Design and Synthesis of Reusable Nanoparticles for Reversible Chemisorption of Hexavalent Chromium Anions from Aqueous Media and Catalysis

Figure 20

Bromination of phenol red to bromophenol blue using Fe₃O₄@SiO₂@LEuH@PW₁₀ as a POM nanocomposite catalyst. The reaction was monitored at time intervals of 30 seconds (1 = 0 s, 2 = 30 s, …, 12 = 330 s). Reaction conditions are as follows: 10 ml of 1.0 mM phenol red in water + 10 ml of 10.0 mM NH₄Br in water + 0.5 g of catalyst + 2.5 mM·H₂O₂, in a round-bottomed flask. T = 298 K and  atm.