| Due to the effects of mining,smelting,agricultural backwater and landfill leachate,a large amount of water resources are contaminated by heavy metal mercury,and mercury is easily migrated,transformed,and enriched in the organism through the biological chain.Accumulation in the body leads to pathological changes in the nervous system,tissues and organs.Therefore,the development of an efficient and environmentally friendly method to deal with mercury pollution in wastewater is the focus of current research.Among the methods for removing toxic metals,the adsorption method is often used to treat mercury ions in wastewater due to its high efficiency,low cost,simple equipment,and no secondary pollution.Because traditional adsorbents can only be recovered by conventional methods such as centrifugation,filtration,and precipitation,it is easy to cause the loss of adsorbents and secondary pollution.Therefore,in this paper used aminated magnetic nanoparticles as a carrier to crosslink biomass materials and polyethylene to prepare magnetic biomass composite adsorption materials.By fourier transform infrared spectra(FT-IR),thermogravimetric analysisb(TGA),X-ray diffraction(XRD),scanning electron microscope(SEM)and transmission electron microscope(TEM)to characterized the composition,structure,and morphology of the two magnetic biomass composites,and explored the influence of the amount of adsorbent input,the pH of the solution,the initial Hg(Ⅱ)concentration,the adsorption time,temperature and coexisting ions on the adsorption effect and the regeneration performance of the adsorbent were investigated.In addition,the adsorption data were analyzed by adsorption kinetics,isothermal adsorption model and adsorption thermodynamics.Firstly,the magnetic nanoparticles were coated with silica,and then amino modified to prepare an aminated magnetic nanomaterial as an adsorbent carrier,glutaraldehyde is used to crosslink the aminated starch and polyethyleneimine to obtain magnetic starch/polyethyleneimine composite adsorbent.Through investigation experiments showed that the removal rate of Hg(Ⅱ)was 97.85%under the conditions of 0.02 g of adsorbent input,120 min of adsorption time,pH 4 and temperature of 20℃ and initial Hg(Ⅱ)concentration of 100 mg/L.It was found that the adsorbent has selective adsorption for Hg(Ⅱ).After 5 desorption-adsorption experiments of the adsorbent,the adsorption capacity accounted for 91.27%of the initial adsorption capacity,and the adsorption capacity was 222.04 mg/g,which indicating that the regeneration performance of the adsorbent was good.By fitting the data,it was found that the adsorption process of Hg(Ⅱ)followed quasi-second-order adsorption kinetic model and Langmuir isotherm adsorption model and adsorption process was the self-releasing reaction.Finally,through adsorption experiments on industrial wastewater containing Hg(Ⅱ)showed the removal rate of Hg(Ⅱ)was 91.38%.Secondly,the aminated magnetic carrier was combined with polyethyleneimine and aminated hydroxyethyl cellulose by tannic acid to prepare the magnetic cellulose/polyethyleneimine composite adsorption material.When the amount of adsorbent was 0.02 g,the adsorption time was 80 min,the pH was 5,temperature of 20℃ and the initial concentration of Hg(Ⅱ)was 100,the removal rate of Hg(Ⅱ)by the adsorbent was 98.89%.Through coexisting ion experiments,it was found that the adsorbent has selective adsorption for Hg(Ⅱ).After 5 desorption-adsorption experiments of the adsorbent,the adsorption amount of the adsorbent accounted for 93.06%of the initial adsorption capacity,and the adsorption amount was 231.29 mg/g.Through data fitting analysis,it was found that the adsorption process of Hg(Ⅱ)followed quasi-second-order adsorption kinetic model and Langmuir isothermal adsorption model,and adsorption process was the self-releasing reaction.Finally,through actual testing of industrial wastewater containing Hg(Ⅱ),the removal rate of Hg(Ⅱ)by the adsorbent was 93.79%. |
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