Optimizing Synthesis Of Iron Oxide Nano-materials For Application In Photo-fenton Degradation Of Bisphenol S Under Visible Light Irradiation

Due to its excellent physical and chemical stability,bisphenol S?BPS?has been regarded as an ideal substitute for BPA?bisphenol A?.And it has been widely applied in the synthesis of macromolecular materials such as polycarbonates,epoxy resins,polyester resins,polysulfone,and so on.At the same time,it has also been used for the production of thermal papers and food package.However,the physiological toxicity of BPS has been uncovered with in-depth study,which is similar to the physiological toxicity of BPA.Even more disturbing,the emergence of BPS in surface water has been reported frequently,which deliver a serious threat for the public heathy.Therefore,it is of great significance to remove BPS from the aqueous systems.Compared with the conventional Fenton technology,homogeneous photo-Fenton technology has exhibited a better application promising.However,it still exist some problems such as strict operation parameters and large amounts of sludge.To address these issues,rational design and synthesis of a catalyst could be a key for building the high-performance heterogeneous photo-Fenton system for degradation of BPS.The primary results of this study can be found below:?1?To address the issues of solid iron oxide?i.e.,limited active sites?,we have first developed a �soft� Si O₂ templating strategy for effective and controllable fabrication of hollow iron oxide nanostructures.And then,the relationships between micro-structure and physicochemical property and photo-Fenton activity have been illuminated.Recycle catalytic tests have shown that the hierarchical hollow iron oxide nanospheres possessed an excellent stability.The mechanic studies have indicated that the dominate active species are the superoxide radicals and hydroxyl radicals.30% BPS can be degraded by the iron oxide hollow nanospheres under visible light irradiation,which is much higher than that of the solid iron oxide nanoparticles?3%?.This excellent photo-Fenton activity could be attributed to the high surface area and well-developed pore structure,thus leading to the effective degradation of BPS.?2?Despite the higher surface area leading to better photo-Fenton activity,the inherent defects of iron oxide?e.g.,rapid recombination of photo-excited carries?still exist.Therefore,graphene with a super-high migration rate has been introduced into the synthesis of iron oxide,thus obtaining the iron oxide/ graphene composite materials.The degradation tests of rhodamine B have shown that the iron oxide quantum dots/graphene composite catalysts exhibit a better photoreactivity.The mechanic studies have indicated that the primary active species are the hydroxyl radicals.83% of BPS can be degraded by the iron oxide quantum dots/graphene composite catalysts under visible light irradiation,which is much higher than that of the s hierarchical hollow iron oxide nanospheres?30%?.This excellent photo-Fenton activity could be attributed to the synergistic coupling effects in these samples: 1)2D graphene sheets could be regarded as ideal conductive substrates,which may improve the electron transport;2)graphene have an excellent ability to absorb the BPS from the water.?3?To achieve the materials with a better catalytic activity,a silica hydrogel-mediated dissolution-recrystallization strategy has been proposed for the fabrication of ultrathin iron oxide nanosheets with a high percentage of exposed?110?facets.As high as 91% of BPS can be degraded by these iron oxide nanosheets under visible light irradiation,which is higher than that of P25 titanium dioxide?56%?and the iron oxide nanoparticles?16.6%?.This outstanding photo-Fenton activity could be attributed to the advantageous properties of iron oxide nanosheets such as efficient charge separation and high surface area,which stem f rom the rationally designed nanoarchitectures of iron oxides?i.e.,ultrathin?³.2 nm?sheet-like nanostructures with a high percentage of?110?facets?.At last,the degradation byproducts of BPS have been identified and the corresponding transformation pathways have also been proposed.