The stabilization/solidification (S/S) technique is generally unable to immobilize organic pollutants when it relies on the simple use of Portland cement as a hydraulic binder. The use of pre-adsorbent agents as cement additives represents a possible way of using S/S to treat soils contaminated with organic pollutants. This research project deals with the possibility of synthesis of pre-adsorbent agents from clays having a good adsorption capacity of organic pollutants. In this context, the adsorption of a highly toxic organic pesticide, pentachlorophenol, was studied on two hybrid nanomaterials of clay. Both materials were synthesized, characterized and their adsorption of PCP was evaluated. The clay-based nanomaterials are an organophilic clay synthesized from bentonite and a surfactant, hexadecyltrimethylammonium bromide (HDTMA) and a carbon nanocomposite synthesized from sucrose and bentonite. The characterization allowed us to confirm the intercalation of surfactants in the interfoliar space and the formation of graphene between the clay particles. The characterization was performed by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), small angle X-ray scattering (SAXS), the determination of hydrophobicity by measuring the contact angle as well as the measurement of the surface charge by the zeta potential. The adsorption study showed that the two materials studied have a high PCP adsorption capacity. The kinetics study showed that the adsorption process followed the pseudo-second order and the adsorption equilibrium results were described by the Langmuir model for both materials. The influence of the pH of the solution was also studied. The pH increase adversely affected the adsorption process due to the negative net charge of the adsorbent and the adsorbate at a higher pH. The presence of arsenic As (V) improved the adsorption process. The adsorption mechanisms can be described by the π-π interaction and hydrogen bonding for Bt-GL and the hydrophobic, electrostatic interaction and hydrogen bonding for Bt-HDTMA.
Jhimi, K. (Author),
Ouellet-Plamondon (Supervisor) &
Dubé (Co-supervisor),
20 Nov 2018Student thesis: Master's thesis › Master in Engineering: Environmental Engineering