Photodegradation of Emerging Contaminant 2-(tiocyanomethylthio) Benzothiazole (TCMTB) in Aqueous Solution: Kinetics and Transformation Products

• Published in: Bulletin of environmental contamination and toxicology Vol. 105; no. 3; pp. 433 - 439
• Main Authors: Bertoldi, Crislaine, de Cássia Campos Pena, Aline, Dallegrave, Alexsandro, Fernandes, Andreia N., Gutterres, Mariliz
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-09-2020; Springer Nature B.V
• Subjects: Algae; Aquatic plants; Aquatic Pollution; Aqueous solutions; Benzothiazole; Contaminants; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Genetic transformation; Industrial plants; Industrial pollution; Industrial wastes; Industrial wastewater; Industrial wastewater treatment; Mercury; Mercury (metal); Mercury lamps; Order parameters; Photodegradation; Photolysis; Pollution; Pressure; Soil Science & Conservation; Sunlight; Toxicity; Waste Water Technology; Wastewater treatment; Wastewater treatment plants; Water Management; Water Pollution Control; Sunlight photolysis; Transformation products; Emerging contaminant
• ISSN: 0007-4861; 1432-0800
• DOI: 10.1007/s00128-020-02954-2

Direct photolysis of the emerging contaminant 2-(thiocyanomethylthio) benzothiazole (TMCTB) was performed in aqueous solution at different concentrations with high-pressure mercury lamp (5.0, 8.0, 13.0, 16.0, 20.0, 23.0, 27.0, 35.0, 40.0, 45.0, and 50.0 mg L
− 1
) and with natural sunlight radiation (6.0, 30.0, and 60.0 mg L
− 1
). TCMTB underwent rapid degradation by direct photolysis with a high-pressure mercury lamp in aqueous solutions, with 99% removal after 30 min at all concentrations studied. For sunlight photolysis, TCMTB degradation was observed with 96%, 81%, and 64% removal for initial concentrations of 6.0, 30.0, and 60.0 mg L
− 1
, respectively, after 7 h of exposure to sunlight. The degradation of TCMTB in lab-scale wastewater had kinetic constant and t
1/2
in the same order when compared to the photodegradation of TCMTB in aqueous solutions. In addition, the results showed that photolysis with a high-pressure mercury lamp and sunlight were governed by the same kinetic order, however the kinetic parameters showed that degradation with sunlight was 40 times slower than photolysis with the mercury lamp. Twelve transformation products (TP) were identified, and eight of the TP have not been described in the literature. Furthermore, prediction of toxicity with ECOSAR software was carried out for fish, daphnids, and green algae species. It showed that photolytic treatment is efficient for reducing the toxicity of the compound, since the degradation formed compounds with lower toxicity than the primary compound. In conclusion, this study suggests that photolysis is an efficient way to remove the studied contaminant, and it highlights the potential of this technique for the degradation of emerging contaminants in industrial wastewater treatment plants.