Physicochemical characterizations and sorption properties of deposited scale from hard water

Abstract

The adsorption behaviour of white scale deposited from hard water has been studied. Chemical analyses along with powder XRD and FTIR spectra show that the calcium and magnesium carbonates (aragonite and calcite) are the primary constituents of deposited scale. Batch equilibrium adsorption study shows that both phosphate and fluoride ions are quickly adsorbed on the deposited scale. The adsorption of phosphate is increased with the increase in <i style="mso-bidi-font-style:normal">p</i>H of adsorbate solution, while the reverse trend is found in case of fluoride. Incomplete desorption of adsorbed phosphate or fluoride from deposited scale over a wide <i style="mso-bidi-font-style:normal">p</i>H range indicates that the adsorption is not solely due to physisorption of these ions.