Phytogenic TiO₂-biochar nanocomposite derived from Prunus dulcis for enhanced Rhodamine B removal from aqueous...

Batch adsorption experiments were carried out to evaluate the removal of Rhodamine B (RhB), a cationic dye, from synthetic wastewater using a multi-walled carbon nanotube/titanium dioxide (MWCNT/TiO₂)-modified biochar composite (CBTM), with pristine biochar (CCB) as a reference. The effects of solution pH, contact time, adsorbent dosage, temperature, and initial dye concentration on adsorption performance were systematically investigated. Maximum RhB removal occurred at pH 3, with equilibrium achieved after 180 min. Under these conditions, CBTM exhibited a higher adsorption capacity (31.43 mg·g^-1) than CCB (17.31 mg·g^-1) at 313 K. Equilibrium data were best described by the Freundlich isotherm, indicating multilayer adsorption on heterogeneous surfaces, while kinetic analysis showed that the pseudo-first-order model provided the most accurate fit, suggesting a physisorption-dominated process. Thermodynamic parameters (ΔG°, ΔH°, ΔS°) confirmed that the adsorption was spontaneous and endothermic. Interestingly, while CBTM demonstrated superior dye removal, antimicrobial assays revealed stronger bacterial inhibition by CCB. These results highlight the potential of CBTM for efficient dye removal and underscore the multifunctional capabilities of biochar-based adsorbents.