Abstract

Several methods for the removal of fluorides in water have been proposed, most of which rely on the use of biomaterials and bone char. In such processes, the adsorbent become loaded with the pre-concentrated pollutant leading to a disposal problem. This study reports on the modification of the maize tassels with triethylamine followed by its subsequent application on the removal of fluoride ions from water. The theory underlying the removal method is based on the interaction of the permanently charged quaternized material with the highly electronegative fluoride ion. This is a regeneratable, affordable, eco-friendly, solution to the problem of secondary pollution and sustainable water remediation method of this toxic water pollutant. The resulting biomaterial derived from agricultural waste was used in the removal experiments on both model solutions and real water samples. The effect of pH, contact time, initial fluoride concentration and biomaterial resin dosage were investigated. It was observed that the amount complexed fluoride ions per unit mass of biomaterial increased with increase in concentration up to a point of saturation. The optimum removal pH was found to be 4.0. The biomaterial was very effective in fluoride removal as 86% of the fluoride was removed within the first 20 min. However, the uptake of fluoride ions in real water samples was found to be slightly lower compared to the model solutions. The experimental data was analysed using Langmuir and Freundlich isotherms. It fitted best in the Langmuir isotherm implying a chemisorption process. The adsorption capacity was found to be 0.19 mg/g and it was also observed that the sorbent when packed in a SPE column could be regenerated by stripping the attached fluoride ions with a dilute hydrochloric acid solution. These findings show that the modified material is suitable for application in the removal of fluorides in water at a point of use. This is intended to offer a solution to the drinking water for the children born by the population living in areas that are naturally fluoridated. Such parents are mean with their smile due to the problem of their permanently brown stained teeth.

This work is licensed under a Creative Commons Attribution 4.0 License.