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.

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 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 Suitability of Different Titanium Dioxide Nanotube Morphologies for Photocatalytic Water Treatment

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 708
Author(s):  
Clayton Farrugia ◽  
Alessandro Di Mauro ◽  
Frederick Lia ◽  
Edwin Zammit ◽  
Alex Rizzo ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Titanium Dioxide ◽  
Water Treatment ◽  
Environmental Remediation ◽  
Survival Rates ◽  
Bacterial Survival ◽  
Nanotubular Structure ◽  
Excellent Activity ◽  
Uva Light ◽  
High Degree

Photocatalysis has long been touted as one of the most promising technologies for environmental remediation. The ability of photocatalysts to degrade a host of different pollutants, especially recalcitrant molecules, is certainly appealing. Titanium dioxide (TiO2) has been used extensively for this purpose. Anodic oxidation allows for the synthesis of a highly ordered nanotubular structure with a high degree of tunability. In this study, a series of TiO2 arrays were synthesised using different electrolytes and different potentials. Mixed anatase-rutile photocatalysts with excellent wettability were achieved with all the experimental iterations. Under UVA light, all the materials showed significant photoactivity towards different organic pollutants. The nanotubes synthesised in the ethylene glycol-based electrolyte exhibited the best performance, with near complete degradation of all the pollutants. The antibacterial activity of this same material was similarly high, with extremely low bacterial survival rates. Increasing the voltage resulted in wider and longer nanotubes, characteristics which increase the level of photocatalytic activity. The ease of synthesis coupled with the excellent activity makes this a viable material that can be used in flat-plate reactors and that is suitable for photocatalytic water treatment.

Dynamic Characteristics and Stability Analysis of Two-Dimensional (2D) Electro-Hydraulic Proportional Directional Valve

2015 ◽  
Author(s):  
S. Li ◽  
J. Ruan ◽  
B. Meng ◽  
W. A. Jia ◽  
H. Y. Xie
Keyword(s):  
Dynamic Characteristics ◽  
Magnetic Force ◽  
Engineering Application ◽  
Proportional Valve ◽  
Acceptable Range ◽  
Hydrostatic Force ◽  
Practical Engineering ◽  
Direct Operation ◽  
Electrohydraulic Valve ◽  
Proportional Directional Valve

A 2D electrohydraulic proportional directional valve is proposed, which integrates both direct and pilot operation of the valve. In this valve, the output magnetic force of the proportional solenoid is converted to rotate the spool through a thrust-torsion coupling and thus the pressure in the valve sensitive chamber is varied. The varied pressure exerted on the areas of the spool end produces a hydrostatic force to move the spool linearly, which will rotate the spool reversely. Theoretical analysis is carried to the proposed valve and the effects of the key geometric parameters on the dynamic characteristics of the 2D valve and stability are investigated. Experiments are also designed to access to the characteristics of the valve working under direct and pilot operation. The 2D electrohydraulic valve can work properly for both direct operation and pilot operation. The hysteresis and frequency response are measured and the results are within the acceptable range in practical engineering application required of the directional proportional valve.

Review on Ferrites and its Application for Environmental Remediation

2021 ◽  
Vol 9 (VII) ◽  
pp. 887-891
Author(s):  
Tooba Jehan
Keyword(s):  
Water Treatment ◽  
Environmental Remediation ◽  
Review Paper ◽  
Current Status ◽  
Energy Devices

During the recent couple of years, there has been an increased level of interest in ferrites. The attractive electrical, optical and different properties of ferrites made them center of attraction because of their utilization in different day to day applications, for example, energy devices like supercapacitors and batteries, water treatment, sun based energy gadgets and attractive liquids. This is the review paper about the ferrites, their current status and development of ferrite technology which is used in various day to day applications.

scholarly journals Testing Metallic Iron Filtration Systems for Decentralized Water Treatment at Pilot Scale

Water ◽  
2015 ◽  
Vol 7 (12) ◽  
pp. 868-897 ◽  
Author(s):  
Raoul Tepong-Tsindé ◽  
Richard Crane ◽  
Chicgoua Noubactep ◽  
Achille Nassi ◽  
Hans Ruppert
Keyword(s):  
Water Treatment ◽  
Metallic Iron ◽  
Pilot Scale
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