Removal of methylene blue by Fenton-like system with alkali-activated montmorillonite supported iron catalyst

Fenton-like technology is one of the most promising water treatment technologies to remove refractory organic pollutants, and it is the key to construction Fenton-like catalysts with high activity and stability. In this work, a series of alkali-activated montmorillonite (Alk-MMT) with different structure and acidity were prepared via Ca-MMT treated with 5 mol/L NaOH solution at different treatment temperature. Fenton-like system composed with Alk-MMT supported iron catalyst (Fe/Alk-MMT) and H₂O₂ was used to remove methylene blue (MB). The material was systematically characterized by XRD, NH₃-Temperature programmed desorption (TPD), XPS, SEM, FTIR, and N₂ adsorption-desorption at low temperature techniques. The results show that the structure and acidity of Alk-MMT are significantly changed compared with Ca-MMT, which is dependent on the alkali treatment temperature. The structure and acidity of Alk-MMT obviously affect the removal performance of MB in Fenton-like system. The Fenton-like system using Fe/Alk-MMT-100 as catalyst exhibits higher removal efficiency of MB (> 98.7%) under the condition of 50℃, the catalyst dosage of 1.25 g/L, the H₂O₂ concentration of 0.85 mmol/L, and a wide pH (3.0-9.0) range for reacting 300 min. Meanwhile, the activity of the catalyst does not decrease after repeated use for 6 times, which exhibiting a good stability.