The Influence Mechanism Of Calcination Temperature On The Catalytic Activity Of Poly-Silicate-Ferric In Heterogeneous UV-Fenton System

Heterogeneous UV-Fenton technology,as one of the promising wastewater treatment technologies,has the disadvantage that the solid-phase catalyst had low catalytic activity.Therefore,the development of a heterogeneous UV-Fenton catalyst with high catalytic activity is particularly important.Poly-Silicate-Ferric(PSF)synthesized from Si,O,and Fe,which is abundant in nature,has a large specific surface area and is expected to become a catalyst with good catalytic activity.Calcination is often used to modify the catalyst.So it is necessary to study the effect of calcination on PSF.In this paper,the catalytic performance of PSFs calcined at different temperatures in heterogeneous UV-Fenton system was compared.The appropriate calcination temperature was selected to enhance the catalytic performance of PSF,and further explored the influence mechanism of calcination on the heterogeneous UV-Fenton system over PSF.Simultaneously,the enhanced mechanism of benzoquinone on PSF-250 in heterogeneous UV-Fenton system was studied.Some conclusions were obtained as follows:1.It was found that calcining PSF at 100～350℃ can enhance its catalytic activity in heterogeneous UV-Fenton system.Based on good photocatalytic performance and high iron recovery ability,250℃ was considered to be the optimum calcination temperature for PSF.The decolorization rate can reach almost 100%in 10 min,and the mineralization rate can reach 91.2%in 30 min over PSF calcined at 250℃.2.The influence mechanism of calcination temperature on the heterogeneous UV-Fenton system over PSF was proposed.The calcination of PSF at 250～300℃can reduce its Fe-O bond energy to a minimum.Low Fe-O binding energy lead to enhance photo-reduction ability of PSF under ultraviolet light,enhance its iron ion release ability in the UV-Fenton system,accelerate the decomposition of H2O2 and the formation of ·OH,and promote degradation of Orange Ⅱ.3.The enhanced mechanism of benzoquinone on PSF-250 in heterogeneous UV-Fenton system was proposed.It was found that benzoquinone and ultraviolet light synergistically reduce Fe3+ to Fe2+ in the heterogeneous UV-Fenton system over PSF-250,thereby promoted the iron cycle in the UV-Fenton system and accelerated the decomposition of H2O2 and the formation of ·OH.Eventually,the decolorization of Orange Ⅱ was greatly promoted.