𝐶𝑎ଶାion Adsorption and Total Hardness Removal Using Synthesised Iron Oxide – Fused Metakaolin: Batch and Column Studies

Abstract

Groundwater hardness, primarily caused by calcium and magnesium ions, poses significant challenges to domestic, industrial and agricultural uses, as well as health risks associated with cardiovascular disease, kidney stones and other ailments. This study aimed to investigate the removal of total hardness from groundwater using a novel iron oxide-fused metakaolin composite. Initially, calcium adsorption isotherm studies were conducted to assess the composite’s adsorption capacity and mechanism. The favourable adsorption of calcium ions justified further investigation, leading to batch and column experiments that evaluated the composite’s performance in reducing total hardness from real groundwater samples. The calcium adsorption isotherm studies revealed that the adsorption of calcium ions is best described by the Langmuir isotherm with a maximum adsorption capacity of 24.33 mg/g and a separation factor (RL value) of 0.398 which shows that adsorption process was favourable (RL< 1). A removal efficiency of 89.78% was achieved for groundwater total hardness using batch studies. Column studies using the adsorbent together with sand and activated carbon as support materials achieved a removal efficiency of 97.37%. The study demonstrates the effectiveness of the synthesised adsorbent in removing total hardness from groundwater, highlighting its potential as a viable treatment option for mitigating health risks and improving water quality.