Chemistry and kinetics of LAS acid thermal decomposition

Abstract

The emission of sulfur dioxide (SO2) from linear alkylbenzene sulfonate (LAS) acid (LASH) at high temperatures has been studied. Rate constants and Arrhenius parameters have been determined, enabling estimation of the amount of SO2 evolved under any time/temperature combination for risk assessment purposes. Further analysis of the kinetic data and comparison with earlier molecular modeling work on the mechanism of sulfonation of linear alkyl benzene (LAB) to make LASH provide insight into the reaction pathway of SO2 formation by thermal decomposition of LASH. For risk assessment purposes, the calculation is as follows: Estimate k from k = 3.9 × 107.e-13,000/(273+7) where T is in degrees C and k is in s-1. Estimate N(SO2,t), the number of moles of SO2 evolved when N(LASH0) moles of LASH are heated for t s at T°C, from: N(SO2,t) = N(LASH0)) × (1 - e-kt).