| High purity nickel is an important raw material and strategic resource for the development of national economy and defence.Up to the present,the high purity nickel resource relies mainly on imports in our country.Therefore,it is extremely necessary to explore new technologies for the preparation of high purity nickel.The contents of impuries involving copper need to be far lower.Thus, it is a key issue to remove trace amounts of copper from high-concentrated nicke with much success. However, there are many disadvantages in those conventional methods because of their poor adsorption selectivity and high operation cost. With much interest, cheating resins method become exceptive based on their good selectivity.In our work, three amino chelating resins, named as IRC747、IRC748and S984, with a good selectivity for copper, were chosen to investigate the adsorption behaviors and separation natures for nickel and copper from single and double component media. Therefore, this work could provide theoretical bases for the practical applications in the removal for trace copper from high-concentrated nickel solutions.For single component, the equilibrium data could be well fitted by Langmuir model. The adsorption capacities for Cu(Ⅱ) were in the following order as S984>IRC748>IRC747, while the opposite order could be found for Ni(Ⅱ). So, the selectivity coefficient for Cu(Ⅱ) is consistent with the former. Additionally, typical thermodynamic data revealed the endothermic and spontaneous nature of each adsorption process. The kinetic data could be better fitted with Lagergren-second-order equation than Lagergren-first-order equation, which told the chemical adsorption might be the rate-controlling step. The initial adsorption rate for Ni(Ⅱ) onto IRC747and IRC748was faster than Cu(Ⅱ), because the ionic radius of Ni(Ⅱ) is smaller than Cu(Ⅱ). Contrarily, that for Cu(Ⅱ) onto S984was faster than Ni(Ⅱ), as is associated with the larger affinity involving N atoms on solid matrix and the former with relatively more softness. Through the structural analysis as to the beads before and after interaction with metals, the resin-metal complex was speculated as N atom and phosphate hydroxy to form tridentate ligand for IRC747, while N and O atom on carboxy to form a steady five-membered ring for IRC748, versue N atoms alongside to form complex for S984.In double system, the adsorption capacities for both Cu(Ⅱ) and Ni(Ⅱ) were smaller than the single cases, which told the direct competition on active sits of adsorbents.The equilibium data could be fitted by Extended Langmuir model with much success. And the S984owned the highest affinity for Cu(Ⅱ) and lowest one for Ni(Ⅱ), so this resin was most suitable for removing trace copper and obtaining high purity nickel. For example, as for the column packed with S984, the purities of Ni(Ⅱ) in the former effluents of2720BV,3140BV and4580BV, could be up to100%,99.999%and99.99%, respectively. Accordingly, the purity of nickel had been increased at several magnitudes.To product high purity nickel with S984, the investment was only12.21yuan per t. Consequently, the process was modern, reliable, efficient, energe-saving, and none sub-pollution, which could provide an important scientific and technological support for the preparation of high purity nickel in our country. |
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