| With the acceleration of industrialization,heavy metal pollution,in particular cadmium ion,has become increasingly conspicuous,and related applications of rare and dispersed elements represented by indium are becoming more and more popular.It has already become an important issue on how to remove cadmium efficiently as well how reclamation of indium can be achieved.Adsorption has been widely applied in the treatment of wastewater containing metal ions and the recovery of metal ions from aqueous solution due to its simplicity,high efficiency and low cost.However,there are numerous and complex components in the untreated wastewater containing metallic ions,which can reduce the efficiency adsorption of target ions during the adsorption process.Therefore,it is the most cutting-edge and notable one of the focused aspects in chemical engineering to design,investigate and develop a new absorbent material that has a good recognition performance and can be used to remove and recover metallic ions from aqueous solution selectively.Metal ion imprinted polymer has a specific recognition property and it has been widely used in the removal and recovery of specific metal ion from aqueous solution.The goal of this research is to remove and recover Cd2+,In3+from aqueous solution selectively.Different types of novel adsorbent materials had been synthesized.The adsorption and recognition performance to target ions were also investigated in detail.Besides,the adsorption and recognition mechanism was revealed,respectively.The main results can be concluded as follows.?1?The Cd?II?ion-imprinted polymer?ATU/Cd?II?-IIP?was prepared by surface imprinting technology using allyl thiourea as a functional monomer and all the required samples were characterized by fourier-transform infrared spectroscopy,thermogravimetric analysis,scanning electron analysis and N 2 adsorption-desorption isotherms to reveal the adsorption and recognition mechanism of the prepared material to the target ions.In addition,the adsorption and recognition ability of the ATU/Cd?II?-IIP towards Cd2+were investigated in detail by batch adsorption and dynamic adsorption experiments.The results showed that the amount of adsorbed of Cd2+by ATU/Cd?II?-IIP increased with the increasing of the p H value in the solution and the maximum removal rate reached 87.20%at p H value of 7.0.The adsorption was a rapid chemical adsorption process which could be described by pseudo-second-order kinetic model,and the equilibrium adsorption was achieved within 16.0 min.The maximum adsorption capacity of ATU/Cd?II?-IIP for Cd2+was calculated to be 38.30 mg·g-1 and the relative lower temperature was beneficial for the adsorption process of Cd2+onto the ATU/Cd?II?-IIP.The sorbent exhibited a good recognition performance to target ions and the relative selectivity coefficients for Cd2+/Cu2+,Cd2+/Ni2+,Cd2+/Co2+,Cd2+/Pb2+and Cd2+/Zn2+were 2.86,6.42,11.50,9.46and 3.73,respectively,in binary metal mixture solutions.It was further proved by dynamic adsorption experiment that the ATU/Cd?II?-IIP prepared in this present study exhibited excellent recognition and adsorption properties towards Cd2+.?2?The Cd?II?ion-imprinted polymer?AMT/Cd?II?-IIP?was prepared using surface imprinting technology,where allyl mercaptan was used as a functional monomer and all the required samples were characterized on the basis of fourier-transform infrared spectroscopy,thermogravimetric analysis,scanning electron analysis and N2 adsorption-desorption isotherms.The adsorption and recognition ability of the AMT/Cd?II?-IIP for Cd2+were investigated in detail by batch adsorption and dynamic adsorption experiments.The results showed that the maximum static adsorption capacity of AMT/Cd?II?-IIP for Cd2+was 73.43 mg·g-1 at p H 7.0.The adsorption was an endothermic and spontaneous process and c ould be described by the Langmuir isotherm model.Cd2+could be rapidly combined with active sites onto the polymer in the solution.The process reached the adsorption equilibrium within 20.0 min and the adsorption followed pseudo-second-order kinetics equation.The process of AMT/Cd?II?-IIP adsorbed Cd2+was considered as a chemical adsorption process and the sorption rate was controlled by both the liquid film diffusion and the intra-particle diffusion.The competitive adsorption experiments results showed that AMT/Cd?II?-IIP had a good recognition performance for Cd2+,and the target ion could be selectively removed from aqueous solution.?3?The In?III?ion-imprinted polymer?VPA/In?III?-IIP?was prepared through surface imprinting technology using vinylphosphonic acid as a functional monomer and all the samples were characterized on the basis of fourier-transform infrared spectroscopy,thermogravimetric analysis,scanning electron analysis and N 2adsorption-desorption isotherms.The adsorption and recognition ability of the VPA/In?III?-IIP and corresponding non-ion imprinted polymer?VPA/In?III?-NIP?for In3+were investigated in detail by batch adsorption and column adsorption experiments,respectively.The results showed that the amounts adsorbed of In3+by VPA/In?III?-IIP and VPA/In?III?-NIP increased with the increase of the p H value in the solution.The adsorption capacity of In3+onto the VPA/In?III?-IIP and VPA/In?III?-NIP were calculated to be 43.87 and 26.53 mg·g-1,respectively,at p H value of 3.0.The adsorption of In3+onto the VPA/In?III?-IIP and VPA/In?III?-NIP was a rapid chemical sorption,the process reache d the adsorption equilibrium within10.0 min and all the adsorption process can be described by the pseudo-second-order rate equation.The results of competitive adsorption experiments showed that the VPA/In?III?-IIP had better recognition for In3+and could be used as a sorbent to selectively remove In3+from aqueous solution.?4?The surface grafted In?III?ion-imprinted polymer?VPA-AMT/In?III?-IIP?was prepared through surface imprinting technology by vinylphosphonic acid and allyl mercaptan as the compound functional monomer to coordinate with In3+synergistically.All the required samples were characterized on the basis of fourier-transform infrared spectroscopy,thermogravimetric analysis,scanning electron analysis and N2 adsorption-desorption isotherms,and the adsorption and recognition ability of the VPA-AMT/In?III?-IIP and corresponding non-ion imprinted polymer?VPA-MT/In?III?-NIP?for In3+were investigated in detail by batch adsorption and column adsorption experiments.The results showed that the solution p H value played an important role on the adsorption of In3+,and the adsorption capacity of In3+onto the VPA/In?III?-IIP and VPA/In?III?-NIP were calculated to be75.83 and 36.70 mg·g-1,respectively,at p H 3.0.The adsorption of In3+onto the VPA-AMT/In?III?-IIP and VPA-AMT/In?III?-NIP was considered to be a rapid chemical sorption.The process reached the adsorption equilibrium within 10.0 min and the adsorption process could be described by the pseudo-second-order rate equation.The competitive adsorption experiments results showed that VPA-AMT/In?III?-IIP presents strong affinity to selectively adsorb In3+from wastewater containing other competitive ions.?5?The multi-carboxyl-functionalized silica gel?SG-MCF?was prepared by surface grafting method using silica gel as a matrix and its structure was characterized by fourier-transform infrared spectroscopy,thermogravi metric analysis,elemental analysis and N2 adsorption-desorption isotherms.The adsorption performance of Zn2+,Ni2+,Cu2+and Cd2+was investigated in detail by batch adsorption and column adsorption experiments.The results showed that the recovery rate o f Zn2+,Ni2+,Cu2+and Cd2+reached 75.54%,52.38%,77.05%and 89.44%,respectively,at the optimum p H value when using the SG-MCF as a sorbent.All of the adsorption processes could be fitted well with the Langmuir adsorption model. |
PDF Full Text Request