Water defluoridation by adsorption on bovine bone activated carbon

Abstract

Fluoride is an essential ion for the formation and strengthening of hard tissues, such as bones and teeth. However, excessive consumption can lead to serious health problems, including dental and skeletal fluorosis. This ion may naturally be present in water, particularly groundwater. Therefore, its concentration should be monitored, and when it exceeds the recommended limits set by health organizations, it should be removed before the water is consumed. In this regard, adsorption on activated carbon has proven to be a promising technique, with bovine bone-derived activated carbon being an interesting alternative due to its availability, cost-effectiveness, and environmental safety. The objective of this study was to produce activated carbon from bovine bone and utilize it for fluoride removal through adsorption. The synthesized carbon was activated with potassium hydroxide (KOH) and subjected to comprehensive characterization, addressing aspects such as yield, moisture content, pH, iodine number, bulk density, specific mass, surface area, zero point of charge, and particle size analysis. Additionally, kinetic analyses were conducted to assess the efficiency of the fluoride removal process from water through adsorption on the produced activated carbon. The carbon was obtained with a yield of 33%, moisture content of 4.03%, pH of 8.12, iodine number of 958.49 mg·g^-1, bulk density and specific mass of 0.792 g·cm^-3 and 2.725 g·cm^-3, respectively, surface area of 0.0644 m²·g^-1, and a zero point of charge of 8.32. Based on the particle size analysis we could conclude that the majority of granule concentrations are smaller than 30 mesh. Fluoride adsorption on activated carbon proved to be efficient, fitting the Langmuir isotherm model with a maximum adsorptive capacity of 0.875 mg·g^-1. Overall, the results demonstrated that the studied adsorbent possesses favorable characteristics for application in water fluoride removal