磷酸盐对硫化亚铁(FeS)吸附Sb(Ⅲ)的影响机理研究

还原环境(如湖泊、海洋沉积物)中,FeS是重金属的重要载体。在富营养化过程中,磷酸盐可能对重金属在FeS上的吸附行为产生重要影响。本文通过不同pH、磷酸盐浓度的批次试验,结合X射线衍射仪(XRD)和场发射透射电子电镜-能谱仪(TEM-EDS)固体分析手段,进行磷酸盐对FeS吸附Sb(Ⅲ)的影响研究。结果表明：酸性和中性条件下,磷酸盐会与FeS溶解释放的Fe(Ⅱ)反应生成磷酸亚铁沉淀,促进FeS溶解,同时释放出更多的H₂S(aq)/HS^-与Sb(Ⅲ)结合形成Sb₂S₃沉淀,从而促进溶液中Sb(Ⅲ)的吸附。碱性条件下,FeS对Sb(Ⅲ)只有吸附作用,而磷酸盐会占据FeS表面部分的吸附位点,与Sb(Ⅲ)形成竞争关系,进而抑制溶液中Sb(Ⅲ)的吸附。     

Quantifying Vision Zero: Crash avoidance in rural and motorway accident scenarios by combination of ACC,AEB, and LKS projected to German accident occurrence

Abstract

Objective: The Vision Zero initiative pursues the goal of eliminating all traffic fatalities and severe injuries. Today’s advanced driver assistance systems (ADAS) are an important part of the strategy toward Vision Zero. In Germany in 2018 more than 26,000 people were killed or severely injured by traffic accidents on motorways and rural roads due to road accidents. Focusing on collision avoidance, a simulative evaluation can be the key to estimating the performance of state-of-the-art ADAS and identifying resulting potentials for system improvements and future systems.

This project deals with the effectiveness assessment of a combination of ADAS for longitudinal and lateral intervention based on German accident data. Considered systems are adaptive cruise control (ACC), autonomous emergency braking (AEB), and lane keeping support (LKS).

Methods: As an approach for benefit estimation of ADAS, the method of prospective effectiveness assessment is applied. Using the software rateEFFECT, a closed-loop simulation is performed on accident scenario data from the German In-Depth Accident Study (GIDAS) precrash matrix (PCM). To enable projection of results, the simulative assessment is amended with detailed single case studies of all treated cases without PCM data.

Results: Three categories among today’s accidents on German rural roads and motorways are reported in this study: Green, grey, and white spots.

Green spots identify accidents that can be avoided by state-of-the-art ADAS ACC, AEB, and LKS. Grey spots contain scenarios that require minor system modifications, such as reducing the activation speed or increasing the steering torque. Scenarios in the white category cannot be addressed by state-of-the-art ADAS. Thus, which situations demand future systems are shown. The proportions of green, grey, and white spots are determined related to the considered data set and projected to the entire GIDAS.

Conclusions: This article describes a systematic approach for assessing the effectiveness of ADAS using GIDAS PCM data to be able to project results to Germany. The closed-loop simulation run in rateEFFECT covers ACC, AEB, and LKS as well as relevant sensors for environment recognition and actuators for longitudinal and lateral vehicle control.

Identification of green spots evaluates safety benefits of state-of-the-art level 0–2 functions as a baseline for further system improvements to address grey spots. Knowing which accidents could be avoided by standard ADAS helps focus the evolution of future driving functions on white spots and thus aim for Vision Zero.     

Reductive dechlorination of polychlorinated dibenzo-p-dioxins by zerovalent iron in subcritical water

A new method for reductive dechlorination of polychlorinated dibenzo-p-dioxins (PCDDs) and remediation of contaminated soils is described that uses zerovalent iron as the dechlorination agent and subcritical water as reaction medium and extractive solvent. It is found that the zerovalent iron can be applied for stepwise dechlorination of octachlorinated dibenzo-p-dioxin (OCDD) on various matrixes in subcritical water. By using iron powder as matrix higher chlorinated congeners were practically completely reduced to less than tetra-substituted homologues. A significant part of residual OCDD, when it was spiked in to soils, and formed less chlorinated congeners are extracted with water in the given conditions. The solubility of OCDD was increased by a 4–6 orders over its solubility at ambient conditions. The new method of contentious-flow extraction is described.     

乳化纳米铁(EZVI)强化地下水氯代烃还原脱氯

对氯代烃污染地下水进行厌氧微生物还原脱氯时,存在微生物驯化时间长、pH值持续降低、有毒中间产物累积等限制修复效率的问题,为解决上述问题,本课题组制备了一种乳化油(EVO)包覆纳米零价铁(NZVI)的修复试剂,即乳化纳米铁(EZVI),其可以抑制NZVI钝化,增强反应速率并促进厌氧微生物脱氯反应.通过静态批实验探究了EZVI与三氯乙烯的反应动力学及EZVI对四氯乙烯(PCE)还原脱氯的中间代谢产物,并阐明了该过程机理.结果表明EZVI可以有效延缓NZVI钝化、提高反应活性,反应符合一级反应动力学,k_obs=0.182d^-1;EZVI还原PCE可以减少中间产物二氯乙烯的积累,10天内去除PCE达到97.2%,比EVO还原体系提高了68.9%;反应过程中pH值保持在6.5~7.5,ORP值在-50~10mV,提供了良好的还原环境,有效促进了厌氧微生物脱氯反应进行.     

Enhanced remediation of Cr（Ⅵ）-contaminated groundwater by coupling electrokinetics with ZVI/Fe3O4/AC-based permeable reactive barrier

Although widely used in permeation reaction barrier（PRB） for strengthening the removal of various heavy metals, zero-valent iron（ZVI） is limited by various inherent drawbacks, such as easy passivation and poor electron transfer. As a solution, a synergistic system with PRB and electrokinetics（PRB-EK） was established and applied for the efficient removal of Cr（Ⅵ）-contaminated groundwater. As the filling material of PRB, ZVI/Fe₃O₄/activated carbon（ZVI/Fe₃O₄     

Microbes team with nanoscale zero-valent iron: A robust route for degradation of recalcitrant pollutants

Integrating nanoscale zero-valent iron (nZVI) with biological treatment processes holds the promise of inheriting significant advantages from both environmental nano- and bio-technologies. nZVI and microbes can perform in coalition in direct contact and act simultaneously, or be maintained in separate reactors and operated sequentially. Both modes can generate enhanced performance for wastewater treatment and environmental remediation. nZVI scavenges and eliminates toxic metals, and enhances biodegradability of some recalcitrant contaminants while bioprocesses serve to mineralize organic compounds and further remove impurities from wastewater. This has been demonstrated in a number of recent works that nZVI can substantially augment the performance of conventional biological treatment for wastewaters from textile and nonferrous metal industries. Our recent laboratory and field tests show that COD of the industrial effluents can be reduced to a record-low of 50 ppm. Recent literature on the theory and applications of the nZVI-bio system is highlighted in this mini review.     

异化还原铁泥合成蓝铁矿/微生物复合材料固载铅研究

铁基复合材料具备优异的吸附/固载重金属性能,常用于钝化土壤中的铅,但常规的化学合成方法成本较为昂贵.为此,本文研发一种基于芬顿铁泥（Iron Sludge, IS）资源化利用的铅钝化材料,即通过异化铁还原菌（Shewanella Oneidensis MR-1）调控形成官能团丰富、比表面积大、表面负电荷量高的蓝铁矿/微生物复合材料（Vivi/MR-1）,并研究其对铅的吸附固载性能.结果发现,Vivi/MR-1对铅的最大吸附容量为118 mg·g^-1,高于MR-1（78 mg·g^-1）、IS（61 mg·g^-1）、Vivi（52 mg·g^-1）,且具有较宽的pH工作范围,受环境中其他金属离子的影响较小.结合X射线衍射仪（X-ray diffractometer, XRD）、傅里叶红外光谱（Fourier Transform Infrared Spectrometer, FTIR）等表征技术,确定吸附成矿、官能团络合是Vivi/MR-1钝化铅的主要机制.最后,通过土壤钝化实验进一步验证该复合材料对土壤中铅的固载性能,研究表明,Vivi/MR-1可将土壤中酸溶解态铅降低93.6%,极大地降低了铅的迁移性.     

富氧空位MoO2强化Fe2+/过一硫酸盐体系降解四环素

采用NaBH₄超声还原法合成了富含氧空位的MoO₂,并通过多种表征方法证明了氧空位的存在.10-MoO₂作为助催化剂显著增强了Fe²⁺/过一硫酸盐体系催化性能,构建的10-MoO₂/Fe²⁺/PMS体系可快速降解四环素（TC）,10 min内对TC的降解率接近100%.系统研究了各种影响因素对TC降解效果的影响,探讨了助催化剂的稳定性及该体系的实用性.电化学、铁离子循环及自由基捕获实验的结果表明,由于氧空位（O_vacancy）的存在,降低了MoO₂的电阻,增强了电子转移能力,加速了Fe³⁺/Fe²⁺循环,提高了活性氧物种的产率,从而增强了Fe²⁺/PMS类芬顿体系的催化活性.本研究为类芬顿法处理抗生素废水提供了一种新的视角.     

Effects of using arsenic–iron sludge wastes in brick making

The arsenic–iron sludge generated in most of the treatment systems around the world is discharged into the nearest watercourse, which leads to accumulative rise of arsenic and iron concentrations in water. In this study, attempts were made to use the arsenic–iron sludge in making bricks and to analyze the corresponding effects on brick properties. The water treatment plant sludge is extremely close to brick clay in chemical composition. So, the sludge could be a potential substitute for brick clay. This study involved the addition of sludge with ratios 3%, 6%, 9% and 12% of the total weight of sludge–clay mixture. The physical and chemical properties of the produced bricks were then determined and evaluated and compared to control brick made entirely from clay. Results of different tests indicated that the sludge proportion and firing temperature were the two key factors in determining the quality of bricks. The compressive strength of 3%, 6%, 9% and 12% sludge containing brick samples were found to be 14.1 MPa, 15.1 MPa, 9.4 MPa and 7.1 MPa, respectively. These results indicate that the compressive strength of prepared bricks initially increased and then decreased with the increase of sludge proportion. Leaching characteristics of burnt bricks were determined with the variation of pH at a constant temperature. The optimum amount of sludge that could be mixed with clay to produce good bonding of clay–sludge bricks was found to be 6% (safely maximum) by weight.     

钢渣资源化利用技术现况和探讨

介绍了目前我国钢渣预处理工艺和尾渣资源化利用的主要方法,并对钢渣的资源化利用发展进行了探讨。我国钢渣的资源化利用主要受到地域、钢渣性质以及市场3方面因素的限制。建议大力推广钢渣有压热闷等先进钢渣预处理技术,使钢渣处理更加高效、环保。钢渣尾渣用于制备胶凝材料和道路建设是大批量消纳钢渣的可行方法,应争取政府和财政的支持,推动跨行业的合作,促进钢渣的资源化利用。