| Imprinting technology is a novel and significant method which can be used to prepare smart materials with the memory effect.According to the development and application situation of imprinted materials,it is found that they are widely concerned and studied in the environmental field because they can effectively recognize and selectively separate target substances.However,there are some problems need to be further studied to expand their application fields and promote the process of their industrial applications.As for the conventional molecular(ion)imprinted materials,there are some problems need to be further studied:1)their physical and chemical properties,the mechanism of recognition and adsorption for targets,and the other theoretical problems;2)whether they can maintain good selectivity for targets in the face of complex interference environments;3)acid treatment and organic solvent extraction are common regeneration methods,which will consume lots of chemical reagents,and lead to the damage and dissolution of adsorption sites,environmental pollution,and the other practical problems.In addition,the unstability and poor solubility of gas molecules cause that they are not easy to be controlled and dissolved in the polymerization reaction system during the preparation processes of gas molecular imprinted polymers(MIPs).Therefore,choosing suitable alternative template molecules is extremely significant for preparing gas-MIPs,which limits the applications of imprinting technology in gas purification fields,and leads to the current research only involving CO2,NO,and partial VOCs.However,the composition of industrial gases is complex and diverse.If novel gas-MIPs can be developed,they are expected to play an important role in the sensitive detection,efficient purification and transformation of gases,which is also a valuable research direction for industrial production.As for the current situation of hydrogen sulfide pollution and sulfur resource shortage,the solid desulfurization materials still have some problems need to be improved,such as low sulfur capacity,poor selectivity and regeneration performance,and the transformation and recovery of sulfur resource.Therefore,H2S-MIPs were designed and prepared to realize the selective capture of H2S and the transformation and recovery of sulfur resource,which can not only be beneficial for gas purification and valuable resource recovery,but also widen the application fields of imprinting technology.On the other hand,in consideration of the market demand and recovery situation of lithium resource,this study developed several novel imprinted materials to promote the extraction and recovery of lithium resource,and reported an environmental-friendly regeneration method to avoid the pollution problems in the regeneration process.In addition,the related adsorption mechanism was analyzed by thermodynamic calculation,kinetic and adsorption isotherm models to provide the theoretical support.The contents of this thesis contain the following four parts:1)PMo12@Zr-MOFs(UiO-66)were synthesized via the one-pot hydrothermal process in the presence of Keggin-type phosphomolybdic acid hydrate(H3PMo12O40).Based on the surface of PMo12@UiO-66,novel core-shell-structured PMo12@UiO-66@H2S-MIPs were synthesized by surface imprinting technology(SIT)using H2O as the alternative template of H2S,acrylamide(AAM)and ethyleneglycol dimethacrylate(EGDMA)as the functional monomer and cross-linker,respectively.In addition,benzoyl peroxide and N,N-dimethyl aniline were used as the initiator,and mixed solutions of acetonitrile and ethyl acetate were used as the solvent.The effects of relevant factors of preparation H2S-MIPs on the desulfurization performance were studied by dynamic desulfurization experiments at room temperature,and the optimal conditions were obtained as follows:a mole ratio of H2O/AAM/EGDMA of 1:4:10,a volume ratio of acetonitrile to ethyl acetate of 1:1,and a polymerization time of 24 h.The characterization results of FT-IR,SEM,TEM and XRD showed that H2S-MIPs were successfully loaded on the surface of PMo12@UiO-66,and the prepared PMo 12@UiO-66@H2S-MIPs had the core-shell structure.Compared with PMo12@UiO-66(carrier),PMo12@UiO-66@H2S-MIPs exhibited the better removal ability for H2S,and their H2S adsorption capacity could attain 24.05 mg/g.The effect of water steam on the desulfurization performance of PMo12@UiO-66@H2S-MIPs was investigated.The results demonstrated that water steam played a positive role in H2S removal.In the interference of CO2,PMo12@UiO-66@H2S-MIPs still could maintain highly effective adsorption for H2S,suggesting that they had excellent separation ability for H2S/CO2.About the regeneration of PMo12@UiO-66@H2S-MIPs after adsorption,they were first purged using an air pump at 180? and then treated with O3 at room temperature.The recycling experiments showed that the H2S adsorption capacity only decreased by 11.5%after 6 cycle experiments.The results of XPS and TGA of PMo12@UiO-66@H2S-MIPs before and after adsorption proved the formation of elemental S after adsorption,illustrating that H2S was successfully transformed into sulfur resource.We compared the desulfurization performance of PMo12@UiO-66@H2S-MIPs,PMo12@UiO-66 and UiO-66@H2S-MIPs,and combined with the characterization results of FT-IR,BET,XRD,XPS,ESR and TGA to analyze the desulfurization mechanism.The selective removal mechanism of PMo12@UiO-66@H2S-MIPs for H2S can be expressed as:H2S is first adsorbed by H2S-MIPs on the surface of PMo12@UiO-66@H2S-MIPs,and the adsorbed H2S is transferred into the interior of PMo12@UiO-66@H2S-MIPs through the pore channels of UiO-66 with the accumulation of H2S.Then,the adsorbed H2S is oxidized to elemental S through the redox role of PMo12 in the interior of PMo12@UiO-66@12S-MIPs,where Mo6+is reduced to Mo5+.In addition,the Mo5+in the PMo12@UiO-66@H2S-MIPs after adsorption is oxidized to Mo6+ by air purge at 180? and O3 treatment at room temperature to realize the effective regeneration of PMo12@UiO-66@H2S-MIPs.Therefore,PMo12@UiO-66@H2S-MIPs have excellent selectivity,adsorption and regeneration performance,which are expected to be applied to the industrial fields of fine desulfurization and sulfur recovery of low H2S concentration.?)Based on the multi-wall carbon nanotubes(MWCNTs)treated by HC1,lithium ion imprinted polymers(IIPs)were prepared by SIT.Wherein,dibenzo-14-crown-4(DB14C4)and a-methacrylic acid(a-MAA)were used as the chelating reagent and functional monomer,respectively.The physical and chemical properties of IIPs were characterized by FT-IR,SEM and BET.The results demonstrated that imprinted polymers were loaded on the surface of MWCNTs,namely,IIPs were successfully synthesized.The results showed that the best adsorption ability(1362.56 ?mol/g)of IIPs for Li+was obtained at 25? and pH 6.0.Through the fitting of kinetic and adsorption isotherm models,it could be found that the pseudo-first-order and Langmuir models were consistent with the adsorption behavior of IIPs for Li+,illustrating that IIPs had homogeneous adsorption sites to some degree.In the complex adsorption environment containing Li+,Na+,K+,Cu2+and Zn2+,IIPs could maintain the adsorption superiority for Li+,suggesting that IIPs had the ideal selective adsorption performance for Li+.In addition,the saturated IIPs were treated by 1 mol/L HNO3 several times to realize their regeneration and reusability.After ten adsorption-desorption cycle experiments,the Li+adsorption capacity only decreased by 10.3%,illustrating that IIPs could be efficiently regenerated,and their binding sites could maintain good adsorption stability.?)To obtain low-cost and efficient adsorbents,we chose the vermiculite from building material markets as the raw material,and pretreated it by HNO3 vapor and ultrasound waves to improve its properties.Based on the pretreated vermiculite,lithium ion imprinted polymers(IIPs)and non-ion imprinted polymers(NIPs1 and NIPs2)were prepared by SIT.The effect of the treatment time of HNO3 vapor on the adsorption performance was studied,and the results showed that the optimal time was 6 h.The effects of main components of preparation IIPs on the adsorption performance were studied,and the optimal preparation conditions were obtained as follows:a mole ratio of template molecules(LiNO3)/functional monomers(a-MAA)/cross-linkers(EGDMA)of 1:5:20,and a volume ratio of methanol and N,N-dimethylformamide(DMF)of 1:2.The results of BET?FT-IR?SEM and XRD showed that the treatment method of HNO3 vapor could increase the specific surface area of vermiculite and achieve the exfoliation of stacked lamellas,and demonstrated that IIPs were successfully synthesized.The results demonstrated that the Li+adsorption capacity decreased with the increase of temperature.Under the conditions of 25? and pH 7.0,IIPs exhibited the best adsorption property with the maximum adsorption capacity of 2852.61 ?mol/g According to the thermodynamic calculation,it was found that the adsorption process was exothermic and spontaneous.The isothermal adsorption fitting results showed that Langmuir model could well describe the adsorption behavior of IIPs,illustrating that IIPs were basically homogeneous,and the adsorption behavior should be a monolayer adsorption.Compared with NIPs1 and NIPs2,IIPs exhibited better selectivity for Li+in the presence of Na+,K+and Mg2+,suggesting that IIPs can selectively separate Li+in the face of interference ions.In addition,the saturated IIPs were regenerated by HNO3 treatment.The adsorption-desorption experiments showed that Li+ adsorption capacity had no obvious decrease with the increase of cycle times,and it only decreased by 13.1%after 10 cycle experiments,suggesting that IIPs had stable adsorption ability.?)In previous studies,lithium ion imprinted polymers were regenerated by the method of acid pickling.Although this regeneration method has good regeneration efficiency,it is accompanied by the problems of consuming lots of chemical reagents and producing a large amount of elution wastewater.To solve the above problems,a green and simple regeneration method based on light was proposed in this part.Therefore,photo-responsive lithium ion imprinted polymers(P-IIPs)were designed and prepared by SIT using azobenzene(AB)derivative and DB14C4 as the functional monomer.The results of FT-IR,BET,SEM,TEM and XRD showed that P-IIPs were successfully synthesized.The photo-controlled experiment showed that UV irradiation promoted P-IIPs to release the adsorbed Li+,and visible irradiation was beneficial for the adsorption behavior of P-IIPs for Li+.In addition,P-IIPs still exhibited the alternating behavior of desorption and adsorption for Li+during the repeated process of UV-vis alternating irradiation,illustrating that P-IIPs had the photo-controlled adsorption-desorption performance.The kinetic results showed that the adsorption rate of P-IIPs under visible irradiation was faster than that in darkness,and the adsorption capacity under visible irradiation was obviously higher than that in darkness,which further demonstrated that visible irradiation can promote P-IIPs to adsorb Li+.In addition,the kinetic data could be well described by pseudo-second-order kinetic model,which is commonly associated with the chemical adsorption process.The Li+adsorption capacity of P-IIPs increased with the increase of temperature,and the optimal temperature was 50?.Under the condition of 50?,P-IIPs had better adsorption ability under visible irradiation than in darkness,indicating that the thermal effect and visible irradiation played a synergistic role in promoting the adsorption behavior of P-IIPs.At room temperature,the maximum adsorption capacity of P-IIPs could attain 3280.5 ?mol/g,and Langmuir model could fit their adsorption process well.The selective experiment showed that P-IIPs could maintain the adsorption superiority for Li+in the presence of Na+,K+and Mg2+,demonstrating their good selectivity for Li+.The regeneration of the saturated P-IIPs was performed by dispersing them into distilled water,treating them with UV light and.ultrasound waves.The results showed that desorption rate of the saturated P-IIPs was 90%,and the Li+adsorption capacity exhibited a slight decrease after five cycle experiments.According to the above results,we analyzed the selective adsorption mechanism of P-IIPs for Li+as follows:on the one hand,DB14C4 has the matched cavities with Li+,leading to that Li+can get into the cavities and combine with four oxygen atoms in cavities to form stable complexes;on the other hand,AB and its derivatives have the property of reversible trans-cis photo-isomerization under UV-vis irradiation.Therefore,P-IIPs combining DB14C4 and the AB derivative have selectivity and photo-controlled adsorption-desorption properties for Li+. |
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