Iron-glutamate-silicotungstate ternary complex as highly active heterogeneous Fenton-like catalyst for 4-chlorophenol degradation

A novel iron-glutamate-silicotungstate ternary complex (FeIIIGluSiW) was synthesized from ferric chloride (FeIII), glutamic acid (Glu), and silicotungstic acid (SiW), and used as a heterogeneous Fenton-like catalyst for 4-chlorophenol (4-CP) degradation at neutral pH value. The prepared FeIIIGluSiW was characterized using inductively coupled plasma atomic emission spectroscopy, thermogravimetry, Fourier-transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, X-ray diffraction, and field-emission scanning electron microscopy. The results showed that FeIIIGluSiW has the formula [Fe(C5H8NO4)(H2O)]2SiW12O40·13H2O, with glutamate moiety and Keggin-structured SiW12O404– heteropolyanion. The catalyst showed high catalytic activity in 4-CP degradation in the dark and under irradiation. Under the conditions of 4-CP 100 mg/L, FeIIIGluSiW 1.0 g/L, H2O2 20 mmol/L, and pH = 6.5, 4-CP was completely decomposed in 40 min in the dark and in 15 min under irradiation. When the reaction time was prolonged to 2 h, the corresponding total organic carbon removals under dark and irradiated conditions were ca. 27% and 72%, respectively. The high catalytic activity of FeIIIGluSiW is resulted from hydrogen bonding of H2O2 on the FeIIIGluSiW surface. The enhanced degradation of 4-CP under irradiation arises from simultaneous oxidation of 4-CP through Fenton-like and photocatalytic processes respectively catalyzed by ferric iron and the SiW12O404– hetropolyanion in FeIIIGluSiW.

Graphical AbstractThe high catalytic activity of the catalyst is due to the hydrogen bonding of H2O2 on the surface. The enhanced degradation of 4-chlorophenol (4-CP) under irradiation is due to simultaneous oxidation of 4-CP through Fenton-like and photocatalytic processes.Figure optionsDownload as PowerPoint slide