Cobalt adsorption by Ca(OH)₂ Modified quartz rock particles adsorbent: Equilibrium isotherm, kinetics, and thermodynamic studies

The presence of cobalt ions Co(II) in wastewater poses major threats to both humans and the environment. The effectiveness of the adsorption of modified quartz rock particles (MQRP) adsorbent with calcium hydroxide solution Ca(OH)₂ for eliminating Co(II) from a water solution was examined. MQRP had a maximum ability to adsorb 47.112 mg g⁻¹ for Co(II) at pH 6.0 and a contact time of 2 h. The HCl stripping agent offered the highest desorption efficiency to regenerate the adsorbent for use again for a new cycle of adsorption. The equilibrium isotherms of the adsorption characteristics were experimentally identified, and the results of adsorption aligned with the principles of the Langmuir model. Under the examined temperature conditions, thermodynamic evaluation proved that Co(II) adsorption on adsorbent vacancies was spontaneous and exothermic. The outcomes of the kinetic process demonstrated that the process closely conformed to a pseudo-second-order pattern. Therefore, the high silica content of MQRP makes it an important adsorbent, and it could be applied as a cost-effective and efficient adsorbent to control the release of Co(II) ions in industrial wastewater.