| Odor pollution is one of the biggest nuisances second only to noise. In order to find out more efficient treatment technology, the removal of medium-low concentration hydrogen sulfide (H2S) and carbon disulfide (CS2) from gas stream were studied experimentally with Ultraviolet (UV) photolysis, which is emitted by novel electrodeless lamps powered by microwave discharge or condenser discharge.Through regulating the gas initial concentration, gas residence time and applied voltage, removal efficiency under different conditions were studied. The effects of different filling materials in the lamp to removal efficiency were also studied. Effectiveness, e.g. the remocal efficiency (n), specific energy density (SED), absolute removal amount (ARA) and energy yield (EY), of the self-made discharge reactors had been studied, to evaluate the application potential of the experimental system both technically and economically. A comparaison was made between the removal efficiency of H2S and CS2. The irradiation wavelength and filling materials of the electroless UV lamp were also discussed. The results are as follows:Medium-low concentration of hydrogen sulfide and carbon disulfide could be removed effectively by microwave discharge electrodeless UV lamp and condenser discharge electrodeless UV lamp. The UV irradiation emitted from electrodeless lamp can disrupt bonds of H2S and CS2 molecules (direct degradation). Reactive radicals such as O2·-, HO2·, O·, OH·, produced by molecules of H2O, CO2, O2 in gas stream absorbing UV irradiation, can also degrade target gases through collision with hydrogen sulfide molecules or carbon disulfide molecules (indirect degradation). In addition, microwave discharge plasma and condenser discharge plasma can also contrubite to the degradation of hydrogen sulfide and carbon disulfide (indirect degradation) other than powering the electrodeless lamp.Microwave discharge electrodeless lamps, with mercury lamp (MDEL-Hg) emitting 185/253.7 nm filled with binary mixtures of Ar and Hg, iodine lamp (MDEL-I2) emitting 178.3/180.1/183/184.4/187.6/206.2 nm filled with binary mixture of Kr and I2, respectively, were employed to degrade H2S with concentration ranging from 0 to 25 mg/m3. Experimentas results showed that the removal efficiency of hydrogen sulfide (ηH2S) was decreased dramatically with increasing initial H2S concentration and increased slightly with gas residence time;ηH2S was decreased dramatically with enlarged tube diameter. Under the experimental conditions with tube diatmeter of 36 mm, gas flow rate of 0.6 m/s,ηH2S was 89.4% with initial H2S concentration of 1.6 mg/m3 by MDEL-Hg,ηH2S was 52.3% with initial H2S concentration of 19.5 mg/m3, ARA was 4.30μg/s, and EY was 77.3 mg/kWh; whileηH2S was 87.6% with initial H2S concentration of 1.3 mg/m3 by MDEL-I2,ηH2S was 56.0% with initial H2S concentration of 18.9 mg/m3, ARA was 4.48μg/s, and EY was 80.5 mg/kWh.Removal of CS2 with concentration ranging from 0 to 130 mg/m3 was experimentally studied with the similiar MEDL-Hg (185/253.7 nm) and MEDL-I2 (178/183.1/206.3/253.2 nm) filling with different amount of Kr/I2. Under ambient tempreture, with relative humidity of 40%, tube diatmeter of 46 mm, gas flow rate of 0.2 m/s (gas residence time of 2 s), initial CS2 concentration of 100 mg/m3,ηCS2was above 75% by MDEL-Hg and above 50% by MEDL-I2.ηCS2was 35.1% with initial CS2 concentration of 110.0 mg/m3 when gas flow rate was 2 m/s (gas residence time was accordingly 0.2 s), ARA was 103.91μg/s, EY was 1870.5 mg/kWh. Under the above reaction conditions,ηCS2was 22.2% with initial CS2 concentration of 120.3 mg/m3 when ARA was 72.07μg/s, EY was 1297.2 mg/kWh.The experiments were last conducted to study the removal of H2S via conderser discharge electrodeless iodine lamp (CDEL-I2) and bromine lamp (CDEL-Br2), filling with I2 and Br2, respectively, both with inert gas Kr served as buffer gas. The effects of gas flow rate, gas pressure of Kr, filling amount of I2/Br2, applied voltage and initial gas concentration to the removal efficiency of H2S was studied. Under ambient tempreture, with relative humidity of 40%, gas flow rate of 0.5 m/s (gas residence time of 0.4 s), applied voltage of 7500 V,ηH2S was above 70% with initial H2S concentration of 102.8 mg/m3 via CDEL-I2 filling with 50 Torr Kr and 5 mg I2, ARA was 19.7μg/s, while EY was 500.8 mg/kWh;ηH2Swas about 70.0% with initial H2S concentration of 115.4 mg/m3 via CDEL-Br2 filling with 1 Torr Kr and 1 Torr Br2, ARA was 20.6μg/s, while EY was 467.6 mg/kWh.In addition, IC and FT-IR were employed to detect and analyze the photolysis products of H2S with electrodeless UV lamp, the safety of the products was also discussed.
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