Biosorption of Fluoride from Water Using Aluminum Hydroxide Modified Activated Carbon from Composte Coffee Husk and Corn Cob

Abstract

The earth's crust contains the highest concentration of fluoride minerals. Long-term exposure to water containing fluoride concentrations higher than the 1.5 mg/L WHO recommendation can be harmful to one's health and cause dental, skeletal fluorosis, neurological, and thyroid problems. Therefore, it is imperative to create an affordable, accessible, and eco-friendly way to remove fluoride from water using activated carbon made from a locally available composite of maize cob and coffee husk. In this study, coffee husk and maize cob were ground, dried, and calcined in a muffle furnace at 500°C for two hours. The materials were then activated with a 30% aqueous Al (OH)3 solution. To describe its properties, the resultant activated carbon—known as CMAC (coffee husk and maize cob derived activated carbon) was put through proximate and ultimate analysis. Using batch adsorption methods, the impact of several parameters, including pH, sorbent dosage, contact time, and initial fluoride concentration, is investigated with respect to the extraction of fluoride. The adsorption kinetics were investigated using pseudo first and second-order kinetic analysis, and Freundlich and Langmuir isotherms were used for analysis. The study's maximum fluoride removal efficiency of 88.1 percent was attained with an initial fluoride concentration of 10 mg/L, pH of 3, contact time of 90 minutes, and adsorbent dosage of 3 grams. It is discovered that CMAC works well as an adsorbent to remove fluoride from water. The study's adsorption data had pseudo-second-order kinetics (R^2 = 0.957) and a high coefficient of determination (R^2 = 0.976), indicating a good fit to the Freundlich isotherm model. These results point to a high potential for efficiently removing fluoride from aqueous solution using the modified adsorbent CMAC composite.