Removal of Fluoride in Water Using Activated Carbons Prepared From Selected Agricultural Waste Materials

Water is essential to life, but many people do not have access to clean and safe drinking water and many die of water borne or water related infections. Fluoride is one of the anionic contaminants which are found in excess in both surface and groundwater due to geochemical reactions and anthropogenic sources like industrial wastewater disposal. Many methods like coagulation, precipitation, membrane processes, electrolytic treatment and ion – exchange are some of the methods used for the defluoridation of water. But the most widely used method is the adsorption process. Though various conventional and non-conventional adsorbents have been assessed for the removal of fluoride from water, this research aims to promote innovative use of local raw materials and relatively low cost techniques in the production of activated carbons for fluoride adsorption. Activated carbons were prepared from coconut shells, cocoa pod husks and palm kernel shells by carbonisation of the residues to obtain chars which were activated at 900 o C using steam as the activating agent. Analysis of fluoride was done before and after treating water with the derived activated carbons. The water treatment experiment using fluoride as a model pollutant demonstrated that activated carbons prepared from agricultural waste materials have a good potential for fluoride removal. Adsorption of fluoride was also found to be influenced by the type and concentration of other ions in the treated water. Keywords: fluoride, adsorption, carbons, waste, pH, ions, fluorosis, Langmuir isotherms

Effects of Physical Activation Procedure on the Production Yield, Surface Chemistry and Surface Pores of Coconut Shells Based Activated Carbons

Activated carbons are produced either by physical or chemical activation or both. However, due to different experimental protocols used in preparing and characterising these carbons, it has been difficult in comparing their yields, surface chemistry and pore developments. In this study the effects of physical activation procedure on yields, surface chemistry and surface pore developments of activated carbons prepared by three physical activation procedures using the same protocols were compared. The results of the yields revealed that during the production of activated carbons better yields are obtained when the particle size of the precursor is reduced to the required size of the expected activated carbon prior to carbonisation and activation. The spectra produced by Fourier transmission infrared spectroscopy demonstrated shift in bands and changes in wavelength numbers and absorbance between the raw and the derived activated carbons  during pyrolysis or activation. Comparing the micrographs of the Scanning electron microscope of the derived carbons also showed an irregular and heterogeneous surface morphology with a well-developed porous structure. Keywords: porosity, micrographs, surface area, yield, activation, spectroscop