Hagenia abyssinica leaf powder as a novel low-cost adsorbent for removal of methyl violet from aqueous solution: Optimization, isotherms, kinetics, and thermodynamic studies

Abstract

Dye effluents generated by industries have a significant impact on water quality. Unfortunately, traditional wastewater treatment techniques are incapable of dye removal from polluted water at the required levels. Nowadays, wastewater treatment needs the development of eco-friendly and profitable pollutant adsorbents. In this study, Hagenia abyssinica leaf powder (HALP) adsorbent was used to eliminate methyl violet dye (MVD) from aqueous solution. HALP adsorbents before and after MVD adsorption were analyzed using scanning electron microscopy (SEM) and a Fourier transform infrared (FT-IR) spectrometer. Batch adsorption experiments were conducted to examine the effects of initial concentration, adsorbent dose, contact time, and solution pH on MVD adsorption using HALP. As a result, 0.2 g adsorbent dose, 100 mg/L MVD solution, 50 min contact time, and a solution pH of 6 were determined as the optimum adsorption process conditions. Adsorption isotherms were used to test the experimental data and the result is well-fitted to the Langmuir model with a maximum adsorption capacity of 68.96 mg/g. Adsorption kinetics were studied using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models, and the experimental data is well-fitted with the pseudo-second-order model. The thermodynamic data Δ H ∘ (9.564 kJ/mol), Δ G ∘ (-2824.744 to -1693.976 J/ mol) and Δ S ∘ (37.373 J/(mol.K)) indicated that the adsorption process is endothermic, spontaneous, and rise randomness at HALP/solution interface, respectively. The current work confirmed that HALP is one of the most effective, eco-friendly, and sustainable dye adsorbents from solutions compared to those derived from a household, agricultural, and industrial waste. • Hagenia abyssinica leaf powder (HALP) was employed to remove methyl violet dye (MVD). • HALP adsorbent before and after MVD adsorption were analyzed. • After dye adsorption, the surface structure and absorption peak position changed. • The adsorption process depends on initial concentration, dose of HALP, time of contact, and pH. • HALP can successfully remove MVD molecules from aqueous solutions.