Synthesis And Properties Of MgO And MgFe₂O₄ Adsorbent

In recent years,heavy metals and dyes wastewater pollution is one of the most serious environmental pollution problems in our country.It restricts our economic development and progressing.Therefore,it is important that an economic,efficiency and environmental friendly treatment is demanded to deal with heavy metal ions and dyes wastewater.The fleeciness structure material,with high specific surface areas and special functional groups,is a useful adsorbent to remove heavy metal ions and organic dyes in wastewater through physical or chemical method.In this work,mesoporous MgO nanosheets were fabricated by a precipitation-distillation method.And MgO/MgFe₂O₄composite materials were prepared with sol-gel method using the obtained MgO as raw material.Both the mesoporous MgO nanosheets and MgO/MgFe₂O₄ composite materials were applied in the treatment of wastewater containing organic dyes and heavy metal ions.The results showed that all the samples had obvious adsorption of organic dyes（Congo red,methyl orange and fuchsine）and heavy metal ions（Ni（II））.Distillation is an effective method to improve specific surface area and the pore of product.Mesoporous MgO nanosheets were synthesized with precipitation-distillation method,using Mg（NO₃）₂ as the source of magnesium;（NH₄）₂CO₃ as the precipitants and HO（CH₂CH₂O）_nH as dispersants.The effects of material ratio and the calcining temperature on morphologies and adsorption properties were studied.We also explored the mechanism of mesoporous MgO nanosheets in a distillated process.The adsorption property of heavy metals（Ni（II））and organic dyes（methyl orange,Congo red and fuchsine）were tested and the adsorption mechanism of Ni（II）was studied.The MgO obtained by the above method were all mesoporous nanosheet structure.Furthermore,the MgO obtained by 1:4proportions and annealed at 600°C exhibited the maximum capability for Ni（II）.In order to syntheses magnetic adsorbent with large specific surface areas,we synthesized the magnetic MgO/MgFe₂O₄ composite adsorption materials by the in-situ sol-gel method,using the above obtained MgO as raw material and the citric acid as complexing agent.The relation between the synthesis conditions and the structure,morphology and adsorption properties for Ni（II）were studied.It is found that the adsorption properties of MgO/MgFe₂O₄ obtained by the ratio of 4:1and annealed at 800℃is the optimum.In order to compared the effect of the compound property obtained by different methods,we prepared MgO/MgFe₂O₄ by immersion precipitation and hydrothermal after sol-gel methods at the same condition.By comparing the analysis the sample of MgO/MgFe₂O₄ prepared sol-gel method had the suitable structure and morphology to be the adsorbent.Also the MgO/MgFe₂O₄ synthesized by sol-gel showed the optimum adsorption properties for Ni（II）.