Temperature impacts PFAS Adsorption on Activated Carbon

Abstract

While PFAS adsorption on activated carbon has been widely studied, the effect of temperature at environmentally relevant concentrations remains unclear. This study investigated the adsorption of eight PFAS at 10, 20, and 30 °C. Short-chain PFAS adsorption decreased up to 4-fold with a temperature increase from 10 to 30 °C, whereas long-chain PFAS were minimally affected. The Freundlich isotherm described all equilibrium adsorption data with a single parameter value of n = 0.5. The Langmuir model provided a good fit for all short-chain PFAS but failed to yield a consistent maximum adsorption capacity (qmax) at different temperatures. Extending Langmuir to the Frumkin isotherm provided a constant qmaxand revealed that reduced short-chain PFAS adsorption at higher temperatures is due to increased lateral interactions between adsorbed molecules. Kinetic analysis showed that intraparticle diffusion coefficients increased with temperature, with stronger effects for short-chain PFAS. Using isotherm and kinetic parameters, breakthrough curve predictions showed that for short-chain PFAS, an increase in temperature from 10 to 30 °C reduced the number of treated bed volumes before breakthrough by a factor of 3, whereas long-chain PFAS remained unaffected. These findings highlight the importance of considering temperature effects in PFAS removal using activated carbon.