Synthesis of CaWO4 nanoparticles and its application for the adsorption-degradation of organophosphorus cyanophos

Calcium tungstate (CaWO4) nanoparticles was successfully synthesized via the microwave route and characterized using Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Atomic force microscopy (AFM) instruments. This work focuses mainly on the adsorption-degradation reaction of cyanophos (O-4-cyanophenyl O, O-dimethyl phosphorothioate) as an organophosphorus pesticide on the CaWO4 nanoparticles and monitored by the P-31 nuclear magnetic resonance ((PNMR)-P-31) and Gas chromatograph-mass spectrometer (GC-MS). The effect of various experimental parameters including contact time, catalyst dose and initial concentration of cyanophos on the removal efficiency of this pesticide were studied. (PNMR)-P-31 results denoted that cyanophos was successfully removed by the catalyst with a yield more than 92% under optimized conditions. The parameters such as: contact time (180 min), catalyst dose (0.4 g/L), and initial pesticide concentration (5 mg/L) were investigated as optimized conditions for this reaction. Furthermore, the reaction kinetic information was studied by applying first order model. The values of the rate constant (k) and half life (t(1/2)) were determined as 0.0127 min(-1) and 54.5669 min, respectively. The main product resulted from degradation reaction between cyanophos and CaWO4 is dimethyl phosphorothioic acid (DMPA) which is less toxic than primary pesticide. (C) 2016 Elsevier Ltd. All rights reserved.