Removal of Acid Orange G Azo Dye by Polycation‐Modified Alpha Alumina Nanoparticles

Polycation PVBMA was synthesized, characterized, and applied as an effective α-Al₂O₃ modifier on adsorptive removal of azo dye AOG. Approximately 98.9% of the AOG was excluded from aqueous solution. The PVBMA-AOG electrostatic attractions were dominant. The AOG adsorption was better suitable with Langmuir isotherm and pseudo-second models. The α-Al₂O₃ adsorbent was highly reusable with about 90.1% of the AOG removal efficiency after 6 reused cycles.

Abstract

Highly positively charged poly(vinyl benzyl trimethylammonium chloride) (PVBMA) was successfully synthesized with approximately 82% of yield. The PVBMA was characterized by the molecular weight (M _w) of 343.45 g mol⁻¹ and the molecular weight distribution, (Đ) of 2.4 by ¹H NMR and SEC measurements. The PVBMA was applied as an effective agent for α-Al₂O₃ surface modification in the adsorptive removal of the azo dye acid orange G (AOG). The AOG removal performance was significantly enhanced at all pH compared to without surface modification. The experimental parameters were optimal at pH 8, free ionic strength, 15 min of adsorption time, and 5 mg mL⁻¹ α-Al₂O₃ adsorbents. The AOG adsorption which was mainly controlled by the PVBMA-AOG electrostatic attractions was better applicable to the Langmuir isotherm and the pseudo-second kinetic model. The PVBMA-modified α-Al₂O₃ demonstrates a high-performance and highly reusable adsorbent with great AOG performances of approximately 90.1% after 6 reused cycles.

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