The photolysis of simulating low concentration of hydrogen sulfide malodorous gas was studied under UV irradiation emitted by self-made microwave discharge electrodeless lamps (i.e. microwave UV electrodeless mercury lamp (185/253.7 nm) and iodine lamp (178.3/180.1/183/184.4/187.6/206.2 nm)). Experiments results showed that the removal efficiency (eta H2S) of hydrogen sulfide was decreased with increasing initial H2S concentration and increased slightly with gas residence time; H2S removal efficiency was decreased dramatically with enlarged pipe diameter. Under the experimental conditions with pipe diameter of 36 mm, gas flow rate of 0.42 standard l s(-1), eta H2S was 52% with initial H2S concentration of 19.5 mg m(-3) by microwave mercury lamp, the absolute removal amount (ARA) was 4.30 microg s(-1), and energy yield (EY) was 77.3 mg kW h(-1); eta H2S was 56% with initial H2S concentration of 18.9 mg m(-3) by microwave iodine lamp, the ARA was 4.48 microg s(-1), and the EY was 80.5mg kW h(-1). The main photolysis product was confirmed to be SO4(2-) with IC. 相似文献
A trimetal oxide was developed as a fluoride adsorbent by coprecipitation of Fe(II), Al(III) and Ce(IV) salt solutions with a molar ratio of 1:4:1 under alkaline condition. The material retained amorphous structure and maintained relatively stable fluoride adsorption performance at calcination temperatures lower than 600 degrees C. The optimum pH range for fluoride adsorption was 6.0-6.5 and the adsorbent also showed high defluoridation ability around pH 5.5-7.0, which is preferable for actual application. A high fluoride adsorption capacity of 178 mg g(-1) was acquired under an equilibrium fluoride concentration of 84.5 mg l(-1), adsorbent dose of 150 mg l(-1) and pH 7.0. The adsorption isotherm could be better described by the two-site Langmuir model than the one-site model, suggesting the existence of two types of active sites on the adsorbent surface. Coexistence of high concentrations of phosphate or arsenate only led to partial inhibition of fluoride adsorption, which further suggests the existence of heterogeneous adsorption sites. Sulfate and chloride did not affect fluoride adsorption, and nitrate influenced it only when the concentration of NO(3)(-)-N exceeded 50 mg l(-1). A high desorption efficiency of 97% was achieved by treating fluoride loaded Fe-Al-Ce oxide with NaOH solution at pH 12.2. A column experiment using the adsorbent fabricated into 1mm pellets was performed at an initial fluoride concentration of 5.5 mg l(-1), space velocity of 5h(-1) and pH of 5.8, and 2240 bed volumes were treated with the effluent fluoride under 1.0 mg l(-1). 相似文献
The variation in grain cadmium (Cd) concentrations was evaluated among 600 barley genotypes grown in the same field condition to select low Cd accumulating genotypes. The results showed that there is considerable genotypic variation in grain Cd concentrations in barley grain samples, with the mean concentration of 0.16 mg kg(-1) DW and the variation of 0 (not detected) to 1.21 mg kg(-1) DW, and 47.2% of the grain samples exceeded the maximum permissible concentration (MPC) for Cd in cereal grains. In addition, differences between genotypes over the two years were fairly consistent, and Beitalys and Shang 98-128 showed the lowest grain Cd concentration, being 97.5% lower than that in the two highest Cd accumulators E-barley 6 and Zhenong 8 in the second harvest year. The great genotypic differences in Cd concentrations indicated that it is possible to lower Cd content of barley through cultivar selection and breeding for use at sites where Cd concentration in grain exceeds the MPC. Significant genotypic difference was also found in microelement concentrations. Correlation analysis showed that only Mn accumulation is synergetic with Cd accumulation, despite slightly positive relationship between Cd and Zn, Cu, or Fe in accumulation in barley grains. 相似文献
China is among the largest emitters of carbon dioxide (CO2), worldwide Thus, its emissions mitigation is of global concern. The power generation sector is responsible for nearly half of China’s total CO2 emissions and plays a key role in emissions mitigation. This study is an integrated evaluation of abatement technologies, including both low-carbon power generation technologies and retrofitting options for coal power plants. We draw marginal abatement cost curves for these technologies using the conservation supply curve method. Using scenario analysis for the years 2015 to 2030, we discuss the potential performance of abatement technologies. Marginal costs for the analyzed abatement technologies range from RMB ? 357.41/ton CO2 to RMB 927.95/ton CO2. Furthermore, their cumulative mitigation potential relative to the baseline scenario could reach 35 billion tons of CO2 in 2015–2030, with low-carbon power generation technologies and coal power abatement technologies contributing 55% and 45% of the total mitigation, respectively. Our case study of China demonstrates the power generation sector’s great potential to mitigate global emissions, and we suggest nuclear power, hydropower, and the comprehensive retrofitting of coal power as key technology options for the low-carbon transition of the energy system and long-term emissions mitigation strategies.