Architecture Of Micro-nano Composite Structure And Its Application In Water Treatment

Due to its rich morphology and complex hierarchical structure,micro-nano composite structures have gained more and more architectural research,especially in sewage treatment applications.Adsorption and photocatalysis are the most important technologies for water pollution treatment.The micronanocomposite catalysts with synergistic effect of adsorption and photocatalysis can solve the problem of low-concentration water pollution in real life.BiPO₄ is a broadband semiconductor and could be a very good photocatalyst due to that photogenerated electrons and holes have a very strong redox ability.But their response to visible light is limited due to the wide bandgap.The high specific surface area of the hydrotalcite-like structures?LDHs?due to their lamellar cutting structure and the exchangeability of interlayer anions,and LDHs are widely used as adsorbents in the field of adsorption.In addition,the calcined mixed-metal oxides?CLDH?from calcination of LDHs can be used as semiconductors to photocatalyze organic contaminants in wastewater.More importantly,they can form photo-catalytic properties of heterojunction-reinforced composites and even combining with BiPO₄ to response to visible light.However,LDHs tend to agglomerate in a dry environment to reduce adsorption performance and are not easily recovered.Therefore,the introduction of biotemplates can not only increase the surface area of the catalyst material,reduce the difficulty of its recycling,but also can form C-doping levels in the catalyst material,reduce the band gap of BiPO₄.This could be more conducive to the formation of heterojunctions to promote the catalytic performance through the synergistic degradation of low-concentration water pollution.For the antibiotic pollution in the ecological environment,the problem of recycling is needed.Molecular imprinting is the most effective means for identifying and enriching it.The introduction of magnetic micromotors makes it possible to rapidly concentrate and recover antibiotics.Thermo-sensitive hydrogels use temperature to achieve time-dependent enrichment and release of antibiotics.The in situ replication morphology introduced by the biological template increases the specific surface area of the adsorbent to increase the recognition site,while also reducing the weight of the adsorbate itself and reducing the resistance of the motor movement.1.The C-doped BiPO₄/ZnCoAl-CLDH micro/nanocomposite catalyst was successfully prepared by using pine pollen as a biotemplate.It has the ability of adsorption and photocatalysis to synergistically degrade organic po llutants.The morphology and physical properties of C-doped BiPO₄/ZnCoAl-CLDH were characterized and analyzed by SEM,TEM,XRD and FT-IR.The results show that the C-doped BiPO₄/ZnCoAl-CLDH maintains the overall spheroid morphology of the original pine pollen and has a complex hierarchical porous structure with a higher specific surface area than the BiPO₄/ZnCoAl-CLDH catalyst without template introduction.In addition,the adsorption performance of methylene blue dye was studied.Adsorption results showed that the prepared C-doped BiPO₄/ZnCoAl-CLDH micro/nano composite catalysts exhibited excellent adsorption performance,and the adsorption process conformed to the pseudo-second-order kinetics model.At the same time,the photocatalytic performance of methylene blue dye was studied.The photocatalytic results show that under visible light irradiation,the methylene blue exhibits good photocatalytic performance,and the degradation process is in accordance with the pseudo first order photocatalytic kinetic equation.The main active species involved in photocatalytic degradation are electron,hole and hydroxyl free.More over,the prepared C-doped BiPO₄/ZnCoAl-CLDH micro-nano composite catalyst has good reusability.2.Molecularly imprinted temperature-controlled magnetic micro-nano motors were successfully synthesized using lotus pollen as a template.The micromorphology and physical properties of temperature-controlled magnetic micromotors for molecular imprinting were characterized and analyzed.The results showed that the molecularly imprinted temperature-controlled magnetic micro-motors basically maintained the spherical structure of the original pine pollen,and the hydrogel was semi-coated on the surface of the magnetic micromotor.Also,a low critical phase transition temperature of a temperature-controlled magnetic micro-nano motor molecularly imprinted was obtained.Then,the adsorption and release properties of the antibiotic erythromycin molecule against the imprint were studied.The results showed that the molecularly imprinted temperature-controlled magnetic micro-nano motors have the excellent performance of rapid timing-specific recognition and release of erythromycin.