Study On Adsorption Characteristic Of SMZ On Modified Activated Alumina

Sulfamethoxazole(SMZ)is a broad spectrum antibiotic,but account of their structure is stable,they can easily stay in the environment for a long time and seriously threaten people's health,so SMZ in water caused widely public concern.Adsorption,because of its low cost,still has a potential advantage on the low concentration antibiotic depth removal from water.Adsorption characteristics of adsorbent is one of the most critical factors affecting adsorption.Activated alumina is a kind of normal adsorbent.The adsorption capacity of ordinary activated alumina is low,so it must be modified in order to attain a higher adsorption characteristic.This article aims to improve the adsorption capacity of SMZ on activated alumina,to select the best modification methods by activated alumina modified.Adsorption characteristic,adsorption mechanism and regeneration method were researched and investigated detailedly.The results of experiment as below:1.The adsorption characteristic of SMZ on ordinary activated alumina was first studied in order to provide the basis for modification.Static adsorption experiment was carried out to investigate the influence of equilibrium time,initial concentration and pH value on adsorption of SMZ on activated alumina.The results indicated that the adsorption capacity increased quickly in the initial adsorption 2h,and adsorption rate curves were basically reached the adsorption equilibrium after adsorption 12 h.And as the initial concentration increased,the adsorption capacity was added.When the solution pH increased from 3 to 10,the adsorption quantity of antibiotics increased first and then reduced,the activated alumina presented maximum adsorption capacity especially at pH 6-7.2.The adsorption effect of activated alumina modified with oxalic acid and ferric chloride was best.The best modification condition:the activated alumina was soaked in 0.01% oxalic acid solution for 30 min with a solid-liquid ratio of 1:2 and then soaked in 0.05% ferric chloride solution for 1h with a solid-liquid ratio of 1:2.The maximum adsorption capacity of activated alumina was only 0.22mg/g,the maximum adsorption capacity of modified activated alumina was 2.63 times compared to unchanged activated alumina.3.The adsorption kinetics on the modified activated alumina was well described by the pseudo-second-order kinetic model.As the temperature increased,the secondary reaction kinetics constant k2 was also increased.The adsorption behaviour was in accordance with the Freundlich Equation which made better fitted than Langmuir isotherm.During the adsorption,?G0<0,?H0>0,?S0>0.It showed that the adsorption thermodynamics is a entropy increase process.4.The calculation result of activation energy was 172.82kJ/mol which indicated that chemisorption was predominant.The experiment also studied mass transfer process on the surface of SMZ and modified activated alumina.Results showed that the rate-limiting step was intraparticle diffusion and film diffusion.5.Activated alumina was analyzed through XRD,BET,FT-IR and SEM.The results indicated that the surface area and the number of pore of activated alumina was increased after modified.The crystal structure of activated alumina was not damaged after modified with oxalic acid and ferric chloride.6.Research on regeneration of the saturated modified activated alumina showed that the saturated modified activated alumina could maintain a high adsorption capacity after five regeneration recycles.The best regeneration condition:the saturated modified activated alumina was desorbed in 0.01mol/L NaOH for 1h with a solid-liquid ratio of 1:5,and then activated in the best conditions of oxalic acid and ferric chloride.