Study On Preparation Of EDTA Functional Magnetic Chitosan And Its Removal Of Methyl Blue And Heavy Metals

With the wide use of metal materials and organic dyes in the process of industrial development,these two types of pollutions commonly inevitably co-exist in industrial wastewater.Its high toxicity,biodegradability and environmental persistence pose a serious threat to the environment and human health.So far,the vast majority of researches focus on the single removal of heavy metals or organic dyes,and a few researches for the simultaneous removal of co-exist pollutants.Therefore,it is necessary to develop a simple and environmentally friendly method for the simultaneous/synergism removal of these two pollutants.Based on the idea of"simultaneous/synergetic"removal,The Fe₃O₄-CS/EDTA adsorbent was successfully prepared by binding chitosan?CS?to anionic dyes with excellent adsorption properties,strong attraction of EDTA to heavy metals and magnetic separation of Fe₃O₄nanoparticles.This adsorbent was applied to the simultaneous/cooperative removal of heavy metals and dyes from composite polluted wastewater.The specific experimental results are as follows:?1?Cu???and Pb???were selected as target adsorbates,and the effects of different conditions on the adsorption of heavy metals by Fe₃O₄-CS/EDTA were systematically studied.The results showed that the adsorption of Cu???or Pb???had a strong dependence on pH,and the adsorption capacity increases with the increase of pH.The adsorption of Cu???or Pb???on Fe₃O₄-CS/EDTA could be better described by pseudo-second-order kinetics and Langmuir isotherms,with maximum adsorption capacities of 225.03 mg/g for Cu???and 219.99 mg/g for Pb???.The thermodynamic experiments showed that the adsorption of heavy metals were a spontaneous and endothermic reaction.More importantly,the recycling effect of the adsorbent was satisfactory in the Up water and the model textile effluent.?2?The MB was selected as target adsorbate,and the effects of different conditions on the adsorption of MB by Fe₃O₄-CS/EDTA was systematically studied.The results showed that the adsorption capacity of MB decreases with the increase of pH.The adsorption of MB on Fe₃O₄-CS/EDTA could be better described by pseudo-second-order kinetics and Langmuir isotherms,with maximum adsorption capacities of 459.89 mg/g.The thermodynamic experiments showed that the adsorption of MB was a spontaneous and endothermic reaction.The significant increase in MB adsorption after addition of NaCl could be attributable to the increased dimerization of MB.More importantly,the recycling effect of the adsorbent was satisfactory in the Up water and the model textile effluent.?3?The Cu???-MB and Pb???-MB binary pollution systems were selected as research objectives.The effect of the presence of coexisting contaminants on the adsorption of target adsorbates was studied.The results showed that the presence of Cu???or Pb???slightly decreased the MB adsorption.However,the adsorption capacity decreased for Cu???or Pb???with increasing MB concentration at pH 6.0,but the result was totally the opposite at pH 3.0.