Synergistic effect of arsenic removal from petroleum condensate via liquid-liquid extraction: Thermodynamics, kinetics, DFT and McCabe-Thiele method

Abstract

This work presents the purification of petroleum condensate by removing arsenic ions via liquid-liquid extraction (LLE). Influence of pure and synergistic extractants is investigated. In terms of the practicability, following parameters are examined: the type of extractant, operating time, and temperature. Response surface methodology is used to design parameters such as organic-aqueous ratio and extractant concentration. Under optimal conditions; a mixture of 1 mol/L HCl and 0.02 mol/L thiourea with an organic/aqueous ratio of 1:4 at 323.15 K for 60 min, the extraction of arsenic reached 78.2 %. Further, batch simulation via two-stage counter-current extraction, and estimation by McCabe-Thiele diagram proved to be enhanced arsenic extraction to 95.3 %. Analysis by FTIR show that arsenic ions in petroleum condensate are formed as triphenylarsine compound ((C ₆H ₅) ₃As). The process of arsenic removal proved to be zero-order endothermic, irreversible and spontaneous reaction. The results obtained from the density functional theory (DFT) confirm that arsenic ions react with the synergistic extractant: effectively forming a covalent bond (As–S).

Graphical abstract

Highlights

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  Elimination of arsenic from petroleum condensate was investigated via LLE.

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  Arsenic removal was successfully achieved by the synergistic extractant.

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  95.33 % extraction of arsenic was obtained via two-stage counter-current extraction.

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  Thermodynamics and kinetics of the LLE system were studied.

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  Protonate and extraction reactions were examined via DFT.