Synthesis, physical characteristics, and Cd²⁺ sorption studies of amorphous Fe(OH)₃

Abstract

This work investigates the physical characteristics of amorphous Fe(OH)₃ synthesized by precipitation method for the sorption studies of Cd²⁺ ions. The exchange of surface protons was determined by potentiometric titration method. The particle size distribution shows the agglomeration of smaller particles and also the presence of nanoparticles. Batch sorption studies are performed with respect to concentration, pH, and temperature of the solution. The adsorption of Cd²⁺ ions is found to increase with increasing concentration and temperature of the solution. To interpret the sorption data, Langmuir and Freundlich models are used. The values of both the adsorption enthalpy ΔH and entropy ΔS are found to be positive, suggesting that sorption process is endothermic and spontaneous in nature. The Fe dissolved from the solid is found to be less than 1 mg/L, which proves the integrity of the adsorbent. Further, the mechanism of the sorption reaction is also explored.

Keywords:

• Cadmium
• Characterization
• Iron hydroxide
• Sorption
• Synthesis