All kinds of spherical ultrafine nickel powders, varied in mean particle size (0.1-5μm),were prepared by chemical reduction in aqueous solution. The pH effect on the production of nickel powder and the main factors o...All kinds of spherical ultrafine nickel powders, varied in mean particle size (0.1-5μm),were prepared by chemical reduction in aqueous solution. The pH effect on the production of nickel powder and the main factors of their morphological control were studied. The nickel powder with purity 98.5% was obtained in the Na2CO3-NaHCO3 buffer system at pH 9.2-11. The surface-rubbed stirring oar helped to the preparation of nickel particles. The mean particle size was decreased to subndcron range by using AgNo3 as nucleating agent. PVP was an efficient agent to regulate particle shape andreduce aggregation.展开更多
The reduction of Cr（Ⅵ） in aqueous solution by using bauxite ore was investigated.Experimental results for Cr（Ⅵ）reduction in aqueous solution depending on some factors such as time,sulfuric acid amount,bauxite do...The reduction of Cr（Ⅵ） in aqueous solution by using bauxite ore was investigated.Experimental results for Cr（Ⅵ）reduction in aqueous solution depending on some factors such as time,sulfuric acid amount,bauxite dosage,initial Cr（Ⅵ）concentration,formic acid concentration,daylight and temperature were presented.The obtained results show that sulfuric acid amount,bauxite dosage and initial Cr（Ⅵ） concentration of solution are most effective parameters on the reduction process.Also,it has been found that the 60 g/L of bauxite dosage is sufficient to reduce up to 100% of Cr（Ⅵ） from acidic solution under the condition of low initial Cr（Ⅵ） mass concentrations such as 10 mg/L.The reduction reaction is completed within 30 min at 25 ℃ under the experimental conditions：bauxite dosage of 60 g/L,amount of sulfuric acid 40-60 stoichiometric and initial mass concentration of Cr（Ⅵ）,10 mg/L.It was determined that reduction percentage is decreasing with increasing initial Cr（Ⅵ） concentration.The chemical oxygen demand of bauxite ore was found to be 26 mg COD/g.展开更多
文摘All kinds of spherical ultrafine nickel powders, varied in mean particle size (0.1-5μm),were prepared by chemical reduction in aqueous solution. The pH effect on the production of nickel powder and the main factors of their morphological control were studied. The nickel powder with purity 98.5% was obtained in the Na2CO3-NaHCO3 buffer system at pH 9.2-11. The surface-rubbed stirring oar helped to the preparation of nickel particles. The mean particle size was decreased to subndcron range by using AgNo3 as nucleating agent. PVP was an efficient agent to regulate particle shape andreduce aggregation.
文摘The reduction of Cr（Ⅵ） in aqueous solution by using bauxite ore was investigated.Experimental results for Cr（Ⅵ）reduction in aqueous solution depending on some factors such as time,sulfuric acid amount,bauxite dosage,initial Cr（Ⅵ）concentration,formic acid concentration,daylight and temperature were presented.The obtained results show that sulfuric acid amount,bauxite dosage and initial Cr（Ⅵ） concentration of solution are most effective parameters on the reduction process.Also,it has been found that the 60 g/L of bauxite dosage is sufficient to reduce up to 100% of Cr（Ⅵ） from acidic solution under the condition of low initial Cr（Ⅵ） mass concentrations such as 10 mg/L.The reduction reaction is completed within 30 min at 25 ℃ under the experimental conditions：bauxite dosage of 60 g/L,amount of sulfuric acid 40-60 stoichiometric and initial mass concentration of Cr（Ⅵ）,10 mg/L.It was determined that reduction percentage is decreasing with increasing initial Cr（Ⅵ） concentration.The chemical oxygen demand of bauxite ore was found to be 26 mg COD/g.
