Investigation On The Adsorption Characteristics Of Endocrine Disrupting Compounds Onto Activated Carbon Based On Corncob

Endocrine disrupting compounds(EDCs),one sort of emerging persistent contaminants,have attracted public attention because they can affect the nervous system and endocrine system even at trace concentration.It is urgent to find a way to efficiently treat EDCs-embedded wastewater because EDCs have been found in surface water,sediments and the atmosphere.The adsorption characteristics of four typical EDCs including bisphenol S(BPS),bisphenol A(BPA),bisphenol F(BPF)and 4,4′-thiodiphenol(TDP)were investigated by activated carbon prepared from corncob(CCAC).Adsorption conditions including contact time,adsorbent dosage,initial concentration and pH were optimized by central composite design(CCD)under response surface methodology(RSM).The optimal conditions for BPS were initial BPS concentration of 88.4 mg/L,contact time of 244 min,adsorbent dosage of 0.2 g/L and pH 4.3.The optimum parameters for BPA adsorption were found to be adsorption time 238 min,adsorption dosage 0.2 g/L,the initial concentration of BPA 90.0 mg/L and pH 6.3.The adsorption equilibrium data of BPS and BPA were found to fit the Langmuir isotherm model and Koble-Corrigan isotherm model well.The maximum monolayer adsorption uptake of BPS and BPA were found to be 617.29 mg/g and 770.09 mg/g at 298 K,respectively.Considering the thermodynamic parameters,the adsorption process of BPS and BPA were spontaneous and exothermic in nature,which indicated that low temperature was favorable for the adsorption of BPS and BPA onto CCAC.Adsorption kinetics data were well described by the pseudo-second-order model.Intra-particle diffusion model showed that it was not the only rate-controlling step and the membrane diffusion controlled the adsorption process to some degree.In order to explore the adsorption behavior of EDCs,the adsorption characteristics of BPF and TDP were investigated.The experiments were performed under various conditions including adsorption time,absorbent dosage,pH and initial concentration.The adsorption equilibrium data were well described by Langmuir isotherm models.The maximum monolayer adsorption capacity of BPF and TDP were 583.15 mg/g and 809.12 mg/g at 298 K,respectively.The adsorption process of BPF was also well described by Redlich-Peterson model.Thermodynamic parameters revealed that the adsorption process of BPF and TDP were spontaneous and exothermic in nature.The kinetic studies indicated that adsorption of BPF and TDP followed the pseudo-second-order.Intra-particle diffusion and membrane diffusion may control the adsorption process together.CCAC were characterized by SEM,FTIR and BET.The adsorption behaviors and adsorption mechanisms of BPS,BPA,BPF and TDP were investigated.It can be considered to be a potential biomass adsorbent for the removal of EDCs because of a relatively large adsorption capacity of BPS,BPA,BPF and TDP.