Effect of seawater salinity on the synthesis of zeolite from coal fly ash

A novel method for the synthesis of zeolite was developed in this paper. The synthesis was carried out by hydrothermal activation after alkali fusion and coal fly ash （CFA） was used as raw material with seawater of different salinities. Seawater salinity was varied from 32 to 88 for zeolite crystallization during the hydrothermal process. The results show that seawater salinity plays an important role in zeolite synthesis with CFA during hydrothermal treatment. The products were a mixture of NaX zeolite and hydroxysodalite; seawater salinity more strongly affected the crystallization than the type and chemical composition of the zeolites. The yield of CFA transformed into zeolite gradually rose with the increase in salinity, reaching a transformation rate of 48%--62% as the salinity increased from 32 to 88, respectively. The proposed method allows for the efficient disposal of by-products; therefore, the application of seawater in zeolite synthesis presents promising economic and ecological benefits.     

Cation exchange resin supported nanoscale zero-valent iron for removal of phosphorus in rainwater runoff

Self-made cation exchange resin supported nanoscale zero-valent iron （R-nZVI） was used to remove phosphorus in rainwater runoff. 80% of phosphorus in rainwater runoff from grassland was removed with an initial concentration of 0.72 mg. L-1 phosphorus when the dosage of R-nZVl is 8 g per liter rainwater, while only 26% of phosphorus was removed when using cation exchange resin without supported nanoscale zero-valent iron under the same condition. The adsorption capacity of R-nZVI increased up to 185 times of that of the cation exchange resin at a saturated equilibrium phosphorous concentration of 0.42 mg. L-1. Various techniques were implemented to characterize the R-nZVI and explore the mechanism of its removal of phosphate. Scanning electron microscopy （SEM） indicated that new crystal had been formed on the surface of R-nZVI. The result from inductive coupled plasma （ICP） indicated that 2.1% of nZVI was loaded on the support material. The specific surface area was increased after the load of nanoscale zero-valent iron （nZVI）, according to the measurement of BET-N2 method. The result of specific surface area analysis also proved that phosphorus was removed mainly through chemical adsorption process. X-ray photoelectron spectroscopy （XPS） analysis showed that the new product obtained from chemical reaction between phosphate and iron was ferrous phosphate.     

Novel synthetic approaches and TWC catalytic performance of flower-like Pt/CeO2

A novel Ultrasonic Assisted Membrane Reduction （UAMR）-hydrothermal method was used to prepare flower-like Pt/CeO2 catalysts. The texture, physical/chemical properties, and reducibility of the flower-like Pt/CeO2 catalysts were characterized by X-Ray Diffraction （XRD）, Scanning Electron Microscope （SEM）, Transmission Electron Microscope （TEM）, N2 adsorption, and hydrogen temperature programmed reduction （HE-TPR） techniques. The catalytic performance of the catalysts for treating automobile emission was studied relative to samples prepared by the conventional wetness impregnation method. The Pt/CeO2 catalysts fabricated by this novel method showed high specific surface area and metal dispersion, excellent three-way catalytic activity, and good thermal stability. The strong interaction between the Pt nanoparticles and CeO2 improved the thermal stability. The Ce4＋ ions were incorporated into the surfactant chains and the Pt nanoparticles were stabilized through an exchange reaction of the surface hydroxyl groups. The SEM results demonstrated that the Pt/CeO2 catalysts had a typical three-dimensional （3D） hierarchical porous struc- ture, which was favorable for surface reaction and enhanced the exposure degree of the Pt nanoparticles. In brief, the flower-like Pt/CeO2 catalysts prepared by UAMR-hydrothermal method exhibited a higher Pt metal dispersion, smaller particle size, better three-way catalytic activity, and improved thermal stability versus conven- tional materials.     

Effects of bicarbonate and cathode potential on hydrogen production in a biocathode electrolysis cell

A biocathode with microbial catalyst in place of a noble metal was successfully developed for hydrogen evolution in a microbial electrolysis cell （MEC）. The strategy for fast biocathode cultivation was demonstrated. An exoelectrogenic reaction was initially extended with an H2-full atmosphere to enrich Ha-utilizing bacteria in a MEC bioanode. This bioanode was then inversely polarized with an applied voltage in a half-cell to enrich the hydrogen-evolving biocathode. The electrocatalytic hydrogen evolution reaction （HER） kinetics of the biocathode MEC could be enhanced by increasing the bicarbonate buffer concentration from 0.05 mol·L-1 to 0.5 mol· L-1 and/or by decreasing the cathode potential from -0.9 V to - 1.3 V vs. a saturated calomel electrode （SCE）. Within the tested potential region in this study, the HER rate of the biocathode MEC was primarily influenced by the microbial catalytic capability. In addition, increasing bicarbonate concentration enhances the electric migration rate of proton carriers. As a consequence, more mass H＋ can be released to accelerate the biocathode-catalyzed HER rate. A hydrogen production rate of 8.44 m3. m 3. d1 with a current density of 951.6 A. m-3 was obtained using the biocathode MEC under a cathode potential of - 1.3 V vs. SCE and 0.4 mol· L-1 bicarbonate. This study provided information on the optimization of hydrogen production in biocathode MEC and expanded the practical applications thereof.     

Using crosslinked polyvinyl alcohol polymer membrane as a separator in the microbial fuel cell

Separator between anode and cathode is an essential part of the microbial fuel cell （MFC） and its property could significantly influence the system perfor- mance. In this study we used polyvinyl alcohol （PVA） polymer membrane crosslinked with sulfosuccinic acid （SSA） as a new separator for the MFC. The highest power density of 7594-4 mW-m-2 was obtained when MFC using the PVA membrane crosslinked with 15% of SSA due to its desirable proton conductivity （5.16 x 10-2 S.cml）. The power density significantly increased to 11064- 30 mW.m-2 with a separator-electrode-assembly config- uration, which was comparable with glass fiber （11704- 46 mW.m-2）. The coulombic efficiencies of the MFCs with crosslinked PVA membranes ranged from 36.3% to 45.7% at a fix external resistance of lO00f2. The crosslinked PVA membrane could be a promising alter- native to separator materials for constructing practical MFC system.     

Application of probabilistic risk assessment at a coking plant site contaminated by polycyclic aromatic hydrocarbons

Application of Probabilistic Risk Assessment （PRA） and Deterministic Risk Assessment （DRA） at a coking plant site was compared. By DRA, Hazard Quotient （HQ） following exposure to Naphthalene （Nap） and Incremental Life Cancer Risk （ILCR） following exposure to Benzo（a）pyrene （Bap） were 1.87 and 2.12 × 104. PRA revealed valuable information regarding the possible distribution of risk, and risk estimates of DRA located at the 99.59th and 99.76th percentiles in the risk outputs of PRA, which indicated that DRA overestimated the risk. Cleanup levels corresponding acceptable HQ level of 1 and ILCR level of 104 were also calculated for both DRA and PRA. Nap and Bap cleanup levels were 192.85 and 0.14mg.kg-1 by DRA, which would result in only 0.25% and 0.06% of the exposed population to have a risk higher than the acceptable risk, according to the outputs of PRA. The application of PRA on cleanup levels derivation would lift the cleanup levels 1.9 times for Nap and 2.4 times for Bap than which derived by DRA. For this coking plant site, the remediation scale and cost will be reduced in a large portion once the method of PRA is used. Sensitivity analysis was done by calculating the contribution to variance for each exposure parameter and it was found that contaminant concentration in the soil （Cs）, exposure duration （ED）, total hours spent outdoor per day （ETout）, soil ingestion rate （IRs）, the air breathing rate （IRa） and bodyweight （BW） were the most important parameters for risk and cleanup levels calculations.     

间作栽培对连作马铃薯根际土壤微生物区系的影响

为探究不同间作栽培模式缓解马铃薯（Solanum tuberosum）连作障碍的可行性及作用机制,以马铃薯单作为对照,研究马铃薯间作玉米（Zea mays）、蚕豆（Vicia faba）和荞麦（Fagopyrum esculentum）3种模式对连作马铃薯根际土壤养分含量及微生物区系的影响.结果表明,间作种植模式下马铃薯根际土壤全氮、全磷、速效磷和速效钾含量显著低于马铃薯单作,根际土壤速效磷降幅最大,达45％以上,土壤pH值明显下降.间作栽培模式改变了马铃薯根际土壤微生物群落结构,降低了根际土壤真菌的数量;间作栽培模式对马铃薯根际土壤微生物群落的碳源利用能力也有明显影响,其中马铃薯间作蚕豆和间作玉米处理马铃薯根际土壤微生物培养120 h的平均颜色变化率分别比对照高13.39％和4.30％.马铃薯根际土壤微生物群落总体上对碳水化合物利用率较高,对芳香化合物的利用率较低.间作蚕豆明显促进了马铃薯根际土壤微生物群落的碳源代谢强度,而且能维持较稳定的产量,因而可能是一种有利于改善马铃薯连作栽培根际微生态环境、缓解连作障碍的栽培模式.     

白云岩单轴压缩试验声发射特性研究

在单轴压缩条件下,进行白云岩破坏全过程的声发射试验研究,得到应力、声发射特性与时间的关系,并研究了岩体的Kaiser效应。结果表明:（1）岩石单轴压缩破坏过程中并不是所有试验岩样有具有典型的声发射特征阶段,部分岩样AE曲线中可以找到Kaiser效应特征点,但是多数岩样的Kaiser效应特征点不明显;（2）岩样的AE现象在应力达到峰值前会经过一个平静期,而在岩石发生破坏直至彻底破坏阶段,AE现象明显增加,这个先平静后剧增的过程可以作为预报岩爆发生的一种警示信号;（3）大多数岩样都在AE能量达到最大时发生彻底破坏。     

基于生态过程模型和森林清查数据的森林生长量估算对比研究

利用遥感驱动的生态过程模型-Boreal Ecosystem Productivity Simulator （BEPS）、2001-2006年国家森林资源连续清查数据（一类清查-样地尺度）和2003-2009年森林资源规划设计调查数据（二类调查-区域尺度）,分别计算江西省吉安市的森林生态系统生长量,从不同空间尺度和森林类型对3种数据源估算的森林生长量进行了分析。结果表明,样点尺度上,BEPS模型模拟的森林生长量（4.18 Mg·hm^-2·a^-1）低于群落生长量（5.86 Mg·hm^-2·a^-1）,与乔木层生长量（4.29 Mg·hm^-2·a^-1）基本一致,模型模拟结果与两者的拟合R2分别为0.48和0.43。区域尺度上,BEPS模型模拟、二类调查数据计算的群落及乔木层生长量分别为4.65、4.36和3.34 Mg·hm^-2·a^-1,BEPS模型估算的吉安市各县森林总生长量与二类调查数据计算的群落、乔木层生长总量拟合R2分别达0.84和0.83。一类清查数据计算结果高于二类清查数据计算结果,BEPS模型模拟森林生长量分别与基于一类清查数据计算的乔木层生长量及二类调查数据群落生长量较为一致。从研究区两种主要森林类型来看,常绿阔叶林年平均生长量高于常绿针叶林,常绿针叶林与模型估算结果差异小于常绿阔叶林。最后利用模型估算了研究区2001-2010年平均生长量,为认识研究区的森林生长空间分布差异及更新森林生物量提供支持。     

Ozone kinetics of dimethyl sulfide in the presence of water vapor

The outdoor smog chamber was used to thorough investigate the rate constants of gas-phase reaction between dimethyl sulfide （DMS） and ozone （O3） under conditions of relative humidity 55.0%-67.8% at （296±2）K for the first time. The rate constants were measured, at a total pressure of 1 atm, to be （10.4±0.2） × 10^-19 cm^3·molecule^-1·s^-1 at relative humidity of 67.5%±0.3% at 298K, （10.1±0.1） × 10^-19cm^3·molecule^-1·s^-1 at relative humidity of 66.5%±0.5% at 296K, （7.75±0.39） × 10^-19cm^3·molecule^-1·s^-1 at relative humidity of 64.8%± 0.1% at 294K and （3.42±0.21） × 10^-19cm^3·molecu- le^-1·s^-1at relative humidity of 55.8%±0.8% at 295K. Base on these results, it is possible to see the reaction of O3/ DMS in the presence of water vapor as an important sink for DMS in the earth atmosphere.