Coconut Shell Charcoal and Eggshell Charcoal Mixture is Effective for Water De-Fluoridation

Abstract

Consumption of potable water with high concentrations of fluoride causes serious health issues. Fluoride ions are released into groundwater primarily as a result of rock erosion. Among several methods for removal of fluoride from water, adsorption method receives much attention because of its simplicity. In this context, amongst various materials, calcium containing minerals and animal bones have been used. The present study is to remove fluoride from water using a blend of coconut shell charcoal and eggshell powder in a packed continuous flowing column system and in a simple batch system. The fluoride removal efficiency (FRE) was determined as a percentage of the ratio of removed concentration to the initial fluoride concentration. The effect of several factors such as the ratio of the mass of coconut shell charcoal to the eggshell in the mixture, the flow rate of fluid in the column system and contact time of water with adsorbents in batch system were studied. Adsorbing materials in powder-form were prepared by breaking down precleaned shells and heating in the oven at 1050 C for 3 hours and sieving through a 2 mm sieve separately. The mixture of coconut shell charcoal and eggshell was prepared with different mass ratios. Fluoride concentration in water was determined by colorimetric method by measuring the colour intensity reduction of SPANDS reagent by Fluoride ions. Calibration curve was prepared for known concentrations. The results demonstrate that the continuous system is excellent for removing low initial fluoride concentrations from water, whereas the batch method is best for removing high initial fluoride concentrations. Different ratios of eggshell and coconut shell powder were prepared separately. The eggshell Charcoal system's 3:1 ratio shows that approximately 97% and 65.5% of the initial concentration (0.5 ppm) of Fluoride ions could be removed in the continuous flow and batch systems, respectively, in 8 hours. However, when the initial concentration of Fluoride ions was increased to 4.5 ppm, only 51% of the initial concentration was taken from the water, indicating that defloration is limited by the eggshell surface. Results demonstrate that only the high efficiency of the eggshell powder technique removes a high concentration of fluoride from water. Furthermore, Batch system and column system effectively remove fluoride from potable water.