Papers by Keyword: Ni²⁺

Abstract: Surface modification of activated carbon (AC) could be done through different methods in order to modify their specific physical and chemical properties to facilitate metals removal from wastewater. Three methods were used to modify the rice husk AC (RHAC) including the use of (1) HNO₃, (2) dithizone and (3) the combination of HNO₃ with dithizone. These modification agents were increased its affinity towards the desired pollutant. The modification methods demonstrated the effective process for the metal ions adsorption capability and the removal of them from water. For Ni²⁺ and Cd²⁺ adsorption, RHAC was modified by HNO₃ giving the best adsorption capacity in comparison with using dithizone or the combination of HNO₃ with dithizone. That adsorption was reached 17.23 mg/g for Ni²⁺ and 29.61 mg/g for Cd²⁺. Additionally, the surface area, which was characterized by BET (Brunauer–Emmett–Teller) of RHAC, was 710.8 m²/g and DA micropore volume was 0.447 (cm³/g). Especially, the only modified RHACs had the peak of N-H functional group by using Fourier transform infrared spectrum (FTIR). Besides, the only RHAC modification by HNO₃ had peak of C=O. That significantly contributed to increase the metal ions adsorption capacity of RHAC.

Abstract: In this work, effects of Ni²⁺ ions on soda lime silicate glasses have been investigated. Glasses were prepared in formula (65-x)SiO₂ : 25Na₂O : 10CaO: xNiO (where x is 0.00, 0.02, 0.04, 0.06, 0.08 and 0.10 mol%). The densities of glasses not depend on Ni²⁺ concentration. The refractive indices decreased with increasing of NiO concentration. The optical absorption spectra were measured by uv-visible spectrophotometer and show peaks correspond with Ni²⁺ in glass matrices. Both of octahedral transitions and tetrahedral transition from Ni²⁺ ion were found around 450 and 625 nm respectively. The color of glasses were also measured in CIE L* a* b* system.

Abstract: The process of solvent extraction was applied to separate and recover Cu²⁺ and Ni²⁺ from plating wastewater from copper and nickel alloy plating process, because there are abundant Cu²⁺ and Ni²⁺. And the influence parameters have been investigated. Lix984 was chosen as the extractant due to it has good performance to extract metals from the water. The results showed the separation of Cu²⁺ and Ni²⁺ from sulphate medium can be realized by adjusting pH value with the help of Lix984, And more, the optimal pH values for extracting Cu²⁺and Ni²⁺ are 4 and 10, respectively. The maximal extraction efficiency for Cu²⁺ and Ni²⁺ can reach above to 90.6% and 93.5% by single-stage extraction. The recovered Cu²⁺ and Ni²⁺ were stripped in 170g/L and 200g/L H₂SO₄ medium, respectively. And the stripping of Cu²⁺ and Ni²⁺ are >99.2% and >99.4%, respectively. It can be successfully applied to the field of plating wastewater, decreasing the environment pollution from Cu²⁺ and Ni²⁺ and providing a kind of new copper and nickel resource.

Abstract: Sewage sludge incineration residue was obtained from a sewage treatment plant in Guangzhou and used as a low-cost sorbent for removing Ni²⁺ from wastewaters. The adsorption effectiveness and their factors of Ni²⁺ in aqueous solutions were simulated detailed using the adsorbents of the sludge incineration residue. The simulation contents and the factors included the adsorption time, the pH of solution and the dosage of adsorbents and so on. The results showed that at room temperature, the adsorption equilibrium of Ni²⁺ can be achieved in 6h and the best pH value of the solution was about 7.0. The removal rates of Ni²⁺ were increased with the adsorbent concentration increasing and the optimal concentration of adsorbent was 10g/L with the initial concentration of Ni²⁺ less than 30mg/L.At the best adsorption conditions, the removal rate of Ni²⁺ reached more than 70%.

Abstract: The spin Hamiltonian parameters (zero-field splitting D and the g factors) for NiX2 and CdX2:Ni2+ (X=Cl, Br) are quantitatively investigated from the perturbation formulas of these parameters for a 3d8 ion in trigonally distorted octahedra based on the cluster approach. In the calculations, the trigonal field parameters  and ′ are determined from the superposition model and the local structures of Ni2+ in the halides. The theoretical g factors show reasonable agreement with the observed values, and the experimental D for CdX2:Ni2+ are also interpreted by considering suitable lattice distortions (angular decreases) in the impurity-ligand bond angles related to the C3 axis due to the size mismatching substitution. The contributions from the ligand orbital and spin-orbit coupling interactions are important and should be taken into account.

Abstract: The defect structures and the electron paramagnetic resonance (EPR) parameters zero-field splitting and the g factors for the tetragonal and cubic Ni2+ centers in AgX (X=Cl, Br) are theoretically studied from the perturbation formulas of these parameters for a 3d8 ion in tetragonal and cubic octahedra. In these formulas, the ligand s-orbital contributions, which were usually neglected in the previous studies, are taken into account based on the cluster approach. The ligand X− intervening in the Ni2+ and the next nearest neighbour Ag+ vacancy VAg is suggested to suffer a small inward displacement (≈ 0.11 or 0.15Å for AgCl or AgBr, respectively) towards Ni2+ along the [100] (or C4) axis. The calculated EPR parameters based on the above defect structures show reasonable agreement with the experimental data.