Abstract

Abstract
The aim of this work is firstly to produce a stable W/O primary emulsion capable of extracting a wide variety of heavy metals (charged solutes), namely Cu2+, Zn2+, Pb2+, Ni2+, Co2+ et Hg2+. The appropriate conditions through which a better extraction was obtained are: concentration of Span 80 (4 wt%); concentration of TEA (10 wt%); diluent (kerosene); internal phase (HCl 0.5 M); emulsification time (4 min); Vmemb/Vint (2.08); Vemul/Vext (0.1); pH of the external solution (4.7) and stirring speed (150 rpm). A second recycling of the emulsion resulted in a drop in extraction about 40%. The morphological study confirmed a good dispersion of internal globules and a good stability of emulsion for up to 60 days. The extraction of metal cations showed very high extraction (> 90%) with very fast kinetics. However, it has been shown that the type of anion to which the metal cation is bound, only affects the extraction efficiency above 100 mg/L. Results extraction of heavy metals are in good analogy with evolution of the osmotic pressure difference between the internal and external phases, leading to a significant swelling of emulsion, while de-extraction also appears to be in accord with extraction with a slightly slower rate.
The second part of the work aimed to evaluate the extraction efficiency of neutral solutes, namely glucose and PEG 2000 contained in aqueous solutions, using the emulsified liquid membrane (ELM) technique. The W/O emulsion was formulated using Span 80 as the surfactant (3 wt %), kerosene as the diluent, di-2-ethylhexyl phosphoric acid (D2EHPA) (6 wt %) as the extractant, a sulphuric acid solution (0.5 M) as the internal phase, an emulsification time equal to 3 min, a stirring speed of 200 rpm, a volume ratio of the organic phase to the internal phase: (1:1) and a volume ratio of emulsion to external phase: (1:5).
The difference in molecular weight between the two solutes, glucose and PEG, significantly affected the extraction yield and the osmotic pressure gradient, whereas the emulsion swelling rate did not seem to be influenced by the type of neutral solute. The de-extraction of glucose (Rdes = 29.29%) is very slow compared to its extraction (Rext = 73.13%) while that of PEG 2000 (Rdes = 33.43%) is in agreement with its extraction (Rext = 38.89%).
The transfer of these solutes from the external phase to the internal phase was confirmed by IR and UV-Visible spectroscopic analyses and by COD measurement, while the thermodynamic study proved that the extraction of glucose is an exothermic, feasible and spontaneous reaction inducing less disorder in the solution.
Keywords: Extraction; De-extraction; Emulsified liquid membrane; Stability; Charged solutes; Neutral solutes; Osmotic pressure; Swelling; Transfer.

Information

Item Type:	Thesis
Divisions:	» Faculty of Science and Technology
ePrint ID:	5025
Date Deposited:	2024-06-30
Further Information:	Google Scholar
URI:	https://www.univ-soukahras.dz/en/publication/article/5025

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