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Extraction, recovery and characterization of aluminum chloride from Ethiopian kaolin by leaching and crystallization

Adamu Esubalew Kassa, Nurelegne Tefera Shibeshi, and Belachew Zegale Tizazu

Department of Chemical Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia



Received: 4 February 2022  Accepted: 16 April 2022


Due to the global increased aluminum demand, researchers have been working to produce aluminum from non-bauxite ores. Kaolin could be used as alternative raw materials for aluminum extraction because of limited availability of bauxite in most countries. The present work aimed to extract aluminum chloride from calcined kaolin using hydrochloric acid, and investigates the optimum conditions of extraction parameters, viz. acid concentration, solid-to-liquid ratio, temperature and time to maximize aluminum extraction yield. The optimum aluminum extraction yield of 92.6% was obtained at the optimum extraction parameters of 5 M HCl concentration, 0.10 g mL–1 solid-to-liquid ratio, 80 °C and 165 min. The crystallization efficiency of aluminum chloride hexahydrate crystals increased with volume of concentrated HCl. The crystallization efficiency was reached more than 90%. The results of XRD, FTIR, TGA and zeta potential analysis revealed that the extracted aluminum was in the form of aluminum chloride hexahydrate with trigonal crystalline; the hydroxide group band was detected at 2975 cm–1, the mass loss was 75% in the degradation temperature range from 120 to 450 °C; and the zeta potential of aluminum chloride hexahydrate was + 6.38 mV (pH = 4.3), respectively. The morphology of aluminum chloride hexahydrate crystals was irregular shape particles with some pseudo-hexagonal form and agglomerates of different sizes. The purity of the recovered aluminum chloride hexahydrate crystals was 98.4%

Keywords: Kaolin; Extraction; Crystallization; Aluminum chloride; Characterization; Optimization

Full paper is available at

DOI: 10.1007/s11696-022-02241-w


Chemical Papers 76 (8) 5087–5103 (2022)

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