Study On The Adsorption Characteristics Of Antibiotics To Coal Gangue And Its Modified Products

With people pay more attention to the pollution of antibiotics,how to effectively remove antibiotics in water has become a research hotspot.Adsorption is one of the popular methods because it is efficient,simple to design and operate.Coal gangue,which is like kaolin in components and structure,can be used as adsorbent,and the related researches have been seen in many reports.However,there are few reports about the adsorption behavior of different antibiotics on coal gangue.In this paper,eight kinds of antibiotics were selected for adsorption,and the adsorption isotherm,adsorption kinetics,adsorption thermodynamics and the effects of pH and ionic strength on the adsorption were investigated.FTIR was also discussed for the adsorption mechanism in the study.The results show that Datong coal gangue(180-220 mesh)could adsorb ciprofloxacin,ofloxacin,norfloxacin,tetracycline and oxytetracycline(adsorption capacity was 2.30mg/g,1.18mg/g,1.43mg/g,1.44mg/g,0.96mg/g,respectively)but did not adsorb the sulfonamides antibiotics.The Freundlich model and the pseudo-second-order kinetic model could describe the adsorption process.The FTIR spectra of the adsorption of quinolones and tetracycline antibiotics on Datong Coal Gangue show the presence of electrostatic attraction between the protonated amine group and the surface charges of adsorbent,and hydrogen bond between the hydrogen of the carboxylic acid groups and the oxygen of the adsorbent could be formed.Calcined for 1 hour at 500 oC was applied to regenerate the used Datong coal gangue,it was found that after three rounds of recycling,the adsorption capacity of ciprofloxacin,ofloxacin,norfloxacin,tetracycline and oxytetracycline was decreased by 14.7%,24.6%,24.5%,30.6%,30.2%,respectively.The adsorption properties of 8 kinds of pharmaceuticals compounds on Xishan coal gangue were better than that of Datong coal gangue.To seek a coal product as adsorbent to adsorb sulfonamide antibiotics,the Datong coal was processed under the atmosphere containing oxygen and water vapor at the temperature of 800 oC.The adsorption capacity of sulfonamide,sulfadiazine and sulfamethoxazole on Coke were 2.75 mg/g,1.41mg/g,1.14 mg/g,respectively.The Xishan coal gangue was also processed under above condition,the adsorption capacity of the modified Xishan coal gangue for ciprofloxacin,tetracycline and sulfonamide was 8.69mg/g,8.01 mg/g,1.96 mg/g,respectively.The Freundlich model and the pseudo-second-order kinetic model fit the adsorption process well.Adsorption thermodynamic studies indicate that the adsorption of coke and modified Xishan coal gangue were spontaneous exothermic process.Environmental conditions have an influence on the adsorption properties of adsorbent.The adsorbent performed well under the acidic conditions.The the adsorption capacity of antibiotic decreased with the increase of ion concentration and ionic valence.The cations play a competitive role in the adsorption process.