Catalytic fast pyrolysis of walnut shell for alkylphenols production with nitrogen-doped activated carbon catalyst

• N-doped activated carbon was prepared for catalytic pyrolysis of walnut shell. • Alkylphenols were selectively produced from catalytic pyrolysis process. • The alkylphenols yield increased by 8.5 times under the optimal conditions. • Formation mechanism of alkylphenols was proposed. Alkylphenols are a group of valuable phenolic compounds that can be derived from lignocellulosic biomass. In this study, three activated carbons (ACs) were prepared for catalytic fast pyrolysis (CFP) of walnut shell to produce alkylphenols, including nitrogen-doped walnut shell-derived activated carbon (N/WSAC), nitrogen-doped rice husk-derived activated carbon (N/RHAC) and walnut shell-derived activated carbon (WSAC). Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were carried out to reveal the influences of AC type, pyrolytic temperature, and AC-to-walnut shell (AC-to-WS) ratio on the product distributions. Results showed that with nitrogen doping, the N/WSAC possessed stronger capability than WSAC toward the alkylphenols production, and moreover, the N/WSAC also exhibited better effects than N/RHAC to prepare alkylphenols. Under the catalysis of N/WSAC, yields of alkylphenols were significantly increased, especially phenol, cresol and 4-ethylphenol. As the increase of pyrolytic temperature, the alkylphenols yield first increased and then decreased, while high selectivity could be obtained at low pyrolytic temperatures. Such a trend was also observed as the AC-to-WS ratio continuously increased. The alkylphenols production achieved a maximal yield of 44.19 mg/g with the corresponding selectivity of 34.7% at the pyrolytic temperature of 400°C and AC-to-WS ratio of 3, compared with those of only 4.67 mg/g and 6.1% without catalyst. In addition, the possible formation mechanism of alkylphenols was also proposed with the catalysis of N/WSAC.     

Remediation of arsenic contaminated soil by sulfidated zero-valent iron

• Sulfidation significantly enhanced As(V) immobilization in soil by zerovalent iron. • S-ZVI promoted the conversion of exchangeable As to less mobile Fe-Mn bound As. • Column test further confirmed the feasibility of sulfidated ZVI on As retention. • S-ZVI amendment and magnetic separation markedly reduced TCLP leachability of As. In this study, the influences of sulfidation on zero-valent iron (ZVI) performance toward As(V) immobilization in soil were systemically investigated. It was found that, compared to unamended ZVI, sulfidated ZVI (S-ZVI) is more favorable to immobilize As(V) in soil and promote the conversion of water soluble As to less mobile Fe-Mn bound As. Specifically, under the optimal S/Fe molar ratio of 0.05, almost all of the leached As could be sequestrated by>0.5 wt.% S-ZVI within 3 h. Although the presence of HA could decrease the desorption of As from soil, HA inhibited the reactivity of S-ZVI to a greater extent. Column experiments further proved the feasibility of applying S-ZVI on soil As(V) immobilization. More importantly, to achieve a good As retention performance, S-ZVI should be fully mixed with soil or located on the downstream side of As migration. The test simulating the flooding conditions in rice culture revealed there was also a good long-term stability of soil As(V) after S-ZVI remediation, where only 0.7% of As was desorbed after 30 days of incubation. Magnetic separation was employed to separate the immobilized As(V) from soil after S-ZVI amendment, where the separation efficiency was found to be dependent of the iron dosage, liquid to soil ratio, and reaction time. Toxicity characteristic leaching procedure (TCLP) tests revealed that the leachability of As from soil was significantly reduced after the S-ZVI amendment and magnetic separation treatment. All these findings provided some insights into the remediation of As(V)-polluted soil by ZVI.     

Recent advances in the photocatalytic reduction of carbon dioxide

Fossil fuels are currently the major energy source and are rapidly consumed to supply the increasing energy demands of mankind. CO₂, a product of fossil fuel combustion, leads to climate change and will have a serious impact on our environment. There is an increasing need to mitigate CO₂ emissions using carbon–neutral energy sources. Therefore, research activities are devoted to CO₂ capture, storage and utilization. For instance, photocatalytic reduction of CO₂ into hydrocarbon fuels is a promising avenue to recycle carbon dioxide. Here we review the present status of the emission and utilization of CO₂. Then we review the photocatalytic conversion of CO₂ by TiO₂, modified TiO₂ and non-titanium metal oxides. Finally, the challenges and prospects for further development of CO₂ photocatalytic reduction are presented.     

压力容器设计中的环境温度与最低设计金属温度

环境温度在容器设计中不仅影响设计压力的合理确定,而且更影响最低设计金属温度的确定直至影响材料的正确选择。通过对规程标准的解读,结合液化石油气储罐设计对此进行了讨论,认为环境温度应视为容器的特例工况条件,容器设计应将与其对应的设计压力一起作为设计载荷条件,不仅要对容器的壁厚进行校核,而且尚需根据容器的一次应力判断并确认是否需要修订完善容器设计的选材、制造及检验等技术要求,使容器设计文件正确完整,保证容器制造的安全可靠性。     

Storm-induced transfer of particulate trace metals to the deep-sea in the Gulf of Lion (NW Mediterranean Sea)

In order to calculate budgets of particulate matter and sediment-bound contaminants leaving the continental shelf of the Gulf of Lion (GoL), settling particles were collected in March 2011 during a major storm, using sediment traps. The collecting devices were deployed in the Cap de Creus submarine canyon, which represents the main export route. Particulate matter samples were analyzed to obtain mass fluxes and contents in organic carbon, Al, Cr, Co, Ni, Cu, Zn, Cd, Pb and La, Nd and Sm. The natural or anthropogenic origin of trace metals was assessed using enrichment factors (EFs). Results are that Zn, Cu and Pb appeared to be of anthropogenic origin, whereas Ni, Co and Cr appeared to be strictly natural. The anthropogenic contribution of all elements (except Cd) was refined by acid-leaching (HCl 1 N) techniques, confirming that Zn, Cu and Pb are the elements that are the most enriched. However, although those elements are highly labile (59–77 %), they do not reflect severe enrichment (EFs <4). Most particles originate from the Rhone River. This has been confirmed by two different tracing procedures using rare earth elements ratios and concentrations of acid-leaching residual trace metals. Our results hence indicate that even in this western extremity of the GoL, storm events mainly export Rhone-derived particles via the Cap de Creus submarine canyons to the deep-sea environments. This export of material is significant as it represents about a third of the annual PTM input from the Rhone River.     

Plume rise and spread in buoyant releases from elevated sources in the lower atmosphere

This study focuses on the influence of emission conditions—velocity and temperature—on the dynamics of a buoyant gas release in the atmosphere. The investigations are performed by means of wind tunnel experiments and numerical simulations. The aim is to evaluate the reliability of a Lagrangian code to simulate the dispersion of a plume produced by pollutant emissions influenced by thermal and inertial phenomena. This numerical code implements the coupling between a Lagrangian stochastic model and an integral plume rise model being able to estimate the centroid trajectory. We verified the accuracy of the plume rise model and we investigated the ability of two Lagrangian models to evaluate the plume spread by means of comparisons between experiments and numerical solutions. A quantitative study of the performances of the models through some suitable statistical indices is presented and critically discussed. This analysis shows that an additional spread has to be introduced in the Lagrangian trajectory equation in order to account the dynamical and thermal effects induced by the source conditions.     

N2O emission from a sequencing batch reactor for biological N and P removal from wastewater

Nitrous oxide （N2O） is a greenhouse gas that can be released during biological nitrogen removal from wastewater. N2O emission from a sequencing batch reactor （SBR） for biological nitrogen and phosphorus removal from wastewater was investigated, and the aims were to examine which process, nitrification or denitrification, would contribute more to N2Oemission and to study the effects of heterotrophic activities on N2O emission during nitrification. The results showed that N2O emission was mainly attributed to nitrification rather than to denitrification. N2O emission during denitrification mainly occurred with stored organic carbon as the electron donor. During nitrification, NaO emission was increased with increasing initial ammonium or nitrite concentrations. The ratio of N2O emission to the removed ammonium nitrogen （N2O- N/NH4-N） was 2.5% in the SBR system with high heterotrophic activities, while this ratio was in the range from 0.14% to 1.06% in batch nitrification experiments with limited heterotrophic activities.     

MLX微机消谐小电流接地选线装置与变电运行安全

对供电系统中发生的接地现象以及接地而造成的谐振进行了阐述,重点对微机消谐小电流接地选线装置特点及工作过程进行分析,对装置的不足提出了相应的对策.     

Use of different soft tissues of Perna viridis a s biomonitors of bioavailability and contamination by heavy metals (Cd,Cu, Fe,Pb, Ni,and Zn) in a semi-enclosed intertidal water,the Johore Straits

Green-lipped mussels, Perna viridis, were collected from the eastern and western parts of the Johore Straits in September 2004 and January 2005. Based on the heavy metal concentrations in the different soft tissues (gonad, foot, mantle, gills, muscle, and remaining soft tissues) of these mussel samples, the eastern part of the Johore Straits (which is divided into two portions by a causeway), recorded higher levels of bioavailability and contamination by Cd, Cu, Fe, Ni, and Zn when compared to the western part, while Kg. Pasir Puteh in the eastern part was found to record the highest bioavailability and contamination by heavy metals. The use of different soft tissues of P. viridis as biomonitors of bioavailability and contamination by Cd, Cu, Fe, Pb, Ni, and Zn in the semi-enclosed Johore Straits is proposed, since erroneous results due to spawning and the problem of defecation before dissection could be overcome. Hence, a more accurate interpretation of the bioavailability and contamination by heavy metals in coastal waters could be obtained. To our knowledge, this is the most detailed study on the bioavailability and contamination of heavy metals in the Johore Straits on the Malaysian side of the waterway carried out by using the different soft tissues and metal distribution based on the Mussel Watch approach.     

Trichoderma atroviride as a bioremediator of Cu pollution: An in vitro study

Isolated Trichoderma atroviride from Cu-polluted river sediment at the Serdang Industrial Area was studied under in vitro conditions to understand the mechanisms that allowed the fungi to thrive in the Cu-polluted freshwater ecosystem. From this study, adsorption was recognized as the main mechanism of Cu tolerance with 50–85% adsorption during the in vitro experiment. The uptake capacity of the isolate in liquid medium ranged from 0.8 to 11.2 mg g^?1 in the potato dextrose broth medium with increasing Cu concentrations from 25 to 300 mg L^?1. It was found that 2.7–5.0% of Cu was lost due to washing. The high percentage of Cu adsorption and the high uptake capacity of Cu by T. atroviride suggest that it is a potential bioremediator of Cu. However, further studies are needed to confirm its practical use as a bioremediating agent for Cu under field conditions.