Utilization of Active Ni to Fabricate Pt-Ni Nanoframe/NiAl Layered Double Hydroxide Multifunctional Catalyst through In Situ Precipitation.

Integration of different active sites into metallic catalysts, which may impart new properties and functionalities, is desirable yet challenging. Herein, a novel dealloying strategy is demonstrated to decorate nickel-aluminum layered double hydroxide (NiAl-LDH) onto a Pt-Ni alloy surface. The incorporation of chemical etching of Pt-Ni alloy and in situ precipitation of LDH are studied by joint experimental and theoretical efforts. The initial Ni-rich Pt-Ni octahedra transform by interior erosion into Pt3 Ni nanoframes with enlarged surface areas. Furthermore, owing to the basic active sites of the decorated LDH together with the metallic sites of Pt3 Ni, the resulting Pt-Ni nanoframe/NiAl-LDH composites exhibit excellent catalytic activity and selectivity in the dehydrogenation of benzylamine and hydrogenation of furfural.

Developed and developing world responsibilities for historical climate change and CO2 mitigation.

At the United Nations Framework Convention on Climate Change Conference in Cancun, in November 2010, the Heads of State reached an agreement on the aim of limiting the global temperature rise to 2 °C relative to preindustrial levels. They recognized that long-term future warming is primarily constrained by cumulative anthropogenic greenhouse gas emissions, that deep cuts in global emissions are required, and that action based on equity must be taken to meet this objective. However, negotiations on emission reduction among countries are increasingly fraught with difficulty, partly because of arguments about the responsibility for the ongoing temperature rise. Simulations with two earth-system models (NCAR/CESM and BNU-ESM) demonstrate that developed countries had contributed about 60-80%, developing countries about 20-40%, to the global temperature rise, upper ocean warming, and sea-ice reduction by 2005. Enacting pledges made at Cancun with continuation to 2100 leads to a reduction in global temperature rise relative to business as usual with a 1/3-2/3 (CESM 33-67%, BNU-ESM 35-65%) contribution from developed and developing countries, respectively. To prevent a temperature rise by 2 °C or more in 2100, it is necessary to fill the gap with more ambitious mitigation efforts.

Development of a dynamical statistical analog ensemble forecast model for landfalling typhoon disasters.

In this report, the development of a Dynamical Statistical Analog Ensemble Forecast model for landfalling typhoon disasters (LTDs) and some applications over coastal China are described. This model consists of the following four elements: (i) obtaining the forecast track of a target landfalling typhoon, (ii) constructing its generalized initial value (GIV), (iii) identifying its analogs based on the GIV, and (iv) assembling typhoon disasters of the analogs. Typhoon track, intensity, and landfall date are introduced in GIV at this early development stage. The pre-assessment results show that the mean threat scores of two important damage levels of LTDs reach 0.48 and 0.55, respectively. Of significance is that most of the damage occurs near the typhoon centers around the time of landfall. These results indicate the promising performance of the model in capturing the main damage characteristics of typhoon disasters, which would help coastal community mitigate damage from destructive typhoons.

Applying rail transit construction waste to make building materials: using the theory of sustainable development.

With the rapid development of the rail industry, a large amount of construction waste will be generated during the construction phase, posing a significant risk of environmental pollution and exacerbating the plight of global resource shortages. This study establishes a green disposal system for rail transportation based on the theory of sustainable development. Shield slag, shield weathered sand, shale, and engineering slag are used as raw materials, and sintered bricks are adopted as their innovative disposal method. The heavy metals in the four types of construction waste and recycled products were tested by X-ray fluorescence analysis technique to analyze the actual environmental pollution risk and explore the influence of the firing stage on the performance of the recycled products through the enrichment factor evaluation method. The results of the physical and chemical property tests of the fired samples showed that the environmental pollution risk of the four recycled products after firing was at a low-risk level (EF < 2), the strength test results showed that the best specimens had a strength rating of 20 MPa and the other performance indicators (frosting degree, lime bursting test) measured also met the requirements of the recycled bricks. This study achieves the harmless treatment of construction waste, provides a disposal system for the green recycling of construction waste from rail transport, and provides a theoretical basis for subsequent studies on the effects of different external conditions on such recycled products.

Comparative study on polychlorinated biphenyl sorption to activated carbon and biochar and the influence of natural organic matter.

The sorption isotherms of polychlorinated biphenyls (PCBs) on carbons (coal based activated carbon named AC and hardwood derived biochar named BC) and natural organic matter (NOM) loaded carbons were examined and carbon-water partition coefficients (KC-W-PCB) were calculated. The purpose was to accurately predict the effectiveness of in-situ carbon treatments on the sediment impacted with hydrophobic organic chemicals (HOCs). For 1 month sorption, AC KC-W-PCB values were significantly higher than BC, corresponding to the much larger surface area (particularly in mesopores) for AC. BC KC-W-PCB values were correlated with PCB total surface area (TSA) and octanol-water partition coefficient (logKow). After loading with NOM, AC adsorption to PCBs strongly reduced and the fitted Freundlich exponents (n) decreased with increasing NOM level. However, NOM loading slightly impacted BC sorption and exhibited an opposite effect on BC n values. It is illustrated that the sorption mechanisms are different between AC and BC thereby the influences of NOM on sorption characteristics differ vastly. As the sorption time increased from 1 month to 6 months, an increase is observed in BC sorption extent but simultaneously NOM reduction effect on BC sorption increases, implying that more accurately evaluating BC application as an in-situ sorbent amendment for HOC impacted sediment need further investigation. On the contrary, AC adsorption attenuation caused by NOM coating greatly decreases over time, encouraging AC application as a sediment amendment.

Quantitative methods for predicting underground construction waste considering reuse and recycling.

The construction industry has been greatly developed in the past few decades, especially in the extensive use of underground space. The increasing amount of waste (e.g., soil, sludge, and rock) generated in the underground construction constitutes an important part of construction and demolition waste (CDW), but the related problems are rarely addressed in an independent quantitative study. In order to facilitate recycling of underground construction waste (UCW), quantitative methods for predicting UCW are proposed based on mass conservation in this study. Through on-site investigation and literature review, the source characteristics of UCW and corresponding recycling potential are firstly analyzed. Secondly, the corresponding quantitative method is proposed for predicting each type of UCW according to the principle of mass conservation. Finally, the proposed quantitative methods are applied in two real underground infrastructure projects to verify the accuracy. The results show that the accuracy of quantitative methods for predicting shield sludge and engineering soil is 82.03-95.79% and 94.49% respectively. The quantitative methods for predicting the amount of UCW proposed in this study is effective. In both cases, underground construction produced a large amount of construction waste with great recycling potential. UCW can theoretically reach 100% recycling, and full reuse and recycling of UCW will bring huge benefits and be conducive to the sustainable development of the construction industry.

Exploring the environmental properties and resource utilization of construction waste in Beijing-Tianjin-Hebei region.

Beijing-Tianjin-Hebei region is a capital economic circle for the future. Promoting the coordinated development of its population, economy, resources and environment is a major national strategy. And as towns and cities continue to expand, the volume of construction waste is gradually expanding, posing a major challenge to the sustainable development of the construction industry. In order to solve this problem, this paper used portable X-ray fluorescence spectrometry to realize the on-site rapid monitoring of heavy metals in construction waste, and the correlation analysis result was R2 = 0.9908. The visualization of enrichment factor evaluation results was realized through ArcGIS. The Beijing-Tianjin-Hebei region is mainly polluted by heavy metal elements Cr, Zn, Pb and Hg, showing regional pollution characteristics, and the results of mercury morphology analysis show that all are inorganic mercury pollution, and methylmercury is not detected, and the cause can be traced to heavy industrial production in Tangshan City, which is consistent with industrial ecology. The results of leaching toxicity and cation anion analysis showed that the construction waste in Beijing-Tianjin-Hebei region had environmental risks to the surrounding surface water and groundwater. The resource treatment and disposal path were determined by means of XRD, ternary phase diagram and oxide composition analysis to avoid secondary pollution. This study explores the environmental properties and resource utilization pathways of construction waste in the Beijing-Tianjin-Hebei region, laying the foundation for research work on construction waste in the development of national urban agglomerations, effectively solving regional environmental pollution problems and promoting the sustainable development of the construction industry.

Prediction Model for Compressive Strength of Porous Concrete with Low-Grade Recycled Aggregate.

As the first batch of products after the resource utilization of construction and demolition waste, low-grade recycled aggregate (RA) has not been fully utilized, which hinders the development of the comprehensive recycling industry of construction waste. Therefore, this paper studies the mechanical properties of porous concrete (POC) with low-grade RA. An improved relationship between porosity and compressive strength of brittle, porous materials is used to express the compressive strength of POC with recycled aggregate (RPOC), and the prediction for compressive strength of porous concrete with low-grade RA is constructed by analyzing the mechanism of compressive damage. The results show: the compressive strength of porous concrete decreases with the addition of low-grade recycled aggregate, but the effect is not obvious when the replacement rate is less than 25%. The error range of the relationship between porosity and compressive strength of RPOC is basically within 15% after improvement. The prediction model for compressive strength based on the ideal sphere model of aggregate can accurately reflect the compressive strength of porous concrete with low-grade RA. The results of this study can provide a reference for the staff to learn about the functional characteristics of recycled products in advance and provide security for the actual project.

Predictive model for cadmium uptake by maize and rice grains on the basis of bioconcentration factor and the diffusive gradients in thin-films technique.

It is possible for heavy metals in soils to be adsorbed by crop roots and then accumulated in crops, which eventually causes great health risk when the crops are ingested by humans. Thus, it is valuable to understand the enrichment model of heavy metals in crops. Diffusive gradients in thin-films (DGT) technique, as an in-situ passive sampling method, can be used to evaluate the bioavailable heavy metals contents in soils. In this study, data of the bioavailable cadmium (Cd) in soils determined by DGT and Cd contents uptake in rice and maize grains in Tianjin, Zhejiang and Guangxi provinces of China were collected from previous references in Web of Science. By comparing bioconcentration factors, it was found that the heavy metal concentrations accumulated in rice and maize followed a general order roots > stems or leaves > grains. An accurate and robust model for the prediction of Cd content in maize and rice grains was established based on bioconcentration factor (BCF) and the bioavailable Cd content determined by DGT method, with R2 0.986 and root mean square error (RMSE) 0.128. This result suggests that the DGT method can be good tool for predicting heavy metals uptake in crops.

Ecological risk assessment of heavy metals in farmland soils in Beijing by three improved risk assessment methods.

Beijing, as the capital of China, still has soil pollution problems that cannot be ignored. However, there are few studies on the overall ecological risks of heavy metals in farmland soils in Beijing. This study selected 432 soils and crops heavy metal content data of eight districts in Beijing from academic papers and academic journal papers. In this study, the improved Hakanson method, improved analytic hierarchy process (AHP), and integrated quality impact index (IICQ) comprehensively were used to evaluate the impact of Pb, As, and Cd pollution on the farmland soil environment, and the applicable conditions of these methods were discussed. The results by improved Hakanson method showed that both Pb and As were at the normal ecological risk level, while Cd was the largest contributor to potential ecological risk which accounted for 72.54% of the total risk and is mainly at a moderate ecological risk level. The analysis by improved AHP showed that the average comprehensive index of soil heavy metal pollution in the study area was 0.2317, which was at a light pollution level. The IICQ of soil and agricultural products were between 0 and 1 demonstrating that the soil was clean. In summary, the pollution of heavy metals Pb, As, and Cd in the study area is at a relatively low level, and there is no significant risk to the surrounding environment and human health. IICQ method is suitable for the evaluation of soil heavy metal composition and individual impact and can be more accurately used for the overall ecological evaluation of soil-crop-human health system.

Determination of Labile Cadmium in Soils Using a New Sodium Alginate-Polyglutamic Acid-Diffusive Gradient in Thin Films.

Sodium alginate-polyglutamic acid was used to develop a new diffusive gradient in thin films (SA-PGA-DGT) device, which was proven to be suitable for the investigation of labile Cd in soil. The adsorption capacity of Cd was calculated to be approximately 16.8 µg/cm2 , which was hardly affected by factors including pH (5-9), ionic strength (0.1-100 mM), and the presence of other metals (Pb, Cu, Ni, and Cr). The SA-PGA gel has dense and uneven pores with large specific surface area, which ensures the adsorption of Cd by functional groups of the gel. A kinetics study indicated that the adsorption rate of Cd by the binding gel can be described as a pseudo-second-order reaction. Deployment of the SA-PGA-DGT in the soils of Tang Gu (located in Binhai New District, Tianjin, China) showed a strong positive linear correlation between Cd measured by the device and exchangeable Cd measured by the Tessier method (R = 0.73, p < 0.01). Cadmium determined by the SA-PGA-DGT device was less affected by soil properties. This new SA-PGA-DGT has obvious advantages over other methods in respect of the labile Cd analysis in soil. The innovative novel device expands the variety of existing DGT technologies and can be utilized to monitor the level of labile Cd in soil effectively. Environ Toxicol Chem 2021;40:1559-1569. © 2021 SETAC.

Heterogeneous selective hydrogenation of ethylene carbonate to methanol and ethylene glycol over a copper chromite nanocatalyst.

Heterogeneous selective hydrogenation of ethylene carbonate (EC), a key step in indirect conversion of CO2, was realized over a copper chromite nanocatalyst prepared via a hydrothermal method followed by calcination. The selectivities towards methanol (60%) and ethylene glycol (93%) were higher than those achieved over other usual hydrogenation catalysts.