Study On Adsorption Characteristic Of SMZ On Magnetic Activated Carbon

Sulfonamides?SAs?are a kind of broad-spectrum antibacterial agent that is synthesized artificially.Because of their chemical stability in water environment,SAs can exist in the environment for a long time and pose a serious threat to the health of humans,animals and plants.Therefore,it is of great significance to study the removal of SAs from water.Sulfamethoxazole?SMZ?was selected as the target compound and the powdered activated carbon?PAC?was prepared into the magnetic activated carbon?MAC?by a chemical co-precipitation method in this study.The adsorption behavior of SMZ in pure water by MAC was studied,and the effects of pH and other factors on the treatment efficiency were investigated.The regeneration method of MAC was also studied and its repeatability was evaluated.Moreover,surface properties of magnetic composite materials were characterized by automatic surface area and pore analyzer,fourier transform infrared spectrometer and vibrating sample magnetometer.The main results were as follows.1.The dynamic and static equilibrium adsorption experimental results show that the MAC of SMZ in water adsorption rate showed a trend of fast after slow first,2 h before belongs to the fast adsorption stage,finally in 5 h to reach adsorption equilibrium,on the final SMZ removal rate reached 96%.The adsorption kinetics is more suitable for the second order kinetics model.The adsorption process was more consistent with the Freundlich isotherm,and the saturated adsorption capacity of MAC to SMZ was 4.81 mg/g.2.Iron oxides have no effect on the removal of SMZ from water by MAC,and Na⁺and Ca²⁺have no obvious effect on the adsorption during the adsorption process,so there is no competitive adsorption.pH is the direct effect of changing the adsorption capacity of MAC.When the pH is in the range of 3.0 to 10.0,the higher the acidity,the higher the adsorption capacity,and the optimum pH condition is around 3.0.In the temperature range of298K-318K,the removal rate of SMZ in water increases with the increase of temperature,which is conducive to increase the adsorption rate.When the amount of adsorbent was increased from 0.025 g to 0.2 g,the removal rate of SMZ increased gradually after adsorption equilibrium,and the dosage continued to increase,and the removal rate did not change significantly.Humic acid has inhibitory effect on adsorption in the range of 10-50mg/L.When the concentration was 10 mg/L,the inhibitory effect was the strongest,while the removal rate of SMZ was reduced by 12%,and the concentration of humic acid was increased,and the inhibitory effect was reduced.Humic acid and SMZ have competitive adsorption,but the interference ability is weak.3.In the experiment of magnetic carbon regeneration method,methanol,5%acetic acid and 5%ammonia solution were selected to elucidate the SMZ on the MAC.The recovery rate of the drug was 28.78%,9.22%and 90.76%respectively,so the methanol containing ammonia was selected as the regenerated solution.Comparing the leaching rates of SMZ with different volume ratios of methanol in methanol,it was found that when the volume ratio of ammonia to methanol was 10:90,the recovery of SMZ was the highest,which was98.16%.Therefore,the final methanol solution of 10%ammonia was determined as the best elution solvent.4.The results of MAC regeneration and reuse experiments showed that after MAC was recovered and regenerated five times,the adsorption capacity of SMZ decreased from the initial 1.60 mg/g to 1.44 mg/g.The adsorption capacity of the adsorbent after regeneration has been reduced,but the adsorption effect is still good,and it has certain recycling and reuse value.5.The specific surface area measurement results showed that compared with PAC,the specific surface area and pore volume of MAC were slightly reduced.Infrared spectroscopy results showed that iron oxides were successfully loaded on the PAC.6.The vibration sample magnetometer test results show that the prepared MAC saturation magnetization?Ms?is 13.8 emu/g,slightly lower than the iron oxide saturation magnetization value,and has a small residual magnetization and coercive force.According to the shape and trend of hysteresis loop,the MAC belongs to superparamagnetism.Moreover,there was no magnetic particles agglomerate during the experiment.It can be seen that the MAC is easily separated from the solution under the appropriate external magnetic field.Therefore,the adsorbent has the value of recovery and reuse.