpha-hydroxyacrylic acid) (PHA) were defined by analysing the escaping oxygen content on-line by gas-phase mass spectrometry. A statistically significant regression model with good fit describing the system was developed and its response surfaces were generated. Furthermore, a pseudo-second order kinetic expression was established for a system including the effect of PHA. PHA was found to generate a stabilising effect over hydrogen peroxide in the presence of 2 mg/kg metals Fe and Mn at pH 10, but the stabilisation ability is limited to temperatures below ca. 60 degrees C. Under typical bleaching conditions for mechanical pulp, i.e. pH 9 and T=70 degrees C, a slight optimum of approximately 150 mg/kg in terms of PHA content can be seen. Introduction of PHA generally exposes the system more to the effects of pH and temperature.