Photocatalytic degradation of the insecticide acetamiprid on TiO2 catalyst

Abstract

O trabalho está relacionado com a degradação fotocatalítica da acetamipride, uma base piridínica amplamente utilizada em inseticida neonicotinóides, em suspensões aquosas de O 2 /TiO 2 irradiada por UV. A taxa de degradação foi estudada por HPLC/DAD e espectrofotometria UV. Verificou-se que a reação é de pseudo-primeira ordem, no intervalo de concentração de (0,5-2,0 mg cm-3). A análise de RMN de 1 H indicou que além do acetaldeído, ácido fórmico e acético, foram formados intermediários contendo piridina (por exemplo, o ácido 6-chloronicotínico). Medidas por CLAE/EM revelaram também a presença da degradação de aromáticos intermediários. Durante o processo fotocatalítico o pH sofreu alteração de três unidades, de 5 a 2. Em contraste com os resultados obtidos nas condições experimentais na degradação fotocatalítica, a acetamipride mostrou-se estável. Para ter uma visão específica do complexo processo fotocatalítico da acetamipride, a degradação fotocatalítica do ácido 6-cloronicotínico, também foi investigada o produto detectado da degradação da base piridínica. The work is concerned with the photocatalytic degradation of acetamiprid, a widely used pyridine-based neonicotinoid insecticide, in UV-irradiated aqueous suspensions of O 2 /TiO 2. The rate of degradation was studied by HPLC/DAD and UV spectrophotometry. It was found that the reaction in the investigated concentration range (0.5-2.0 mg cm-3) is of a pseudo-first order. The 1 H NMR analysis indicated that beside acetaldehyde, formic and acetic acid, pyridine-containing intermediates (e.g. 6-chloronicotinic acid) formed during the process. The HPLC/MS measurements also proved the presence of aromatic degradation intermediates. During the photocatalytic process the pH changed by even three units, from 5 to 2. In contrast to the photocatalytic results in the photolytic experimental conditions, acetamiprid appeared to be stable. To get a deeper insight into the complex photocatalytic process of acetamiprid, the photocatalytic degradation of 6-chloronicotinic acid, the detected pyridine-based degradation product, was also investigated.

Biodegradation of the neonicotinoid insecticide acetamiprid in surface water by the bacterium Variovorax boronicumulans CGMCC 4969 and its enzymatic mechanism

“…11 The AAP residues in water may affect the sensitive aquatic invertebrates living in it and therefore produce risks to the ecosystem. AAP is known to be stable under alkaline conditions and can persist for more than 30 d. 12 Elimination of AAP residues from the environment by chemical and photochemical methods have been largely reported. Khan et al reported heterogeneous photocatalysed degradation of AAP in aqueous suspensions of a semiconductor.…”

Determination of H2O2 by MnO2 modified screen printed carbon electrode during Fenton and visible light-assisted photo-Fenton based removal of acetamiprid from water

“…The photostability and degradation of ACT in the presence of TiO 2 [5][6][7][8], Ag doped-TiO 2 [9], under UV irradiation [10] or using Fenton-based processes have been investigated so far [11,12].…”

Comparison of different iron-based catalysts for photocatalytic removal of imidacloprid

“…Chemical catalytic systems such as Fenton and photo-Fenton catalytic reactions [1][2][3], H 2 O 2 /UV process [4], and TiO 2 -mediated photocatalysis [5][6][7][8][9][10] have been used under a range of experimental conditions to reduce the toxicity of a variety of organic pollutants. In the case of homogenous catalysis like photo-Fenton reactions, the iron ions remain in the water solution at the end of the process.…”

“…Imidacloprid ((EZ)-1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine) is the most frequently used insecticide from the group of neonicotinoids. There are numerous literature reports on the oxidation and hydrolysis studies of this insecticide and its formulated products [2,3,9,10,12,[16][17][18][19][20][21][22][23]. Our recent studies showed that the O 2 /TiO 2 , UVA light system (400-320 nm) can be successfully applied for the photocatalytic removal of pyridine-based neonicotinoids such as imidacloprid [9] and acetamiprid [9,10].…”