Catalytic ozonation of an azo-dye using a natural aluminosilicate

N. INCHAURRONDO; C. DI LUCA; G. ZERJAV; J.M. GRAU; A. PINTAR; P. HAURE

CATALYSIS TODAY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2021 vol. 361 p. 24 - 29

0920-5861

Catalytic ozonization of Orange II (100 mg/L) in the presence of the aluminosilicate Montanit300® (M), modified with H2SO4 (MS) and HCl (MH), was studied. The samples were characterized through various techniques (SEM/EDX, FTIR, XRD, FRX, TPD pyridine, surface area, pHPZC). The acid treatment increased surface area, hydrophobicity and quantity of acid sites, but reduced pHPZC and eliminated Fe and Mn labile species. In ozonation experiments, complete decoloration and TOC conversions of 66, 65, 88 and 91% were obtained by ozonation and catalytic ozonation with MH, MS and M, respectively. Higher M and MS activity at acidic pH was associated to Mn leaching. The decreased mineralization efficiency in the presence of tert-butanol suggests a radical mechanism. At neutral pH, M showed no activity and 80MS presented only reduced activity associated to enhanced interactions between catalyst surface and ozone/pollutants, promoted by its enlarged hydrophobicity and quantity of acid sites. For M sample, mineralization levels were mostly sustained over 20 h. MS quickly deactivated, which can be delayed increasing ozone dose.Overall, the presence of Mn in this cheap natural material and the dynamic cycle combining its reduced and oxidized forms, are the key for the outstanding activity observed.