Photocatalytic degradation of gaseous toluene by using immobilized titania/silica on aluminum sheets

Purpose

The aim of this study was to prepare a highly active immobilized titania/silica photocatalyst and to test its performance in situ toward degradation of toluene as one of the major toxic indoor contaminants.

Methods

In this work, two different titania layers immobilized on Al sheets were synthesized via low temperature sol?Cgel method employing presynthesized highly active titania powders (Degussa P25 and Millennium PC500, mass ratio 1:1): (a) with a silica/titania binder and a protective layer and (b) without the binder. The photocatalysts were characterized by X-ray diffraction, nitrogen sorption measurements, scanning electron microscopy (SEM), infrared spectroscopy, and UV?Cvis diffuse reflectance spectroscopy (DRS). The in situ photocatalytic degradation of gaseous toluene was selected as a probe reaction to test photocatalytic activity and to verify the potential application of these materials for air remediation.

Results

Results show that nontransparent highly photocatalytically active coatings based on the silica/titania binder and homogeneously dispersed TiO₂ powders were obtained on the Al sheets. The crystalline structure of titania was not altered upon addition of the binder, which also prevented inhomogeneous agglomeration of particles on the photocatalyst surface. The photoactivity results indicate that the adsorption properties and photocatalytic activity of immobilized photocatalysts with the silica/titania binder and an underlying protective layer were very effective and additionally, they exhibited considerably improved adhesion and uniformity.

Conclusion

We present a new highly photocatalytically active immobilized catalyst on a convenient metallic support, which has a potential application in an air cleaning device.     

AIRPORT WASTES AND WATER QUALITY1

ABSTRACT: Waste waters from various operations at the Miami International Airport are characterized. Servicing, maintenance, overhauling, and washing of aircraft seem to be the most significant waste water producing operations. Pollutional constitutents commonly found in the airport wastes include acids, alkalis, detergents, oil, grease, and oxygen demanding substances. Phenols are of concern when stripping and repainting operations occur. Although most airport wastes may be treatable, a great reduction in influent load can be achieved by proper housekeeping methods.     

Thiram: degradation, applications and analytical methods

In this review a brief introduction to thiram (tetramethylthiuram disulfide; TMTD) pesticide has been given along with other applications. All the important methods available are systematically arranged and are listed under various techniques. Some of these methods have been applied for the determination of thiram in commercial formulations, synthetic mixtures in grains, vegetables and fruits. A comparison of different methods is the salient feature of this review.     

Health risk assessment for toxic emissions from a manufacturing facility

This paper presents the risk associated with the release of toxic chemicals from a manufacturing facility, following the State of California's approach to risk assessment. The facility emits five toxic substances from eight stacks. The building downwash is considered during dispersion calculations. The zone of impact, identified using a risk criteria (i.e. excess cancer risk of 10 in a million), is located in the southeast quandrant from the plant. The size of the impact area is 3.3 km². The cancer and non-cancer effects are considered for chromium (VI), benzene, formaldehyde, gasoline vapors, methylene chloride, and selenium using the California Air Pollution Control Officers Association Guidelines. No significant non-cancer effects are found due to the emissions. The maximum calculated risk is 1.197×10^-5 and is an extremely conservative value. Analysis shows that the use of realistic assumptions for exposure duration and unit risk factors during the risk calculations could reduce the zone of impact to 0 km².     

Lead-induced alterations in protein-deficient rat liver–role of zinc

This study was designed to determine the protective effects of zinc (Zn) using liver marker enzymes in the serum and liver along with hepatic elemental profile in lead (Pb)-treated protein-deficient (PD) Sprague–Dawley male rats. Zn in the form of zinc sulfate at a dose of 227?mg?L^?1 in drinking water was administrated to control, PD as well as Pb-treated PD rats for 8 weeks. Pb treatment was given orally as lead acetate at a dose level of 100?mg?kg^?1 body weight to control and PD rats. The effects of different treatments were studied on the activities of enzymes that included alkaline phosphatase (ALP), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum. The status of different elements (Cl, K, Mn, Fe, Cu, Zn, Se, Rb, Pb) in liver was also studied. Rats given PD diet and Pb showed significant inhibition in serum ALP activity associated with significant elevation in both AST and ALT activities. Serum ALP activity showed a significant inhibition week 1 until week 8 in Pb-treated PD rats. In contrast, serum AST activity was elevated both at 3 and 8 weeks while serum ALT activity was elevated at 8 weeks in Pb-treated PD rats. Pb treatment to PD rats elevated hepatic ALP, AST and ALT activities but depressed hepatic AST. Zn supplementation to Pb-treated PD rats restored the altered enzyme activities. The levels of K, Fe, Cu, Zn, Se and Rb were altered in protein deficiency. Furthermore, treatment with Pb to these animals depressed the Cu levels. Zn treatment to Pb-treated PD animals tended to restore the levels of altered elements. Hence, the present study clearly suggests that Zn plays an important role in regulating the liver marker enzymes and essential elements under conditions of Pb toxicity and protein deficiency.     

Ameliorating effect of N-acetylcysteine and curcumin on pesticide-induced oxidative DNA damage in human peripheral blood mononuclear cells

Endosulfan, malathion, and phosphamidon are widely used pesticides. Subchronic exposure to these contaminants commonly affects the central nervous system, immune, gastrointestinal, renal, and reproductive system. There effects have been attributed to increased oxidative stress. This study was conducted to examine the role of oxidative stress in genotoxicity following pesticide exposure using peripheral blood mononuclear cells (PBMC) in vitro. Further possible attenuation of genotoxicity was studied using N-acetylcysteine (NAC) and curcumin as known modulators of oxidative stress. Cultured mononuclear cells was isolated from peripheral blood of healthy volunteers, and exposed to varying concentrations of different pesticides: endosulfan, malathion, and phosphamidon for 6, 12, and 24 h. Lipid peroxidation was assessed by cellular malondialdehyde (MDA) level and DNA damage was quantified by measuring 8-hydroxy-2'-deoxyguanosine (8-OH-dG) using ELISA. Both MDA and 8-OH-dG were significantly increased in a dose-dependent manner following treatment with these pesticides. There was a significant decrease in MDA and 8-OH-dG levels in PBMC when co-treated with NAC or/and curcumin as compared to pesticide alone. These results indicate that pesticide-induced oxidative stress is probably responsible for the DNA damage, and NAC or curcumin attenuate this effect by counteracting the oxidative stress.     

Recent trends in microbial nanoparticle synthesis and potential application in environmental technology: a comprehensive review

Environmental Science and Pollution Research - Microbial technology comprising environment in various aspects of pollution monitoring, treatment of pollutants, and energy generation has been put...     

Underutilization of occupant restraint systems in motor vehicle injury crashes: A quantitative analysis from Qatar

Introduction: Restraint systems (seat belts and airbags) are important tools that improve vehicle occupant safety during motor vehicle crashes (MVCs). We aimed to identify the pattern and impact of the utilization of passenger restraint systems on the outcomes of MVC victims in Qatar.

Methods: A retrospective study was conducted for all admitted patients who sustained MVC-related injuries between March 2011 and March 2014 inclusive.

Results: Out of 2,730 road traffic injury cases, 1,830 (67%) sustained MVC-related injuries, of whom 88% were young males, 70% were expatriates, and 53% were drivers. The use of seat belts and airbags was documented in 26 and 2.5% of cases, respectively. Unrestrained passengers had greater injury severity scores, longer hospital stays, and higher rates of pneumonia and mortality compared to restrained passengers (P = .001 for all). There were 311 (17%) ejected cases. Seat belt use was significantly lower and the mortality rate was 3-fold higher in the ejected group compared to the nonejected group (P = .001). The overall mortality was 8.3%. On multivariate regression analysis, predictors of not using a seat belt were being a front seat passenger, driver, or Qatari national and young age. Unrestrained males had a 3-fold increase in mortality in comparison to unrestrained females. The risk of severe injury (relative risk [RR] = 1.82, 95% confidence interval [CI], 1.49–2.26, P = .001) and death (RR = 4.13, 95% CI, 2.31–7.38, P = .001) was significantly greater among unrestrained passengers.

Conclusion: The nonuse of seat belts is associated with worse outcomes during MVCs in Qatar. Our study highlights the lower rate of seat belt compliance in young car occupants that results in more severe injuries, longer hospital stays, and higher mortality rates. Therefore, we recommend more effective seat belt awareness and education campaigns, the enforcement of current seat belt laws, their extension to all vehicle occupants, and the adoption of proven interventions that will assure sustained behavioral changes toward improvements in seat belt use in Qatar.