Abstract
This research work aims to introduce a new method of purifying clays and to assess the effectiveness of the retention of fluorine adsorption in local Tunisian clay using adsorption through a filtration membrane. Detailed chemical analysis was been carried out using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), liquid nitrogen adsorption desorption analyses by measuring the specific surface area (BET), scanning electron microscopy (SEM), and solid-state nuclear magnetic resonance (NMR) in order to compare the new elaborated purification approach to the classical method of preparation. The absence of the bands at 2510, 1796, 1426, and 712 cm
−1
from the spectra of F3 and F5 as well as the absence of the endothermic peak up to 680 °C on the thermogram of OTNa(b), corroborated the departure of the calcite after purification. Oxide of aluminum, iron and magnesium increased respectively from (15.25, 5.72, and 2.52%) to (16.25, 6.26, and 2.78%) when compared to the classical method. Raw clay was used to treat fluoride in four types of drinking water. The adsorption kinetics confirmed the physisorption interaction between F
−
ions and OT clay. Adsorbent equilibrium data were successfully described by the pseudo-second model (
R
2
= 0.989, 0.993, 0.988, 0.9798, 0.998) revealing maximum adsorption capacities of 1.131 mg g
−1
, 0.768 mg g
−1
, 0.856 mg g
−1
, 0.988 mg g
−1
, and 2.079 mg g
−1
, respectively. Furthermore, the synthesized solution offered easy and better adsorption with high efficiency (> 79%). This part of study sheds light on the effectiveness and feasibility of the raw carbonate clay in terms of the removal of fluoride ions from naturally contaminated water and synthesized aqueous solution.