Elaboration et caractérisation de matériaux hybrides inorganiques/organiques pour le piégeage des métaux lourds.

Abstract

The pollution caused by heavy metals has been increasing in recent years, posing a threat to ecosystems and human health. This study focuses on the adsorption and cation exchange of chromium (III) and manganese (II) on activated carbon, two representative elements of heavy metal water pollution. The experimental studies included both thermodynamic and kinetic aspects. The theoretical study involved modeling at equilibrium state (Langmuir and Freundlich models) and for kinetics (determination of reaction order). The effect of temperature on the adsorption process was studied at three temperatures: 25°C, 35°C, and 45°C. In the second part of the study, ionic liquids were intercalated into sodium montmorillonite (Kunipia by Kunimine Industries, Japan) and natural bentonite (Maghnia, Algeria). Three ionic liquids were used: 1-methyl-3-butylimidazolium chloride (BMImCl), 1-methyl-3- octylimidazolium chloride (OMImCl), and 1-octylpyridinium bromide (OPyrBr). Each intercalation was carried out using five different methods: microwave irradiation, ultrasonic irradiation at two different frequencies (20 KHz and 45 KHz), reflux heating at 60°C, and classical agitation at room temperature. After synthesis, the structures of the mixed materials were determined using three complementary analytical techniques : thermogravimetry, infrared spectroscopy, and X-ray diffraction. X-ray diffraction measurements of interlayer distance confirmed intercalation regardless of the ionic liquid used. The amount of ionic liquids adsorbed on montmorillonite was always higher than that measured on bentonite. The adsorption capacity of the ionic liquids varies according to the nature of the cation and the length of the alkyl chain of the ionic liquid, following the order: OPy+ > OMIm+ > BMIm+.