Insights into coextraction of water and ammonia with nickel(II) through structural investigation

Insight into the Mechanism of Cobalt-Nickel Separation Using DFT Calculations on Ethylenediamine-Modified Silica Gel

The separation of Co(II) and Ni(II) from leaching solution is gaining interest because Co(II) and Ni(II) are increasingly used in emerging strategic areas, such as power batteries. Herein, the surface of silica gel is functionalized with 1,2-ethylenediamine and used for the separation of Co(II) and Ni(II). The Co(II) removal efficiency of the modified silica is 80.2%, with a 4-fold improvement in the separation factor. The geometry, frequency, and electrostatic potential of the ethylenediamine modified silica gel (en/SG) are calculated. The corresponding properties of M²⁺ (M-Co, Ni) adsorbed on en/SG in an aqueous solution are simulated and analyzed. The results show that ethylenediamine tends to form [Men(H₂O)₄]²⁺ after binding to M²⁺, and the binding ability of Co(II) to ethylenediamine is stronger. Besides, the thermodynamic calculations show that en/SG has a more negative Gibbs free energy when absorbing Co(II) in aqueous solution, so en/SG is more inclined to bind with Co(II) preferentially. It is the difference in complexation ability between Ni, Co, and ethylenediamine that enlarges the difference in the original physical adsorption, thus strengthening the separation performance. This work will provide guidance for a rational design of high-performance nickel-cobalt adsorption materials.

Efficient [Formula: see text] adsorption using peach stone-derived granular activated carbon

Agricultural wastes have attracted attention as alternative precursors for the production of granular activated carbon. Using batch sorption studies, we demonstrated that granular activated carbon prepared through chemical activation using zinc chloride followed by physical activation in nitrogen environment at high temperatures can effectively adsorb aurocyanide from solution. Furthermore, gold recovery process using the granular activated carbon was amenable to optimization of adsorption parameters such as carbon dosage, initial aurocyanide concentration and contact time. These results may open new fronts on the application of low-cost granular activated carbon, particularly in the carbon-in-pulp metallurgical process.