Application of microwave irradiation for the treatment of adsorbed volatile organic compounds on granular activated carbon

The purpose of this laboratory scale experimental research was to investigate the application of integrated microwave irradiation and granular activated carbon adsorption for removing volatile organic compounds [VOCs] from emissions released from industrial processes and considered major pollutants of the environment. A stream containing 300 ppm toluene was supplied and passed through the granular activated carbon [GAC]. The saturated adsorbent was placed in a quartz glass reactor and treated by microwave [MW] irradiation at heating frequency of 2450 MHz at different power levels. Adsorption capacity was evaluated through breakthrough curves and the residue analyzed by gas chromatography. Breakthrough results showed that the high relative humidity of the inlet gaseous stream could lead to decreased GAC adsorption capacity. We found that GAC could absorb microwave irradiation and dissipate heating energy increasing its temperature up to 600 Degree C in a short time mainly depending on the microwave power level. Our experimental results indicated that most of the toluene vapor passed over GAC was decomposed under 900 watt microwave irradiation after around 10 minutes. The addition of water vapor in the inlet stream slightly decreased pollutant removal rate over the GAC while the overall oxidation removal remain the same compared to stream with low content of water vapor. Adsorption isotherms showed that GAC surface area and porosity values increased slightly under microwave irradiation. We concluded that simultaneous application of GAC and microwave irradiation may be an effective approach for removing VOCs from gaseous stream

Fluoride compounds and their biological effects in aluminum potroom

Respiratory system disorders occur in aluminum potroom workers despite pre-employment medical examinations. The aims of this study were to measure fluoride and its compounds in the potroom workplace atmosphere as well as workers' breathing zone air, examine the blood eozinophile cells count in the workers exposed to the fluoride compounds, and evaluate the respiratory symptoms and dysfunctions caused during the occupational exposure in potroom workers. To achieve these objectives, a study was carried out in 10 workplaces [potrooms] of Aluminum Producing Plants in Arak city located at Central Iran. Through this study, the data obtained from 160 workers [100 cases and 60 controls] were statically processed. The selected controls were matched for age, year of starting employment, smoking habit, and body mass index [BMI]. The total fluoride compounds concentration of potroom, mean concentration of workers' breathing zone air at different job positions were measured showed high concentration compared to the Threshold Limit Value-Time Weighted Average [TLV-TWA]. The incidence of respiratory symptoms, the number of blood eozinophile, and WBC counts were higher than normal range in case group. During this study, the susceptible aluminum potroom workers to occupational asthma were also identified. Through this study, it was concluded that, workers employing in the potroom in aluminum industries are at risk for respiratory disorders and a continuous workplace monitoring is needed to evaluate workers exposures