Kinetic, equilibrium and phytotoxicity studies for dyes removal by low cost natural activated plant-based carbon

Abstract

The capacity of commercial natural activated plant-based carbon (CNAC) to remove different dyes such as methylene blue (MB), eosin yellow (EY) and rhodamine B (RB) was studied. Also, the germination index (GI) was calculated in order to examine the dyes toxicity on various plant seeds by recording and measuring the number of germinated seeds and root length, respectively. Generally, the results showed that high concentrations of dyes inhibit the seed germination by changing their colors and affecting their growth. The inhibition of corn seeds germination in RB was very low in the studied range of concentration. The adsorption behavior of dyes onto CNAC surface was investigated through isotherm and kinetics modeling. The parameters predicted from the Langmuir and Freundlich isotherms suggested a favorable adsorption of the considered dyes onto CNAC surface. The kinetic studies showed that the adsorption followed pseudo-second-order kinetic model for MB and RB removal, but was not adequate for EY removal.