EQUILIBRIUM AND KINETIC STUDIES FOR THE ADSORPTION OF MN(II) AND CO(II) FROM AQUEOUS MEDIUM USING AGAR–AGAR AS SORBENT

Abstract

An extensive increase in industrial activities and environmental accidents in recent years have greatly contributed to increasing metal pollution in water resources, thereby causing threats to terrestrial as well as aquatic life. The toxicity of metal pollution is slow and long lasting, as these metal ions are nonbiodegradable. The most appropriate solution for controlling the biogeochemistry of metal contaminants to produce high-quality treated effluents from polluted wastewaters is sorption technique. Agar–agar, a readily available seaweed, was used as sorbent for the removal of Mn(II) and Co(II) from aqueous media. Batch experiments were performed to study adsorption as a function of process parameters: sorption time, initial pH, concentration of sorbate and sorbent. The Freundlich model fitted best with the experimental equilibrium data between the two adsorption isotherm models tested. The kinetic data correlated well with the Lagergren pseudo-second-order kinetic model for the sorption of both Mn(II) and Co(II) using agar–agar. Adsorbed metal ions were quantitatively recovered from the spent adsorbent using 5.0 mol L⁻¹ HCl. The efficiency of agar–agar for decontaminating Mn(II) and Co(II) from electroplating effluent has also been evaluated. The results proved agar–agar to be a favorable adsorbent to remove and recover Mn(II) and Co(II) from waste effluent for further use in diversified industrial applications.

Keywords:

• Adsorption
• Agar–agar
• Cobalt(II)
• Desorption
• Electroplating industrial effluent
• Equilibration
• Kinetics
• Manganese(II)

Acknowledgment

The financial support to one of the authors provided by the Ministry of Human Resource and Development (MHRD), New Delhi, India is gratefully acknowledged.