Nanomaterials With Confined-Space Structure:Design,Synthesis And Applications In The Management Of Contaminated Water

The rapid development of global economy has inevitably caused a series of serious problems,such as ecosystem degradation and environmental pollution.Lately,scholars have made extensive efforts to restore the contaminated water resource,striving to achieve the harmonious development of human and nature.The development of nanomaterials with confined-space structure opens a new opportunity for the environmental water purification fields.The exploring of confined-space behavior of substances will helpful for the understanding of molecular characteristics,creating harmonious and healthy green chemistry.Meanwhile,the construction of nanoscale confined-space framework provides a platform for the studying of confined behavior characteristics.As a consequence,from the point of view for designing and developing nanomaterials with confined-space architecture,this work developed a series of advanced functional nanomaterials and explored the chemical reaction characteristics of nanomaterials in confined space.Various contaminants were efficiently enriched and degraded by the synthesized nanomaterials,which showed huge application prospects in the water purification field.In addition,this work also developed varieties of advanced synthetic schemes,providing a new perspective for the design and synthesis of nanomaterials.The main contents were as follows:(1)Through in situ conversion of the zeolite precursor RUB-15,two-dimensional layered magnesium silicate nanosheet with a regular morphology and confined-space interlayer distance of 1.27 nm was synthesized by hydrothermal method.Two-dimensional layered magnesium silicate nanosheet was composed of tiny lamella units,and containing abundant micropores and mesoporous.The unique two-dimensional framework and large interlayer spacing promoted the full exposure of active sites and ensured the fluency during mass transfer and diffusion process.At 298.15 K,the saturation adsorption capacity of U(?)on magnesium silicate was as high as 473.83 mg/g.In addition,the adsorbent possessed of wide pH suitability and stability under high ionic strength with good recycling.In combination with experiments and a series of characterization,it was confirmed that the adsorption mechanism mainly involved the ion exchange between Mg2+and U(?),as well as the surface complexation.Therefore,magnesium silicate possessed of a highly promising future for use in the remediation of radioactive U(?)contaminated aquatic environments.(2)Developing a confined interlayer growth strategy,a series of novel ultrathin two-dimensional metal oxide nanosheets with-high crystallinity have been successfully created,including 2D TiO2,2D Co3O4,2D Cr2O3,2D Mn2O3 and 2D SnO2.The unique chemical states on the surface of two-dimensional ultrathin metal oxide nanosheets endowed them with some remarkable properties,which was expected to have broad application in various fields.At the same time,this work provided a simple intercalation route for the shaping of two-dimensional frameworks.The template could be any layered materials.and the intercalation objects could also be choosed freely.(3)Inheriting the confined interlayer growth strategy under dry-chemical condition.we further explored the growth process of iron-based catalyst in the interlayer of RUB-15.Meanwhile,the problem of iron-based catalyst was prone to hydrolysis during wet synthetic process was overcame.The surface of two-dimensional ultrathin iron oxide nanosheets were rich of oxygen vacancies,which greatly improved the reactivity in peroxymonosulfate activation for the degradation of organic pollutants.Experiments,characterization and theoretical calculations confirmed that the transformation pathway involved a nonradical pathway(mediated electron transfer)accompanying with radical generation(·OH and SO4·-)during the degradation of bisphenol A.The unique electronic configuration and framework enhanced its catalytic activity.This work further verified that the confined interlayer growth strategy for shaping two-dimensional framework was universal and could be extended to the synthesis of ideal target two-dimensional architecture.(4)Through the sugar-blowing route and post-oxidation modification,a free-standing three-dimensional graphene oxide foam with confined-space structure was achieved.The architecture was consisting of less layered graphitic membranes,which were tightly conglutinated and spatially supported by the graphitic constructions.The spatial connectivity within three-dimensional foam structure provided abundant active reaction sites on interface.which greatly reduced the mass transfer resistance during adsorption process and opened up a shortcut for the removal of various phenolic pollutants.Selecting several common phenolic pollutants to evaluate the adsorption capacity of three-dimensional graphene oxide.With ultrafast removal rate,stability under high ionic strength and wide pH suitability,we found that the adsorbent was especially suitable for the remediation of complex water bodies where multiple phenolic pollutants coexisted.(5)Through hard template method.N.P.S co-doped graphene-like carbon nanospheres with three-dimensional inverse opal structure was synthesized.Compared with single doping,the heteroatoms co-doping could introduce larger asymmetric spin and charge density in carbon matrix.The synthetic framework contained interconnected spherical confined-space with a diameter of about 400 nm.This unique structure not only provided a short diffusion distance for the mass transfer during adsorption process,but also increased the relative specific surface area and enriched the active sites on surface.The synthesized adsorbent was suitable for wide pH environments and the equilibrium time was very short,the saturated adsorption capacity of bisphenol A reached up to 255.39 mg/g at 25?.Combining the experiments,characterization and theoretical calculations,verifying that the heteroatoms co-doping in graphene architecture had a synergistic effect during the adsorption process,which promoted the adsorption process together with other forces.In summary,this work was dedicated to the development of advanced nanomaterials with confined-space architecture for environmental water purification.Meanwhile,the physical and chemical properties of as-prepared nanomaterials were optimized and explored for the enhance removing of various inorganic and organic pollutants.Combining experiments,various characterization methods and theoretical calculations to verify the mechanism of reaction process,this work open a new vision for the environmental water purification field.