Performance catalytic ozonation over the carbosieve in the removal of toluene from waste air stream

Toluene is a volatile organic compound, one of 189 hazardous air pollutants [HAP[s]] and the most important pollutant found in most industries and indoor environments; owing to its adverse health, toluene must be treated before being released into the environment. In this research study, a continuous-flow system [including an air compressor, silica gel filters and activated charcoal, impinger, an ozone generation and a fixed bed reactor packed with the carbosieve in size 1.8-2.3 mm, specific surface: 972 m[2]/g,] was used. This glass reactor was 0.7 m in height; at a distance of 0.2 m from its bottom, a mesh plane was installed so as to hold the adsorbent. Moreover, 3 l/min oxygen passed through this system, 0.43 g/h ozone was prepared. The flow rate of waste airstream was 300 ml/min. The efficiency of this system for removal of toluene was compared under the same experimental conditions. Under similar conditions, performance of catalytic ozonation was better in toluene removal than that of ozonation and carbosieve alone. On average, increasing the removal efficiency was 45% at all concentrations. When carbosieve and ozone come together, their synergistic effects increased on toluene degradation. Catalytic ozonation is a suitable, high-efficient and available method for removing toluene from various concentrations of waste air stream. This process due to the short contact time, low energy consuming and making use of cheap catalysts can be used as a novel process for removing various concentrations of volatile organic compounds

Study on the performance of wet electroscrubber in purifying airborne particles

In this study, an electroscrubber was designed and experimented for evaluation of integrating particle and droplet charging effects separately and jointly on collection efficiency of a spray tower and also to discover the optimal condition. A homogenous concentration of relatively fine particles was introduced to influent air stream and electroscrubber efficiency in purifying them was determined through the measurement of input and output particles concentration. The effect of various conditions such as particles and droplets charging alone and together [bipolar] for several applied voltages has been studied. In all of experiments, the applied charging voltage has a key role in promotion of electroscrubber efficiency. Maximum collection efficiency has achieved for 15 Kilovolt [Kv]. The effectiveness of bipolar charging of particles and droplets with 15 Kv was higher than that of no-charging and singly charging. In other words, efficiency can be increased from 84.43% to 93.22 for total particles and from 50.8% to 75.16% for submicron particles. The maximum improvement of collection efficiency [42.2%] relates to bipolar charging of the initial size group with diameter smaller than 0.3 micrometer [microm] and the minimum [0.5%] to sizing group of 11 with diameter 4-5 microm. This approach can be an appropriate option for the purpose of purifying submicron particles in spray tower scrubbers

Investigation of qualitative and quantitative of volatile organic compounds of ambient air in the Mahshahr petrochemical complex in 2009

Volatile organic compounds [VOCs] are human-made chemicals widely spread in the environment and produced by petrochemical industries and petroleum refineries. The aim of this research was to evaluate the distribution of VOCs in the ambient air of Mahshahr Petrochemical Complex, Iran. This study was a cross-sectional research performed in 2009. We used the method numbered 1501, 1500, 2000, 1003, 1005, 1010, 2555, 1300 and 1400 of the National Institute of Occupational Safety and Health [NIOSH] for the sampling and analysis of compounds in the air. A total of 204 samples were analyzed using Gas Chroma-tography-Mass Spectrometry [GC-MS] and a Gas Chromatography-Flame Ionization Detector [GC-FID]. The mean of concentrations of the pollutants in the winter is less than in summer and a strong variation occurred among the sampling site, attributed to the change in meteorology. The results indicated high concentrations of benzene in most factories. In addition, a significant difference occurred between the concentrations of the compounds in the ambient air inside and outside the factories in both seasons [P<0.050]. It seems that the atmospheric conditions of the workplace affect the spreading of the pollutants, causing the concentration of the pollutants in the summer to be higher than in the winter. In addition, the frequent prevailing wind speed in the region plays a major role in the distribution of the pollutants from Mahshahr Petrochemical factories