Volatile organic compounds (VOCs) emitted from industrial gas cause equipment failure and fire accidents due to the rapid flow and concentration changes of VOCs. Therefore, it is crucial to attenuate the concentration of VOCs to ensure a constant emission rate before the control process. This study proposed an encapsulation technique to fabricate calcium- alginate gel beads containing paraffin oil as an effective absorbent. The prepared absorbent was physically characterized, and a column test observed its absorption capacity. When the oil content was 30%, the prepared beads showed the best spherical shape, attaining 96% emulsion stability, 0.014 sphericity factor, 62.7% weight variation ratio, and 4.21 ± 0.06mm diameter. In the column test that was packed with the prepared beads, the toluene absorption capacity was 497.6mg/kg. The net effect of the beads was to attenuate the peaks of toluene concentration, and to make the VOC-laden air stream more receptive for the subsequent treatment unit.

Two lab-scale trickle-bed type biofilters with a single fungal species (Aspergillus fumigatus, Acidomyces acidophilus, respectively) have been studied to investigate the simultaneous removal of inorganic (hydrogen sulfide) and organic (butyl acetate) compounds. The biofilter with Aspergillus fumigatus treated simultaneously two different compounds with removal capacity of 1,511 mgS/m3/hr and 6,324 mgC/m3/hr; and the biofilter inoculated with Acidomyces acidophilus had the removal capacity of 1,254 mgS/m3/hr and 6,045 mgC/m3/hr. Stable operational performance was observed in both biofilters under an acidic condition of pH 2 to 4. Based on pseudo-first-order removal rates as a function of depth in the biofilter, Aspergillus fumigatus showed a twice faster rate of hydrogen sulfide removal than Acidomyces acidophilus, 15.9% (Aspergillus fumigatus) and 17.9% (Acidomyces acidophilus) of total sulfur removed were oxidized to produce sulfates, and 77.8% (Aspergillus fumigatus) and 79.4% (Acidomyces acidophilus) were accumulated in the form of S0 through the bed in both biofilters, respectively.

This study was conducted to evaluate the applicability of a carrier media with natural minerals as packing material in a biofilter to remove odor-causing compounds. The carriers were prepared by mixing powdered zeolite, barley stone, and clay. They have a pellet type with a length of 5m m to 10 mm, 3.2 m2/g of a specific surface area, and 0.04 cm3/g of a pore volume. The adsorption capacity and the biodegradation by biomass formation on the media were experimented with toluene and ammonia as the test compounds. The carrier possessed the ability to adsorb toluene and ammonia. The adsorption capacity of toluene and ammonia at the inlet concentration of 100 ppmv was 58 g/g and 96 g/g, respectively. In the biofilter using the carrier as the packing material, the biofilter performances were different depending on the supply of moisture and liquid-nutrient. The critical loading was found to be 33.13 g/m3/hr for toluene removal and 6.5g /m3/hr for ammonia removal even when no nutrients were supplied. The proposed material has been confirmed to be capable of adsorbing inorganic and organic compounds, and can be effectively applied as packing materials for the biofiltration.

In this study, the effects of Sm addition (0, 0.05, 0.2, 0.5 wt%) on the microstructure, hardness, and electrical and thermal conductivity of Al-11Si-1.5Cu aluminum alloy were investigated. As a result of Sm addition, increment in the amount of α-Al and refinement of primary Si from 70 to 10 μm were observed due to eutectic temperature depression. On the other hand, Sm was less effective at refining eutectic Si because of insufficient addition. The phase analysis results indicated that Sm-rich intermetallic phases such as Al-Fe-Mg-Si and Al-Si-Cu formed and led to decrements in the amount of primary Si and eutectic Si. These microstructure changes affected not only the hardness but also the electrical and thermal conductivity. When 0.5 wt% Sm was added to the alloy, hardness increased from 84.4 to 91.3 Hv, and electric conductivity increased from 15.14 to 16.97 MS/m. Thermal conductivity greatly increased from 133 to 157 W/m·K.

Titanium dioxide (TiO2) is a typical inorganic material that has an excellent photocatalytic property and a high refractive index. It is used in water/air purifiers, solar cells, white pigments, refractory materials, semiconductors, etc.; its demand is continuously increasing. In this study, anatase and rutile phase titanium dioxide is prepared using hydroxyl and carboxyl; the titanium complex and its mechanism are investigated. As a result of analyzing the phase transition characteristics by a heat treatment temperature using a titanium complex having a hydroxyl group and a carboxyl group, it is confirmed that the material properties were different from each other and that the anatase and rutile phase contents can be controlled. The titanium complexes prepared in this study show different characteristics from the titania-formation temperatures of the known anatase and rutile phases. It is inferred that this is due to the change of electrostatic adsorption behavior due to the complexing function of the oxygen sharing point, which crystals of the TiO6 structure share.

The Odor-causing compounds from grilled meat restaurants are mainly ammonia, aldehydes, and volatile organic compounds (VOCs). Acetaldehyde is known to have the greatest odor contribution. This study examines the application of silica gel for acetaldehyde in gas stream. Heat-pretreated silica gel showed relatively good adsorption performance and at 150oC, its breakthrough capacity reached up to 51 mg/g. By using Thomas' dynamic model, which well estimated the adsorption performance in this study, the effects of inlet concentration and retention time on adsorption capacity were evaluated. The adsorbent saturated with acetaldehyde was regenerated by reducing the pressure, which was controlled by the vacuum pump. The design factors were found to be 10 sec−1 of space velocity, -184 kPa·hr of desorption condition, and 10 to 1 of the ratio of cross sectional area to the height for the fixed-bed. The cyclic operation of adsorption and desorption step in the fixed bed packed with silica gel appeared to have 7.0-8.8 mg/g of acetaldehyde removal capacity and 99% of regeneration.

The objective of this study was to investigate the effect of shoe dust on the indoor environment, and the effectiveness of shoe dust control on indoor air quality. Test dust was resuspended to reach a mass concentration of particles (2.5-10 μm size) more than 3 times compared to background level, and 1.5 times for particles less than 1 μm in size. The shoes, which were used for actual walking purposes in the outdoor environment, increased indoor PM10 concentration by 118±9%. The removal of shoe dust by water washing and mechanical suction brought about an improvement of indoor air quality. In particular, in circumstances where 27 people walked for one hour into the indoor environment, the mechanical suction of shoe dust decreased PM10 concentration by about 17% (based on the mass balance analysis).

We analyzed volatile organic compounds (VOCs) of petroleum-based laundry solvents in closed systems by static headspace analysis and investigated the emission characteristics of odorous compounds emitted from organic solvents in the small-scale dry cleaning process. The compounds containing eight to eleven carbon atoms were analyzed to account for 96.92% of the total peak area in a GC-MS chromatogram. It was found that the compounds with ten carbon atoms showed the largest proportion. In the small-scale dry cleaning process (3 kg of laundry and 40 min of drying time), a total of 36 VOCs was quantified, and the odor contribution of these compounds was evaluated. The sum of the odor quotient (SOQ) was analyzed up to 151±163 in the first 12 min of operation. The main odor-causing compounds were acrolein, ethylbenzene, hexane, acetone, and decane, and their odor contributions were 32.28%, 13.47%, 10.52%, 10.20%, and 8.08%, respectively.

Indoor Volatile organic compounds (VOCs) are classified as known or possible toxicants and odorants. This study characterized VOC levels in 11 homes in an area in the capital of Seoul by using two different methods of VOCs sampling, which are the active sampling using a thermal sorption tube and the passive sampling using a diffusion sampler. When using the active sampling method, the total target VOC concentration ranged from 41.7 to 420.7 μg/ m3 (mean 230.4 μg/m3; median 221.8 μg/m3) during winter and 21.3 to 1,431.9 μg/m3 (mean 340.1 μg/m3; median 175.4 μg/m3) during summer. When using the passive method, 29.6 to 257.5 μg/m3 (mean 81.8 μg/m3; median 49.4 μg/m3) during winter and 1.2 to 5,131.1 μg/m3 (mean 1,758.8 μg/m3; median 1,375.1 μg/m3) during summer. Forty-nine VOCs were quantified and toluene showed the highest concentration regardless of the season and the sampling method studied. The distribution of VOCs was relatively varied by using the active method. However, it showed a low correlation with indoor environmental factors such as room temperature, humidity and ventilation time. The correlation between indoor environmental factors and VOCs were relatively high in the passive method. In particular, these characteristics were confirmed by principal component analysis.

A lab-scale biofilter with fungal growth has been studied to investigate the removal of gas-phase hydrogen sulfide. The biofilter inoculated initially with the aerobic activated sludge was operated for 100 days under acidic condition, and 0.36 L/d of the buffered nutrient with 0.05 g/L Chloramphenicol and Gentamicin was injected into the biofilter. The critical removal capacity of hydrogen sulfide was up to 22 g/m³/h. The pH of the effluent liquid was stable at pH 1.5-2, corresponding to the volatile suspended solids of 20-50 mg/L. In microbial analysis through the plate count method, it was found that fungi were dominant over bacteria. The fungi isolated from biomass in the bilfilter were identified as Acidomyces acidophilus and Aspergillus fumigatus. Sulfate and thiosulfate were also detected in liquid samples, as a result of the biological sulfur oxidation in the biofilter bed. For the analysis of sulfur mass balance, the accumulated mass of sulfate and thiosulfate reached up to 67.5% of inlet sulfur. Sulfur was also detected on the biomass collected from the biofilter through Scanning electron microscopy/Energy dispersive X-ray spectroscopy.

Two sewage treatment facilities were selected to identify odor emission characteristics, focusing on volatile organic compounds (VOCs) and sulfur compounds. The complex odor, 5 kinds of sulfur compounds and 23 kinds of VOCs were analyzed from gas and sludge storages. Hydrogen sulfide was detected in the highest concentration and had the highest odor quotient among the odorous compounds monitored in this study, demonstrating that the contribution of hydrogen sulfide to the complex odor reached up to 90%. For VOCs, the overall contribution to the complex odor was not critical but VOCs can sufficiently trigger an odorous sensation because the sum of the odor quotient reached up to 2.89.

The labeled magnitude scale (LMS) was proposed as the magnitude estimation of perceived odor intensity while the direct olfactory method is a basis of odor evaluation. Six chemicals (pyridine, ethanol, ethyl acetate, acetone, trimethylamine, and β-phenylethyl alcohol) were tested to demonstrate the limitation of the current odor intensity scale and the possibility of the alternative method. The 6-point odor intensity reference scale, which is wildly used in the field, has the inevitable limitation of the perceived magnitude of odor intensity. It has failed to express the magnitude objectively when odor intensity increased and the magnitude scale was limited. It was experimentally proven that LMS presents the function of the existing method and effectively evaluates the wide range of odor intensity.