Crystal Violet Removal from Aqueous Solution Using Urtica Dioica Leaves Powder as A Low-Cost Natural Adsorbent: Isotherm, Kinetics and Thermodynamics Studies

The crystal violet (CV) dye adsorption from aqueous solution is investigated onto a natural abundant and low-cost adsorbent using Urtica Dioica leaves (UDL) powder. FTIR and X-RAY spectroscopic techniques performed the identification of the morphological properties of UDL and the nature of possible UDL-CV interactions. The influence of parameters such as adsorbent dose, initial adsorbate concentration, contact time, temperature, and Ionic strength is also examined. The obtained data were fitted to different kinetic and isotherm models, with a maximum removal efficiency of 93.68% at the optimum contact time of 60 min, adsorbent dose of 0.4 g, initial dye concentration of 30 mg.L-1, pH 9,and a temperature of 20 C-degrees. The adsorption equilibrium follows the Langmuir isotherm model and the pseudo-second-order kinetic model with high correlation coefficients of R-2 > 0.999 and a maximum monolayer capacity of 312.5 mg.g(-1) indicating that the adsorption rate is principally controlled by chemisorption. Thermodynamics studies indicated that the removal of crystal violet dye by UDL is exothermic, spontaneous at low and non-spontaneous at high temperatures, with decreasing randomness at the UDL/CV dye interface. The study has also proven that Urtica Dioica Leaves powder would make a promising cost-effective biosorbent for textile dye adsorption, contributing to scientific development and reduction of dye's environmental impact. [GRAPHICS]