Environ. Sci., 5(3) : 163-1.71 (1992) 163

Removal of Hydrogen Sulfide, Methanethiol

and Dimethyl Sulfide by Wet Activated Carbon Fiber

Jong Jueng CHOI*, Mitsuyo HIRAI** and Makoto SHODA**

Abstract

Activated carbon fiber (ACF) fortified with commonly used carbon fiber and felt

type unwoven cloth by needle punch method removed hydrogen sulfide (H2S) effective-

ly under the condition of its moisture content of 80%, 200 ppm of its inlet concentration

and 100 h-1 of its space velocity (SV=flow rate/packed volume) (load=11.01 g H2S-

S/kg dry fiber•Eday). Complete removal of H2S lasted for one month and a half.

Although drastic decrease of the removal ratio was found at pH value less than 0.5 in

drain water due to the accumulated sulfuric acid(H2SO4) resulting from the oxdiation

of H2S in the fabrics, oxidizing ability was recovered by washing out H2SO4 in the

fiber. A single supply of methanethiol (MT) resulted in the production of dimethyl

disulfide (DMDS), but MT was perfectly oxidized to methanesulfonic acid in the mixed

supply with H2S. Dimethyl sulfide(DMS) was not removed even at half inlet sulfur

load of MT.

Key Words : activated carbon fiber, hydrogen sulfide, methanethiol, dimethyl sulfide, deodorization,

remove MT, but also to attain high efficiency of Introduction DMS removal16,17) Physical and/or chemical methods of deodor- The authors found that H2S was oxidized ization have been commonly used for the chemically by wet ACF. In this paper, removal of sulfur compounds in exhaust gases. removal characteristics of H2S oxidation by Recently, biological deodorizing method are ACF were studied and compared to granular attracting more attention, especially because of activated carbon (GAC) which is a popular their low running and maintenance costs, and material to remove H2S. Adsorption and oxi- soil bed, scrubber method by sludge and peat dation of other malodorous sulfur containing deodorizations are in practical use. The compounds (MT, DMS) over ACF were also authors have been studying to develop the bio- investigated. logical deodorizing device by peat, referred to Materials and methods as a peat biofilter1•`15) To enhance the removal efficiency, selection of a carrier of Packing materials ACF (Actor, proprietary microorganisms is primarily important. number FN-2000F-15 ; Osaka Gas Co. Ltd.,

Activated carbon fibers (ACF) were found to be Osaka) made from coal tar was used. This a good carrier for microorganisms not only to fiber is fortified with commonly used carbon

Received February 28, 1992 * Present address : Department of Chemical Engineering, Kyung-Nam Junior College, 167 Jurea-bong, Buk-ku, Pusan, Korea ** Research Laboratory of Resources Utilization, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 227, Japan. 164 CHOI, HIRAI and SIIODA fiber (Dona Carbo S ; Osaka Gas Co. Ltd., with air to appropriate concentration. A

Osaka) in mixing ratio of 20% (weight basis) mixed gas of H2S and MT was prepared by which is inert to oxdiation of H2S. Relative mixing each as from each cylinder with air to surface area, micropore radius and micropore intended oncentration. Details of experimen- volume of ACF are 1,500 m2/g, 9 A and 0.8 cm3/ tal conditions are summarized in Table 1. g, respectively. ACF is processed by needle Analysis Inlet and outlet H2S concentrations punch method to a felt type unwoven cloth were measured by gas chromatography (GC- having 200 g/cm2 of its basis weight to hold its 14A, Shimadzu, Kyoto) equipped with a flame shape strength. GAC (Calgon BPL ; 30-60 photometric detector and a glass column (i.d. 3 mesh, Toyo Calgon Co. Ltd., Tokyo) made mm ; length, 3 m) packed with a ƒÀ, ƒÀ'-oxydi- from coal tar was used as control experiments. propionitrile on 60-80 mesh chromosorb W.

Fxperimental Figure 1 shows the flow chart The concentration of sulfur dioxide (SO2) was of the experiment. A glass column (50 mm¢ x measured by the gas detection tubes, (No. 5L

500 mmH) was packed with the chips of ACF, Gastec), which covers the range from 1.25 to each about 10 mm X 10 mm in size. 50 ml of 200 ppm of SO2. Sulfate ion concentration was distilled water was sprayed by hand every three determined by ion chromatography (HIC-6A, days to maintain its moisture content of 80%. Shimadzu) equipped with CDD-6A conductivity

GAC was packed in a column (10 mmƒÓ •~ 150 detector and a Shimapack IC-Al column. mmH glass) where distilled water was supplied Oxidation product in drain water in mixed every 12 h at 3.5 ml/15 min by a peristaltic supply of H2S and MT (Run 9 in Table 1) was pump. Each gas of H2S, MT and DMS was determined' qualitatively in Rf values of thin- supplied to the column at 15-20•Ž from each layer chromatography by comparing them with cylinder (H2S ; 20,000 ppm in N2, MT ; 8,000 those of authentic samples on TLC aluminum ppm in N2, DMS ; 2,000 ppm in N2) by mixing sheets Silica gel 60F254 (Merck) developed with

Fig. 1. Exprimental apparatus for deodorization

1. Air 2. Regulator 3. Pressure gauge 4. Control valuve

5. Flow meter 6. H2S gas cylinder 7. MT gas cylinder

8. DMS gas cylinder 9. Three way cock

10. Glass column (50 mmƒÓ•~ 500 mmH)

11. Glass column (10 mmƒÓ•~ 150 mrH) 12. Butyl stopper 13. Saran net

14. ACF 15. GAC 16. Peristaltic pump 17. Timer 18. Water Removal of Sulfur Compounds by Activated Carbon Fiber 165

Table 1. Reaction Conditions of Each Run

1) Activated carbon fiber. 2) Granular activated carbon n-C4H9OH : CH3CN : NH4OH(28%)=1 : 1 : 1 (v/v/v). Iron content was analyzed by the following procedure. ACF and GAC were ground to pass through a 2 mm sieve, burned at 650•Ž in a furnace overnight, and digested with conc. HC1. After evaporating HCI, iron con- centration was measured by a spectro- photometric method using o-phenanthroline18). Data are shown in Table 2. Elemental analysis was carried out by micro elementary analyzers, C, H, N, Corder (MT-2 Yanagimoto Kyoto) for C, H, and N contents, and Sulfur and Halogen Micro Elementary Analyzer (Mitamura Riken Kogyo, Tokyo) for total-S content after drying at 105•Ž for overnight.

Results

1. Removal of H2S by ACF and GAC (Runs 1 to 4)

Results of Runs 1 and 2 which correspond to Fig. 2. Removal of H2S by ACF in Run 1 moisture content 80% and 0% in ACF (Table (A) and in Run 2 (B). 1), respectively are shown in Fig. 2 (A and B). (•œ) Inlet concentration of H2S.

A breakthrough curve was observed in dry ACF (•›) Outlet concentration of H2S.

(Fig. 2B). In contrast, ACF with 80% of (•¢) pH. moisture content showed almost 100% removal of H2S during 45 days and pH of the drain C for overnight. Results are shown in Table 2. water decreased drastically due to accumulated The increase in total sulfur content is obvious. sulfate ion (5042-) (Fig. 2A). When H2S was After 85 day supply of H2S, all of the packed detected in the outlet, ACF was sampled from ACF was removed from the column, and wa- the column and dried. One part of it was shed with distilled water until no 5042-in extracted by carbon disulfide and the rest was mother liquid was detected, when pH of mother used for elemental analysis after drying at 105•‹ liluid was 6.5. Then, the ACF was re-packed 166 Cnoi, HIRAI and SII0DA

Table 2. Analytical Data of Packing Materials

1) Activated carbon fiber 2) Granular activated carbon in the column and the supply of H2S gas under the pH of drain water and SO2 was detected 20 the same condition was resumed. 100% of days later. In Fig. 4B, SO2 was evolved in 8 removal of H2S was observed again for another days. In Fig. 5, oxidation of H2S in GAC with 45 days. The washing of ACF was, then, car- varying moisture content is shown, suggesting ried out by filling the column with 95 ml of tap that SO2 evolution was significant especially at water and draining naturally eight times, when moisture content 10%. pH of the last washing was 3.2. After the 2. Removal of MT by ACF (Runs 5 and 6) washing, H2S gas was effectively removed as Figure 6A shows the removal pattern of MT before. Figure 3 shows the removal pattern of on wet ACF in Run 5. No detection of sulfur H2S in the experiment where ACF with initial 80% of moisture content was subjected to natu- ral drying by H2S gas supply without water supply. Removal of H2S began to deteriorate at moisture content of less than 30%, and H2S and sulfur dioxide (S02) were detected in the outlet. Results of H2S oxidation by GAC in Runs 3 and 4 are shown in Fig. 4 (A and B). In Fig. 4A, H2S was oxidized to 5042- which lowered

Fig. 3. Removal of H2S by ACF accord- Fig. 4. Removal of H2S by GAC in Run 3 ing to change in moisture content. (A) and in Run 4 (B).

(•œ) Inlet concentration of HZS. (•œ) Inlet concentration of H2S.

(•›) Outlet concentration of H2S. (•›) Outlet concentration of H2S.

(•£) Outlet concentration of SO2. (•£) Outlet concentration of SO2.

(•¡) Moisture content. (•¢) pH. Removal of Sulfur Compounds by Activated Carbon Fiber 167 compounds at outlet was observed during 3 amount of supplied MT and successively in just days from the start of experiment, but DMDS half equivalent amount of MT. No descend of which is a oxidized product of MT was detected pH in drain water was found. In dry ACF at outlet initially in more than half equivalent (Run 6) (Fig. 6B), 20 ppm MT at inlet was adsorbed for 6 days from the start of experi- ment, followed by production of DMDS here- after. 3. Removal of DMS by ACF (Runs 7 and 8) Figures 7A and 7B show the results of Runs 7 and 8. ACF was inert for DMS removal both in wet and dry conditions except for only 2 days adsorption in dry condition. 4. Removal of H2S and MT by ACF in mixed gas supply Result of mixed supply of 200 ppm H2S and Fig. 5. Removal of H2S by GAC accord- 20 ppm MT to wet ACF in the condition of Run ing to change in moisture content. 9 is shown in Fig. 8. 200 ppm of H2S was (•œ) Inlet concentration of H2S. removed during 55 days. Methanethiol of (a) Outlet concentration of H2S.

(A) Outlet concentration of SO2. which load was the same as a single supply of

(/) Moisture content. MT in Run 5 (load= 1.04 g-CH3SH-S/g dry

fiber•Eday) was also perfectly removed and no

DMDS was detected at the outlet. The value

Fig. 6. Removal of MT by ACF in Run 5 (A) and Run 6 (B). (•œ) Inlet concentration of MT. Fig. 7. Removal of DMS by ACF in Run 7

(•›) Outlet concentration of MT. (A) and Rum 8(B).

(•Ÿ) Outlet concentration of (•œ) Inlet concentration of DMS.

DMDS.(•¢) pH. (•›) Outlet concentration of DMS. 168 CHOI, HIRAI and SIIODA

at 170•Ž26). Humidity in air related to the oxidation rate of H25 and conversion of H2S reached 80% in 80-90% humidity 27). So far, no data on H2S oxidation by GAC and ACF have been published in wet condition at room temper- ature. Results in Fig. 2A clearly proved that ACF oxidizes 200 ppm of H2S to H2SO4 effectively for 45 days only by maintaining the moisture content at 80% at SV=100 h-1. Washing of Fig. 8. Removal of H2S and MT by ACF packed ACF every one and a half month was in Run 9. necessary to keep constant removal of H2S for (•œ) Inlet concentration of H2S. longer period of time. However, in the case of (•¡) Inlet concentration of MT. dry ACF (Fig. 2B), breakthrough of H2S was (•›) Outlet concentration of H2S.

(• ) Outlet concentration of MT. completed in about 2 days, followed about 10

(•~) Outlet concentration of removal of H2S resulting from the humidity in

DMDS. air. Figure 3 shows that the 100% removal of H2S by ACF without detection of SO2 is guaran- of pH in the drain water after 42 days was 0.3. teed only by maintaining more than 50% of Drain water was analyzed by the thin-layer moisture. chromatography and methanesulfonic acid The oxidation mechanisms of H2S under wet (CH3SO3H) and H2SO4 were detected in refer- ACF condition may be speculated as follows. ence to the Rf value of their authentic samples (Rf =0.54 for CH3SO3H, Rf =0.34 for H2SO4) .

Discussion

GAC is commonly used in stack gas desulfur- ization. Although basic studies on the removal •¬(1) of H2S by GAC have been intensively carried out19•`27), most of them dealt with reaction mechanisms from the kinetic data of H2S Under wet ACF condition at room temperature decrease. The main points of previous reports it is presumed that partially oxidized 502 is on the catalytic oxidation of H2S on GAC are dissolved into water to form sulfite ion (5032-) as follows ; elemental sulfur (S0) and H2O were which enhances the reaction rate to sulfate produced and almost no 502 was detected at (SO42-) in comparison to the dry and high lower temperature less than 100•Ž. At temper- temperature oxidation condition where only ature above 130•Ž, as the promoting factors of oxidation-reduction reaction with SO2 and H2S the catalytic oxidation, the autoxidation of proceeded. To verify the above scheme, the trapped S0 inside of the micropore (3 •ƒ r •ƒ 40 •¬ ) distribution of each element was calculated for of GAC19), and the effect of transition metal the ACF after 45 days in Run 1 by using data in ions contained in GAC20) were demonstrated. Table 2. 2.14% of H in used ACF are com- No detection of 502 was explained by the posed of H in original ACF and H in H2O. H results of oxidation-reduction reaction with in H2O was estimated as 1.84% by using both

H2S and SO221). There are conflicting results the carbon content 34.21% and C/H ratio of whether sulfur deposited on GAC original ACF (112.2). Thus, 0 originated from accelerates19•`21) or self-fouls the oxidation of H2O was 14.72%. Assuming that total-S con-

H2S22•`25). Production of SO2 occurred when sists of elemental sulfur (50) and SO3-S, the flow gas mixing ratio of H2S/air is 1:10 (v/v) amount of 503-S is 18.27%, resulting in 27.35% Removal of Sulfur Compounds by Activated Carbon Fiber 169

of O in 503. Total summation of C, H, N, S, O treatment plant, waste water treament plants and ash was led to 99.62%. This fact suggests and kraft pulping process, where MT co-gener- almost no existence of any other sulfur com- ates with H2S, and H2S concentration is higher pounds in used ACF. SO3 is supposed to be in one or two order of magnitude over that of present in the micropores of ACF by forming MT. Both dry and wet ACFs were weak in H2SO4 with H2O which can not be evaporated adsorption capacity for DMS (Fig. 7). Thus, if by the overnight treatment at 105•Ž before the mixture of H2S, MT and DMS is to be elemental analysis. Elemental sulfur which treated, two packed columns in series should be was not washed out by water, but was extract- prepared. In the first column, H2S and MT are ed by carbon disulfide, may be deposited in oxidized chemically, and in the second column, micropores of ACF and the deposited sulfur ACF seeded with DMS degrading microorgan- may accelerate step (a). Property of ACF isms remove DMS biologically. We have with a good water retaining capacity, promotes already reported that ACF was the best carrier fast reaction in steps (b) and (c) and results in to remove DMS biologically17). Generally, bio- complete oxidation of H2S to HZSO4. Recov- logical deodorization has an advantage over ery of the catalytic activity by washing out of other physical and chemical ones in that it is 5042- by water indicates that sulfate inhibits maintenace free and low running cost. As oxidation steps (b) and (c) in water. ACF used in this study has several advanta- In wet GAC (Fig. 4A), oxidation activity geous properties over GAC such as flexibility, dropped in only 20 days under almost the same lightness, a good water retaining capacity by sulfur load as ACF (Table 1), mainly because needle punching to form felted unwoven cloth the maintenance of GAC under uniform wet and a fortified strength by mixing with com- condition was rather difficult (Fig. 5). SO2 monly used carbon fiber. Thus, the combina- was detected for GAC in Fig. 4, but not for ACF tion of chemical and biological methods by in Fig. 2. The difference may arise from poor using ACF will promise an advanced deodoriza- water retaining capacity of GAC, the content of tion system to treat sulfur containing gases. Fe and/or other unknown catalytic substances within ash components. References

Adsorption capacity of H2S, MT and DMS on 1) Furusawa, N., I. Togashi, M. Hirai, M. Shoda dry ACF was estimated to be 14.4, 162.5 and 25.2 and H. Kubota (1984) Removal of hydrogen sulfide by a peat biofilter with fibrous peat. J. g-S/kg dry fiber, respectively from Figs 2B, 6 B Ferment. Technol., 62(6), 589-594. and 7B. However, on wet ACF, all of MT was 2) Wada, A., M. Shoda, H. Kubota, T. Kobayashi, converted into DMDS by partial oxidation after Y. Katayama-Fujimura and H. Kuraishi (1986) a short period of MT adsorption (Fig. 6A). Characteristics of H2S oxidizing bacteria in- Although DMDS is of low odor threshold value habiting a peat biofilter. J. Ferment. Technol., (about 1/40 of MT), it is one of offensive odor 64(2), 161-167. substances. In contrast with inert property of 3) Togashi, I., M. Suzuki, M. Hirai, M. Shoda and

ACF in single supply of MT, MT was removed H. Kubota (1986) Removal of NH3 by a peat perfectly in mixed supply with H2S without biofilter without and with nitrifier. J. Ferment. Technol., 64(5), 425-432. production of DMDS (Fig. 8). From the 4) Hirai, M., M. Terasawa, I. Inamura, K. Fujie, results identified by thin-layer chromatogra- M. Shoda and H. Kubota (1988) Biological phy, it is verified that MT underwent profound removal of organosulfur compounds using peat oxidation to methanesulfonic acid under the biofilter. J. Odor Research and Eng., 19(6), 305 condition of 1.04 g-CH3SH-S/kg dry fiber•Eday. -312. Although the detail of oxidation mechanism is 5) Zhang, L., M. Suzuki, M. Terasawa, M. Hirai not clear, function of wet ACF on the mixture and M. Shoda (1990) A long-term experiment of two gases is useful in practical application in of a pilot-scale peat biofilter to remove sulfur- containing gases from waste water treamtment treatment of exhaust gases from night soil 170 Ciioi, HIRAI and SxonA

plant. J. Odor Research and Eng., 21(1), 1-9. a carrier of microorganisms. J. Ferment. 6) Hirai, M., M. Ohtake and M. Shoda (1990) Bioeng., 68(6), 437-442. Removal kinetics of hydrogen sulfide, meth- 17) Tiwaree, L. S., K.-S. Cho, M. Hirai and M. anethiol and dimethyl sulfide by peat biofilters. Shoda : Biological deodorization of dimethyl J. Ferment Bioeng., 70(5), 334-339. sulfide using different fabrics as the carriers of 7) Cho, K.-S., L. Zhang, M. Hirai and M. Shoda microorganisms. App. Chem. and Biotechnol., (1991) Removal characteristics of hydrogen (in mess). sulphide and menhanethiol by Thiobacillus sp. 18) Motomura, S. and M. Kobayashi : Analytical isolated from peat in biological deodorization. method of soil nutrient, The Committee of Soil J. Ferment. Bioeng., 71(1), 44-49. Nutrient Measurement Ed. Yokendo Press, 8) Zhang, L., I. Kuniyoshi, M. Hirai and M. Shoda Tokyo, p 299. (1991) Oxidation of dimethyl sulfide by 19) Steijns, M. and P. Mars (1974) The role of Pseudomonas acidovorans. Biotechnol. Lett., 13 sulfur trapped in micropores in the catalytic (3), 223-228. partial oxidation of hydrogen sulfide with 9) Cho, K.-S., M. Hirai and M. Shoda (1991) oxygen. J. Catal., 35(1), 11-17. Removal of dimethyl disulfide by the peat 20) Steijns, M. and P. Mars (1977) Catalytic oxida- seeded with night soil sludge. J. Ferment. tion of hydrogen sulfide, Effect of pore struc- Bioeng, 71(4), 289-291. ture and chemical composition of various 10) Cho, K.-S., M. Hirai and M. Shoda (1991) porous substances. Ind. Eng. Chem., Prod. Res. Degradation characteristics of hydrogen sul- Dev., 16(1), 35-41. fide, methanethiol, dimethyl sulfide and 21) Steijns, M., F. Derks, A. Verloop and P. Mars

dimethyl disulfide by Thiobacillus thioparus (1976) The mechanism of the catalytic oxida- DW44 isolated from peat biofilter. J. Ferment. tion of •Ehydrogen sulfide : II. Kinetics and Bioeng., 71(6), 384-389. mechanism of hydrogen sulfide oxidation catal-

11) Zhang, L., M. Hirai and M. Shoda (1991) yzed by sulfur. J. Catal., 42(1), 87-95. Removal characteristics of dimethyl sulfide, 22) Cariaso, O. C. and P. L. Walker Jr. (1975) methanethiol and hydrogen sulfide by Oxidation of hydrogen sulfide over micropor- Hyphomicrobium sp. 155 isolated from peat ous carbons, Carbon, 13(3), 233-239. biofilter. J. Ferment. Bioeng., 72(5), 392-396. 23) Coskun, L. and E. L. Tollefson (1980) Oxida- 12) Cho, K.-S., M Hirai and M. Shoda (1991) A tion of low concentration of hydrogen sulfide newly isolated heterotrophic bacterium, Xanth- over activated carbon. Can. J. Chem. Eng., 58 omonas sp. DY44 to oxidize hydrogen sulfide to (1), 72-76. polysulfide. Biotechnol. Lett., 13(12), 923-928. 24) Pan, Z.-L., H.-S. Weng, H.-Y. Feng and J. M. 13) Cho, K.-S., M. Hirai and M. Shoda (1992) Smith (1984) Kinetics of the self-fouling oxida- Enhanced removal efficiency of malodorous tion of hydrogen sulfide on activated carbon. gases in a pilot-scale peat biofilter inoculated AIChE Journal., 30(6), 1021-1025. with Thibacillus thioparus DW44. J. Ferment. 25) Sreeramamurthy, R, and P. G. Menon (1975) Bioeng., 73(1), 46-50. Oxdiation of hydrogen sulfide on activated 14) Cho, K.-S., M. Hirai and M. Shoda (1992) carbon catalyst. J. Catal., 37(2), 287-296. Degradation of hydrogen sulfide by Xanth- 26) Pun, B. R., D. D. Singh and S. K. Verma (1979) omonas sp. DY44 isolated from peat biofilter. Studies in catalytic reaction of carbon : Part Appl. Environ. Microbiol. 58(4), 1183-1189. VIII-Oxidation of hydrogen sulphide by air in 15) Cho, K.-S., M. Hirai and M. Shoda (1992) presence of active carbons. Indian J. Chem. Enhanced removability of odorous sulfur- Sect. A., 18A(5), 388-391. containing gases by mixed cultures of purified 27) Kaliva, A. N. and J. W. Smith (1983) Oxidation bacteria from peat biofilters. J. Ferment. of low concentration of hydrogen sulfide by air Bioeng. 73(3), 219-224. on a fixed activated carbon bed. Can. J. Chem. 16) Lee, S.-K. and M. Shoda (1989) Biological Eng., 61(2), 208-212. deodorization using activated carbon fabric as Removal of Sulfur Compounds by Activated Carbon Fiber 171

活性炭繊維 による含硫化合物 (硫化 水素,メ チ ル メル カプ タ ン,硫 化 メチ ル)の 除 去

豊 鍾 槙 ・平 井 光 代 ・正 田 誠

(東京工業大学 資源化学研究所,〒227神 奈川県横浜市緑区長津田町4259)

摘 要

活 性 炭 繊 維 に 汎 用 炭 素 繊 維 を混 綿 し て 形 状 保 持 性 を 良 く し,ニー ドル パ ン チ 法 で 不 織 布

と しフ ェ ル ト化 した繊 維(ACF)を カ ラム に充 填 し,繊 維 の 含 水 率 を約80%に 保 ち ,硫 化 水 素(H2S)ガ ス を 含 む空 気 を,入 口濃 度200ppm,空 塔 速 度100h-1(SV=通 気 量/繊 維 充 填 体 積)(負 荷=11.01gH2S-S/kg dry fiber・day)で 通 気 す る と,1ヶ 月 半 の 間 効 率 よ くH2Sを 除 去 で き た。 そ の 間 に繊 維 に 硫 酸 が 蓄 積 しpHは 低 下 した 。 除 去 効 率 はpHが0 .5 以 下 に な る と急 激 に悪 化 す るが,蓄 積 し た 硫 酸 を洗 浄 除 去 す る こ とに よ っ てH2S酸 化 能 が 回復 し た 。 メ チ ル メ ル カ プ タ ン(MT)は 入 口濃 度20ppm,SV=100h-1(負 荷=1.04g- CH3SH-S/kg dry fiber・day)の 単 独 通 気 で は,部 分 酸 化 し た 二 硫 化 メ チ ル(DMDS)が 出 口 で 検 出 され た。MTとH2Sと の混 合 通 気 で は,H2SとMT両 者 が1ヶ 月 半 の 間 完 全 に 除 去 さ れ,出 ロ ガ ス 中 にDMDSは 検 出 さ れ ず,ド レイ ン水 中 に は硫 酸 と メ タ ン ス ル ホ ン酸 が 検 出 さ れ た 。 硫 化 メ チ ル(DMS)はMTの 半 分 の 負 荷 で も殆 ど除 去 さ れ な か っ た 。

キ ー ワ ー ド:活 性 炭 繊 維,硫 化 水 素,メ チ ル メ ル カ プ タ ン,硫 化 メ チ ル,脱 臭