Fixed-bed column adsorption of methyl orange by poly(vinyl pyrrolidone)-functionalized manganese oxide

BACKGROUND: Fixed-bed column adsorption provides a practical approach for decontamination of wastewater from toxic azo dyes. A novel water-stable poly(vinyl pyrrolidone)-functionalized manganese oxide hydrothermally prepared for methyl orange azo dye adsorption is reported. RESULTS: Surface studies of the composite were conducted using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and surface area analysis. The surface area of the composite (113 m2 g−1) was greater than that of plain metal oxide (108 m2 g−1). The point of zero charge was calculated using the salt addition method. A continuous flow of methyl orange was carried out in a 40 cm long glass column under different operating conditions determining the breakthrough curve and the breakthrough point time. Experiments were carried out as a function of initial dye concentration (10–30 mg L−1), bed height (0.6–1.5 cm) and rate of flow (5–20 mL min−1) from the column at constant temperature and pH. CONCLUSIONS: The saturation time increases from 700 to 3500 min with increase in bed length. The saturation time decreases from 2000 to 400 min with an increase in initial dye concentration. Similarly, when the flow rate is increased the saturation time and dye adsorption are reduced and the breakthrough curve becomes steeper. The adsorption data were evaluated using the Thomas model to calculate maximum adsorption at various flow rates and the Yoon–Nelson model to identify exactly the saturation point, confirming that the rate of reaction increases with increasing flow rate. © 2022 Society of Chemical Industry (SCI).