Volatilization kinetics and mechanisms of arsenic during vacuum distillation

The volatilization characteristics and kinetic mechanisms of arsenic were investigated in the temperature range of 623-773 K and pressure ranges of 10-10000 Pa. The experimental results reveal that the evaporation rate increases with increasing temperature and decreasing pressure. Surface reaction control dominates at low pressures (<100 Pa), whereas diffusion control dominates at high pressures (>5000 Pa). The evaporation behavior is successfully described by an Arrhenius-type model for temperature dependence and Logistic model for pressure dependence. Key kinetic parameters, including the critical pressure, maximum evaporation rate and evaporation coefficient, were calculated. The evaporation coefficient varies between 0.010 and 0.223, and the critical pressures vary between 281 and 478 Pa with temperature.