Degradation of four organophosphorous pesticides catalyzed by chitosan-metal coordination complexes

Abstract

Three types of chitosan with high (3.40 × 10(6)), medium (2.11 × 10(5)), and low (5.89 × 10(4)) molecular weights were chosen as ligands to synthesize chitosan magnesium, calcium, iron(III), and zinc coordination complexes. Degradation of four organophosphorous pesticides (dichlorvos, omethoate, dimethoate, and chlorpyrifos) by the above complexes in a heterogeneous system was studied using solid-phase extraction (SPE) and gas chromatography (GC). The degradation effect is related to the different types of chitosan, metal, and organophosphorus pesticides (OPs). Complexes of transition metals and the low molecular weight chitosan showed high hydrolytic activity. The chitosan-iron(III) complex was further used to study its catalytic kinetics on the hydrolysis of OPs. At pH 7.0 and 20 °C, the half-life of dichlorvos hydrolyzed by chitosan iron(III) was 52 h, whereas that of spontaneous dichlorvos hydrolysis was 105 h. The degradation ratio of omethoate and dimethoate increased to 38 and 52 %, respectively, which were 34 and 48 % higher than the control after 6 days at pH 7.0 and 20 °C. For all tested conditions, an increase of pH and temperature resulted in a higher degradation rate.

Utilization of Fly Ashes from the Coal Burning Processes to Produce Effective Low-Cost Sorbents

“…As follows from the literature data in the case of divalent ions, the capacity to sorb Zn(II) ions is higher than that for Ca(II). This indicated that the coordination selectivity of chitosan was independent of cation size or ion hardness 66 and their coordination occurs by the −OH and −NH 2 groups. Future application of the findings.…”

Photodegradation kinetics of organophosphorous with hydroxyl radicals: Experimental and theoretical study

“…6 Unfortunately due to the widespread use, OP compunds have been detected in water, soil, even in the fruits and vegetables. 7 It has been determined that the amount of OP in water is up to 506.6 µg L -1 . 8 OPs pose serious threats to human health with harmful effects such as cytotoxicity, immunotoxicity, genotoxicity, and the joint effect of different OPs may pose a more toxic to health.…”

Biodegradation of omethoate by Bacillus sp. YB-10: optimization of culture conditions and degradation characteristics

“…Omethoate (O,O-dimethyl-S-methylcarbamoylmethylthiophosphate, C 5 H 12 NO 4 PS) is one of the acute organophosphorus pesticides that are widely used to prevent, destroy, repel, or mitigate agricultural and domestic insects in developing countries [1][2][3][4]. For example, 8,000 tons of omethoate are applied to agricultural crops annually in China [5].…”