Degradation of herbicide paraquat by Fenton reagent and UV light irradiation

Fenton 시약 및 UV 광 조사에 의한 제초제 paraquat의 분해

  • Kim, Byung-Ha (Department of Agricultural Chemistry, College of Agriculture, Kyungpook National University) ;
  • Ahn, Mi-Youn (Department of Agricultural Chemistry, College of Agriculture, Kyungpook National University) ;
  • Kim, Jang-Eok (Department of Agricultural Chemistry, College of Agriculture, Kyungpook National University)
  • 김병하 (경북대학교 농과대학 농화학과) ;
  • 안미연 (경북대학교 농과대학 농화학과) ;
  • 김장억 (경북대학교 농과대학 농화학과)
  • Published : 1999.12.30

Abstract

This study was to investigate the potential degradation of a herbicide paraquat by Fenton reagents(ferric ion and hydrogen peroxide) under UV light irradiation(365 nm) in an aqueous solution. When $10{\sim}500$ mg/L of paraquat was reacted with either ferric ion or hydrogen peroxide in the dark or under UV light, no degradation was occurred. However, the simultaneous application of both ferric ion(0.8 mM) and hydrogen peroxide(0.140 M) in paraquat solution(500 mg/L) caused dramatic degradation of paraquat both in the dark (approximately 78%) and under UV light(approximately 90%). The reaction approached an equilibrium state in 10 hours. In the dark, when $0.2{\sim}0.8$ mM ferric ion was added, $20{\sim}70%$ paraquat of $10{\sim}500$ mg/L was degraded, regardless of hydrogen peroxide concentrations($0.035{\sim}0.140$ M), while under UV light, 95% of 10 and 100 mg/L paraquat was degraded regardless of ferric ion and hydrogen peroxide concentrations. At paraquat concentration of 200 and 500 mg/L, paraquat degradation increased with increasing ferric ion concentrations as in the dark. However the increase in hydrogen peroxide concentration did not affect the extent of paraquat degradation. The initial reaction rate constants(k) for paraquat degradation ranged from 0.0004 to 0.0314, and 0.0023 to 0.0367 in the dark and under UV light, respectively. The initial reaction rate constant increased in proportion to the increase in ferric ion concentration in both conditions. The half-lives of paraquat degradation(t1/2) were 20 - 1,980 and 19 - 303 minutes in the dark and under UV light, respectively. This study indicates that Fenton reagents under UV light irradiation are more potent than in the dark in terms of herbicide paraquat degradation in an aqueous solution.

Keywords

Fenton reagent;UV light;paraquat;ferric ion;hydrogen peroxide;reaction rate constant;half life;oxidizing agent