Synthesis and characterization of alkali metal molybdates with high catalytic activity for dye degradation

Abstract

In this contribution, the synthesis and catalytic activity of alkali metal molybdates for the degradation of cationic dyes under ambient conditions were systematically studied. The influences of Na and Mo precursors, Na/Mo ratio, and calcination temperature on the chemical composition and catalytic activity of sodium molybdates were investigated. Among all the obtained sodium molybdates, Na₂Mo₂O₇ showed the highest catalytic activity for the degradation of cationic red GTL, safranine T, and methylene blue, etc. Particularly for cationic red GTL, a degradation efficiency of 98.5% could be achieved within 5 min. The optimal synthesis conditions for the formation of pure Na₂Mo₂O₇ are also presented. The morphology and structure of Na₂Mo₂O₇ were carefully characterized using XRD, SEM, HR-TEM and SAED, and FT-IR. In addition to sodium molybdates, potassium and lithium molybdates were also similarly synthesized, which also showed excellent catalytic activities for dye degradation. This work will shed light on the synthesis of novel active catalysts for the catalytic wet air oxidation of dyes.