Removal of bisphenol S from drinking water by adsorption using activated carbon and the mechanisms involved

Bisphenol S, an alternative chemical to bisphenol A, has a negative effect on living organisms and has frequently been detected in drinking water systems. A promising and cost-effective method for removing bisphenol S from tap water is adsorption by activated carbon. However, activated carbon significantly decreased the adsorption capacity of bisphenol S in tap water comparing with that in deionized water based on the experimental results. Dissolved organic matter in tap water was likely responsible for it. The adsorption kinetics can be described by a pseudo-second-order model. The Langmuir isotherm model can well describe the process, suggesting monolayer adsorption. The maximum adsorption capacity was calculated as 83.19 mg g(-1). Higher temperature and pH were unfavorable to the process. Changes in entropy, enthalpy, and Gibbs free energy were calculated and implied a spontaneous and exothermic adsorption process. Fourier transform infrared spectroscopic analysis found that hydroxyl and amino functional groups are the main groups involved. The research provides a substantial basis for understanding bisphenol S removal from drinking water by adsorption using activated carbon to limit direct exposure to bisphenol S in drinking water.