Natural diatomites: Efficient green catalyst for Fenton-like oxidationof Orange II

N. INCHAURRONDO; J. FONT; C. P. RAMOS; P. HAURE

APPLIED CATALYSIS B-ENVIRONMENTAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 181 p. 481 - 494

0926-3373

The Fenton-like oxidation of the anionic azo-dye Orange II (100-500 mg/L) was batchwise performed using commercial grade diatomites (3.5% Fe content) thermally treated. Solid samples were thoroughly characterized by several techniques. Peroxidation experiments were performed varying the diatomite calcination temperature (500, 700, 1000 C), reaction temperature (50,60, 70, 80 C), catalyst load (0.47, 0.94, 1.89 and 3.78 g), H2O2 concentration (11.0, 13.7, 20.6 mmol/L) and dosing, pH (2-3.5) and initial dye concentration (0.28, 0.57, 1.43 mmol/L). The influence of NaCl andoxalic acid on the catalytic performance and stability was also addressed. The best results were obtained with samples calcined at 700 C, with initial pH 3, at 70 C and using the stoichiometric amount of H2O2, since complete decoloration, TOC reduction close to 67% and negligible Fe leaching were achieved. The stability of the catalyst maintains after 20 h of usage, with a final Fe loss of 2.25%. An average of 0.88 mg/L of iron leached after each run, which is below the discharge limit.