Chromium (III) removal by weak acid exchanger Amberlite IRC-50 (Na)

Area of Science:

• Environmental Science
• Materials Science
• Physical Chemistry

Background:

• Chromium (III) is a pollutant with significant environmental and health impacts.
• Ion exchange resins are effective materials for removing heavy metals from aqueous solutions.
• Amberlite IRC-50 is a weakly macroporous cation exchanger with potential for chromium remediation.

Purpose of the Study:

• To investigate the kinetics and thermodynamics of chromium (III) sorption onto Amberlite IRC-50 (Na).
• To determine the rate-limiting step in the chromium sorption process.
• To understand the influence of temperature and pH on chromium removal efficiency.

Main Methods:

• Sorption experiments were conducted as a function of time and temperature.
• Rate constants for film and particle diffusion were calculated.
• Langmuir adsorption isotherm was used to model equilibrium data.
• Thermodynamic parameters (enthalpy, entropy, Gibbs free energy) were determined.

Main Results:

• Sorption rate increased with temperature, confirming a positive effect on diffusional processes.
• High activation energy values indicated that particle diffusion is the rate-limiting step.
• pH variations revealed competition between Cr(OH)(2+) and H+ ions for resin exchange sites.
• Langmuir equation accurately described the equilibrium sorption data.

Conclusions:

• Amberlite IRC-50 effectively removes chromium (III) from aqueous solutions.
• The sorption process is primarily controlled by particle diffusion and is endothermic.
• Temperature and pH are critical factors influencing chromium sorption efficiency on this resin.