Enhanced adsorption of hexavalent chromium by a biochar derived from ramie biomass (<Emphasis Type=Italic>Boehmeria nivea</Emphasis> (L.) Gaud.) modified with β-cyclodextrin/poly(L-glutamic acid)

This paper explored biochar modification to enhance biochar’s ability to adsorb hexavalent chromium from aqueous solution. The ramie stem biomass was pyrolyzed and then treated by β-cyclodextrin/poly(L-glutamic acid) which contained plentiful functional groups. The pristine and modified biochar were characterized by FTIR, X-ray photoelectron spectroscopy, specific surface area, and zeta potential measurement. Results indicated that the β-cyclodextrin/poly(L-glutamic acid) was successfully bound to the biochar surface. Batch experiments were conducted to investigate the kinetics, isotherm, thermodynamics, and adsorption/desorption of Cr(VI). Adsorption capacities of CGA-biochar were significantly higher than that of the untreated biochar, and its maximum adsorption capacity could reach up to 197.21 mg/g at pH 2.0. Results also illustrated that sorption performance depended on initial solution pH; in addition, acidic condition was beneficial to the Cr(VI) uptake. Furthermore, the Cr(VI) uptake was significantly affected by the ion strength and cation species. This study demonstrated that CGA-biochar could be a potential adsorbent for Cr(VI) pollution control.     

离子色谱法测定钻井废水中的S~(2-)

川东气田生产过程中产生的废水含有硫化物,且色度深、浊度大。为测定废水中的Ｓ２－含量,实验探索了将Ｓ２－氧化成ＳＯ２－４后用离子色谱测定的方法。进行了Ｓ２－的转化率实验,结果表明：Ｓ２－含量在０～２．７ｍｇ／Ｌ范围内可以被完全氧化成ＳＯ２－４,转化率为９８．８％～１０８．０％。同时进行了该方法的精密度和准确度实验,并与碘量法进行了对比,对同一标样和实际样品的测定两种方法的结果吻合较好,该方法测定钻井废水中的Ｓ２－含量,可以避免色度、浊度的干扰,且简便、灵敏、准确     

A scientometric review of emerging trends and new developments in agricultural ecological compensation

Environmental Science and Pollution Research - Agricultural ecological compensation has drawn an increasingly broad range of interest since early 1990s. In recent years, the volume of the...     

The extract of aquatic macrophyte Carex cinerascens induced colony formation in bloom-forming cyanobacterium Microcystis aeruginosa

Environmental Science and Pollution Research - Colony formation in Microcystis aeruginosa played important roles in blooms formation. To study the effects of plant allelopathy on colony formation...     

H型钢混组合梁耐火极限时间研究∗

为探究 H 型钢混组合梁的耐火极限时间,采用 ANSYS 软件建立 H 型钢混组合梁的热-结构耦合计算模型, 分析了火源类型、外荷载大小、腹板厚度、受火区长度对 H 型钢混组合梁耐火极限时间的影响。结果表明：在设定的火灾场景下,油罐车燃烧时 H 型钢混组合梁的耐火极限时间为 36 min,而小汽车的燃烧不会造成 H 型钢混组合梁的下挠破坏;外荷载越大、腹板越薄、受火区越长,H 型钢混组合梁的耐火极限时间越短,其耐火极限时间最多分别缩短了 11、8、8 min。在此基础上提出了提升 H 型钢混组合梁耐火极限时间的建议。     

TiO2/Schwertmannite nanocomposites as superior co-catalysts in heterogeneous photo-Fenton process

The heterogeneous photo-Fenton reaction is an effective technique in combating organic contaminants for both soil and water remediation,and extensive studies have focused on enhancing its efficiency and reducing its costs.In this work,we developed novel photoFenton catalysts by simply milling commercially available TiO_2(P25)with Schwertmannite(Sh),a natural iron-oxyhydroxysulfate nanomineral.We expect that the photo-generated electrons from TiO_2could continuously migrate to Sh,which then could enhance the separation of electron-hole pairs on TiO_2and accelerate the reduction of Fe(III)to Fe(II)on Sh,leading to high degradation efficiency of the target organic contaminants.SEM and TEM results showed the distribution of TiO_2on Sh surface for the nanocomposites(TiO_2/Sh).Under simulated sunlight irradiation,the much higher content of Fe(II)was determined on TiO_2/Sh than on Sh via a common method in the iron ore,and the consumption of H_2O_2and the production of·OH were more significant in the TiO_2/Sh system than those in the TiO_2and Sh systems.These results well support our hypothesis that the photo-generated electrons could migrate from TiO_2to Sh on the composites,and can also explain the much higher degradation efficiency of Rhodamine B(RhB)in the TiO_2/Sh system.Besides,TiO_2/Sh had lower Fe dissolution as compared with Sh,and retained high catalytic stability after four repeated cycles.Above merits of the TiO_2/Sh composites,in combining with their simple synthesis method and low-cost property,indicated that they should have promising applications as heterogeneous photo-Fenton catalysts.     

Ground-level ozone in the Pearl River Delta and the roles of VOC and NO(x) in its production

In many regions of China, very rapid economic growth has been accompanied by air pollution caused by vehicle emissions. In one of these regions, the Pearl River Delta, the variations of ground-level ozone and its precursors were investigated. Overall, the ambient concentrations of NO(2) increased quickly between 1995 and 1996, but then slightly decreased due to stringent nitrogen oxide (NO(x)) emission controls. Nonetheless, ambient NO(2) levels in the Pearl River Delta remained high. The regional average concentrations of volatile organic compounds (VOCs) were 290 ppbC in summer and 190 ppbC in autumn. Local emissions and long-distance transportation of pollutants play important roles in the regional distribution of VOCs. Ambient O(3) production is significant in urban areas and also downwind of cities. The relative incremental reactivities (RIRs), determined by an observation-based model, showed that ground-level ozone formation in the Guangzhou urban area is generally limited by the concentrations of VOCs, but there are also measurable impacts of NO(x).     

Source apportionment of PM2.5 light extinction in an urban atmosphere in China

Haze in China is primarily caused by high pollution of atmospheric fine particulates (PM_2.5). However, the detailed source structures of PM_2.5 light extinction have not been well established, especially for the roles of various organic aerosols, which makes haze management lack specified targets. This study obtained the mass concentrations of the chemical compositions and the light extinction coefficients of fine particles in the winter in Dongguan, Guangdong Province, using high time resolution aerosol observation instruments. We combined the positive matrix factor (PMF) analysis model of organic aerosols and the multiple linear regression method to establish a quantitative relationship model between the main chemical components, in particular the different sources of organic aerosols and the extinction coefficients of fine particles with a high goodness of fit (R² = 0.953). The results show that the contribution rates of ammonium sulphate, ammonium nitrate, biomass burning organic aerosol (BBOA), secondary organic aerosol (SOA) and black carbon (BC) were 48.1%, 20.7%, 15.0%, 10.6%, and 5.6%, respectively. It can be seen that the contribution of the secondary aerosols is much higher than that of the primary aerosols (79.4% versus 20.6%) and are a major factor in the visibility decline. BBOA is found to have a high visibility destroying potential, with a high mass extinction coefficient, and was the largest contributor during some high pollution periods. A more detailed analysis indicates that the contribution of the enhanced absorption caused by BC mixing state was approximately 37.7% of the total particle absorption and should not be neglected.     

杭州市郊菜区大气及蔬菜中氟化物的含量和分布

本文分析调查了杭州市郊菜区大气及一些主要蔬菜中氟化物的含量及分布，并对蔬菜中氟化物含量与大气氟污染的关系进行了相关分析。结果表明，杭州市郊菜区个别蔬菜中氟化物含量已超过有关标准，这主要与工业污染源的分布有关；蔬菜中氟化物含量与大气氟浓度之间存在着明显的相关关系。     

超细颗粒的旋风除尘

针对细颗粒旋风除尘 ,以分子筛 空气为实验物系 ,测定了 3种不同结构的环流循环除尘系统的分离性能。实验结果表明 ,加设带有导流锥整流器的除尘系统分离效率最高 ,但压降也略有增加。由该除尘系统的粒级效率曲线可以看出 ,直径在 2 8μm左右的细颗粒由于容易被大颗粒夹带分离 ,其分离效率比 4 μm左右的颗粒高