High-performance raw biosorbent derived from Algerian Zean oak sawdust for removing methylene blue from aqueous environments

This work aimed to use Algerian Zean oak (AZO) sawdust in its raw state, without undergoing any physico-chemical treatment, to estimate its efficiency for removing methylene blue (MB), a cationic dye widely used in the textile industry. The physico-chemical properties of the biomaterial were characterized by scanning electron microscopy, Fourier-transform infrared, X-ray diffraction, and Brunauer-Emmet-Teller for measuring its specific surface area. The chemical characteristics of the AZO sawdust surface were further examined by the zero-charge point (pHPZC), iodine, MB numbers, and Boehm titration tests. The batch study was performed by varying parameters such as contact time, particle size, pH, temperature, adsorbent dose, and initial dye concentration. By optimizing these parameters, an adsorption capacity of 52.376 mg/g was attained, at pH = 7 and room temperature, using a dose of 1 g/L AZO at C0 = 20 mg/L for an equilibrium time of 45 min. The adsorption capacity of the MB is enhanced by increasing the initial dye concentration and the biosorbent dose. The kinetic data were modeled using the pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. The results reveal that the pseudo-second-order model better describes the experimental data. Furthermore, the adsorption isotherms well follow the Sips and Langmuir models. The thermodynamic study revealed that the adsorption process of MB on AZO sawdust is a spontaneous, exothermic, and favorable phenomenon. Therefore, AZO sawdust could be considered an efficient biosorbent and a preferred alternative to activated carbon to remove MB.

Automated summary

This study aimed to evaluate the efficiency of Algerian Zean oak (AZO) sawdust for removing methylene blue (MB) without any physico-chemical treatment. By characterizing the physico-chemical properties of the AZO sawdust, the researchers optimized various parameters to achieve an adsorption capacity of 52.376 mg/g. Kinetic data and adsorption isotherms were modeled, revealing that the pseudo-second-order and Sips/Langmuir models best describe the experimental data. The thermodynamic study showed that the adsorption process of MB on AZO sawdust is spontaneous, exothermic, and favorable, highlighting its potential as an efficient and preferred alternative to activated carbon for MB removal.