Synthesis of carbon nanofiber incorporated with TiO₂ nanoparticles for malachite green removal from water: Statistical and kinetics studies

Carbon nanofiber incorporated with titanium nanoparticles (TiO₂-CNFs) was designed, characterized, and evaluated for the adsorption of malachite green dye (MG). The experimental variables which impact the malachite green (MG) removal such as dosage of composite (100–600 mg), the concentration of dye (1–30 mg/L), pH level (2–8), and contact time (15–60 min), were systematically optimized. Factorial design analysis was conducted to estimate the significance level of the experimental variables used in the factorial design. MG adsorption equilibrium data fitted to Langmuir isotherm modeling (R² = 0.996) and high adsorption capacity (q_m) of TiO₂-CNFs composite was determined as 439.2 mg g⁻¹ from this model under the optimized experimental circumstances as pH 5, solution temperature (23 °C), adsorbent dose (300 mg) and contact duration (30 min). The kinetic findings exhibited relatively higher R²(0.997) for PSO than the PFO model for the adsorption mechanism of MG onto the nanocomposite adsorbent. The primary adsorption mechanisms were proposed as hydrogen bonding and electrostatic attraction between the cationic MG dye and TiO₂-CNFs composite. These results revealed that TiO₂-CNFs composite was a stable sorbent for MG adsorption and could be used up to six adsorption cycles with insignificant change in its removal capacity. The results exposed that the synthesized TiO₂-CNFs composite adsorbent is very efficient for MG adsorption from wastewater.