Water hardness removal by coconut shell activated carbon

Abstract

The present study reports the water softening by adsorption of hardness ions onto Coconut Shell Activated Carbons (CSAC). Characterization of CSAC was identified by FT-IR and SEM techniques. Batch experiments were carried out to determine the effect of various adsorbent factors such as adsorbent dose, initial pH, contact time, and temperature, on the adsorption process using synthetic and field collected water samples. Removal efficiency at nearly neutral pH of 6.3 for both synthetic and field collected water samples were 60% and 55% respectively. Temperature study (303 K-333 K) shows that the softening process in synthetic and field hard water is endothermic as removal efficiency was increasing from 40% and 29% at 303 K to 47% and 38% at 333 K respectively. Removal efficiency increases with the increase in contact time and adsorbent dose until 15 hours and 0.24g/cm 3 respectively, for both field and synthetic hard water, which was considered to be maximum. Equilibrium isotherms have been analyzed using Langmuir and Freundlich isotherm models, and both Freundlich and Langmuir isotherm models fit to explain the adsorption behavior of hardness ions onto CSAC.