Preparation of layered nickel aluminium double hydroxide from waste solution of nickel G. Barik, E. Padhan ⇑ , B. Dash, K. Sarangi, T. Subbaiah CSIR – Institute of Minerals and Materials Technology, Bhubaneswar 751013, India article info Article history: Received 30 April 2014 Accepted 22 July 2014 Keywords: Nickel Zinc Solvent extraction Precipitation TOPS-99 Ni–Al layered double hydroxide abstract The separation of nickel has been carried out from a waste solution containing 3.18 g/L Ni with other impurities such as Fe, Zn, Cu and As. Iron was removed by precipitation and Cu and Zn were removed by solvent extraction using LIX 622N and NaTOPS-99, respectively. After removal of all these impurities nickel was extracted by 1.5 M NaTOPS-99 in two counter-current stages at A:O ratio of 3:1 and the loaded organic was stripped with 30 g/L H 2 SO 4 at phase ratio of unity. The strip solution of nickel was treated with Al 2 (NO) 3  9H 2 O for co-precipitation by increasing the pH of solution with 1 M NaOH up to 10. The Ni–Al layered double hydroxide was confirmed through XRD characterization. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction The demand of nickel has been increasing day by day because of its use in various products such as electronic devices, magnets, rechargeable batteries, stainless steel, super alloy coins and cata- lysts. So any waste containing nickel should be treated for recovery of nickel. In the copper plant, during electropurification of copper, the bleed stream obtained from liberated cell contains significant amount of Cu, Ni, H 2 SO 4 and trace amount of As, Fe etc. (Agrawal et al., 2008). From such a bleed stream Cu and Ni were recovered by solvent extraction. Solvent extraction is the most suitable technique to obtain pure Ni from a mixed solution. Many authors have worked on extraction of Ni using various extractants such as D2EHPA (Reddy and Bhaskara Sarma, 2001; Cheng, 2000), PC88A (Lin et al., 2006), Cya- nex 272 (Sarangi et al., 1999) and LIX84I (Tanaka and Alam, 2010; Parija and Bhaskara Sarma, 2000). The extraction of nickel was enhanced by the synergistic effect of LIX 860 and D2EHPA (Zhang et al., 2001). The mixed extractant extracted nickel and cobalt very effectively from an acidic aqueous solution with pH < 3.0. Separation of nickel and cobalt was carried out from 1 M chloride solution using Na-Cyanex 272 and the mixture of Na-Cyanex 272 with Na-PC88A (Sarangi et al., 1999). The separa- tion factors in the case of Na-PC88A as extractant and Na-Cyanex 272 as synergist was 5.6 times higher than that using Na-Cyanex 272 alone. Nickel extraction was studied from ammoniacal med- ium by LIX 54 in an aliphatic diluent (Alguacil and Cobo, 1998). The effect of different parameters such as pH, equilibration time, temperature, counter anion sulphate and extractant concentration on extraction was studied. The sulphuric acid was used as the stripping agent. The extraction of nickel decreased with increase of temperature. Also due to the presence of sulphate as ammonium sulphate nickel extraction decreased. The nickel extraction was studied from ammoniacal–ammonium carbonate solution using LIX 87QN (Bhaskara Sarma and Nathsarma, 1996). The extraction of nickel decreased with increasing equilibrium pH from 8.6 to 10.0 and with increasing ammonium carbonate concentration in aqueous phase. The complete nickel extraction was possible from a solution containing 5.21 g/L Ni and 60 g/L ammonium carbonate in two counter current stages at an A:O ratio of 2:3. The loaded organic contained 0.15 g/L ammonia, which was removed by single stage scrubbing with dilute sulphuric acid at an equilibrium pH > 7.0. The layered double hydroxides (LDHs), also known as anionic clays or hydrotalcite (HT)-like constitute a family of layered mate- rials where Mg 2+ /M 3+ substitution takes place. The unique proper- ties of LDHs are that they have anionic exchange capacity as well as the ability to capture organic and inorganic anions. The application of these materials includes a wide range of fields such as catalysts, ion-exchange, adsorption, pharmaceutics, photochemistry and electrochemistry (Li and Duan, 2006). The layered Nickel–Alumin- ium double hydroxide (Ni–Al LDH) is one such layered double hydroxide and much work has been reported on preparation of http://dx.doi.org/10.1016/j.mineng.2014.07.015 0892-6875/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Mobile: +91 7873111893; fax: +91 6742567637. E-mail address: eliza.patra@gmail.com (E. Padhan). Minerals Engineering 69 (2014) 107–112 Contents lists available at ScienceDirect Minerals Engineering journal homepage: www.elsevier.com/locate/mineng