Adsorption Characteristics And Mechanisms Of Sulfonamides Antibiotics On Carbonaceous Materials

With the extensive use of antibiotics,more and more antibiotics enter the environment through various ways.Due to the refractory nature of antibiotics and the limitations of treatment technology,the antibiotics' danger on the environment,human and animal body has greatly increased.Sulfonamides antibiotics are widely used because of its low-cost,stable chemical properties and wide antimicrobial spectrum.In recent years,China's surface water,groundwater and wastewater treatment plant were detected sulfonamides antibiotics.It's a serious threat to the environment and human health,so the search for efficient sulfonamides antibiotics removal technology is urgent.Carbonaceous materials are often used to solve environmental pollution due to their high specific surface area,abundant pore structure and strong interaction.But using a variety of carbonaceous materials simultaneously for comparative research on the adsorption characteristics and mechanisms of sulfonamides antibiotics is less.The carbonaceous materials mainly include activated carbon from water purification plant,activated carbon from the filter of household water purification equipment,graphene and graphene oxide.In this paper,fifteen carbonaceous materials were used as adsorbents to study the adsorption and removal properties and mechanisms of sulfonamides antibiotics.Sulfamerazine(SM1),sulfamethazine(SM2)and sulfamethoxazole(SMX)were used as adsorbates.The equilibrium time,equilibrium adsorption capacity,kinetics and isotherm parameters of sulfamethoxazole on adsorbents were studied to determine four carbonaceous materials with good performance in all kinds of materials.The adsorbents were characterized by scanning electron microscopy(SEM),specific surface area and pore volume analysis and fourier transform infrared radiation(FT-IR).In single adsorption system,the adsorption and desorption properties of carbonaceous materials to SMX were studied,including the effects of different water chemical conditions(temperature,pH value,ionic strength,dosage of adsorbents,initial concentration of contaminant and reaction time),kinetics,isotherms and thermodynamics.The adsorption mechanism of carbon material was analyzed.In co-adsorption system,the effect of SM1 and SM2 on SMX adsorption isotherms was studied by fixing the concentration of competitive substances.Through the above research,the optimum factor combinations of adsorption reaction were obtained and the adsorption mechanism was explained from many angles.The experimental results showed that the adsorption process of most of the carbonaceous materials conformed to the Freundlich adsorption isotherm model.According to the model parameters,SMX was easily adsorbed on carbonaceous materials.The kinetic experiments showed that the experimental data was in accordance with the pseudo-second-order kinetic model and the intra-particle diffusion model.The thermodynamic experiments showed that the adsorption reaction was spontaneous.A series of desorption and re-adsorption experiments were carried out using sodium hydroxide as the desorption solution.The results showed that the desorption efficiency of the activated carbon was very good,and the adsorption capacity of the adsorbent after desorption was almost unchanged.It provided a foundation for the regeneration and recycling of the adsorbents in the actual environment.The results of SMX isotherm in co-adsorption system showed that the addition of competitive adsorbates could improve the adsorption capacity of main adsorbates at high concentration.And the addition of competitive adsorbates would improve the adsorption properties of adsorbents.This phenomenon provided a new idea for efficient removal of many contaminants simultaneously.