Preparation Of Novel Functional Natural Materials And Their Adsorption Properties For Heavy Metals

Heavy metal pollution is an environmental ecology problem that needs to be solved urgently.The development of new high-performance heavy metal adsorbents has important application prospects.In this thesis,green natural polymer-chitosan and inorganic mesoporous material-Herlotite were used as raw materials to synthesize terminal amino hyperbranched molecules by silanization,Michael addition and amidation reaction.And imprinted polymerization to prepare a novel adsorption material for Cd???with intelligent p H-sensitive selection or specific imprinting identification and adsorption properties,test material properties,and analyze the adsorption characteristics of materials for heavy metal ions,and then combine with electrochemical detection methods to prepare Ion-imprinted electrochemical sensors clarify the electrochemical properties of the new sensors.The main research work is as follows:?1?Using magnetic chitosan?CMC?as raw material,magnetic carrier particles?MNP?were prepared by co-precipitation method.On the surface of MNP,silanization,Michael addition and amidation reaction were used to synthesize terminal amino hyperbranched molecules in a"divergent"form.Then,a novel magnetic supramolecular functional adsorption material?CCMD?having a"shell-core"structure was prepared by cross-linking with the activated carboxymethyl chitosan molecule.Characterization of product structure by Fourier transform infrared spectroscopy?FT-IR?,BET specific surface area tester,elemental analyzer,thermogravimetric analyzer?TG?;X-ray diffractometer?XRD?,scanning/transmission electron microscopy?SEM/TEM?The crystal form and apparent morphology of the sample were analyzed;the vibrating sample magnetometer?VSM?and the Ze-ta potential analyzer were used to measure the photoelectromagnetic properties of the material,and the adsorption properties were studied.The results showed that the target functional adsorbent?CCMD?was successfully synthesized and the material was in the paramagnetic magnetite crystal structure.The magnetization values of MNP,MD and CCMD in VSM analysis were 11.6,11.3 and 9.0 emu·g^-1,respectively.The zeta potential test showed that the MD and CCMD potentials decreased with increasing p H,and the surface charge of CCMD was higher than that of MD.The adsorption performance test showed that CCMD has a p H-smart response characteristic,which can selectively adsorb yin with environmental p H changes.cation.When the p H was 11.0 and 5.0,respectively,CCMD showed the maximum adsorption capacity for Cd???and F ions,which were 79.12 mg·g^-1 and 65.05mg·g^-1,respectively.The adsorption process accorded with quasi-secondary kinetics and Langmuir adsorption model.The repeated adsorption-desorption experiments showed that the removal rates of Cd???and F by CCMD were all above 80%,indicating that the new magnetic adsorption material CCMD has better regeneration performance.?2?Using the halloysite nanotubes?HNTs?as raw materials,and gradually introducing the terminal amino supramolecular group on the surface by"diverging",and then using the terminal amino hyperbranched molecule and polyacrylamide?PMA?as functional monomers.Cd???is a template ion,epichlorohydrin?ECH?is a cross-linking agent,azobisisobutyronitrile?AIBN?is used as an initiator,and surface selective ionography is used to prepare a specific selection and recognition for Cd???.New type of halloysite ion-imprinted polymer?Cd-IIP?.The molecular structure was characterized by Fourier transform infrared spectroscopy?FT-IR?,EDS spectrum analyzer and thermogravimetric analyzer?TG?.X-ray diffractometry?XRD?and scanning/transmission electron microscopy?SEM/TEM?were used to analyze the crystal form of the sample.And apparent morphology of the material;atomic absorption spectrophotometer?FAAS?analysis of material adsorption properties.The results showed that the target functional adsorbent?Cd-IIP?was successfully synthesized,and the crystal form of the material remained unchanged before and after the reaction.Compared with the non-imprinted ionic polymer?NIIP?,the surface of Cd-IIP was coarse and finely porous and porous.The adsorption performance test results showed that the saturated adsorption capacity of Cd-IIP to Cd???could reach 64.37 mg·g^-1 at p H=7.0.The specific recognition performance showed that the imprinting factor?of Cd-IIP was 2.62.The factor?is 1.78,and the choice of Cd-IIP for Cd???/Pb???,Cd???/Cu???,Cd???/Ni???,Cd???/Cr?III?The coefficients are 2.9614,1.8012,4.5032,and 4.5680,respectively,indicating that Cd-IIP has a unique selective adsorption performance for template ion Cd???.The adsorption characteristics of Cd-IIP were analyzed.The results show that the adsorption process accords with quasi-secondary kinetics and Langmuir adsorption model.Repeated adsorption-desorption experiments show that the Cd-IIP has a 75%rejection rate for Cd???.The above shows that the new ion imprinted material Cd-IIP has better regeneration performance.?3?A novel ion-imprinted sensor?Cd-IIP/FCNTs/GCE?was prepared by using a new cadmium ion-imprinted polymer?Cd-IIP?modified glassy carbon electrode,using Cyclic Voltammetry?CV?and AC impedance method.?Electrochemical Impedance Spectroscopy,EIS?characterized the new sensor,differential pulse voltammetry?DPV?to investigate the adsorption performance and specific energy of the new sensor for cadmium ions.The results showed that a new cadmium ion imprinted sensor was successfully prepared.The new sensor has a good imprinting effect.The imprinting factor?is 6.95 and the selection factor?is 5.95,which shows high specificity and strong recognition ability.There is a quantitative relationship between the peak current of the sensor and CCd???in the range of CCd????1.0×10^-6 mol·L^-1;the electrochemical impedance spectrum of each electrode of the sensor is analyzed to obtain R1?CPE1?R2?CPE2?R3????)The equivalent circuit model.Fitting and calculating the parameters of each component in the equivalent circuit of each sensor,the result confirms that the theoretical value of the analog equivalent circuit is consistent with the measured value.The new sensor has certain application value.