ABSTRACT
Background: Noise induced hearing loss [NIHL] is one of the most important occupational diseases worldwide. NIHL has been found to be potentiated by some of air pollutants. Exposure to noise plus carbon monoxide is common in occupational and environmental settings. This study was performed to evaluate the effect of noise and carbon monoxide exposure simultaneously on rabbits' hearing system by Auditory Brain stem Response [ABR] assessment
Materials and Methods: In this experimental study, 24 male adult white rabbits were divided to four groups: control group, noise exposure group, noise plus carbon monoxide exposure group and carbon monoxide exposure group. Auditory Brain stem Responses of the four groups were determined: before exposure, 1 hour after exposure and 14 days after exposure by click and tone burst stimulus
Results: The latency mean time of V wave in the ABR test for the group exposed to noise plus carbon monoxide, 1 hour after exposure at 1, 2, 4 and 8 KHz frequency were respectively 5.43+/-0.08, 5.50+/-0.07, 5.71+/-0.07 and 5.75+/-0.07 millisecond. These values were significantly more than the same values in the other groups
Conclusion: NIHL may be potentiated by carbon monoxide in the simultaneous exposure. Thus, it seems occupational and environmental exposure to noise plus carbon monoxide may increases hearing loss risk
ABSTRACT
Advanced oxidation processes such as Fenton reagent generates highly reactive hydroxyl free radicals to oxidize various compounds in the water and wastewater. The efficiency of different Fenton-related oxidative processes such as Fenton, solar-Fenton, UV-Fenton and Fenton reactions in different batch reactors was examined using benzene as pollutant in aqueous solutions. A batch study was conducted to optimize parameters like pH, hydrogen peroxide concentration, temperature, reaction time and ferrous ion concentration governing the Fenton process. The concentrations of produced phenol were measured at the end of the reactions. The role of sequence reaction was tested for decreasing phenol formation during benzene conversion. At optimum conditions, different Fenton-related processes were compared for the degradation of benzene. Increased degradation efficiency was observed in photo-Fenton processes as compared to conventional Fenton process. The formation of phenol in Fenton reaction depended on reaction time, sequence in reaction, purity of hydrogen peroxide and other compounds such as alcohols that contributed into the reaction. In the Fenton process, carboxylic acids like acetic acid and oxalic acid were formed as the end products during the complete degradation of benzene. With the increase in mono-valence, two-valence ions and hardness, Fenton's efficiency decreased, respectively. Sequence Fenton reaction produced less phenol and its end products had smaller COD as compared to conventional Fenton process
ABSTRACT
Ammonia in air can be hazardous to human and animal life and should be removed from the environment. Recently the removal of environmental pollutants such as ammonia by means of natural and modified zeolites has attracted a lot of attention and interests. In this study the capability of three Iranian natural zeolites [Clinoptilolite] in point of view of removal of ammonia from air was investigated. Through this research, different zeolites from various regions of Iran including Semnan, Meyaneh, and Firoozkooh resources were considered to be studied. These samples of zeolites were ground and granulized into 425 microm to 4 mm and were utilized in dynamic sorption experiments. Curves of sorption were plotted and breakthrough and saturated points of zeolite samples were obtained. The adsorption capacities at different ammonia concentrations, temperatures, and flow - rates were also calculated. Results obtained showed that, the natural Iranian zeolite [Clinoptilolite] was identified to be more efficient adsorbent than the others to remove ammonia from the air. In the same conditions, the obtained breakthrough time for clinoptilolite sample of Meyaneh was longer than the others [ 135min ], while, the adsorption capacity of Semnan clinoptilolite was higher than adsorbents [ 6.30 mg /g] [P<0.0001].