scholarly journals Control of Contaminant Transport Caused by Open-Air Heavy Metal Slag in Zhehai, Southwest China

2019 ◽  
Vol 16 (3) ◽  
pp. 443
Author(s):  
Jiang Zhao ◽  
Zhihua Chen ◽  
Tao Wang ◽  
Caijuan Xiang ◽  
Mingming Luo ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Contaminant Transport ◽  
Atmospheric Precipitation ◽  
Ex Situ ◽  
Outflow Channels ◽  
Slag Heap ◽  
Clay Layers ◽  
And Control ◽  
Infiltration Recharge

Slag heaps are formed by mining waste materials, and the improper treatment of leachate from such heaps can threaten nearby aquifers. The Zhehai slag heap in Yunnan Province, China, contains 2.7 million tons of zinc and cadmium slag, and is considered a heavy metal source threatening the local groundwater safety, however, the severity of contamination remains unknown. In this study, numerical modeling was used to predict the groundwater flow and contaminant transport in this area based on field data. The results show that the atmospheric precipitation infiltration recharge at the top of the heap is 81.8 m3/d, accounting for 93.76% of total infiltration. The south and east sides of the area are the main outflow channels for contaminants, accounting for 93.25% of the total discharge around the heap. To reduce aquifer contamination, an in situ system involving a “controlling the source, ‘breaking’ the path, and intercepting the flow” (CSBPIF) strategy is established. The results indicate that the system performs well because it not only decreases the flow velocity but also reduces the concentrations of contaminants adsorbed by clay media. Moreover, the equivalent bottom liner thicknesses of the clay layers were calculated to improve the applicability of the CSBPIF system. Compared with ex situ disposal, this scheme provides an economic and effective solution and can be used to prevent and control groundwater pollution in China.

scholarly journals Heavy metal phytoremediation: Potential and advancement

2020 ◽  
pp. 81-93
Author(s):  
Pushpa Chaudhary Tomar ◽  
Shilpa Samir Chapadgaonkar ◽  
Varsha Panchal ◽  
Arpita Ghosh
Keyword(s):  
Heavy Metal ◽  
Industrial Waste ◽  
Research Work ◽  
Industrial Effluents ◽  
Ex Situ ◽  
Plant Tissues ◽  
Land Resource ◽  
Environmental Friendly ◽  
Different Types

Industrial activities lead to the release of different types of toxic metals into the environment. Phytoremediation has been established as one of the environmental-friendly and economical processes that have the potential for the remediation of industrial waste. Phytoremediation is used to extract metals from industrial effluents using ex-situ and in-situ treatments. Also, phytoremediation may be used to reclaim the polluted land resource for agricultural purposes. Moreover, this also prevents the bioaccumulation and biomagnification of xenobiotics from farming activities if carried out from polluted land. Phyto-mining can be done to recover and reuse the heavy metals from plant tissues after phytoremediation by plants. This study aimed to give a comprehensive review of recent research work in heavy metal phytoremediation.

Tuning the Terrace and Step Stability of 6H-SiC (0001) for Graphene Film Deposition

2015 ◽  
Vol 821-823 ◽  
pp. 953-956
Author(s):  
Gemma Rius ◽  
Narcis Mestres ◽  
Osamu Eryu ◽  
Philippe Godignon
Keyword(s):  
Crystal Surface ◽  
Graphene Film ◽  
Film Deposition ◽  
Ex Situ ◽  
Surface Roughening ◽  
Single Crystal Surface ◽  
Planar Technology ◽  
Graphene Films ◽  
And Control

Graphene is a 2D material with potential for almost any purpose, thanks to a combination of excellent characteristics, e.g. high electrical conductivity. Graphene grown on SiC wafers is one of the promising routes for graphene integration into planar technology electronic applications. Synthesis is based on the decomposition of a SiC single crystal surface at high temperature, where Si-terminated SiC substrates require the formation of the C buffer layer. In spite of numerous experimental and theoretical works the understanding and control upon crucial factors such as step and terrace stability or surface roughening is far from been fully comprehended and then technologically optimized. We present experimental results on the deposition of graphene onto Si-terminated 6H-SiC. We analyze the effect of ex situ and in situ conditionings of the SiC surface in the thermal decomposition and reconstruction of the SiC terraces, toward higher control upon the growth process of graphene films.

scholarly journals Status mutu air dan kandungan logam berat pada air dan sedimen di muara Krueng Aceh, Kota Banda Aceh

DEPIK ◽  
2018 ◽  
Vol 7 (2) ◽  
pp. 91-99
Author(s):  
Iqbalul Hadi ◽  
Suhendrayatna Suhendrayatna ◽  
Zainal Abidin Muchlisin
Keyword(s):  
Water Quality ◽  
Heavy Metal ◽  
Metal Content ◽  
Research Result ◽  
Heavy Metal Content ◽  
Ex Situ ◽  
Left Bank ◽  
Average Value ◽  
Quality Status

The aim of this research was to examine the status of water qaility of the Krueng Aceh estuary and heavy metal content in water and sediment. Data were taken by direct measurement in the field (in situ) and in the laboratory (ex situ). Three sampling stations were determined by purposive sampling, namely; in the left bank (nearest location with TPA), right bank (nearest location to market) and middle river (middle river area often passed by fisherman boat). Heavy metal analysis was conducted using AAS (Atomic Absorption Spectrophotometer) method and water quality status determined by STORET method. Based on the research result showed that that water quality parameters that have passed the standard of PP RI No. 82 Year 2001 Group III is TDS with an average value of 3332.78 mg / L, Pb with an average value of 0.052 mg / L, and Cd with an average value of 0.015 mg / L. The quality status of Krueng Aceh estuary water is classified into a moderate polluted or class C with a score of -23. The highest heavy metal content found in water sample is Pb with concentration of 0.106 mg / L. While, the average value of Pb was 0.052 mg / L and Cd was 0.015 mg /L, its have passed the quality standard specified in PP RI no. No. 82 of 2001. In addition, the highest heavy metal content found in sediment was Zn with the concentration of 29.633 mg /kg and its average value was still below the standard set by ANZECC ISQG-Low.Penelitian ini dilakukan untuk mengetahui status mutu kualitas air muara Krueng Aceh dan kandungan logam berat yang terdapat pada air dan sedimen. Metode yang digunakan dalam penelitian ini adalah metode survey. Data parameter yang diambil melalui pengukuran langsung di lapangan (in situ) dan di laboratorium (ex situ). Penentuan stasiun sampling secara purposive, yaitu pada muara Krueng Aceh dengan menetapkan tiga titik sampling yaitu pada tepi kiri (lokasi terdekat dengan TPA), tepi kanan (lokasi terdekat dengan pasar) dan tengah sungai (daerah tengah aliran sungai yang sering dilalui boat nelayan). Analisis logam berat dilakukan dengan metode SSA (Spektrofometri Serapan Atom) dan status mutu air ditentukan dengan metode STORET. Berdasarkan hasil penelitian dapat diketahui parameter kualitas air yang telah melewati baku mutu PP RI No 82 Tahun 2001 Golongan III adalah TDS dengan dengan nilai rata-rata 3332,78 mg/L, Pb dengan nilai rata-rata 0,052 mg/L, dan Cd dengan nilai rata-rata 0,015 mg/L. Status mutu air muara Krueng Aceh diklasifikasikan ke dalam tercemar sedang atau kelas C dengan skor -23. Kandungan logam berat tertinggi yang ditemukan pada sampel air di muara Krueng Aceh adalah Pb dengan konsentrasi 0,106 mg/L. Nilai rata-rata Pb 0,052 mg/L dan Cd 0,015 mg/L telah melewati baku mutu yang ditetapkan dalam PP RI No. 82 Tahun 2001. Kandungan logam berat tertinggi yang ditemukan pada sampel sedimen di muara Krueng Aceh adalah Zn dengan konsentrasi 29,633 mg/Kg dan nilai rata-ratanya masih berada di bawah baku mutu yang ditetapkan oleh ANZECC ISQG-Low. 

scholarly journals Advances in Heavy Metal Bioremediation: An Overview

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ali Sayqal ◽  
Omar B. Ahmed
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Heavy Metal Contamination ◽  
Ex Situ ◽  
Toxic Heavy Metals ◽  
Heavy Metal Remediation ◽  
Land Farming ◽  
Biological Methods ◽  
Metal Bioremediation

The pollution of toxic heavy metals is considered one of the most important environmental issues which has accelerated dramatically due to changing industrial activities. This review focuses on the most common methods, strategies, and biological approaches of heavy metal bioremediation. Also, it provides a general overview of the role of microorganisms in the bioremediation of heavy metals in polluted environments. Advanced methods of heavy metal remediation include physicochemical and biological methods; the latter can be further classified into in situ and ex situ bioremediation. The in situ process includes bioventing, biosparging, biostimulation, bioaugmentation, and phytoremediation. Ex situ bioremediation includes land farming, composting, biopiles, and bioreactors. Bioremediation uses naturally occurring microorganisms such as Pseudomonas, Sphingomonas, Rhodococcus, Alcaligenes, and Mycobacterium. Generally, bioremediation is of very less effort, less labor intensive, cheap, ecofriendly, sustainable, and relatively easy to implement. Most of the disadvantages of bioremediation relate to the slowness and time-consumption; furthermore, the products of biodegradation sometimes become more toxic than the original compound. The performance evaluation of bioremediation might be difficult as it has no acceptable endpoint. There is a need for further studies to develop bioremediation technologies in order to find more biological solutions for bioremediation of heavy metal contamination from different environmental systems.

Heavy Metal Pollution and its Management

2016 ◽  
pp. 27-50 ◽  
Author(s):  
Ashok K. Rathoure
Keyword(s):  
Heavy Metal ◽  
Metal Pollution ◽  
Heavy Metal Pollution ◽  
Ex Situ ◽  
Management Tool ◽  
Contaminated Site ◽  
Anthropogenic Activity ◽  
Toxic Heavy Metals ◽  
Metabolic Degradation

Environmental degradation has become a major societal issue thanks to uncontrolled anthropogenic activity, besides natural factors. Entry of toxic heavy metals and minerals in human system mainly through contaminated water, food and air, leads to overt and insidious health problems. Heavy metal pollution, a global concern today, can be managed by using bioremediation, an eco-friendly alternative. Bioremediation is one of the most promising technological approaches to the problem of hazardous waste. It is a technology for removing pollution from environment, restoring contaminated site and preventing future pollution. Bioremediation can be performed in situ or ex situ. Microorganisms directly degrade contaminants rather than merely transferring them from one medium to another, employ metabolic degradation pathways and can be used in situ to minimize disturbance of the cleanup site. Hence, microorganisms can be effective, economical and non-disruptive tools for eliminating hazardous chemicals. Its advantage generally outweigh the disadvantage, therefore may be used as management tool.

scholarly journals Na-Influenced Bulk and Surface Properties of the So-Called Iota(ι)-Alumina: Spectroscopy and Microscopy Studies

2021 ◽  
Vol 9 ◽  
Author(s):  
Ali Bumajdad ◽  
Shamsun Nahar ◽  
Mohamed I. Zaki
Keyword(s):  
Ir Spectroscopy ◽  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Ex Situ ◽  
Pure Alumina ◽  
X Ray ◽  
Laser Raman ◽  
Gas Phase Molecules ◽  
And Control

The test alumina (the so-called ι-Al2O3) was thermally recovered at 1,100°C from chitosan-AlOx hybrid films and found to contain Na and Ca impurity ions inherited from the parent chitosan. Two different modifications of pure alumina, namely, γ- and α-Al2O3, were adopted as control samples. The test and control aluminas were examined for 1) the bulk elemental constitution by atomic absorption spectroscopy (AAS), 2) the surface chemical composition by X-ray photoelectron spectroscopy (XPS), 3) the bulk phase composition by X-ray powder diffractometry (XRD), ex-situ Fourier-transform infrared spectroscopy (IR), and Laser Raman (LRa) spectroscopy, 4) the surface area, topography, and morphology by N2 sorptiometry, and atomic force (AFM) and scanning electron microscopy (SEM), 5) the surface adsorptive interactions with pyridine and 2-propanol gas-phase molecules by in-situ IR spectroscopy of the adsorbed species, and 6) the surface catalytic interactions with 2-propanol gas-phase molecules by in-situ IR spectroscopy of the gas phase. Results obtained could clearly show that the test alumina (ι-Al2O3) is only hypothetically pure alumina since in reality its bulk structure is majored by mullite-type Na-aluminate (Na0.67Al6O9.33/NaAlO2) and minored by Na-β-alumina (Na1.71Al11O17) and β-alumina (NaAl11O17). Consistently, observed Na-influenced modifications of the surface chemistry, topology, and morphology, as well as adsorptive and catalytic interactions with pyridine and 2-propanol gas-phase molecules, showed significant deviations from those exhibited by the control pure aluminas (γ- and α-Al2O3).

Heavy Metal Pollution and its Management

2020 ◽  
pp. 1013-1036 ◽  
Author(s):  
Ashok K. Rathoure
Keyword(s):  
Heavy Metal ◽  
Metal Pollution ◽  
Heavy Metal Pollution ◽  
Ex Situ ◽  
Management Tool ◽  
Contaminated Site ◽  
Anthropogenic Activity ◽  
Toxic Heavy Metals ◽  
Metabolic Degradation

Environmental degradation has become a major societal issue thanks to uncontrolled anthropogenic activity, besides natural factors. Entry of toxic heavy metals and minerals in human system mainly through contaminated water, food and air, leads to overt and insidious health problems. Heavy metal pollution, a global concern today, can be managed by using bioremediation, an eco-friendly alternative. Bioremediation is one of the most promising technological approaches to the problem of hazardous waste. It is a technology for removing pollution from environment, restoring contaminated site and preventing future pollution. Bioremediation can be performed in situ or ex situ. Microorganisms directly degrade contaminants rather than merely transferring them from one medium to another, employ metabolic degradation pathways and can be used in situ to minimize disturbance of the cleanup site. Hence, microorganisms can be effective, economical and non-disruptive tools for eliminating hazardous chemicals. Its advantage generally outweigh the disadvantage, therefore may be used as management tool.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

The use of transmission and analytical electron microscopy in studying reactions and phase transformations in thin film

1993 ◽  
Vol 51 ◽  
pp. 842-843
Author(s):  
K. Barmak
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transformations ◽  
Analytical Electron Microscopy ◽  
Ex Situ ◽  
Multilayer Thin Films ◽  
Absolute Concentration ◽  
Analytical Electron ◽  
Deposition Step

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

1989 ◽  
Vol 47 ◽  
pp. 462-463
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

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