Silicate Materials Based Advanced Oxidation Processes For The Removal Of Organic Poluttants From Wastewater

Environmental pollution has raised awareness of a potential global crisis a long time ago.The development of robust approaches at lower cost and less energy while at the same time reducing the use of chemicals and impact on the environment is an urgent task for the sustainable development of human society.Advanced oxidation processes(AOPs)are one of the most promising strategies to overcome the environmental problems by generating highly reactive species such as hydroxyl and sulfate radicals that destroy organic contaminants,producing innocuous carbon dioxide,water or other harmless by-products.Furthermore,Silicate materials also received a broad interest due to their special physicochemical properties,low cost,excellent thermal and chemical stability,and environmentally benign nature.In addition to that,their crystal structure and dimensionality usually determine the properties and applications of materials.Herein,Silicate based materials were synthesized and applied as catalyst/photocatalyst to decompose the organic pollutants into harmless compounds in the wastewater using the generated radical species.The performance of the as-prepared materials strongly depends on their surface structure and surface sites,which are very sensitive to the preparation method,pretreatment or reaction conditions,and the size.1.Activation of peroxymonosulfate via cobalt silicate nanotubes for the degradation of organic pollutants:Faster mass transportation of ions and sufficient active site exposure are two critical factors for catalyst,which can be provided by the hierarchical nanostructured materials.In this work,hierarchical cobalt silicate hollow nanotubes(CoSNTs)are synthesized under hydrothermal reaction by using mesoporous silica nanotubes as morphology template and silicon sources.The hollow and hierarchical pore structure would help to shorten the diffusion pathway of ions and boost the mass transport.Additionally,the high specific surface area and large pore of the volume provided by the nanopetals on the outer wall of CoSNTs would expose more active sites for a better catalytic performance.A complete degradation of MB and other dyes was achieved within 12 min and 9 min,respectively confirming that CoSNTs are highly efficient in catalytic decomposition.2.Visible light driven degradation of MB using 3D flowerlike iron oxide decorated by Ag6Si2O7:During the photocatalytic process,single semiconductors can display some drawbacks because of the high recombination rate of photo-induced hole-electron pairs.So,the construction of heterostructure photocatalyst by coupling different semiconductors can be an effective approach to overcome the problems.Based on that,?-Fe2O3/Ag6Si2O7 heterostructures with multiple synergetic functions were prepared for the photodegradation of organic pollutants in which Ag6Si2O7 NPs were anchored on the surface of 3D flowerlike ?-Fe2O3 via in-situ process.An enhancement in the photocatalytic activity of ?-Fe2O3/Ag6Si2O7 heterostructures under the visible light was observed when the photodegradation of the as-prepared composites was tested which can be ascribed to both the wide visible light absorption and the effective charge separation originated from the internal electric field generated by polar crystal structure of the photocatalyst.The properties of this silicate based composites makes them ideal candidates for solving the wastewater problems.