Applied Mechanics and Materials Vol. 737

Abstract: PM_2.5 particulate matters were collected in Taiyuan from November 2012 to October 2013. The total concentrations of seven kinds of typical heavy metal element (Fe, Pb, Mn, Cu, Ni, Cr, Cd) in particles were quantified by acid digestion method, then determined by flame atomic absorption spectrophotometer. The results showed that the concentration of PM_2.5 in Taiyuan was six times higher than the Ambient Air Quality Standard (GB 3095-2012) II, and the atmospheric particles in Taiyuan are high in Fe, Pb, Cu, Mn, followed by Ni, Cr, Cd. The concentrations of Fe, Cd, Cu, Mn, Ni, Cr in industrial area were high, while the contents of Pb was high in commercial area, all of them were low in educational and residential area.

Abstract: Volatile organic compounds (VOCs) were analyzed in straw burning period and non-straw burning period in the center of Chengdu city. The results showed that the concentrations of TVOC during straw burning were significantly higher than that in the non-straw burning period in Chengdu. The main components were alkanes, aromatic hydrocarbons and esters in straw burning period while aromatic hydrocarbons, alkanes, esters, aldehydes and ketones as the main contents in the period of non-straw burning. The correlation of TVOC, SO₂, NO₂, PM₁₀, PM_2.5, CO, O₃ and the API index was discussed and the NO_X-sensitive of photochemical reaction type was determined by the ratio of TVOC / NO₂ during straw burning period.

Abstract: Beijing, Tianjin, Shanghai, Guangzhou and Chongqing are the five national central cities in China. Base on the method of Spearman rank correlation, concentrations of the main atmospheric pollutans declined generally from 2002 to 2013 in the five cities and the decreasing trends of SO₂ were more significant than those of NO₂, probably due to the wide use of desulfurization and increasing number of vehicles. However, the air pollution was still serious in 2013 and the contamination caused by atmospheric particulate matter was prominent. Transformations between gaseous pollutants (including SO₂ and NO₂) and PM₁₀ were observed and different among the cities. The variations of PM₁₀ were closely related to SO₂ in Shanghai and NO₂ in Tianjin, respectively. While in other three cities, both of SO₂ and NO₂ probably contributed to the formation of PM₁₀.

Abstract: The concentrations of heavy metals (Cr, Cu, Ni, Pb and Mn) were determined using flame atomic absorption spectrophotometer after digested with four acids. The samples were collected from seven kinds of different functional areas in Taiyuan, China. The concentration of the heavy metals were found in Taiyuan is higher than the soil background values in Shanxi Province, which appeared different levels of accumulation. High concentrations of Cr, Ni, Mn were found in the samples from industrial area and Cu was noted from economic development area. The correlational analysis and principle component analysis showed that the heavy metals of surface dust in Taiyuan were mainly influenced by industrial activities.

Abstract: In this study, a high-efficient snow-dissolving agent with coloration function was made, the main raw material was calcium chloride (CaCl₂).The advantage of this agent was that we could control the spreading dosage according to the color change. The optimal proportion of the raw materials was obtained through experiment. The experimental results show: the ice melting amount of homemade snow-dissolving agent increased with time ; homemade snow-dissolving agent had the best effect on snow melting compared with CaCl₂,NaCl and commercial snow-dissolving agent.

Abstract: Radon is a radioactive gas, high concentrations of radon in the environment can cause lung cancer, leukemia and other diseases. In this paper, indoor radon concentration in different places were measured and analyzed by using the RAD-7 radon monitor in a university and its adjacent areas. On-site measurements show that within 24 hours the indoor radon concentration versus time has certain regularity, different interior architectural decoration materials has a certain influence on the radon concentration, the radon concentrations in long confined spaces are significantly higher than those places frequently ventilated, floor height and ventilation conditions have a greater impact on the radon concentration. This research can provide a reference for future prevention and control of radon hazards.

Abstract: In this paper, a mixed microbial population biotrickling filter (BTF) was investigated for styrene removal with two different packings at different empty bed residence times and gas-liquid ratio(GLR). The two biotrickling filters inoculated with a Pyrocarbon-sawdust and ceramic-raschig-rings-sawdust mixed packings were filled respectively in two identical laboratory-scale biotrickling filters which were operated in parallel. The results showed that the BTF filling with pyrocarbon-sawdust packings had higher rate of bio-film formation and removal efficiency of styrene than that of ceramic-raschig-rings-sawdust packings. When an inlet gas concentration of 50 to 450 mg/m³, an Empty Bed Residence Time (EBRT) of 21.6 to 43.2 s, and a gas-liquid ratio (GLR) of 110.7 to 55.3, a maximum styrene removal load is up to 153.1 g/(m³·h). During shock-load experiments with shutdown, the styrene removal efficiency of the BTF could gradually reach 92 % to 100 % by 14 h.

Abstract: Three kinds of Mg/Fe layered double hydroxides (LDHs) with different intercalation anions (NO₃^-, Cl^- and CO₃^2-) were synthesized and used as adsorbents for the removal of phosphate in aqueous solutions. Results showed that the phosphate removal decreased with the increase of solution pH from 3.0 to 11.0. The adsorption behavior of phosphate followed the Freundlich adsorption isotherm. LDHs-NO₃^- had the highest adsorption ability for phosphate, the followed order was LDHs-Cl^- and LDHs-CO₃^2-. The adsorption kinetics of phosphate onto the three kinds of LDHs fit the pseudo-second-order kinetic model.

Abstract: The low-temperature plasma technology has the comprehensive action of high-energy electron, ultraviolet light, ozone etc. The technology that integrates light, electronic and chemical oxidation into one process has a good development prospect in wastewater treatment. In this paper, the research status and development trend of high-voltage pulsed discharge, dielectric barrier discharge, glow discharge for organic wastewater treatment at home and abroad are summarized. The current main existing problems include single treatment object oriented. In the future, the study about this technique should be focused on the optimization process, the reduction of the processing cost and energy consumption, so that this technology can be applied to practical wastewater treatment as soon as possible.Key words: Low temperature plasma technology; High-voltage pulsed discharge; Glow discharge; Dielectric barrier discharge; Wastewater

Abstract: Ferric hydrosulfate minerals are commonly byproducts of biotic oxidation of Fe (II) in acid mine drainage and biohydrometallurgy like biogenic jarosite. In this study, adsorption of Cr (VI) on jarosite was a rapid process and the optimum pH for Cr (VI) adsorption was found at 7.0. The variation of Cr (VI) adsorbed on jarosite fitted the Langmuir adsorption isotherm models and the maximum adsorption capacity was 3.23 mg/g. It was evident that anion exchange mechanism was responsible for Cr (VI) adsorption on jarosite based on the sulfate leaching data and optimum pH experiments.