| Increasing global contamination of water body and deterioration of water qualityhas become a serious issue facing humanity in the current situation. Apparently, theever-increasing demand for clean water environment has triggered intense research onthe advanced technology for water pollution control. Among versatile physical,chemical, and biological technologies in water pollution control, adsorption isconsidered to be an effective, versatile and economical method for the treatment ofpollutants because of its simplicity, high efficiency and low operational costs. As abasis for this technique, the intrinsic characteristic of the adsorbent materials is a keypoint for successful implementation. Nevertheless, conventional adsorbents suffer fromlimited adsorption capacity, low adsorption rate, poor separation ability and undesirableregeneration. Therefore, it is still desirable to design and fabricate highly efficientadsorbents possessing the characteristics of facile separation and cost-effectiveregeneration to meet the fast-developing water treatment requirements. Porousmicro/nanostructures have extraordinary textural characteristics (such as high surfacearea, high pore volume and tunable pore size), well-defined morphology, structuralflexibility, and chemical and thermal stability. They show many good advantages inadsorptive removal of toxic pollutants in water: possessing abundant active adsorptionsites, providing multiple accessible channels for mass transport, having goodmechanical property to maintain structural stability, and exhibiting unique functionality(e.g. optical, electrical and magnetic properties). In this dissertation, we focus on designand fabrication of novel porous micro/nanostructures with unique properties andsystematically investigate their performance towards adsorptive removal of organicdyes in water.1. Hierarchical porous flower-like NiO micro/nanostructures were synthesized by asacrificial template route. The hierarchical porous NiO as a high efficient adsorbentdisplayed remarkable performance towards fast removal of Congo red from aqueoussolution, showing a maximum adsorption capacity reached up to223.8mg·g-1. Thekinetics and isotherm of adsorption process were found to obey thepseudo-second-order kinetics and Freundlich isotherm model, respectively. The effect of solution pH on the adsorption performance was also studied. FTIR spectrum analysisfurther confirmed the electrostatic interaction between NiO surfaces and Congo red.More importantly, porous flower-like NiO micro/nanostructures can be recycled by afacile “adsorption-natural settlement-thermocatalytic regeneration”, displaying apotential application in water treatment.2. Porous polyhedron-shaped MgO micro/nanostructures were synthesized by thethermal transformation of the sacrificial oxalate template. The as-prepared porouspolyhedron-shaped MgO architectures exhibited several advantageous structuralfeatures: hierarchical mesoporous structure, large surface area and positively chargedsurface in a wide pH range. Therefore, they showed a powerful capability to removeCongo red from water, presenting a maximum adsorption capacity reached up to669.0mg g-1, much higher than most of the previously reported hierarchical adsorbents. Theadsorption mechanism was studied in detail, which revealed that the electrostaticinteraction and surface hydrogen bonding co-governed the whole adsorption process.Considering the superior adsorption performance, low-cost materials and facilepreparation method, porous polyhedron-shaped MgO micro/nanostructures providedan ideal platform for treating high concentration dye-containing water.3. A novel hierarchical porous flower-like BiOI micro/nanostructures werefabricated by a facile and rapid microwave nonaqueous route. They displayedremarkable performance towards removal of Congo red from aqueous solution,showing a maximum adsorption capacity reached up to216.8mg g-1. The kinetics andequilibrium of adsorption process were found to follow the pseudo-second-orderkinetic and Freundlich isotherm models, respectively. The BiOI architectures were notonly easy to separate from the reaction system because of the hierarchical structure andlarge sizes, but also attractive to photocatalytic regeneration due to their intrinsicallyprominent photoresponse in visible light region. By means of providing the facilepreparation, high adsorption efficiency, easy solid-liquid separation, and economicalphotocatalytic regeneration, the synthesized BiOI architectures established anoutstanding example for the design of multifunctionalized adsorbent with highperformance for environmental remediation.4. Porous rod-shaped MgFe2O4superstructures were synthesized by a simple thermaltreatment of the sacrificial rod-like oxalate template. They presented excellentperformance towards removal of Congo red from aqueous solution, showing amaximum adsorption capacity reached up to200.0mg g-1. The rod-shaped MgFe2O4superstructures possessed intrinsic magnetic property, which endowed them with a facile magnetic separation under applied magnetic fields. Moreover, the rod-shapedMgFe2O4superstructures had wide photoabsorption in solar spectrum. They also hadstrong ability to activate H2O2. Therefore, they can be recycled by a facile“adsorption-magnetic separation-photocatalytic regeneration”. This multifunctiona-lized and inexpensive rod-shaped MgFe2O4superstructures displayed a potentialapplication in water treatment.5. Metal nanoparticles functionalized micro/nanostructures were designed andextended to apply in water treatment. Ag nanoparticles supported flower-like Ni(OH)2micro/nanostructures were synthesized by a facile one-pot solvothermal method.Microstructural observation showed that Ni(OH)2as a stable supporter could uniformlydistributing and loading Ag nanoparticles. Ag/Ni(OH)2micro/nanostructures exhibitedgood adsorption performance. With the help of functionalized Ag nanoparticles, theyalso displayed remarkable catalytic reduction activity, which could catalytic reductionof4-nitrophenol to4-aminophenol in the presence of NaBH4in a short time. |
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