Removal of Excess Toxic Chloride and Fluoride Anions from Wastewater Employing Eggshells Waste Remains

Eggshells waste was investigated for its sorption abilityas an environmentally-friendly and cheap sorbent for removing excess anions from wastewater. The milled size of the waste was found to be ≤63 µm, with round and smooth morphology. Moreover, the Fourier transform infrared spectrometer spectrum showed functional groups such as carbonate and hydroxyl. The X-ray diffractogram of the eggshells showed the presence of calcite, which mostly compose of calcium and carbonate ions. Multivariate methodology was employed for optimization of factors that affect sorption studies; initial ions concentration which was found to be 24.45 and 23.24 mg/L, the sorbents dose which was found to be 85.20 and 81.56 mg/L, contact time, which were found to be 69.37 and 70.28 min and solution pH 7.19 and 7.97 for chloride and fluoride anion respectively. The eggshells also exhibited high percentage removal efficiencies for chloride (80.70% ± 2.01%) and fluoride ion (93.18% ± 1.67%) from real wastewater samples. The adsorption isotherm was satisfactorily fitted with Langmuir isotherm model. The thermodynamics kinetics studies showed that the adsorption of fluoride and chloride ions onto the eggshells was endothermic and spontaneous and the adsorption data followed second-order kinetics supporting that chemisorption process was involved.