Mechnism And Technology Study On Sulfonamides Pollutants Removal By Hydrous Metal Dioxide

The sulfonamides (SAs) in aqueous solutions has caused potential threats to human health and environment, therefore, using adsorption technology to remove sulfonamides has currently become one of hot research topics in the field of drinking water. The text mainly prepared three adsorbents including hydrous ferric oxides (HFO), hydrous manganese oxides (HMO), ferric and manganese binary oxide (FMBO) and aimed at removing two kinds of synthetic sulfonamides including sulfadiazine (SDZ) and sulfadimethoxine (SDMO). The text completed the study about the adsorption efficiency and influence factors of SDZ and SDMO onto the surface of HFO, HMO, FMBO, explored the potential mechanisms for SDZ and SDMO adsorption on adsorbents, respectively, optimized the parameters of process operation to remove SAs in drinking water based on setting up a FMBO-Zeolite dynamic adsorption columns. Furthermore, the text completed preliminary engineering designing about purifying SAs in drinking water. The main achievements were as follows:The results of the static adsorption experiments showed:the removal of SDZ and SDMO onto the surface of HFO, HMO and FMBO was highly pH dependent and the increasing of ionic strength had negative effect on the the adsorption capacity. And the removal effect of SDZ by HMO and FMBO was significantly better than the SDMO. The pseudo-second-order model fitted well for the kinetic results of SDZ and SDMO adsorption on HMO and FMBO, while the pseudo-first-order model had a good fit for SDZ. The Webber-Morris model showed that SDZ and SDMO adsorption by adsorbents was controlled jointly by the film-diffusion and intraparticle-diffusion. The adsorption isotherms were all well described by Langmuir model. Thermodynamic parameters (△H> 0, △S>0 and △G<0) revealed that the adsorption of SDZ and SDMO on adsorbents was the spontaneous and endothermic process.The potential mechanisms for SDZ adsorption on FMBO and SDMO adsorption on HFO were inferred, respectively, through the analysis of the characterization of samples before and after adsorption (XRD、SEM、BET、Zeta、 FTIR and XPS). The results showed that both of the electrostatic attraction and the hydrogen bonding contributed for the uptake of SDZ by FMBO. While the process of SDMO adsorbed by HFO was mainly account for the replacement of surface hydroxyl groups of HFO by SDMO and the electrostatic attraction between the positively charged surface of HFO and the anions of SDMO-.The results of FMBO-Zeolite dynamic adsorption columns showed that the adsorption capacity of FMBO-Zeolite column for SDZ could reach 3680 BV when the experiment conditions as follows:the initial concentration of SDZ was 400 μg/L; the loading capacity of Fe and Mn was 2.1 mg/g and 0.675 mg/g, respectively; EBTC was 15 min; pH was 7. Therefore, The processing for removing SAs has potential feasibility.A set of purified processing used to remove SAs was designed according to the current pollution situation of SAs in water. The capacity of this processing can reach 192 m3/d. The adsorbent filled in is FMBO-Zeolite and the processing mainly covers adsorption and filtration.