Alumina ativada hidroxilada aplicada na remoção de íons fluoreto da água – um estudo através da metodologia de planejamento experimental

Abstract

Fluoride concentration is an important parameter that must be monitored in drinking water sincewater fluoridation, within the recommended doses, is an essential tool to prevent dental cavitiesin the population. Although, prolonged exposure to high fluoride concentrations may result in dental fluorosis and other severe health problems. In Rio Grande do Sul, the recommendation is that drinking water must have fluoride concentrations in the range of 0.6 to 0.9 mg L-1 . Even though potable water is the main contributor to daily fluoride intake, exposure is also related to the inhabited region, the amount of water ingested even as the food and beverages consumed. Once ingested, fluoride is quickly absorbed by the body, where it is retained, mainly in calciumrich regions, such as bones and teeth. Several methods to remove it are studied and employed, highlighting precipitation, adsorption, electrodialysis, and nanofiltration. Among these, adsorption stands out for being a technique that propitiates the use of different materials to reach the desired efficiency with low costs. Therefore, this work aims modify the surface of activated alumina (AA) – adsorbent material used to remove fluoride – with hydrogen peroxide to evaluate the effectiveness of this process in the fluoride ions removal from water. The physicochemical properties of hydroxylated activated alumina (HAA) with best quality (prepared with 1% hydrogen peroxide solution) were determined through two analytical methods: FTIR e pHPCZ. Subsequently, adsorption capacity and efficiency fluoride removal of hydroxylated activated alumina were verified through experiments carried out in batch. HAA showed values greater than AA, since its efficiency was approximately 1;43 times higher. Through the experimental rotational central composite design was possible to identify that the greater fluoride removal has occurred by using 8.69 g L-1 of HAA, and in a pH range between 4 and 7.