Separation of Ni2+ and Co2+ Using Sorbitol–Stearic Acid-Derived Bio-Based Solvent: A Sustainable Solvent Extraction Approach

Year 2025, Volume: 12 Issue: 4, 241 - 248, 01.12.2025

Bekir Özkan

Abstract

The separation of Ni²⁺ and Co²⁺ is challenging due to their similar physicochemical properties. In industrial processes, solvent extraction is widely used for their refinement; however, the excessive use of petroleum-derived solvents poses significant environmental concerns. To address this, a greener approach was explored in this study by utilizing a bio-based solvent synthesized from sorbitol and stearic acid. The resulting solvent, SSA2, was prepared via Fischer esterification and employed as the organic phase in solvent extraction experiments. After 5 hours of reaction, the acid value (AV) of SSA2 decreased roughly 87%, indicated ester bond formation and the reduction of carboxylic acid groups, confirming successful synthesis. FTIR analysis confirmed the presence of ester bonds in SSA2, which are absent in the starting materials, sorbitol and stearic acid. The separation performance of SSA2 for Ni²⁺ and Co²⁺ was assessed by measuring the distribution coefficient (KD) and separation factor (SF) values as functions of contact time and aqueous phase pH. SSA2 demonstrated higher selectivity towards Co²⁺, achieving a maximum SFCo2+/Ni2+ of 6.20 at pH 5. The highest KD values recorded were 75.6 and 12.2 for Co²⁺ and Ni²⁺ respectively.

Keywords

Solvent extraction , Bio-based solvents , Sorbitol-stearic acid ester , Separation , Nickel and Cobalt

Ethical Statement

The authors declare no competing financial interests.

Supporting Institution

TUBİTAK

Project Number

TÜBİTAK 123C318

Thanks

I would like to thank TÜBİTAK for their financial support on this research with Project Number 123C318

References

• 1. Alvial-Hein G, Mahandra H, Ghahreman A. Sepa-ration and recovery of cobalt and nickel from end of life products via solvent extraction technique: A review. J Clean Prod [Internet]. 2021 May;297:126592. Available from: <URL>.
• 2. Kerns J. Replacing metal with plastic. Mach Des [Internet]. 88(9):34–42. Available from: <URL>.
• 3. Cutler CP. Use of metals in our society. In: Metal Allergy [Internet]. Cham: Springer International Publishing; 2018. p. 3–16. Available from: <URL>.
• 4. Garrett RG. Natural sources of metals to the environment. Hum Ecol Risk Assess An Int J [Internet]. 2000 Nov;6(6):945–63. Available from: <URL>.
• 5. Meshram P, Abhilash, Pandey BD. Advanced review on extraction of nickel from primary and secondary sources. Miner Process Extr Metall Rev [Internet]. 2019 May 4;40(3):157–93. Available from: <URL>.
• 6. Taghdirian HR, Moheb A, Mehdipourghazi M. Selective separation of Ni(II)/Co(II) ions from dilute aqueous solutions using continuous electrodeionization in the presence of EDTA. J Memb Sci [Internet]. 2010 Oct;362(1–2):68–75. Available from: <URL>.
• 7. Sun P, Binter EA, Vo T, Benjamin I, Bera MK, Lin B, et al. Relevance of surface adsorption and aqueous complexation for the separation of Co(II), Ni(II), and Fe(III). J Phys Chem B [Internet]. 2023 Apr 20;127(15):3505–15. Available from: <URL>.
• 8. Juang RS, Wang YC. Use of complexing agents for effective ion-exchange separation of Co(II)/Ni(II) from aqueous solutions. Water Res [Internet]. 2003 Feb;37(4):845–52. Available from: <URL>.
• 9. Armstrong RD, Todd M, Atkinson JW, Scott K. Electroseparation of cobalt and nickel from a simulated wastewater. J Appl Electrochem [Internet]. 1997 Aug;27(8):965–9. Available from: <URL>.
• 10. Gega J, Walkowiak W, Gajda B. Separation of Co(II) and Ni(II) ions by supported and hybrid liquid membranes. Sep Purif Technol [Internet]. 2001 Mar 1;22–23(1–2):551–8. Available from: <URL>.
• 11. Parija C, Bhaskara Sarma PV. Separation of nickel and copper from ammoniacal solutions through co-extraction and selective stripping using LIX84 as the extractant. Hydrometallurgy [Internet]. 2000 Jan;54(2–3):195–204. Available from: <URL>.
• 12. Zhang W, Pranolo Y, Urbani M, Cheng CY. Extraction and separation of nickel and cobalt with hydroxamic acids LIX®1104, LIX®1104SM and the mixture of LIX®1104 and Versatic 10. Hydrometallurgy [Internet]. 2012 May;119–120:67–72. Available from: <URL>.
• 13. Nadimi H, Haghshenas Fatmehsari D, Firoozi S. Separation of Ni and Co by D2EHPA in the presence of citrate ion. Metall Mater Trans B [Internet]. 2017 Oct 1;48(5):2751–8. Available from: <URL>.
• 14. Virolainen S, Fallah Fini M, Laitinen A, Sainio T. Solvent extraction fractionation of Li-ion battery leachate containing Li, Ni, and Co. Sep Purif Technol [Internet]. 2017 May;179:274–82. Available from: <URL>.
• 15. Hanada T, Seo K, Yoshida W, Fajar ATN, Goto M. DFT-Based investigation of Amic–Acid extrac-tants and their application to the recovery of Ni and Co from spent automotive Lithium–Ion batteries. Sep Purif Technol [Internet]. 2022 Jan;281:119898. Available from: <URL>.
• 16. Petrow HG. Solvent extraction. (No. TID-11938) National lead Co Inc raw materials development lab winchester mass. 1956.
• 17. Cvetanović A. Extractions without organic sol-vents: Advantages and disadvantages. Chem Africa [Internet]. 2019 Sep 15;2(3):343–9. Available from: <URL>.
• 18. Capello C, Hellweg S, Badertscher B, Betschart H, Hungerbühler K. Environmental assessment of waste‐solvent treatment options. J Ind Ecol [Internet]. 2007 Oct 8;11(4):26–38. Available from: <URL>.
• 19. Luis P, Amelio A, Vreysen S, Calabro V, Van der Bruggen B. Life cycle assessment of alternatives for waste-solvent valorization: Batch and continuous distillation vs incineration. Int J Life Cycle Assess [Internet]. 2013 Jun 18;18(5):1048–61. Available from: <URL>.
• 20. Smol M, Marcinek P, Duda J, Szołdrowska D. Importance of sustainable mineral resource management in implementing the circular economy (CE) model and the european green deal strategy. Resources [Internet]. 2020 May 5;9(5):55. Available from: <URL>.
• 21. Petrova V. The european green deal and its impact on the raw material industry. Sustain Extr Process Raw Mater J [Internet]. 2021;2:47–53. Available from: <URL>.
• 22. An Z, Zhao Y, Zhang Y. Mineral exploration and the green transition: Opportunities and challenges for the mining industry. Resour Policy [Internet]. 2023 Oct;86:104263. Available from: <URL>.
• 23. Schuur B, Brouwer T, Smink D, Sprakel LMJ. Green solvents for sustainable separation proces-ses. Curr Opin Green Sustain Chem [Internet]. 2019 Aug;18:57–65. Available from: <URL>.
• 24. Flieger J, Flieger M. Ionic liquids toxicity—benefits and threats. Int J Mol Sci [Internet]. 2020 Aug 29;21(17):6267. Available from: <URL>.
• 25. Chiappe C, Pieraccini D. Ionic liquids: Solvent properties and organic reactivity. J Phys Org Chem [Internet]. 2005 Apr 21;18(4):275–97. Available from: <URL>.
• 26. Vovers J, Smith KH, Stevens GW. Bio-based molecular solvents. In: The Application of Green Solvents in Separation Processes [Internet]. Else-vier; 2017. p. 91–110. Available from: <URL>.
• 27. Özkan B, İnan S. Synthesis of bio-based sol-vents derived from sorbitol and stearic acid for the separation of Th, U, and REEs: A solvent extraction study. J Radioanal Nucl Chem [Internet]. 2025 Sep 4;334(9):6677–91. Available from: <URL>.
• 28. Ahsan F, Arnold JJ, Meezan E, Pillion DJ. Sucro-se cocoate, a component of cosmetic preparations, enhances nasal and ocular peptide absorption. Int J Pharm [Internet]. 2003 Jan;251(1–2):195–203. Available from: <URL>.
• 29. Chansanroj K, Betz G. Sucrose esters with various hydrophilic–lipophilic properties: Novel controlled release agents for oral drug delivery matrix tablets prepared by direct compaction. Acta Biomater [Internet]. 2010 Aug;6(8):3101–9. Available from: <URL>.
• 30. Zhang J, Lu M, Ren F, Knothe G, Tu Q. A gree-ner alternative titration method for measuring acid values of fats, oils, and grease. J Am Oil Chem Soc [Internet]. 2019 Oct 27;96(10):1083–91. Available from: <URL>.
• 31. Khan MI, Madni A, Ahmad S, Mahmood MA, Rehman M, Ashfaq M. Formulation design and cha-racterization of a non-ionic surfactant based vesicular system for the sustained delivery of a new chondroprotective agent. Brazilian J Pharm Sci [Internet]. 2015 Sep;51(3):607–15. Available from: <URL>.
• 32. Sarangi K, Reddy BR, Das RP. Extraction studies of cobalt (II) and nickel (II) from chloride solutions using Na-Cyanex 272. Hydrometallurgy [Internet]. 1999 Jun;52(3):253–65. Available from: <URL>.
• 33. Wellens S, Thijs B, Möller C, Binnemans K. Se-paration of cobalt and nickel by solvent extraction with two mutually immiscible ionic liquids. Phys Chem Chem Phys [Internet]. 2013;15(24):9663–9. Available from: <URL>.
• 34. Hereijgers J, Vandermeersch T, Van Oeteren N, Verelst H, Song H, Cabooter D, et al. Separation of Co(II)/Ni(II) with Cyanex 272 using a flat membrane microcontactor: Extraction kinetics study. J Memb Sci [Internet]. 2016 Feb;499:370–8. Available from: <URL>.