• adsorption;
  • eggshells;
  • malachite green;
  • isotherm;
  • kinetics;
  • thermodynamics


The potential of eggshell—a domestic waste to remove hazardous Malachite Green dye from aqueous solution was investigated in a batch experimental setup. Adsorption conditions were studied with respect to particle size, initial solution pH, adsorbent dose, contact time, initial dye concentration, and temperature. The optimum conditions for Malachite Green removal were found to be pH = 9.0, contact time = 90 min, adsorbent dose = 2.0 g L−1, initial dye concentration = 50 mg L−1. The temperature had a strong influence on the sorption process. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and surface area analysis were used to characterize the adsorbent material. FTIR analysis revealed that [BOND]OH, [BOND]C[DOUBLE BOND]O, and [BOND]PO4 functional groups were mainly responsible for the adsorption process. The rate of the adsorption reaction followed the pseudo second-order kinetics while the sorption equilibrium data well fitted to the Freundlich and the Langmuir isotherm models. The Arrhenius and Eyring equations were used to evaluate the activation parameters. A thermodynamic study showed spontaneous and endothermic nature of the adsorption process. Owing to its low cost and high dye uptake capacity, eggshells seem to be one of the most promising adsorbents for removal of Malachite Green from aqueous solutions. © 2011 American Institute of Chemical Engineers Environ Prog, 2011