The purpose of this work is to study the adsorption and desorption characteristics of acetone vapor and toluene vapor from adsorption tower in the VOCs recovery device. The six kinds of activated carbon with different pore structures were used and the adsorption and desorption characteristics were compared according to pore structure, desorption temperature, and adsorption method, respectively. Adsorption capacity of acetone vapor and toluene vapor by batch method was higher than that by dynamic method. Especially, activated carbon with medium-sized or large pores had more difference in adsorption capacity according to adsorption methods as a result of gradually condensation of vapors on relatively mesopore and large pores. Activated carbons with relatively large pores and relatively small saturated adsorption capacity had excellent desorption ability.

Unlike water applications, the photocatalytic technique utilizing light-emitting-diodes as an alternative light source to conventional lamp has rarely been applied for low-level indoor air purification. Accordingly, this study investigated the applicability of UV-LED to annular-type photocatalytic reactor for removal of indoor-level benzene and toluene at a low concentration range associated with indoor air quality issues. The characteristics of photocatalyst was determined using an X-ray diffraction meter and a scanning electron microscope. The photocatalyst baked at 350 ℃ exhibited the highest photocatalytic degradation efficiencies(PDEs) for both benzene and toluene, and the photocatalysts baked at three higher temperatures(450, 550, and 650 ℃) did similar PDEs for these compounds. The average PDEs over a 3-h period were 81% for benzene and close to 100% for toluene regarding the photocatalyst baked at 350 ℃, whereas they were 61 and 74% for benzene and toluene, respectively, regarding the photocatalyst baked at 650 ℃. As the light intensity increased from 2.4 to 3.5 MW cm-1, the average PDE increased from 36 to 81% and from 44% to close to 100% for benzene and toluene, respectively. In addition, as the flow rate increased from 0.1 to 0.5 L min-1, the average PDE decreased from 81% to close to zero and from close to 100% to 7% for benzene and toluene, respectively. It was found that the annular-type photocatalytic reactor inner-inserted with UV-LEDs can effectively be applied for the decomposition of low-level benzene and toluene under the operational conditions used in this study.

Toluene desorption of modified activated carbon for microwave irradiation was evaluated. As a virgin GAC reacted from microwave energy, it created an "arcing" between GAC particles in desorption process. The arcing became more and more vigorous and achieved a red flame of GAC. The silica coated GAC(Si/GAC) was developed to prevent arcing phenomenon and temperature control problem. The result shows virgin GAC with 5wt%, 10wt% and 20wt% silica had no arcing and could control temperature very well. However, the adsorption rate of Si/GAC was decreased by coated silica amount due to decreasing surface area of GAC. The 5wt% Si/GAC adsorption rate was quite similar to virgin GAC adsorption rate. After adsorption, the toluene-loaded GAC and Si/GAC was reactivated by 2450MHz MW irradiation with 300W for 5 min. Quantitative desorption of the toluene was achieved at MW irradiation at 300W with desorption efficiencies as high as 98.59% to 84.65%% after four cycles.

○ 우리나라에 자생하는 관목류 중에서 공기정화 능력이 우수한 식물을 선발하고자 톨루엔 제거 효과 측정 - 관목류 중에서는 소나무, 만병초 그리고 자금우의 톨루엔 제거 효율이 가장 높았다. 그 다음이 호랑가시나무, 광나무, 녹나무 순이었으며, 돈나무와 산호수가 가장 저조한 것으로 나타났다. - 소나무는 실내에서 기를 경우 햇빛이 부족해 기르기가 어렵다. 따라서 가정이나 사무실 등의 실내 공간에서 일반 소비자가 톨루엔 제거를 위해 식물을 기를 경우에는 자금우, 만병초가 가장 우수하다. - 돈나무는 포름알데히드 제거 효율이 매우 높은 반면, 톨루엔 제거 효율은 가장 낮았다. ○ 이끼류에 대한 톨루엔 제거 효과를 측정 - 이끼류는 새집증후군 원인물질인 톨루엔 제거에 매우 효과적인 것으로 나타났다. - 이끼류의 종류별로는 톨루엔 제거 효율의 차이가 거의 없었다. - 식물 상호간에 제거 효율을 비교하기 위해서는 단위엽면적당 톨루엔 제거 효율로 계산하는데 이끼류는 엽면적을 측정할 수 없어 이끼가 놓인 표면적을 기준으로 계산하였다. 실질적으로 엽면적은 표면적보다 클 것으로 보인다. - 엽면적으로 계산한 관목류와 표면적으로 계산한 이끼류를 서로 비교하는 것은 원칙적으로 불가능하다. 그러나 실질적으로 이끼류가 톨루엔 제거에 상당히 효과적이었다.

This paper describes the adsorption/desorpton efficiency of a modified activated carbon by irradiated microwave to treat toluene. By employing microwave energy, the regeneration time was considerably shortened compared with conventional thermal heating regeneration. New adsorbent called ACB(Activated Carbon-Bentonite) was prepared from powder activated carbon with mixing bentonite as a binder. Specific surface area, average pore size and total pore volume of ACB were calculated from the nitrogen adsorption/desorption isotherm. The surface of ACB was characterized with scanning electron microscope(SEM). The results showed that the specific surface area, total pore volume, average pore size of ABC was not influenced by regenerating cycle with microwave irradiation. Toluene was adsorbed onto ACB which desorbed by MW irradiation. Absorption capacity of ACB was 0.117 gtoluene/ gACB. Desorption efficiency of toluene increased as higher microwave output was applied.

Simultaneous removal of NH3, H2S and toluene in a contaminated air stream was investigated over 185 days in a biofilter packed with Zeocarbon granule as microbial support. In this study, multi-microorganisms including Nitrosomonas and Nitrobacter for nitrogen removal, Thiobacillus thioparus (ATCC 23645) for H2S removal, and Pseudomonas aeruginosa (ATCC 15692), Pseudomonas putida (ATCC 17484) and Pseudomonas putida (ATCC 23973) for toluene removal were used simultaneously. The empty bed residence time (EBRT) was 40-120 seconds and the feed (inlet) concentrations of NH3, H2S and toluene were 0.02-0.11, 0.05-0.23 and 0.15-0.21 ppmv, respectively. The observed removal efficiency was 85%-99% for NH3, 100% for H2S, and 20-90% for toluene, respectively. The maximum elimination capacities were 9.3, 20.6 and 17 g/m3/hr for NH3, H2S and toluene, respectively. The results of kinetic model analysis showed that there were no particular evidences of interactions or inhibitions among the microorganisms, and that the three biodegradation reactions took place independently within a finite area of biofilm developed on the surface of the Zeocarbon carrier.

The photodegradation and by-products of the gaseous toluene with TiO2 (P25) and short-wavelength UV (UV254+185nm) radiation were studied. The toluene was decomposed and mineralized efficiently owed to the synergistic effect of photochemical oxidation in the gas phase and photocatalytic oxidation on the TiO2 surface. The toluene by the UV254+185nm photoirradiated TiO2 were mainly mineralized CO2 and CO, but some water-soluble organic intermediates were also formed under severe reaction conditions. The ozone and secondary organic aerosol were produced as undesirable by-products. It was found that wet scrubber was useful as post-treatment to remove water-soluble organic intermediates. Excess ozone could be easily removed by means of a MnO2 ozone-decomposition catalyst. It was also observed that the MnO2 catalyst could decompose organic compounds by using oxygen reactive species formed in process of ozone decomposition.

This study is to investigate the relationship between pore structures of activated carbons and adsorption characteristics of toluene vapor using dynamic adsorption method. The surface areas of below 10Å in the pore diameter of activated carbons used in this experiment were in the range of 72～93％ of total cumulative surface area and the toluene vapor equilibrium adsorption capacities were in the range of 350～390mg/g. Activated carbons having larger toluene adsorption capacity than the compared activated carbons had relatively pores in the pore diameter range of 7～10Å. Linear relationship between equilibrium adsorption capacity and cumulative surface area was in the diameter range of over 7Å. It was thought that toluene vapor was relatively well adsorbed on surfaces of pores of over 7Å.

In recent decades, biofiltration has been widely accepted for the treatment of contaminated air stream containing low concentration of odorous compounds or volatile organic compounds (VOCs). In this study, conventional biofilters packed with flexible synthetic polyurethane (PU) foam carriers were operated to remove toluene from a contaminated air stream. PU foams containing various amounts of pulverized activated carbon (PAC) were synthesized for the biofilter media and tested for toluene removal. Four biofilter columns were operated for 60 days to remove gaseous toluene from a contaminated air stream. During the biofiltration experiment, inlet toluene concentration was in the range of 0-150 ppm and EBRT (i.e., empty bed residence time) was kept at 26-42 seconds. Pressure drop of the biofilter bed was less than 3 mm H2O/m filter bed. The maximum removal capacity of toluene in the biofilters packed with PU-PAC foam was in the order of column II (PAC = 7.08%) > column III (PAC = 8.97%) > column I (PAC = 4.95%) > column IV (PAC = 13.52%), while the complete removal capacity was in the order of column II > column I > column III > column IV. The better biofiltration performance in column II was attributed to higher porosity providing favorable conditions for microbial growth. The results of biodegradation kinetic analysis showed that PU-PAC foam with 7.08% of PAC content had higher maximum removal rate (Vm = 14.99 g toluene/kg dry material/day) than the other PU-PAC foams. In overall, the performance of biofiltration might be affected by the structure and physicochemical properties of PU foam induced by PAC content.

Catalytic combustion of toluene was investigated on CuOx/SnO2-ZrO2, CuOx/SnO2, CuOx/ZrO2 catalysts prepared by impregnation. Characteristics of catalysts loaded on binary support and single support were observed by TPR, TPO, XRD, XPS techniques. The results on catalytic combustion showed that binary supports improve the activity of copper in the combustion of toluene. The reason for high catalytic activity on toluene combustion of CuOx/SnO2-ZrO2 catalyst was ascribed to oxidation·reduction activity at low temperatures and stability of oxidation state after reduction.

Activity of manganese oxide supported on γ-Al2O3 was increased when cerium was added. Also, cerium-added manganese oxide on γ-Al2O3 was more effective in oxidation of toluene than that without cerium. XRD result, it was observed that MnO2+CeO2 crystalline phases were present in the samples. For the used catalyst, a prominent feature has increased by XPS. TPR/TPO profiles of cerium-added manganese oxide on γ-Al2O3 changed significantly increased at a lower temperature. The activity of 18.2 wt% Mn+10.0 wt% Ce/γ-Al2O3 increased at a lower temperature. The cerium added on the manganese catalysts has effects on the oxidation of toluene.

This study was carried out to investigate the correlation between toluene in air and hippuric acid in human urine, which is based in the results of the health check-in and measure of working environment, was investigated for five years. Toluene in air and hippuric acid in urine were checked 116 workers who exposed to toluene in five type of industry. The Mean concentration of toluene in air by type of industry and every year and sex distinction, had positive correlation.(p<0.01) The Mean concentration of hippuric acid in urine by type of industry, every year, sex distinction, disparity of age and term of duty had positive correlation.(p<0.01)

Adsorption characteristics of toluene vapor, which is one of important source of volatile organic compounds (VOCs), by activated carbon were investigated using a fixed bed adsorption column. The operating parameters such as breakthrough curve, adsorption capacity, mass transfer zone (MTZ), and length of unused bed (LUB) were studied. The experimental results showed that the breakthrough time decreased with increasing inlet toluene concentration and gas flow rate. MTZ and LUB increased with the increase of inlet concentration, gas flow rate, and particle size of activated carbon. The adsorption capacity increased with the increase of inlet toluene concentration, while it decreased with increasing particle size. However, it was kept at constant value regardless of the increase of gas flow rate. Adsorption isotherm of toluene vapor could be represented by the Freundlich adsorption equation fairly well. From the adsorption experiments using some VOC gases such as toluene, xylene, butyl acetate. butanol and acetone, it was also found that the adsorption capacity was higher in the case of gas with higher boiling point and lower vapor pressure.

The relationships between subjective symptoms of toluene exposed workers and concentration of their urinary excretion of hippuric acid were investigated. The exposed groups of 146 workers exposed to toluene and the control groups of 47 workers have never been exposed to toluene in Ulsan area were selected and studied. Hippuric acid was measured by HPLC, and counts of blood cells and liver function test were also performed. The mean value of urinary hippuric acid concentration of the control group was 0.322(±0.267) g/L, while that of the exposed group was 1.260(±0.395) g/L. As the concentration of hippuric acid had statistical proximity in 0.1% level, WBC, GOT, and GPT didn't have any proximity(P>0.05). The exposed group showed lower level of leucocyte counts 6522.40(1710.3) than the control group 6891.50(1483.7). The exposed group showed higher level of GOT(25.75), GPT(27.09) than GOT(23.75), GPT(25.21) of the control group. Dried skin was the highest complained symptom of toluene exposed workers, the second strained eye, the third poor auditory function, and the fourth was headache.

This study was carried out to investigate the correlation between toluene in air and hippuric acid in human urine, which is based on the results of the health check-in and the measure of working environment, was investigated for two years. The concentration of toluene in air for the five working places in Yang-San area were ranged from 39.05±10.31 ppm to 4.04±3.38ppm and the mean value of those was 16.89±14.76ppm. The mean value was 16.89±14.76ppm which is below the permissible limit of toluene. The concentration of hippuric acid(HA) in the worker's urine were between 0.47g/ℓ and 0.76g/ℓ. There was mutual correlation (r=0.94) between the concentration of toluene in air and that of hippuric acid in urine. In case of male workers, the mean value of hippuric acid in urine was 0.56g/ℓ and the female workers was 0.57g/ℓ that showed higher than the male's. However, there was no relationship between the workshop and the distinction of sex. From the mean value of toluene in air(T) and that of hippuric acid(H), we obtained the formula, H= 0.3log T+0.235