Study On Properties Effect Of Crystalline Phases By Delafossite CuFeO₂ Catalyzing PMS

In this paper,a series of delafossite CuFeO₂ catalysts were synthesized by hydrothermal method,the catalyst properties were investigated by SEM,XRD,EDS,XPS,FT-IR,UV-vis.The influence of reaction temperature,reaction time,reaction pH and adsorbent on the properties of crytal phases and morphologies were investigated.The synthsis mechanism of different crytal catalysts was discussed.The CuFeO2 was used for activating peroxymonosulfate?PMS?for removal of acid orange?AC?dye pollutants,and the different degradation conditions such as pH and visile-light on catalytic were studied.The mechanism of catalytic PMS were discussed,combining with the influence of tert-butanol,ethanol,phosphate on AC degradation and the results of XPS analysis.This study presented a new synthesis method to obtain delafossite CuFeO₂ at a temperature of 100?within 12 h pH=13.0 by using CuSO₄ and FeSO₄ as reactants,without usage of any additives controlling the oxidation state of copper.It was found that3R and 2H crystal morphology were existed with the 3R content of 89.6%.The SEM showed the catalysts were hexagonal plate with well-defined edges,corners,and smooth surfaces,and the average crystal size of CuFeO₂ was about 0.5?m and 0.2?m thick.The UV-visible absorption spectra indicated that there was a strong absorption of CuFeO₂ in the visible range,and the band gap wass 1.44 eV.The effects of pH and visible light were also investigated,under optimized conditions,the degradation of AC reached to 94.7%in 30 min.And in the dark,the AC degradation was 78.1%,the difference between visible-light and dark environment was 29.6%.The catalytic activity didn't significantly reduce after 4cycles.The pure delafossite 3R CuFeO₂ were synthesized at a temperature of 180?within48 h,using Cu?NO3?2 and Fe?NO3?3 as reactants and glucose as reducing agent.The polyvinylpyrrolidone?PVP?,hexadecyl trimethyl ammonium bromide?CTAB?,NaF,and sodium dodecyl sulfate?SDS?were used to modify 3R CuFeO₂,respectively.The unmodified catalysts were irregular hexagonal plate,and the average crystal size was about5-8?m.The unmodified 3R CuFeO₂ band gap was 1.62 eV,the ratio of?101?/?012?facets intensity was 0.089,the degradation of AC was 8.9%in visible-light or 4.5%in the dark.The SEM images showed that the average crystal size of modified 3R CuFeO₂ were about 8?m.The catalyst morphology was hexagonal plate after adding the PVP or SDS.the band gap decreased to 1.34 eV and 1.21 eV,respectively,the difference of AC degradation between light and dark was 29.6%,14.4%,respectively,the intensity ratio of?101?facets and?012?facets was 0.278,0.159.The crystal morphology changed to octahedral structure,after modifing by CTAB or NaF.The intensity ratio of?101?facets and?012?facets was0.161,0.088,respectively,and the band gap were 1.33 eV and 1.42 eV,respectively.The degradation of AC in visible-light or dark changed little.The result proves that free radicals in the catalytic reaction system were mainly?OH andSO₄^-?.Both elements Cu and Fe in the CuFeO2 were involved in the activation reaction of PMS.