Chitosan Compound Microcapsule:preparation And Its Application In Adsorption Removing Of Cadmium Ion From Water

Among the contaminants that affect human and living organisms are heavy metal,it has attracted considerable amount of attentions and raising human concerns particularly due to their toxicity,wide sources,non-biodegradable properties and accumulative behaviors.China has formulated the "13th Five-Year" environmental protection plan,the prevention and control of heavy metal pollution becomes one of the important tasks.In this work,chitosan based composite microcapsules were prepared and used for adsorption removing cadmium?Cd?ions from aqueous solution.Nano ferroferric oxide?Fe₃O₄?,nano-hydroxyapatite and mesoporous molecular sieve were used to hybridize with humic acid to improve its adsorption performance,which was characterized by using Cd???as the target pollutant.The effect of reaction conditions,such as the pH and reaction time,on the adsorption performance of the adsorbents were discussed.The composite microcapsules were characterized by Fourier transform infrared?FTIR??X-ray diffraction?XRD??Scanning electron microscopy?SEM?and BET.And the adsorption kinetics and adsorption isotherm were carried out.The investigation details were listed as follows.?1?The composite microcapsule of Fe₃O₄/HA@CS were applied to adsorb the Cd???in the solution.The results showed that the removal rate of pH=7 was 97%,and After reacting for 60 min,the reaction reached an adsorption equilibrium.And its saturation adsorption capacity to Cd???were 48.5mg/g.The dynamic test results showed that the Cd???adsorption mechanism may include chemical and physical adsorption process.Adsorption isothermal study shows that the Langmuir isotherm adsorption model can well describe the adsorption process.?2?The composite microcapsule of HAP/HA/CS were applied to adsorb the Cd???in the solution.The results showed that the maximum removal rate of pH=7 was 95%.Adsorption isothermal study shows that the Freundlich isotherm adsorption model can well describe the adsorption process.?3?The composite microcapsule of CS/HA/MCM were applied to adsorb the Cd???in the solution.After reacting for 40 min,the reaction reached an adsorption equilibrium with the adsorption capacity of 92.6mg/g.And pH=7 was the optimal condition with the removal rate of 84%.The adsorption process fitted pseudo-second-order model well,and the Langmuir isotherm adsorption model can well describe the adsorption process.