| In the process of copper electro-refining,sulfate electrolytes contain a lot of iron ion as impurity which seriously affects solvent extraction,current efficiency and final product quality.Therefore,it is necessary to remove the iron ions to improve current efficiency and products quality.Removal of iron ions mainly includes jarosite method,goethite method,hematite method.phosphate method,neutralization hydrolysis method and adsorption method.The neutralization hydrolysis method was widely used in industry due to mild conditons and simple operation process.However,the addition of a large amount of alkali leads to the formation of unnecessary salts,which makes the cost higher,the process complicated,and introduction of new impurites The adsorption method for purification of leachate is a method of low cost,simple process,high efficiency and environmental protection.Magnetic adsorbent,which has the advantages of continuous automation,high removal efficiency and reproducibility,has been widely used in the purification of metal ions.The traditional magnetic adsorbent can not be directly used for purification of acidic copper electro-refining due to its limitation in acid resistance.Therefore,it is particularly important to find a novel magnetic adsorbent that has strong acid resistance,high selective,high adsoption performance,and easy regeneration.Based on the removal of iron in copper electro-refining,we prepared a novel acid-resistant magnetic adsorbent for grafting hydroxypyridone groups onto acid-resistant coatings that can selectively remove iron ions in acid solution and high concentration copper solution.The details are shown as follows:1)Synthesis and characterization of the new adsorbentBased on previous results of our research group,Fe3O4 nanoparticles prepared by co-precipition method were coated by an acid-resistant layer,i.e.hydrophobic layers with a sol-gel method,and then grafted with the 3-aminopropyl-triethoxysilane(APTES)on the silica-coated acid-resistant magnetic particles,and finally modified with the functional groups using 1-hydroxy-2-(1H)-pyridinone-6-carboxylic acid.The structure of magnetic adsorbent was characterized by elemental analysis(EA),infrared spectroscopy(FTIR),specific surface area and pore structure determination(PSD),transmission electron microscopy(TEM),magnetic property analysis(VSM)and X-ray photoelectron spectroscopy(XPS).The acid resistance of the new adsorbent was tested.The new adsorbsent could adsorb Fe3+ from a high concentration of Cu2+solution under acidic conditions.2)Adsorption of the magnetic adsorbentThe adsorption behavior was tested in a simulated solution of a one-component solution containing iron as well as a two-component solution of high concentration of copper with low concentration of iron for characterization of physicochemical process of the above adsorbent.The effect of different conditions such as pH value,initial concentration of metal ions and temperature or solution were studied by a static adsorption experiments.The adsorption capacity on the residence time was studied by the single-component dynamic adsorption experiment.And,the interaction behavior between two metal ions was studied by the static adsorption experiments with different copper-iron concentration rations and the dynamic adsorption with high concentration of copper-iron ratio.3)The regeneration of the above-mentioned megnetic adsorbent with weaker acid elutionThe regeneration of the new adsorbent that strongly adsorbs iron under acidic condition requires stronger acid of even 6 M HCl which is difficult for the equipment generally.Based on the principles of coordination chemistry,we eluted the above-mentioned adsorbents with a combined elute 1 M HCl with 1 M H3PO4,and the regeneration effect was good. |
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