| Organic,heavy metal,and microbial contamination are three major issues that commonly exist in the water environment at present.Adsorption technology usually handles with the first two types of pollution,and less research have been conducted on the antibacterial properties of adsorbents.Therefore,it is of practical significance to develop one kind of adsorbent that can achieve efficient adsorption and good antibacterial properties at the same time.In this paper,one kind of adsorption antibacterial material,CD-CA/PDA-xAg,was finally developed by the methods of esterification cross-linking,dopamine self-polymerization,and in situ regeneration of nano silver(Ag NPs).We examined its application in removing heavy metals,cationic dyes and inhibiting microorganisms.Firstly,CD-CA/PDA was produced by poly-dopamine(PDA)modification of the matrix material(CD-CA)which was got by the esterification crosslinking of citric acid(CA)and ?-cyclodextrin(?-CD).FT-IR,XPS,XRD and other characterization methods were used to characterize properties of materials.Based on pH effect adsorption experiment,adsorption isotherm and kinetic experiments of methylene blue(MB),malachite green(MG),crystal violet(CV)and copper ion(Cu2+),it was found that CD-CA and CD-CA/PDA both had great adsorption performance and a wide range of highly effective adsorption.At the same time,PDA and CD-CA promote each other,and PDA modification greatly enhances the adsorption performance of CD-CA.The adsorption isotherms studies showed that the adsorption behavior had a transition tendency from single-layer adsorption to multi-layer adsorption after PDA modification.The calculated data shows that the adsorption capacity of CD-CA/PDA for MB,MG,CV and Cu2+reaches(582.95 mg/g,1.82 mmol/g),(1174.67 mg/g,3.22 mmol/g),(473.01 mg/g,1.16 mmol/g)and(73.64 mg/g,1.16 mmol/g).In addition,CD-CA and CD-CA/PDA are all chemisorption for these four pollutants.Subsuqently,the tandem adsorption and adsorption-regeneration experiments of CD-CA/PDA showed its good continuous adsorption and repeated adsorption capabilities,which proved the practical application value of the material.CD-CA/PDA mainly adopts electrostatic force for selected target pollutants,followed by intermolecular forces,host-guest inclusion of cyclodextrin cavity and ?-? stacking.Nextly,four kinds of CD-CA/PDA-Ag adsorption antibacterial materials with different silver contents were prepared by using the reductive properties of catechol groups on the surface of CD-CA/PDA to reduce Ag+.EDS,FT-IR,XPS,TEM and FESEM characterizations analyzed the silver content of each material,effect of silver loading contant on the structure and properties and observed the distribution of Ag NPs on the material.We performed CD-CA/PDA-Ag with different silver contents on the diffusion inhibition zone tests and colony formation unit tests to E.coli and S.auerus.Diffusion inhibition zone tests showed that the antibacterial effect of the material increased with the increase of silver content.The results of colony formation unit tests showed that the release of silver ions,the particle size of the material,and the silver content of the material determine the bacteriostatic effect of the material in solution.The silver content of the material itself is the determining factor.These two antibacterial experiments showed that the antibacterial effect of CD-CA/PDA-Ag on E.coli was significantly better than that of S.aureus.Because S.aureus,as Gram-positive bacteria has a thicker and stronger mechanical strength cell wall.The effect of silver content on the adsorption performance of CD-CA/PDA-Ag experiments showed that with the increase of silver content,the adsorption performance(adsorption capacity and adsorption rate)of the adsorbent for methylene blue gradually decreases.Finally,CD-CA/PDA-0.5Ag with a surface silver content of 3.07%retains both efficient adsorption and antibacterial activity,which can be widely used in the purification of dyes,heavy metals and microbial contaminated water bodies. |
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