Removal of Calcium over Apricot Shell Derived Activated Carbon: Kinetic and thermodynamic study

The apricot shells (AS) derived activated carbon (AC) was employed in removing the water hardness ions (calcium) from synthetic hard water. The ZnCl2 activation route was implemented in synthesizing the AC from the AS. The typical AC sample was diagnosed for its morphology by the FESEM technique, elemental analysis using EDX technique, influential surface groups by FTIR spectroscopy, and crystallinity by the XRD. This AC sample was then applied to eliminate the calcium ion (Ca+2) from synthetic hard water by investigating factors affecting the Ca+2 removal efficiency, like the solution pH, Ca+2initial concentration, AC dosage, temperature, and contact time. The outcomes revealed that Ca+2 removal by the so-synthesized AC is pH, temperature, and time-dependent. The best Ca+2 removal % reached 80.12 %, while the best adsorption capacity was 70.42 mg/g. The Langmuir adsorption isotherm and the pseudo-second-order kinetic model demonstrated were best described Ca+2 removal by the AC. The enthalpy and Gibbs free energy functions indicated that Ca+2adsorption is endothermic and spontaneous. Thus, the consequences assured that the ASs derived AC can be exploited as an effective adsorbent to remove Ca+2from the solution.