Degradation of parathion and the reduction of acute toxicity in TiO2 photocatalysis

Abstract

Photocatalytic degradation of methyl parathion was done using a circulating TiO2/UV and TiO2/solar reactor. Indoor experimental results showed that, under the photocatalysis conditions, parathion was more effectively degraded than under the photolysis and TiO2 only conditions. Parathion (38 microM) was completely degraded under photocatalysis within 90 min, and more than 80% TOC decrease after 150 minutes. The main ionic byproducts during the photocatalysis were measured, and almost complete nitrogen recovery was achieved as mainly NO3- NO2-, and NH4+, and 80% of sulfur as recovered as SO4(2)-. Organic intermediates such as nitrophenol and methyl paraoxon were also identified during the photocatalysis of parathion, and these were further degraded after 90 minutes. Microtox bioassay using Vibrio fischeri was used in evaluating the toxicity of solutions treated by photocatalysis and photolysis of parathion. The results showed that the acute toxicity expressed as EC50 almost reduced after 90 min under the photocatalysis condition whereas only 40% reduction of toxicity as EC50 was achieved in photolysis condition. The outdoor results using a TiO2/solar system were similar to the TiO2 indoor system, indicating the possibility of applying TiO2/solar system for the treatment of parathion-contaminated water.

Degradation and byproduct formation of parathion in aqueous solutions by UV and UV/H2O2 treatment

“…This fact indicates that oxidation is the primary pathway for the phototransformation process and a fraction of the produced NO 2 − was subsequently oxidized to NO 3 − . Similar phenomena have also been reported in the TiO 2 photocatalysis of parathion (Zoh and Stenstrom, 2002; Zoh et al, 2005). No NH 4 + was observed in either process, which can be attributed to the oxidative environment of the treatments.…”

Exogenous Physical Irradiation on Titania Semiconductors: Materials Chemistry and Tumor‐Specific Nanomedicine

“…Actually, the biological effects and biocompatibility of titania‐based compound or micro/nanoparticles have been broadly investigated in the past decade, which has also been summarized and discussed in some excellent reviews . Therefore, this review herein focuses more on the biocompatibility and biosafety of some rationally designed novel titania‐based nanoplatforms with unique responsiveness to exogenous physical irradiations.…”

Advanced Oxidation Processes (AOPs) for Removal of Pesticides from Aqueous Media

“…Vinclozoline Hustert and Moza, 1997. Dieldrin Ormad et al, 2010Parathion Zoh et al, 2005Chen et al, 1996;Chiron et al,1997;Herrmann, 1999;Sakkas et al, 2002Pendimetalin Mansour, 1997Moza et al, 1992Diquat Florencio et al, 2004Kinkennon et al, 1995. Paration-metil Sakellarides et al, 2004;Zoh et al, 2005Zoh et al, ,2006 Evgenidou et al, 2007b;Ormad et al, 2010Dimethoate Oller et al, 2006Domínguez et al, 1998;Evgenidou et al, 2006;Ormad et al, 2010PCDD Barbeni et al, 1986Pelizzetti, 1985Diuron Canle et al, 2005Kinkennon et al,1995;Muneer et al, 1998;Farre et al, 2005;Katsumata et al, 2009;Macounova et al, 2003;Ormad et al, 2010PCDF Barbeni et al, 1986Pelizzetti, 1985. Table 3.…”