Enhanced adsorption and dye separation ability of low-cost sepiolite acidified by polyoxometalate acid

Porous clay adsorption is one of the most economical ways to treat organic dye wastewater. However, it takes a long time and cannot separate mixed organic dyes. In this context, we used three low-concentration polyoxometalates of tungstophosphoric acid, silicotungstic acid and phosphomolybdic acid to synthesize acid-activated sepiolite (SEP) using a simple hydrothermal method. Polyoxometalates with excellent dye adsorption ability and separation ability can acidify sepiolite. From the characterization of the sample, it was found that the sepiolite after acid activation had no great influence on its crystal structure and chemical composition. It is worth noting that the morphology of the sample changed. The adsorption test experiment shows that the adsorption capacity of SEP after POMs activation is better than that of raw SEP or SEP treated with NaCl and HCl. The 0.10 mol/L H3PMo12O40-treated SEP can quickly and efficiently capture cationic dyes from mixed dye solutions, and it also has effective separation ability in MB/MO and MO/RhB mixed solutions.