Preparation Of Chitosan-base Composites And Adsorption Of Cu(?),Pb(?),Ni(?) And MB

Adsorption is considered to be an efficient and economical method for treating heavy metal and dye wastewater due to its simple operation,high efficiency and low cost.The adsorption process is sometimes reversible,and the adsorbents can be regenerated by desorption.Therefore,the adsorbents can be reused,which is both conducive to environmental protection and economic benefits.A variety of low-cost adsorbents were developed and used to adsorb dye and metal ions in wastewater.And adsorption method has been proved to have a good application prospect in wastewater treatment.At present,the low adsorption capacity and difficult recovery were the main problems of adsorbents.Therefore,this paper used natural polymer chitosan as the main material to fabrication adsorbents,Fe₃O₄@SiO₂@CS-TETA,Fe₃O₄@SiO₂@CS-TETA-GO and X-CS/NIPAAm for improving the adsorption capacity and solving the recovery of adsorbents.The adsorption behavior of MB and metal ions in water were studied,and the adsorption mechanism was discussed.In the second and third chapters,Fe₃O₄ magnetic cores were synthesized by solvothermal method,and the diameter of the particles were about 460 nm.A thin SiO₂shell?about 64 nm?was coated on the Fe₃O₄ magnetic core by St?ber method,followed by the chitosan was crosslinked on the surface of the SiO₂ shell.TETA containing a large number of amino groups was attached to the surface of Fe₃O₄@SiO₂@CS.In order to further improve the specific surface area of the composite microspheres,we synthesized Fe₃O₄@SiO₂@CS-TETA-GO through a linkage reaction.Then TEM,SEM,XRD,FT-IR and VSM were adopted to characterize the structure of the material.Fe₃O₄@SiO₂@CS-TETA and Fe₃O₄@SiO₂@CS-TETA-GO composite microspheres were used as an absorbent for the absorption of Cu?II?and MB,and the effect of solution p H,initial concentration,absorption time and temperature were studied.The adsorption isotherms and adsorption kinetics well fitted the Langmuir model and the pseudo-second-order model,respectively.The maximum adsorption capacity by Fe₃O₄@SiO₂@CS-TETA was about 312.3 mg g^-1 for MB and 256.7 mg g^-1 for Cu?II?,and the maximum adsorption capacity by Fe₃O₄@SiO₂@CS-TETA-GO was about 529.1 mg g^-1 for MB and 324.7 mg g^-1 for Cu?II?.The adsorption equilibrium was reached within 20min.The adsorbents had such good adsorption properties because of the large amount of functional groups on the surface of the adsorbents.In the fourth chapter,we prepared a kind of X-CS/NIPAAm composite hydrogel.The maximum adsorption capacity of Cu?II?,Pb?II?and Ni?II?were 125.3,185.5 and71.8 mg g^-1,respectively.The adsorption equilibrium was reached within 30 min.The adsorbents had such good adsorption properties because of the large amount of functional groups on the surface of the adsorbents.In order to discuss the selective adsorption behavior of Pb?II?by X-CS/NIPAAm,we designed the adsorption experiment of single-component system and multi-components system.And the adsorption mechanism was analyzed by the Soft and Hard Acid Base theory?SHAB?.The X-CS/NIPAAm composite hydrogel have good reusability and recyclability.