Construction Of Fe(Ⅲ)/calcium Peroxide Fenton-like System With Enhanced Performance Based On Polydopamine And Research On Their Mechanism

Fenton(or F-enton-like)reaction is widely used to degrade organic pollutants in water.However,the instability of liquid H2O2 may bring potential safety issues in the storage and transportation process,and applications of the traditional Fenton(Fenton-like)reaction are restricked by problems such as narrow pH application range and low Fe2+/Fe3+ circulation rate.To break this technical barrier,calcium peroxide nanoparticles(nCaO2)was used to replace liquid H2O2,and polydopamine(PDA)was used to accelerate the reduction of Fe3+,Based on which,calcium peroxide nanoparticles@polydopamine(nCaO2@PDA)and 3D-polydopamine/polyvinyl alcohol(3D-PDA/PVA)nanocomposites was prepared to enhance the comprehensive efficiency of Fenton-like reaction.The specific research contents are as follows:(1)Calcium nitrate(Ca(NO3)2)was used as the precursor,polyvinyl pyrrolidone(PVP)as the surface stabilizer,and nCaO2 paricles were prepared by sol-gel method Then,the self-assembly of dopamine(DA)under alkaline conditions was used to coat nCaO2,and calcium peroxide nanoparticles@polydopamine(nCaO2@PDA)composites with core-shell structures were prepared.The results show that the PDA "shell" of the composite can effectively reduce Fe3+ through the phenol-quinone transformation,while H2O2 provided by the nCaO2 "core" diffuses into the solution thorough the shell,compared to the mixed addition of PDA and nCaO2.RhB removal efficiency increased by 10.50%.In addition,PDA will release H+during the reduction of Fe3+,which is beneficial for reducing the pH value of the reaction system.Even under the condition of pH=11,78.7%of RhB can still be removed,expand the pH applicability of the system to 2-11.(2)The high-density PVA sponge with three-dimensional porous structure was selected as the matrix material,and the PDA coating was carried out on the PVA skeleton by adjusting the addition of DA,thus the 3D-PDA/PVA composite was synthesized.Compared with nCaO2@PDA,the concentration of DA added during the preparation of 3D-PDA/PVA was reduced from 12.3 mg/mL to 3 mg/mL and showed a faster reaction rate(low cost-effectiveness ratio).This is due to the unique pore structure,which can facilitate the adsorption of RhB and improve the loading rate of PDA.The experimental results show that the composite has excellent recyclability and can still remove more than 80.3%RhB after five cycles.