Cationic dye removal (crystal violet) using Equisetum palustre

In this study, the removal of cationic dyes from synthetic wastewater by batch-mode biosorption processes was investigated using Equisetum palustre as a biosorbent. The adsorption capacity of the biosorbent was investigated under the influence of parameters such as adsorbent dose, initial dye concentration, pH and temperature. The isotherm fitting of the experimental data was investigated using isotherm models such as Langmuir, Freundlich, Temkin, Sips, Toth and Khan. The adsorption kinetic behavior of the biosorbent was evaluated using pseudo-first-order, pseudo-second-order and Elovich kinetic models. The obtained experimental results fitted well with the Sips isotherm model and the pseudo-second-order kinetic model. Furthermore, thermodynamic parameters were studied, and the activation energy (E _a) was determined to be 11.142 kJ mol^-1 for an adsorbent dosage of 10 g L^-1, a shaking speed of 150 rpm, an initial dye concentration of 100 mg L^-1 and a pH of 6.2. The enthalpy change (ΔH*) was 8.621 kJ mol^-1, whereas the entropy change (ΔS*) was -0.249 kJ mol^-1. The results revealed that Equisetum palustre (EP) might be exploited as an alternative to conventional biosorbents in wastewater treatment for the elimination of dyes.