Methylene Blue Removal from the Aqueous Phase Using a Magnetic-Calcined Bamboo Composite Adsorbent

In the present study, magnetic-calcined bamboo composite adsorbents (MCBC200, MCBC400, MCBC600, MCBC800, and MCBC1000) were prepared, and their physicochemical characteristics (scanning electron microscope images, differential thermogravimetric analysis, Fourier transform-IR, specific surface area, surface functional groups, and point of zero charge [pH_pzc]) were evaluated. Furthermore, the adsorption capacity of methylene blue (MB, cationic dye) using the prepared adsorbents was assessed. The value of pH_pzc and the specific surface area of MCBC400 were 7.8 and 50.6 m²/g, respectively. The amounts of acidic or basic functional groups of MCBC400 were relatively greater than those of the other adsorbents. The amount of MB adsorbed onto MCBC400 (31.9 mg/g) was higher than that onto other adsorbents. The adsorption of MB using MCBC400 was evaluated in relation to various parameters, including coexistence, solution pH, adsorption temperature, and contact time. The results followed the Langmuir isotherm model and a pseudo-second-order model with correlation coefficients of 0.980-1.000 and 0.996, respectively. MB was selectively adsorbed by MCBC400 in a binary solution system containing anionic dyes. Finally, one of the adsorption mechanisms was determined by analyzing the elemental distribution and the binding energy before and after the adsorption of MB. The current findings provide important information for removing MB with MCBC400 from the aqueous phase.