Construction Of Novel Spinel Functional Materials And The Application Research For The Detection/Catalysis Degradation On Environmental Pollutants

Construction of novel spinel functional materials and the application research for the detection/catalysis degradation on environmental pollutants Organic pollutants emissions and abuse of chemical colorants in food have seriously impacted the global environment and human health, and the pollutions from chemical contaminants in environment have become a major public concern. Settling the environment pollution and monitoring food safety have been attracted a great deal of attentions and become a hot research topic. Based on the above problems, in this article,several novel spinel functional materials were constructed by facile hydrothermal methods,which used in the magnetic solid-phased extraction (MSPE) analysis and photocatalysis degradation for environmental pollutants.Magnetic 3D hollow porous CdFe2O4 microspheres (HS-CdFe2O4) were synthesized,and the morphology, structure, specific surface area and magnetic properties of HS-CdFe2O4 were characterized by using SEM?XRD?BET and VSM. HS-CdFe2O4 was employed as the adsorbent for separation and enrichment of three azo colorants (AR, SY and CR), the optimum extraction and quantitative elution conditions were investigated.The adsorption mechanism of HS-CdFe2O4 towards three colorants were discussed in detail. Magnetic HS-CdFe2O4 can be rapidly separated and recycled by a magnet, HS-CdFe2O4 still maintain high extraction efficiency after six regeneration-extraction cycles.A new method for simultaneous determination of three colorants from food samples based on MSPE coupled with HPLC-UV was developed. The analysis method was evaluated and the analytic results demonstrated that in good linearity range of 2-1000 ng mL-1,the detection limits were obtained in the range of 0.54-1.00 ng mL-1, and the recoveries of analytes obtained were in the range of 87.0-100.7%.A magnetically separable CdFe2O4/RGO photocatalyst was prepared which the morphology, structure, specific surface area and magnetic property were characterized by SEM, XRD, Raman, XPS,BET and VSM, the photocatalytic activity was evaluated by photocatalytic oxidation of methylene blue (MB) under visible-light (?>420 nm)irradiation. The degradation efficiency of CdFe2O4/RGO was obviously better than CdFe2O4 nanoparticles, which was attribute to the introduce graphene into CdFe2O4 nanoparticles. The photocatalytic reaction obeyed the pseudo-second-order model and the reaction rate constant k of CdFe2O4/RGO was 5 times higher than that of CdFe2O4.The photocatalytic deactivation was investigated and the affected degree followed order was SO42->HPO42-/H2PO4>NO3->CO32-. The degradation pathway of MB were detected using HPLC and ion chromatography (IC). Several scavengers, the band structure, as well as Mott-Schottky measurement,were used to identify the roles of active species(h+?·OH and ·O2-) in the degradation process. The holes (h+) and hydroxyl radicals (·OH),played the major roles in the photodegradation of MB. The photocatalytic degradation mechanism was accorded with Z-Scheme mechanism. Benefit from its magnetic property,after four cycles, CdFe2O4/RGO still showed good stability and recyclability.An eco-friendly magnetic 3D porous microspheres/cotton cellulose fiber (HPS-NiMn2O4/CCFs) composite was designed by using hydrothermal-calcination method.Simultaneous separation and enrichment of six bisphenol compounds (BPs) (BPA?BPF?BPAP?TDP?BPC and BPS) based on MSPE method using HPS-NiMn204/CCFs composites as adsorbents was established. The extraction and quantitative elution conditions were optimized,and the extraction mechanism of HPS-NiMn2O4/CCFs towards six BPs were investigated in detail. Because the 3D hollow porous microsphere morphology and the introduction of CCFs greatly improved the specific surface area, the enrichment factor of 400 was obtained. HPS-NiMn2O4/CCFs have stable magnetic separation and recyclability. A new method for determination of six BPs in environment samples based on MPSE coupled with HPLC-UV were developed. Under the optimal conditions, the detection limits of method were in the range of 0.56-0.83 ng mL-1 and the linearity range was 2-500 ng mL-1. The recoveries of analytes in real samples were in the range of 84.3-103.5%.Three different morphology materials of OD NiMn2O4 nanoparticles (NPs-NiMn2O4)?3D hollow porous NiMn2O4 microspheres (HPS-NiMn2O4) and 3D HPS-NiMn2O4/CCFs were designed and synthesized. SEM, BET, XRD and VSM was used to characterized the morphology, specific surface area, structure and magnetic property of the materials.Compared with NPs-NiMn2O4 and HPS-NiMn2O4, HPS-NiMn204/CCFs exhibited superior catalytic properties on reduction of 4-nitrophenol and photodegradation of dye pollutants. Under the addition of excess NaBH4, HPS-NiMn2O4/CCFs can rapidly catalytic reduce 4-nitrophenol in 10 min; HPS-NiMn2O4/CCFs also can photocatalytic degradation of MB dye under visible light irradiation in 120 min. On the basis of UV-Vis,the trap experiments and Mott-Schottky analysis, the mechanisms for the dual-functional catalytic reactions over HPS-NiMn2O4/CCFs were inferred. Because of its magnetic separability,HPS-NiMn2O4/CCF can be potentially applied in catalysis, water purification and green chemistry.Novel three-dimensional nest-like LiFe5O8, nest-like LiFe5O8/RGO and rod-like LiFe5O8, rod-like LiFe5O8/RGO were constructed successfully, which used as photocatalysts for degradation of MB under visible light irradiation. The reaction conditions were optimized and evaluated comprehensively the effects of hydrothermal reaction time on the morphology of nest-like LiFe5O8/RGO. Compared with rod-like LiFe5O8, rod-like LiFe5O8/RGO and nest-like LiFe5O8, the nest-like LiFe5O8/RGO displayed superior photocatalytic activity for degradation of MB under visible light irradiation, which degradation efficiency was 99.6%. The photocatalytic reaction followed the pseudo-second-order model and the reaction rate constant k of nest-like LiFe5O8/RGO was 2.21, 4.52 and 6.04 times higher than that of rod-like LiFe5O8/RGO,nest-like LiFe5O8 and rod-like LiFe5O8. Improved photocatalytic activity of nest-like LiFe5O8/RGO attributed to the higher visible-light harvesting capacity, high specific surface areas, hierarchical porous structure and effective photo-generated electrons migration. Based on the estimated band structure and the trapping experiments,superoxide radical (·O2-) played a major role during photocatalytic degradation,a possible mechanism for the photocatalytic degradation was discussed. Benefiting from its magnetic properties, the nest-like LiFe5O8/RGO can be easily separated and recycled.