Response surface methodology approach for optimization of adsorption of Janus Green B from aqueous solution onto ZnO/Zn(OH)2-NP-AC: Kinetic and isotherm study

• Nanoparticle loaded activated carbon is used as reusable adsorbent for dye removal.
• Dye removal was significantly enhanced in presence of ultrasound.
• Response surface methodology was used for parameter optimization.
• Maximum dye removal was observed within 7 min.
• The pseudo 2nd order kinetic and Langmuir model fits well with experimental data.

The Janus Green B (JGB) adsorption onto homemade ZnO/Zn(OH)2 nanoparticles loaded on activated carbon (AC) which characterized by FESEM and XRD analysis has been reported. Combination of response surface methodology (RSM) and central composite design (CCD) has been employed to model and optimize variables using STATISTICA 10.0 software. The influence of parameters over pH (2.0–8.0), adsorbent (0.004–0.012 g), sonication time (4–8 min) and JGB concentration (3–21 mg L−1) on JGB removal percentage was investigated and their main and interaction contribution was examined. It was revealed that 21 mg L−1 JGB, 0.012 g ZnO/Zn(OH)2-NP-AC at pH 7.0 and 7 min sonication time permit to achieve removal percentage more than 99%. Finally, a good agreement between experimental and predicted values after 7 min was achieved using pseudo-second-order rate equation. The Langmuir adsorption is appropriate for correlation of equilibrium data. The small amount of adsorbent (0.008–0.015 g) is applicable for successful removal of JGB (RE > 99%) in short time (7 min) with high adsorption capacity (81.3–98.03 mg g−1).

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