Removal of Calcium (Ca2+) Ion from Aqueous Solution by Chemically Activated Thuja Occidentalis Leaves Carbon (CATLC)-Application for Softening the Groundwater Samples

Abstract

In this research paper, chemically activated Thuja Occidentalis leaves carbon (CATLC) is used as an adsorbent for the removal of calcium (Ca2+) ion from aqueous solution. CATLC is prepared and characterized by FTIR, SEM and EDX. The impact of pH, adsorbent dosage, contact period and initial concentration of Ca2+ on the adsorption performance of CATLC for Ca2+ removal are examined by batch studies. The results disclose that CATLC has a high potential to adsorb Ca2+ (91% removal) at pH 7.00. To know the equilibrium behaviour of Ca2+ adsorption, Freundlich and Langmuir models are investigated, and the data discloses that Langmuir model (maximum adsorption capacity ‘Qm’ obtained is of 51.28mg/g and R2= 0.9953) fits better than Freundlich model(R2 =0.8723). The Kinetic studies indicate that pseudo-second-order(R2= 0.9909) is the best fit rather than pseudo-first order, intra particle and Elovich models and chemisorptions are the rate-limiting steps for the Ca2+ adsorption using CATLC adsorbent. Regeneration studies showed that CATLC can be regenerated easily and reused for several adsorption cycles, with sodium chloride solution as a regenerating agent. The application of CATLC adsorbent is useful to reduce the hardness concentration in groundwater samples to meet the allowable limit according to WHO-2011 standards.