Adsorption characteristics and mechanisms of plantain peel charcoal in removal of Cu (II) and Zn (II) ions from wastewaters

Abstract

The effects of pH, contact time and temperature on the ability of plantain peel charcoal to remove Zn²⁺ and Cu²⁺ from synthetic wastewaters were investigated. The charcoal used as the adsorbent was prepared from unripe plantain peels. The adsorption process established pH 5 and pH 9 as the respective optimal working pH values  for Zn²⁺ at 30°C and Cu²⁺ at 40°C. Changes in enthalpy (ΔH), entropy (ΔS) and free energy (ΔG) were also   determined. Data evaluation showed that the adsorption of Zn²⁺ and Cu²⁺ followed the pseudo-second order adsorption kinetic model with the Langmuir model being the best fit for the isotherm model. The thermodynamic study revealed that the adsorption was a physisorption process which was spontaneous and endothermic in nature. It was concluded that plantain peel charcoal could efficiently serve as an alternative low cost adsorbent for the removal of heavy metal ions from wastewaters.

Keywords: Adsorption, Heavy Metals, Thermodynamics, Charcoal, Wastewater.