Producing biodiesel from waste animal oil by modified ZnO

Biodiesel produced by transesterification of waste animal oil is a promising green fuel in the future. ZnO-Al₂O₃ and ZnO/Zn₂Al composition oxides were prepared by co-precipitation method and impregnation method, respectively. The above catalysts were characterized by X-ray diffraction (XRD), Brunauer--Emmett--Teller (BET) and CO₂ adsorption and temperature-programmed desorption (CO₂-TPD) and show that the high activity for the catalyst is attributed to its high alkalinity. The reaction parameters were optimized and the results show that the transesterification ratio of waste animal oil can reach 98.7% with 10% ZnO/Zn₂Al catalyst after 2 h. Moreover, 10%ZnO/Zn₂Al compound oxides can be active for the successive cycles. The glycerol as a predominant by-product after transesterification is of high purity with high use value.     

Flow‐Biology Relationships Based on Fish Habitat Guilds in North Carolina

The health of freshwater biota is dependent on streamflow, yet identification of the flow regimes required to maintain ecological integrity remains challenging to states in the United States seeking to establish ecological flows. We tested the relationship between decreases in streamflow and Shannon‐Weaver diversity index of fish species for four flow‐based habitat guilds: riffle, riffle‐run, pool‐run, and pool in North Carolina. We found species that prefer shallow habitats, such as riffles and riffle‐runs were the most sensitive to decreases in streamflow; whereas no significant relationships were found for pool or pool‐run species. The sensitivity to decreases in streamflow was greatest during summer and fall, when streams are naturally lower. When all fish habitat guilds were included in the assessment of flow‐biology relationships, there were no significant relationships to decreases in streamflow. As the sensitivity of fish to reductions in streamflow is not constant across habitat guilds, combining all fish species together for flow‐biology analyses may greatly underestimate the response of fish species to decreases in flow and should be acknowledged when establishing ecological flows.     

Investigation of titanium liquid/gas diffusion layers in proton exchange membrane electrolyzer cells

In a proton exchange membrane electrolyzer cell (PEMEC), liquid/gas diffusion layer (LGDL) is expected to transport electrons, heat, and reactants/products to and from the catalyst layer with minimum voltage, current, thermal, interfacial, and fluidic losses. In addition, carbon materials, which are typically used in PEM fuel cells (PEMFCs), are unsuitable in PEMECs due to the high ohmic potential and highly oxidative environment of the oxygen electrode. In this study, a set of titanium gas diffusion layers with different thicknesses and porosities are designed and examined coupled with the development of a robust titanium bipolar plate. It has been found that the performance of electrolyzer improves along with a decrease in thickness or porosity of the anode LGDL of titanium woven meshes. The ohmic resistance of anode LGDL and contact resistance between anode LGDL and the anode catalyst play dominant roles in electrolyzer performance, and better performance can be obtained by reducing ohmic resistance. Thin titanium LGDLs with straight-through pores and optimal pore morphologies are recommended for the future developments of low-cost LGDLs with minimum ohmic/transport losses.     

Detention Outlet Retrofit Improves the Functionality of Existing Detention Basins by Reducing Erosive Flows in Receiving Channels

By discharging excess stormwater at rates that more frequently exceed the critical flow for stream erosion, conventional detention basins often contribute to increased channel instability in urban and suburban systems that can be detrimental to aquatic habitat and water quality, as well as adjacent property and infrastructure. However, these ubiquitous assets, valued at approximately $600,000 per km² in a representative suburban watershed, are ideal candidates to aid in reversing such cycles of channel degradation because improving their functionality would not necessarily require property acquisition or heavy construction. The objective of this research was to develop a simple, cost‐effective device that could be installed in detention basin outlets to reduce the erosive power of the relatively frequent storm events (~ < two‐year recurrence) and provide a passive bypass to maintain flood control performance during infrequent storms (such as the 100‐year recurrence). Results from a pilot installation show that the Detain H₂O device reduced the cumulative sediment transport capacity of the preretrofit condition by greater than 40%, and contributed to reduced flashiness and prolonged baseflows in receiving streams. When scaling the strategy across a watershed, these results suggest that potential gains in water quality and stream channel stability could be achieved at costs that are orders of magnitude less than comparable benefits from newly constructed stormwater control measures.     

Designing and Implementing a Network for Sensing Water Quality and Hydrology across Mountain to Urban Transitions

Water resources are increasingly impacted by growing human populations, land use, and climate changes, and complex interactions among biophysical processes. In an effort to better understand these factors in semiarid northern Utah, United States, we created a real‐time observatory consisting of sensors deployed at aquatic and terrestrial stations to monitor water quality, water inputs, and outputs along mountain to urban gradients. The Gradients Along Mountain to Urban Transitions (GAMUT) monitoring network spans three watersheds with similar climates and streams fed by mountain winter‐derived precipitation, but that differ in urbanization level, land use, and biophysical characteristics. The aquatic monitoring stations in the GAMUT network include sensors to measure chemical (dissolved oxygen, specific conductance, pH, nitrate, and dissolved organic matter), physical (stage, temperature, and turbidity), and biological components (chlorophyll‐a and phycocyanin). We present the logistics of designing, implementing, and maintaining the network; quality assurance and control of numerous, large datasets; and data acquisition, dissemination, and visualization. Data from GAMUT reveal spatial differences in water quality due to urbanization and built infrastructure; capture rapid temporal changes in water quality due to anthropogenic activity; and identify changes in biological structure, each of which are demonstrated via case study datasets.     

工业烟气氨法-络合法同时脱硫脱硝

在脱硫脱硝喷淋装置上采用氨法-络合法处理工业烟气。考察了吸收液pH、Fe(Ⅱ)EDTA浓度、初始烟气浓度、液气比对烟气同时脱硫脱硝效果的影响。实验结果表明:吸收液的酸碱度通过影响Fe(Ⅱ)与EDTA的络合形式进而影响NO去除率;SO_2去除率主要受吸收液pH和初始SO_2质量浓度的影响;当吸收液pH大于8、吸收液Fe(Ⅱ)EDTA浓度大于0.100 mol/L、初始SO_2质量浓度小于1 500 mg/m3、初始NO质量浓度为1 200 mg/m3时,SO_2去除率均在95%以上,NO去除率为54%;当液气比由1 L/m3增大至4 L/m3时,有效脱硫时间和有效脱硝时间分别增长了7 min和4 min。     

GC/MS法测定润滑油基础油中多环芳烃

对润滑油基础油中多环芳烃的气相色谱/质谱(GC/MS)测定方法进行了研究,探讨了样品的提取,固相萃取柱净化等前处理方法,同时也对仪器测定条件进行了优化.结果表明,在检测润滑油基础油中多环芳烃时,经优化的GC/MS法的加标回收率和精密度均达到较满意的水平.     

An assessment of indoor air quality in recent Mexican immigrant housing in Commerce City, Colorado

An indoor air quality assessment was conducted on 100 homes of recent Mexican immigrants in Commerce City, Colorado, an urban industrial community north of Denver. Head of households were administered a family health survey, filled out an activity diary, and participated in a home inspection. Carbon monoxide (CO) and carbon dioxide (CO₂) were measured for 24 h inside the main living area and outside of the homes. Harvard Impactors were used to collect 24-h samples of PM_2.5 at the same locations for gravimetric analysis. Dust samples were collected by vacuuming carpeting and flooring at four locations within the home and analyzed by ELISA for seven allergens. Mean indoor and outdoor PM_2.5 levels were 27.2 and 8.5 μg m⁻³, respectively. Indoor PM_2.5 and CO₂ were elevated in homes for which the number of hours with door/window open was zero compared to homes in which the number of hours was high (>15 h). Indoor PM_2.5 levels did not correlate with outdoor levels and tended to increase with number of inhabitants, and results indicate that the source of indoor particles were occupants and their activities, excluding smoking and cooking. Mean indoor CO₂ and CO levels were 1170 and 2.4 ppm, respectively. Carbon monoxide was higher than the 24-h National Ambient Air Quality Standard in 3 of the homes. The predominant allergens were cat (Fel d 1) and mouse (Mus m 1) allergens, found in 20 and 34 homes, respectively.     

Polychlorinated biphenyls and organochlorine pesticides in various bird species from northern China

Little data are available on organochlorine contamination in Chinese terrestrial birds of prey. This study examined the presence of PCBs, DDTs and other organochlorine pesticides in various raptors from northern China. DDE exhibited the highest concentrations among targeted compounds. Greatest levels (23.5-1020 mg/kg lipid weight) were observed in Eurasian sparrowhawks. This may be due to their stopover in southeastern China, where high DDT and dicofol applications have been documented. Residential kestrels exhibited much lower DDE, but similar PCB and HCH concentrations. ΣTEQs and PCB-126/-77 concentration ratios exhibited significant positive correlations with ΣPCB concentrations, respectively. Similar results were also demonstrated by a meta-analysis of previously published data across avian species. Possible hepatic sequestration of coplanar PCB-77, -126, -169 and -118 was observed as liver TEQs increased in Eurasian sparrowhawks. These observations may indicate an induction of CYP1A enzymes, as a result of elevated contamination in some species.     

CaO/SiO2对流化床焚烧飞灰熔融过程中重金属挥发的影响

对掺煤混烧的流化床焚烧飞灰熔融过程中重金属在气相(吸收率)中和固相(固定率)中的分布进行了研究,并采用HNO3-NaOH2级吸收方式对气相重金属进行了吸收.结果表明,CaO/SiO2(摩尔比)对重金属的迁移行为有重要影响,CaO/SiO2降低,Cd、Pb固定率总体呈上升趋势;2级吸收对气相重金属的吸收有限,大部分重金属主要溶解在HNO3吸收液中,但NaOH吸收液对Cr的吸收效果好于HNO3吸收液;氯对重金属的挥发有重要影响,当重金属以氯化物形式存在时,其挥发受到SiO2的限制.随着SiO2含量增加,挥发率降低.