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841.
A novel technology of two-step fast microwave-assisted pyrolysis(f MAP) of corn stover for bio-oil production was investigated in the presence of microwave absorbent(Si C) and HZSM-5catalyst. Effects of f MAP temperature and catalyst-to-biomass ratio on bio-oil yield and chemical components were examined. The results showed that this technology, employing microwave, microwave absorbent and HZSM-5 catalyst, was effective and promising for biomass fast pyrolysis. The f MAP temperature of 500°C was considered the optimum condition for maximum yield and best quality of bio-oil. Besides, the bio-oil yield decreased linearly and the chemical components in bio-oil were improved sequentially with the increase of catalyst-to-biomass ratio from 1:100 to 1:20. The elemental compositions of bio-char were also determined. Additionally, compared to one-step f MAP process, two-step f MAP could promote the bio-oil quality with a smaller catalyst-to-biomass ratio. 相似文献
842.
Carbon source is a critical constraint on nutrient removal in domestic wastewater treatment. However, the functions of particulate organic matter (POM) and some organics with high molecular weight (HMW) are overlooked in the conventional process, as they cannot be directly assimilated into cells during microbial metabolism. This further aggravates the problem of carbon source shortage and thus affects the effluent quality. Therefore, to better characterize organic matter (OM) based MW distribution, microfiltration/ultrafiltration/nanofiltration (MF/UF/NF) membranes were used in parallel to fractionate OM, which obtained seven fractions. Hydrolysis acidification (HA) was adopted to manipulate the MW distribution of dissolved organic matter (DOM) and further explore the correlation between molecular size and biodegradability. Results showed that HA pretreatment of wastewater not only promoted transformation from POM to DOM, but also boosted biodegradability. After 8 hr of HA, the concentration of dissolved organic carbon (DOC) increased by 65%, from the initial value of 20.25 to 33.48 mg/L, and the biodegradability index (BOD5 (biochemical oxygen demand)/SCOD (soluble chemical oxygen demand)) increased from 0.52 to 0.74. Using MW distribution analysis and composition optimization, a new understanding on the characteristics of organics in wastewater was obtained, which is of importance to solving low C/N wastewater treatment in engineering practice. 相似文献
843.
Jixing Liu Fuhong Yu Jian Liu Lifeng Cui Zhen Zhao Yuechang Wei Qianyao Sun 《环境科学学报(英文版)》2016,28(10):45-58
A series of meso-microporous Cu-SAPO-34 catalysts were successfully synthesized by a one-pot hydrothermal crystallization method, and these catalysts exhibited excellent NH_3-SCR performance at low temperature. Their structure and physic chemical properties were characterized by means of X-ray diffraction patterns(XRD), Scanning electron microscopy(SEM), Transmission electron microscopy(TEM), N_2 sorption-desorption, nuclear magnetic resonance(NMR), Inductively Coupled Plasma-Atomic Emission spectrometer(ICP-AES), X-ray absorption spectroscopy(XPS),Temperature-programmed desorption of ammonia(NH_3-TPD), Ultraviolet visible diffuse reflectance spectroscopy(UV-Vis DRS) and Temperature programmed reduction(TPR).The analysis results indicate that the high activities of Cu-SAPO-34 catalysts could be attributed to the enhancement of redox property, the formation of mesopores and the more acid sites. Furthermore, the kinetic results verify that the formation of mesopores remarkably reduces diffusion resistance and then improves the accessibility of reactants to catalytically active sites. The 1.0-Cu-SAPO-34 catalyst exhibited the high NO conversion( 90%) among the wide activity temperature window in the range of 150–425℃. 相似文献
844.
正We are very pleased to announce that five Associate Editors have joined the editorial team of the Journal of Environmental Sciences(JES).Professors/Drs.Yong Cai,Paul Lam,Jonathan Martin,Michael Plewa,and Po Keung Wong bring a wealth of expertise in environmental sciences.As preeminent scientists in their chosen areas of research,they have made outstanding contributions to the discipline of environmental 相似文献
845.
Jiang Li Yunguo Liu Pingyang Zhang Guangming Zeng Xiaoxi Cai Shaobo Liu Yicheng Yin Xinjiang Hu Xi Hu Xiaofei Tan 《环境科学学报(英文版)》2016,28(5):40-47
Aquatic macrophytes are considered to be promising in controlling harmful cyanobacterial blooms. In this research, an aqueous extract of Sagittaria trifolia tubers was prepared to study its inhibitory effect on Microcystis aeruginosa in the laboratory. Several physiological indices of M. aeruginosa, in response to the environmental stress, were analyzed. Results showed that S. trifolia tuber aqueous extract significantly inhibited the growth of M. aeruginosa in a concentration-dependent way. The highest inhibition rate reached 90% after 6 day treatment. The Chlorophyll-a concentration of M. aeruginosa cells decreased from 343.1 to314.2 μg/L in the treatment group. The activities of superoxide dismutase and peroxidase and the content of reduced glutathione in M. aeruginosa cells initially increased as a response to the oxidative stress posed by S. trifolia tuber aqueous extract, but then decreased as time prolonged. The lipid peroxidation damage of the cyanobacterial cell membranes was reflected by the malondialdehyde level, which was notably higher in the treatment group compared with the controls. It was concluded that the oxidative damage of M. aeruginosa induced by S.trifolia tuber aqueous extract might be one of the mechanisms for the inhibitory effects. 相似文献
846.
采用超声萃取-高效液相色谱荧光检测法对土壤中苯并[a]芘含量进行定性、定量分析.土壤样品用正己烷/二氯甲烷(1+1)超声萃取,萃取液经硅胶柱或佛罗里硅土柱净化浓缩定容,乙腈-水为流动相,线性梯度洗脱,流速为1.0 mL/min,荧光检测器激发波长为280 nm,发射波长为420 nm,外标法峰面积定量.结果显示:该方法检出限低,苯并[a]芘的检出限为0.15μg/kg.这种方法具有很好的精密度,相对标准偏差为3.9%~8.4%.实际水样加标回收率范围在72.5%~85.8%.能够满足土壤的监测要求. 相似文献
847.
Mercury(Hg), mainly in cinnabar species, has been used in medicine for thousands of years in China, and worldwide concern has been raised on its toxicity. In this work, the amount of bioaccessible mercury in 16 Chinese patent medicines(CPMs) was measured by using an in vitro simulated digestion system, consisting of simulated gastric and intestinal fluid, to investigate the bioavailability of mercury in CPMs and evaluate its potential risk to human health. Total mercury and mercury in the gastrointestinal extracts were measured by inductively coupled plasma mass spectrometry(ICP-MS). The levels of total Hg in 16 CPMs ranged from not detected to 11.89 mg/g, with a mean value of 1.13 mg/g, while the extractable Hg ranged from not detected to 4.37 μg/g, with a mean value of 0.42 μg/g.Mercury bioaccessibility varied significantly in the investigated CPMs, depending on the ingredient. Compared to the CPMs without cinnabar(2.5%–30.9%), the percentage of mercury in the gastrointestinal supernatants for CPMs with cinnabar was quite a bit lower(0.037%). By comparing with the Food and Agricultural Organization/World Health Organization Joint Expert Committee on Food Additives(FAO/WHO) safety guideline, the average daily intake dose(ADD) of Hg in the medicines was then calculated to access the risk of mercury to human health from taking CPMs. 相似文献
848.
849.
850.
山东省汽车喷涂行业VOCs排放特征研究 总被引:2,自引:1,他引:2
采用气袋采样-气相色谱/质谱法,采集并分析了山东省内小型通用车、货车、电动商务车以及半挂车4类典型汽车喷涂企业挥发性有机物(VOCs)的排放特征。结果表明:山东省汽车喷涂企业中VOCs排放总量以及检出数量排序为:半挂车喷涂企业电动商务车喷涂企业货车喷涂企业小型通用车喷涂企业。各类汽车喷涂企业喷漆以及烘干车间排放的VOCs大多以苯类物质为主(小型通用车面漆烘干车间除外),在小型通用车以及半挂车涂装企业废气中烷烃类物质占比较大。不同企业以及各企业不同工序之间特征VOCs排放浓度有较大差别,喷漆车间特征VOCs浓度要远高于烘干车间。 相似文献