Preparation Of Nano-sized Magnesium Oxide And Evaluation Of Adsorption/Degradation Properties Of Pollutants

Organophosphorus pesticides are common organic pollutants,which are neurotoxic and hazardous to human health and the ecological environment.Heavy metal ions are common pollutants in water or soil and have carcinogenic risks to the human body,and the adsorption and degradation of phosphorous pollutants and heavy metal ions is one of the current hot spots of research in the environmental protection field.With abundant active sites and specific nanostructures,nano-MgO possesses a superior ability to absorb and degrade these toxins.However,the preparation of MgO nanoparticles with relatively small sizes and highly active surface areas is still a great challenge nowadays.Therefore,in this paper,different methods and optimized calcined temperatures were e valuated to prepare small-sized,high specific surface area nano-MgO and its composites.The morphology,structures and dimensions were characterized using X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,fully automated specific surface area and porosity analysis（BET）,and infrared spectrum（FT-IR）,respectively.The adsorption degradation effect of nano-MgO and its complexes on paraoxon-ethyl was investigated by ultraviolet spectroscopy（UV-vis）.The adsorption capacity of nano-MgO on Pb²⁺and Cd²⁺was studied by inductively coupled plasma mass spectrometry（ICP-MS）,dynamic simulation analysis.Firstly,AP-Mg（OH）₂ was obtained by sol-gel combined with the hydrothermal method,and nano-MgO（AP-MgO）with different morphology,size,and specific surface area were obtained by high temperature calcined.The results of SEM and TEM test show that the average grain size of the nano-MgO obtained at 600℃（AP-MgO-600）was the smallest,8.7±3.2 nm,and the specific surface area was up to 231.4 m²/g.The degradation for NBT demonstrated that the surface of AP-MgO-600 contained more superoxide radical（·O₂^-）active sites.The maximum degradation of paraoxon-ethyl at room temperature was 57.78mg/g@90 min,and the degradation kinetics was in accordance with the pseudo-second model（R²>0.99）.The adsorption efficiency of 5 mg of AP-MgO-600 on 20 m L of Pb²⁺solution with 100 mg/L reached 99%within 5 min,and the adsorption amount of Cd²⁺was 1731.7mg/g@2h.In addition,nano-MgO（Mw-MgO）and carbon-based doped MgO（MgO@C）nanocomposites with small size and high specific surface area properties were also successfully prepared by microwave-assisted hydrothermal method,and the electrochemical and photocatalytic degradation properties of MgO@C nanocomposites were investigated,which showed better electrical conductivity relative to pure MgO.Both of them had better degradation ability towards paraoxon-ethyl and NBT.Therefore,the serial nano-MgO and its composites prepared in this paper have broad application prospects in environmental remediation.