Nanophotocatalytic UV degradation system for organophosphorus pesticides in water samples and analysis by Kubista model

The photocatalytic degradation of organophosphorus pesticides like methyl parathion (MP) and parathion (PA), under UV irradiation is studied using synthesized Zinc oxide (ZnO) nanocatalyst. Two cases were considered for removal of organophosphorus (OP) pesticides such as only UV (i.e. direct photolysis) and UV–ZnO nanocrystal. The Langmuir–Hinshelwood (L–H) relationship between the initial rate and the initial concentration indicates that the reaction occurs with the adsorbed substrate. Factors affecting the kinetics of the process such as quantum yield, electrical energy per order (EEO), dosage of nanophotocatalyst and L–H model have been discussed. The optimal conditions for degradation were obtained using 85 mg l−1 ZnO, 40% O2 (v/v) with rate constants L–H adsorption equilibrium constant (Kp = 0.127 for MP and 0.122 for PA) and rate constant of surface reaction (Kc = 0.212 for MP and 0.204 for PA). The kinetics of disappearance of OP pesticides (i.e. MP and PA) in water suspension using ZnO nanophotocatalyst illuminated at λ = 253.7 nm and examined. The quantum yield values for photodegradation of pesticides by photolysis and UV–ZnO process under the illumination of UV at 253.7 nm is calculated as 0.00072, 0.012 for MP; 0.00068 and 0.01 for PA. The EEO values for degradation of pesticide by photolysis for UV–ZnO was found to be 20,006, 1392.4 kWh m−3 for MP; 19,089 and 1387.2 kWh m−3 for PA

Extracellular microbial synthesis of gold nanoparticles using fungus Hormoconis resinae

In this study, the fungus Hormoconis resinae was screened from soil near a refi nery and was found to produce stable gold nanoparticles extracellularly.The kinetics of the reaction was studied using UV–Vis spectroscopy and was further characterized by x-ray diffraction, energy dispersive x-ray (EDX)analysis, and high-resolution transmission electron microscopy. These analyses revealed that the gold nanoparticles are spherical and in nano-regime. The most important feature of Hormoconis resinae fungi is the following fact: they have a widespread presence in soil and can produce huge biomass. Such a cheap source of material gives the opportunity for cost-effective preparation of various gold-based nanostructures