Search

An efficient and profitable separation process was proposed to prepare 5N (the purity of the metal solution reaches 99.999%) high-purity nickel from 3N nickel-solutions using Purolite S984. The adsorption performance of this superior resin, especially its selectivity for metal ions, was explored quantitatively. The maximum adsorption capacity for copper was 2.286mmol/g calculated by the Langmuir model, which was twice as large as that for nickel. In the binary systems, the adsorption capacity for nickel was decreased by 45%, indicating direct competition for the active sites. The infinite separation factor for copper versus nickel exceeded 300, revealing the feasibility of preparing 5N-level high-purity nickel solutions, which was further verified using the 800BV (bed volume) effluent in the column dynamic process. According to the cost-benefit analysis, purification contributed to a profit of approximately 60,000USD per cycle, and the investment return period was less than 1/3years. Density functional theory analysis confirmed that four nitrogen atoms would be involved in the coordination complex and thus a structure involving two five-membered rings could be achieved. The X-ray photoelectron spectra confirmed the involvement of nitrogen atoms, implying a coordination ratio of approximately 1:1., (Copyright © 2016. Published by Elsevier B.V.)

Magnetic strongly basic anion exchange resin (MAEX) and weakly acidic cation exchange resin (MCEX) and their combined processes were employed to simultaneously remove such heavy metals (HMs) as Cu(II), Ni(II) and tannic acid (TA). Both MAEX and MCEX resins exhibited co-removal capability for Cu(II) and TA in binary solutions. Complexing-bridging was ascribed as the primary mechanism for the co-removal of TA and Cu(II) based on Density-Functional-Theory (DFT) calculation, fluorescence spectra, Fourier Transform Infrared Spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) characterization. Moreover, an interesting discovery was found that hydrogen bond interaction between both nitrogen atom of the secondary amine ( NH ) and oxygen atom of carbonyl (C O) with un-ionized TA, and quaternary ammonium ( N + (CH 3 ) 3 ) ion exchange with ionized TA were ascribed to the mechanism of TA adsorption onto MAEX. The novel integrative technique based on MAEX and MCEX mixed completely in the same reactor could simultaneously remove Cu(II), Ni(II) and TA with high efficiencies of 92.1%, 94.8% and 88.4%, respectively. Three adsorbates could be successfully recovered with 0.1 M NaOH followed by 0.01 M HCl solution. Given the stable application for five cycles, combined magnetic resin treatment showed great potential in simultaneous removal of Cu(II), Ni(II) and TA. [ABSTRACT FROM AUTHOR]