Desorption experiments and modeling of micropollutants on activated carbon in water phase: application to transient concentrations mitigation

Experimental studies and numerical modeling were conducted to assess the feasibility of a granular activated carbon column to buffer load variations of contaminants before wastewater treatment devices. Studies of cycles of adsorption, and more especially desorption, of methyldiethanolamine (MDEA) and 2,4-dimethylphenol (2,4-DMP) have been carried out on granular activated carbon (GAC). Dynamic variations of contaminants concentrations were run at several conditions of duration (peaks). GAC fixed-bed exhibited a stable adsorption/desorption capacity after undergoing two conditioning cycles. The study of pollution peaks revealed that attenuation is largely dependent on the targeted pollutant: 2.4 ± 0.5 % attenuation/cm of bed for MDEA and 6.0 ± 1.2 % attenuation/cm of bed for 2,4-DMP. Mass balances calculated from both injected and recovered pollutant during peaks were respected. Finally, a coupling of the linear driving force model and isotherms models was used to fit experimental data for both adsorption breakthrough curves and desorption curves. The model was used to predict adsorption and desorption behaviors of following cycles. Good agreement with experimental values was obtained.