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排序方式: 共有165条查询结果,搜索用时 203 毫秒
1.
Yongjiao Xiong Xiangfeng Huang Bin Lu Baoqiang Wu Lijun Lu Jia Liu Kaiming Peng 《环境科学学报(英文版)》2020,32(3):80-89
Waste cutting emulsions are difficult to treat efficiently owing to their complex composition and stable emulsified structure. As an important treatment method for emulsions, chemical demulsification is faced with challenges such as low flocs–water separation rates and high sludge production. Hence, in this study, Fe3O4 magnetic nanoparticles (MNPs) were used to enhance chemical demulsification performance for treating waste cutting emulsions under a magnetic field. The addition of MNPs significantly decreased the time required to attain sludge–water separation and sludge compression equilibrium, from 210 to 20 min. In addition, the volume percentage of sludge produced at the equilibrium state was reduced from 45% to 10%. This excellent flocculation–separation performance was stable over a pH range of 3–11. The magnetization of the flocculants and oil droplets to form a flocculant–MNP–oil droplet composite, and the magnetic transfer of the composite were two key processes that enhanced the separation of cutting emulsions. Specifically, the interactions among MNPs, flocculants, and oil droplets were important in the magnetization process, which was controlled by the structures and properties of the three components. Under the magnetic field, the magnetized flocculant–MNP–oil droplet composites were considerably accelerated and separated from water, and the sludge was simultaneously compressed. Thus, this study expands the applicability of magnetic separation techniques in the treatment of complex waste cutting emulsions. 相似文献
2.
Roseli M. Dias Jessica G. Silv Vicelma L. Cardoso Miriam M. de Resende 《环境科学学报(英文版)》2020,32(5):151-159
Two chromium removal experiments were performed in bioreactors with and without a magnetic field under the same conditions.The release of the chromium present in the biomass was tested in two experiments one with the initial pH of the medium and one with pH 4.0.The objective was to remove Cr(Ⅵ) and total Cr from the effluent,this was carried out by placing biological treatments of synthetic effluent contaminated with 100 mg/L of Cr(Ⅵ) in a bioreactor with neodymium magnets that applied a magnetic field(intensity85.4 mT) to the mixed culture.The removal of Cr(Ⅵ) was approximately 100.0% for the bioreactor with a magnetic field and 93,3% for the bioreactor without a magnetic field for9 hr of recirculation of the synthetic effluent by the bioreactor.The removal of total Cr was61.6% and 48.4%,with and without a magnetic field,respectively;for 24 hr.The desorption of Cr(VI) in the synthetic effluent was 0.05 mg/L,which is below the limit established by Brazilian legislation(0.1 mg/L) for the discharge of effluent containing Cr(Ⅵ) into bodies of water.The results obtained for the removal of chromium in synthetic effluent suggested that there was no significant influence on the viable cell count of the mixed culture.The desorption of Cr(Ⅵ) in synthetic effluent after bioadsorption of chromium by the mixed culture in the process of removal of chromium in bioreactors with and without a magnetic field was not significant in either of the experiments with different initial pHs. 相似文献
3.
4.
综述了环境磁学发展进程中与环境问题的相互联系,以及磁学在气候、土壤、湖泊、生物和环境污染领域的广泛应用。分析了环境磁学进一步发展的研究方向。指出环境磁学以解决环境问题为主要目标。环境磁学方法所具有的样品用量少,灵敏度高,简便快速,非破坏性,费用低等特点,为研究环境问题提供了新途径和新方法。随着人类对环境问题的不断重视,利用环境磁学来追踪污染物的起源以及土壤,湖泊沉积物等物源将是环境磁学服务社会的重要内容。 相似文献
5.
连续式磁性颗粒去除器,是利用稀土永磁Nd-Fe-B为材质,处理含磁性颗粒废水的装置,其主要结构由动力传递,磁块组合体,磁条移动,设备本体,进出口流道及分离部件等组成,该文阐述了永磁分离机理,并通过磁性悬浮颗粒的理论驱进速度和最小捕获粒径的求解,探讨了提高砒生粒去除器捕 方法,实践证明,该装置用于冶金轧钢废水处理中,能代替传统的轧钢废水三级处理工艺,节约投资成本70%,占地减少85%,运行费用亦大幅 相似文献
6.
This work was conducted to determine the practicability of using a new adsorbent 4-ethyl thiosemicarbazide intercalated,organophilic calcined hydrotalcite(ETSC-OHTC) for the removal of uranium(U(VI)),and thorium(Th(IV)) from water and wastewater.The FTIR analysis helped in realizing the involvement of nitrogen and sulphur atoms of ETSC in binding the metal ions through complex formation.Parameters like adsorbent dosage,solution pH,initial metal ions concentration,contact time and ionic strength,that influence adsorption phenomenon,were studied.The optimum pH for maximum adsorption of U(VI) and Th(IV) was found to be in the range 4.0-6.0.The contact time required for reaching equilibrium was 4 hr.The pseudo second-order kinetic model was the best fit to represent the kinetic data.Analysis of the equilibrium adsorption data using Langmuir,Freundlich and Sips models showed that the Freundlich model was well suited to describe the metal ions adsorption.The K F values were 25.43 and 29.11mg/g for U(VI) and Th(IV),respectively,at 30°C.The adsorbent can be regenerated effectively from U(VI) and Th(IV) loaded ones using 0.01mol/L HCl.The new adsorbent was quite stable for many cycles,without much reduction in its adsorption capacity towards the metals. 相似文献
7.
《Journal of Manufacturing Processes》2014,16(4):551-562
Electromagnetic pulse metal processing techniques (EPMPT) such as welding, forming and cutting have proven to be an effective solution to specific manufacturing problems. A high pulse magnetic field coil is a critical part of these technologies and its design is a challenging task. This paper describes a Bitter coil design using a newly developed methodology for a simplified analytical calculation of the coil and complementary finite element models (FE) of different complexity. Based on the methodology a Belgian Welding Institute (BWI) Bitter coil has been designed and tested by means of short circuit experiments, impedance and B-field measurements. A good agreement between the calculated and the experimental design parameters was found. 相似文献
8.
Sustainable method towards magnetic ordered mesoporous polymers for efficient Methylene Blue removal
The difficulty in achieving high removal efficiency for contaminants in textile wastewater over a wide range of pH impedes the progress of its treatment technique greatly. Herein, a facile and sustainable strategy was adopted for constructing magnetic ordered mesoporous polymers (M-OMPs) without the assistance of organic solvent and catalyst. The prepared M-OMPs were endowed with high special surface area and good superparamagnetism simultaneously, and exhibited high removal efficiency (>99%) for Methylene Blue (MB) within a short time (10 min) at a concentration of 50 mg/L. What's more, high removal efficiency was achieved over a wide range of pH 2-12 and the adsorption capacity for MB on M-OMPs was substantially retained even after 5 adsorption-desorption cycles, further demonstrating the application potential of M-OMPs in the decontamination of textile wastewater. 相似文献
9.
应用核磁共振技术找水是核磁共振技术应用的新领域,核磁共振找水是一种直接探测地下水的地球物理方法。本文介绍了在贫水地区一个指定范围内探测地下水例子。比较所做的三个僚共振测点的工作结果,确定出含中水情况较好部位,配合做了率对四极测探,其工作结果指示出一低阻区域,是地下水富集带。在设计的钻井位置钻探探打出了优质 下水,验证了核磁共振找水方法的推断结果。在对该磁共振找水方法研究和实践的基础上,指出:核磁共 相似文献
10.
The Singrauli region in the southeastern part of Uttar Pradesh, India is one of the most polluted industrial sites of Asia.
It encompasses 11 open cast coalmines and six thermal power stations that generate about 7,500 MW (about 10% of India’s installed
generation capacity) electricity. Thermal power plants represent the main source of pollution in this region, emitting six
million tonnes of fly-ash per annum. Fly-ash is deposited on soils over a large area surrounding thermal power plants. Fly-ashes
have high surface concentrations of several toxic elements (heavy metals) and high atmospheric mobility. Fly ash is produced
through high-temperature combustion of fossil fuel rich in ferromagnetic minerals. These contaminants can be identified using
rock-magnetic methods. Magnetic susceptibility is directly linked to the concentration of ferromagnetic minerals, primarily
high values of magnetite. In this study, magnetic susceptibility of top soil samples collected from surrounding areas of a
bituminous-coal-fired power plant were measured to identify areas of high emission levels and to chart the spatial distribution
of airborne solid particles. Sites close to the power plant have shown higher values of susceptibility that decreases with
increasing distance from the source. A significant correlation between magnetic susceptibility and heavy metal content in
soils is found. A comparison of the spatial distribution of magnetic susceptibility with heavy-metal concentrations in soil
samples suggests that magnetic measurements can be used as a rapid and inexpensive method for proxy mapping of air borne pollution
due to industrial activity. 相似文献