Effective adsorption performance and mechanism of methylene blue from dye wastewater by humic acid sucrose-modified red mud

The release control of organic dye pollutants has become a global issue, and improper disposal of red mud(RM) can also cause environmental pollution. In this paper, a novel composite material, RM-SC-HA, was prepared to adsorb MB (methylene blue) from dye wastewater by co-hydrothermal treatment using RM, sucrose, and humic acid as raw materials. RM-SC-HA is simple to prepare and has better adsorption of MB in dye wastewater. The results supported the proposed secondary (R-2 = 0.99) kinetic model, which states that chemisorption is the primary form of adsorption. The maximum amount of adsorption, which was achieved by Langmuir's isothermal model, was 417.12 mg/g. In addition, the adsorption mechanism can be attributed to the role of electrostatic interactions, hydrogen bonding, pi-pi stacking and void diffusion. When RM-SC-HA was used to treat simulated industrial wastewater samples, the removal rate was also maintained at a high level(About 90 %). In addition, RM-SC-HA has good magnetic properties and reusability. Its magnetic properties (saturation magnetization value of 2.49 emu/g) make it easy to separate from water under an applied magnetic field. The present study provides an efficient novel MB adsorbent and promotes the practical application of modified RM composites in water purification.