Document Type : Original Article
Authors
1
Chemical Engineering, Higher Institute of Engineering and Technology, , Menofia, Egypt
2
Higher Institute of Engineering and Technology, Chemical Engineering Department, Menofia, 32821, Egypt.
3
higher institute for engineering and technology, Menofia
4
Petroleum Refinery and Petrochemical Engineering Department, Faculty of Petroleum and Mining Engineering, Suez University
5
Port said University Port Said, Egypt
6
Cairo University, Chemical Engineering Department, Cairo, 12613, Egypt
7
Cairo University Road Faculty of Engineering Chemical Engineering Department
10.21608/ejchem.2025.390539.11845
Abstract
White bean straw (WBS), a low-cost, locally available agricultural waste, was used as a biosorbent for the adsorption of Malachite Green, Alizarin Red S, and Methyl Red dyes. Characterization using scanning electron microscopy, infrared spectroscopy, zeta potential analyzer, and X-ray diffractometer showed that the surface is coarse and heterogeneous and detected functional groups essential for effective adsorption. It was also noted that carbon and oxygen are the primary components of White bean straw. White bean straw is quite an effective adsorbent material for removing both cationic and anionic dyes, as it has two points of zero charge (1.7 and 10.8). The effects of particle size, contact time, dosage, solution pH, temperature, and initial dye concentration on the removal efficiency of each dye by WBS were investigated. It was found that the models that best fit the Methyl Red (MR), Alizarin Red S (ARS), and Malachite Green (MG) dyes were the pseudo second-order adsorption kinetic and Freundlich adsorption isotherm models. The removal efficiency reached approximately 95.7%, 61.2% and 98.2% for MR, ARS and MG, respectively. Physical adsorption is indicated by values of -62.311 J/mol. K. and -81.358 J/mol. K. for MR and ARS, while chemisorption is indicated by values of -227.37 J/mol. K. for MG. The adsorption process is exothermic and largely dependent on electrostatic contact, since enthalpy is negative for each dye. For MR, ARS and MG the process is spontaneous because Gibbs free energy is negative for all at 25°C, 35°C, and 45°C.
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