Photodegradation of 2-mercaptobenzothiazole in the gamma-Fe(2)O(3)/oxalate suspension under UVA light irradiation.

The aim of this study is to investigate the effect of various factors on the photodegradation of organic pollutants in natural environment with co-existence of iron oxides and oxalic acid. 2-Mercaptobenzothiazole (MBT) was selected as a model pollutant, while gamma-Fe(2)O(3) was selected as iron oxide. The crystal structure and morphology of the prepared gamma-Fe(2)O(3) was determined by X-ray diffractograms (XRD) and scanning electron microscopy (SEM), respectively. The specific surface area was 14.36 m(2)/g by Brunauer-Emmett-Teller (BET) method. The adsorption behavior of gamma-Fe(2)O(3) was evaluated by Langmuir model. The effect of the dosage of iron oxide, initial concentration of oxalic acid (C(ox)(0)), initial pH value, the light intensity and additional transition metal cations on MBT photodegradation was investigated in the gamma-Fe(2)O(3)/oxalate suspension under UVA light irradiation. The optimal gamma-Fe(2)O(3) dosage was 0.4 g/L and the optimal C(ox)(0) was 0.8 mM with the UVA light intensity of 1800 mW/cm(2). And the optimal dosage of gamma-Fe(2)O(3) and C(ox)(0) for MBT degradation also depended strongly on the light intensity. The optimal gamma-Fe(2)O(3) dosage was 0.1, 0.25 and 0.4 g/L, and the optimal C(ox)(0) was 1.0, 0.8, and 0.8 mM with the light intensity of 600, 1200 and 1800 mW/cm(2), respectively. The optimal initial pH value was at 3.0. The additional transition metal cations including Cu(2+), Ni(2+) or Mn(2+) could significantly accelerate MBT degradation. This investigation will give a new insight to understanding the MBT photodegradation in natural environment.