scholarly journals Characterizing the Reactivity of Metallic Iron for Water Treatment: H2 Evolution in H2SO4 and Uranium Removal Efficiency

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1523 ◽  
Author(s):  
Arnaud Igor Ndé-Tchoupé ◽  
Rui Hu ◽  
Willis Gwenzi ◽  
Achille Nassi ◽  
Chicgoua Noubactep
Keyword(s):  
Metallic Iron ◽  
Environmental Remediation ◽  
Material Selection ◽  
H2 Production ◽  
H2 Evolution ◽  
Solution Ph ◽  
Neutral Ph ◽  
Uranium Removal ◽  
Initial Reactivity

Metallic iron (Fe0) has been demonstrated as an excellent material for decentralized safe drinking water provision, wastewater treatment and environmental remediation. An open issue for all these applications is the rational material selection or quality assurance. Several methods for assessing Fe0 quality have been presented, but all of them are limited to characterizing its initial reactivity. The present study investigates H2 evolution in an acidic solution (pH 2.0) as an alternative method, while comparing achieved results to those of uranium removal in quiescent batch experiments at neutral pH values. The unique feature of the H2 evolution experiment is that quantitative H2 production ceased when the pH reached a value of 3.1. A total of twelve Fe0 specimens were tested. The volume of molecular H2 produced by 2.0 g of each Fe0 specimen in 560 mL H2SO4 (0.01 M) was monitored for 24 h. Additionally, the extent of U(VI) (0.084 mM) removal from an aqueous solution (20.0 mL) by 0.1 g of Fe0 was characterized. All U removal experiments were performed at room temperature (22 ± 2 °C) for 14 days. Results demonstrated the difficulty of comparing Fe0 specimens from different sources and confirmed that the elemental composition of Fe0 is not a stand-alone determining factor for reactivity. The time-dependent changes of H2 evolution in H2SO4 confirmed that tests in the neutral pH range just address the initial reactivity of Fe0 materials. In particular, materials initially reacting very fast would experience a decrease in reactivity in the long-term, and this aspect must be incorporated in designing novel materials and sustainable remediation systems. An idea is proposed that could enable the manufacturing of intrinsically long-term efficient Fe0 materials for targeted operations as a function of the geochemistry.

scholarly journals Metallic Iron for Environmental Remediation: Starting an Overdue Progress in Knowledge

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 641 ◽  
Author(s):  
Rui Hu ◽  
Huichen Yang ◽  
Ran Tao ◽  
Xuesong Cui ◽  
Minhui Xiao ◽  
...  
Keyword(s):  
Water Treatment ◽  
Literature Review ◽  
Metallic Iron ◽  
Environmental Remediation ◽  
Isotherm Models ◽  
Critical Survey ◽  
Root Cause ◽  
Water Provision ◽  
Adsorption Kinetics And Isotherm

A critical survey of the abundant literature on environmental remediation and water treatment using metallic iron (Fe0) as reactive agent raises two major concerns: (i) the peculiar properties of the used materials are not properly considered and characterized, and, (ii) the literature review in individual publications is very selective, thereby excluding some fundamental principles. Fe0 specimens for water treatment are typically small in size. Before the advent of this technology and its application for environmental remediation, such small Fe0 particles have never been allowed to freely corrode for the long-term spanning several years. As concerning the selective literature review, the root cause is that Fe0 was considered as a (strong) reducing agent under environmental conditions. Subsequent interpretation of research results was mainly directed at supporting this mistaken view. The net result is that, within three decades, the Fe0 research community has developed itself to a sort of modern knowledge system. This communication is a further attempt to bring Fe0 research back to the highway of mainstream corrosion science, where the fundamentals of Fe0 technology are rooted. The inherent errors of selected approaches, currently considered as countermeasures to address the inherent limitations of the Fe0 technology are demonstrated. The misuse of the terms “reactivity”, and “efficiency”, and adsorption kinetics and isotherm models for Fe0 systems is also elucidated. The immense importance of Fe0/H2O systems in solving the long-lasting issue of universal safe drinking water provision and wastewater treatment calls for a science-based system design.

scholarly journals Redirecting Research on Fe0 for Environmental Remediation: The Search for Synergy

2019 ◽  
Vol 16 (22) ◽  
pp. 4465 ◽  
Author(s):  
Hu ◽  
Noubactep
Keyword(s):  
Water Treatment ◽  
Metallic Iron ◽  
Environmental Remediation ◽  
Cathodic Reaction ◽  
Contaminant Removal ◽  
Iron Corrosion ◽  
Basic Relationship ◽  
Kinetics Of ◽  
Center Research

A survey of the literature on using metallic iron (Fe0) for environmental remediation suggests that the time is ripe to center research on the basic relationship between iron corrosion and contaminant removal. This communication identifies the main problem, which is based on the consideration that contaminant reductive transformation is the cathodic reaction of iron oxidative dissolution. Properly considering the inherent complexities of the Fe0/H2O system will favor an appropriate research design that will enable more efficient and sustainable remediation systems. Successful applications of Fe0/H2O systems require the collective consideration of progress achieved in understanding these system. More efforts should be made to decipher the long-term kinetics of iron corrosion, so as to provide better approaches to accurately predict the performance of the next generation Fe0-based water treatment systems.

scholarly journals Water Treatment Using Metallic Iron: A Tutorial Review

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 622 ◽  
Author(s):  
Hu ◽  
Gwenzi ◽  
Sipowo-Tala ◽  
Noubactep
Keyword(s):  
Water Treatment ◽  
Metallic Iron ◽  
Environmental Remediation ◽  
Material Selection ◽  
Engineering Application ◽  
Operating Mode ◽  
Contaminant Removal ◽  
Removal Mechanisms ◽  
Practical Engineering ◽  
Proper Material

Researchers and engineers using metallic iron (Fe0) for water treatment need a tutorial review on the operating mode of the Fe0/H2O system. There are few review articles attempting to present systematic information to guide proper material selection and application conditions. However, they are full of conflicting reports. This review seeks to: (i) Summarize the state-of-the-art knowledge on the remediation Fe0/H2O system, (ii) discuss relevant contaminant removal mechanisms, and (iii) provide solutions for practical engineering application of Fe0-based systems for water treatment. Specifically, the following aspects are summarized and discussed in detail: (i) Fe0 intrinsic reactivity and material selection, (ii) main abiotic contaminant removal mechanisms, and (iii) relevance of biological and bio-chemical processes in the Fe0/H2O system. In addition, challenges for the design of the next generation Fe0/H2O systems are discussed. This paper serves as a handout to enable better practical engineering applications for environmental remediation using Fe0.

A Review on Recent Trends in Nanomaterials and Nanocomposites for Environmental Applications

2020 ◽  
Vol 16 ◽  
Author(s):  
Kannappan Panchamoorthy Gopinath ◽  
Malolan Rajagopal ◽  
Abhishek Krishnan ◽  
Shweta Kolathur Sreerama
Keyword(s):  
Environmental Pollution ◽  
Environmental Remediation ◽  
Carbon Capture ◽  
Potential Applications ◽  
Important Challenge ◽  
Term Basis ◽  
Short And Long Term ◽  
Recent Trends ◽  
Water And Soil Pollution

Background: Depletion and contamination of environmental resources such as water, air and soil caused by human activities is an increasingly important challenge faced around the world. The consequences of environmental pollution are felt acutely by all living beings, both on a short and long-term basis, thereby making methods of remediation of environmental pollution an urgent requirement. Objectives: The objective of this review is to dissect the complications caused by environmental degradation, highlight advancements in the field of nanotechnology and to scrutinize its applications in environmental remediation. Furthermore, the review aims to concisely explain the merits and drawbacks of nanotechnology compared to existing methods. Conclusion: The current and potential applications of nanomaterials and nanocomposites in the prevention, control and reduction of air, water and soil pollution and the mechanisms involved have been elucidated, as have their various merits and demerits. The applications of nanotechnology in the fields of carbon capture and agriculture have also received attention in this review.

scholarly journals Assessment of Long-Term Fermentability of PHA-Based Materials from Pure and Mixed Microbial Cultures for Potential Environmental Applications

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 897
Author(s):  
Neda Amanat ◽  
Bruna Matturro ◽  
Marta Maria Rossi ◽  
Francesco Valentino ◽  
Marianna Villano ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Volatile Fatty Acids ◽  
Rapid Onset ◽  
Pilot Scale ◽  
Point Of View ◽  
Microbial Cultures ◽  
Extraction And Purification ◽  
Fermentation Pattern ◽  
Mixed Microbial Cultures

The use of polyhydroxyalkanoates (PHA) as slow-release electron donors for environmental remediation represents a novel and appealing application that is attracting considerable attention in the scientific community. In this context, here, the fermentation pattern of different types of PHA-based materials has been investigated in batch and continuous-flow experiments. Along with commercially available materials, produced from axenic microbial cultures, PHA produced at pilot scale by mixed microbial cultures (MMC) using waste feedstock have been also tested. As a main finding, a rapid onset of volatile fatty acids (VFA) production was observed with a low-purity MMC-deriving material, consisting of microbial cells containing 56% (on weight basis) of intracellular PHA. Indeed, with this material a sustained, long-term production of organic acids (i.e., acetic, propionic, and butyric acids) was observed. In addition, the obtained yield of conversion into acids (up to 70% gVFA/gPHA) was higher than that obtained with the other tested materials, made of extracted and purified PHA. These results clearly suggest the possibility to directly use the PHA-rich cells deriving from the MMC production process, with no need of extraction and purification procedures, as a sustainable and effective carbon source bringing remarkable advantages from an economic and environmental point of view.

CdSe Quantum Dots/White Graphene Hexagonal Porous Boron Nitride Sheet (h-PBNs) Heterostructure Photocatalyst for Solar Driven H2 Production

2021 ◽  
Author(s):  
Raheman Shakeelur ◽  
Rupali S. Mane ◽  
Higgins Wilson ◽  
Neetu Jha
Keyword(s):  
Active Site ◽  
Charge Separation ◽  
High Surface ◽  
High Surface Area ◽  
H2 Production ◽  
H2 Evolution ◽  
The World ◽  
2D Nanomaterials ◽  
White Graphene ◽  
Photogenerated Charge Separation

In the world of photocatalytic hydrogen (H2) evolution two-dimensional (2D) nanomaterials have attracted widespread attention owing to their high surface area, abundant active site, and excellent photogenerated charge separation properties....

scholarly journals Green synthesis of the innovative super paramagnetic nanoparticles from the leaves extract of Fraxinus chinensis Roxb and their application for the decolourisation of toxic dyes

2019 ◽  
Vol 8 (1) ◽  
pp. 256-271 ◽  
Author(s):  
Imran Ali ◽  
Changsheng Peng ◽  
Dichu Lin ◽  
Iffat Naz
Keyword(s):  
Environmental Remediation ◽  
Degradation Mechanism ◽  
Pseudo First Order Reaction ◽  
Solution Ph ◽  
Factors Affecting ◽  
Toxic Dyes ◽  
Degradation Of Dyes ◽  
Stability Structure ◽  
Ft Ir ◽  
Fraxinus Chinensis

Abstract The leaves extract of Fraxinus chinensis Roxb was used for the synthesis of the innovative phytogenic magnetic nanoparticles (PMNPs) without adding toxic surfactants. The formation, morphology, elemental composition, size, thermal stability, structure and magnetic properties of these PMNPs were examined by UV-visible spectrophotometry, FT-IR, XRD, SEM, EDX, TEM, VSM, XPS, BET and TGA. The reactivity of the obtained PMNPs against decolourising toxic dyes, namely, malachite green (MG), crystal violet (CV) and methylene blue (MB), were investigated by UV-vis spectrophotometry. Further, the factors affecting the removal of dyes, including solution pH, adsorbent dosages, initial concentration of dyes, reaction temperature and contact time, were also investigated. The results revealed the decolourisation of 99.12% of MG and 98.23% of CV within 60 min, and 97.52% of MB within 200 min by the PMNPs using dyes concentration of 25 mg/l at pH 6.5 and 298.15 K. The kinetics outcome indicated that the degradation of dyes matched well to the pseudo first-order reaction kinetics model. Furthermore, the probable degradation mechanism of dyes by the PMNPs, including the adsorption of cationic dye molecules onto the negatively charged surface of adsorbent and the oxidation of the Fe° in the solution, were discussed. Thus, the PMNPs can be produced by the bulk and have great potential to be employed for biomedical/environmental remediation.

scholarly journals Dragonfly Inspired Smart Soft Robot

2020 ◽  
Author(s):  
Vardhman Kumar ◽  
Ung Hyun Ko ◽  
Yilong Zhou ◽  
Jiaul Hoque ◽  
Gaurav Arya ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Stimuli Responsive ◽  
Complex Environments ◽  
Soft Robots ◽  
Responsive Materials ◽  
Environmental Perturbations ◽  
Integration Strategies ◽  
Soft Actuators ◽  
Harsh Conditions

Recent advancements in soft robotics have led to the development of compliant robots that can exhibit complex motions driven by living cells(1, 2), chemical reactions(3), or electronics(4). Further innovations are however needed to create the next generation of soft robots that can carry out advanced functions beyond locomotion. Here we describe DraBot—a dragonfly-inspired, entirely soft, multifunctional robot that combines long-term locomotion over water surface with sensing, responding, and adaptation capabilities. By integrating soft actuators, stimuli-responsive materials, and microarchitectural features, we created a circuitry of pneumatic and microfluidic logic that enabled the robot to undergo user- and environment-controlled (pH) locomotion, including navigating hazardous (acidic) conditions. DraBot was also engineered to sense additional environmental perturbations (temperature) and detect and clean up chemicals (oil). The design, fabrication, and integration strategies demonstrated here pave a way for developing futuristic soft robots that can acclimatize and adapt to harsh conditions while carrying out complex tasks such as exploration, environmental remediation, and health care in complex environments.

scholarly journals Sustainable Construction by Means of Improved Material Selection Process

2019 ◽  
Vol 3 (1) ◽  
pp. 85 ◽  
Author(s):  
Koorosh Gharehbaghi ◽  
Maged Georgy
Keyword(s):  
Energy Savings ◽  
Material Selection ◽  
Selection Process ◽  
Sustainable Construction ◽  
Construction Operation ◽  
Selection Factors ◽  
Strength And Durability ◽  
Operation Cost ◽  
Selection Of

Whilst sustainable construction relates to both a building’s structure and the use of proper life cycle processes, the selection of the most appropriate material/s is deemed a considerable undertaking. Throughout a building’s lifecycle that extends from design, construction, operation, maintenance, renovation, until demolition, the selection of sustainable material/s is a particularly crucial task for the development and establishment of such structures. Traditionally, there are three main materials for general construction: (1) Steel, (2) Concrete and (3) Timber. These materials not only influence the function within the structure, but also affect the operation cost and energy usage. Operation cost reduction and energy savings are typically elements of the sustainable construction sphere. However, in developing countries, there is a variety of highly critical factors, which can impact material selection as well as the long-term sustainability of the structure, including: Fire Performance, Environmental Impact, Structural Performance (strength and durability), and Functioning Capabilities. Accordingly, this paper will first compare the sustainability of these three key materials and then converse with appropriate processes for material selection. Attention will be given to the sustainable construction recompense associated with the different material selection factors. Doing so ensures a more sustainable built environment by means of an improved material selection process.

scholarly journals Comparison of the Corrosion Behavior of Tank 51 Sludge-Based Glass and a Nonradioactive Homologue Glass

1996 ◽  
Vol 465 ◽  
Author(s):  
L. Nuñez ◽  
W. L. Ebert ◽  
S. F. Wolf ◽  
J. K. Bates
Keyword(s):  
Corrosion Behavior ◽  
Lower Solution ◽  
Solution Ph ◽  
Consistency Test ◽  
Glass Corrosion ◽  
Dissolution Tests ◽  
One Year ◽  
The Relationship ◽  
Solution Volume

ABSTRACTWe are characterizing the corrosion behavior of the radioactive glass that was made with sludge from Tank 51 at the Defense Waste Processing Facility (DWPF) and a nonradioactive glass having the same composition, except for the absence of radionuclides. Static dissolution tests are being conducted in a tuff groundwater solution at glass surface area/solution volume ratios (S/V) of 2000 and 20,000 m−1. These tests are being conducted to assess the relationship between the behavior of this glass in a 7-day Product Consistency Test and in long-term tests, to assess the effects of radionuclides on the glass corrosion behavior, and to measure the disposition of radionuclides that are released as the radioactive glass corrodes. The radioactive glass reacts slower than the nonradioactive glass through the longest test durations completed to date, which are 140 days for tests at 2000 m−1 and about 400 days for tests at 20,000 m−1. This is probably because radiolysis results in lower solution pH values being maintained in tests with the radioactive glass. Rate-affecting alteration phases that had formed within one year in tests with other glasses having compositions similar to the Tank 51 glass have not yet formed in tests with either glass.

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