scholarly journals Characterizing the Suitability of Granular Fe0 for the Water Treatment Industry

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 652 ◽  
Author(s):  
Rui Hu ◽  
Xuesong Cui ◽  
Minhui Xiao ◽  
Pengxiang Qiu ◽  
Mesia Lufingo ◽  
...  
Keyword(s):  
Water Treatment ◽  
Ethylenediaminetetraacetic Acid ◽  
Batch Experiments ◽  
Iron Corrosion ◽  
Experimental Conditions ◽  
Initial Stage ◽  
Intrinsic Reactivity ◽  
First Time ◽  
Kinetics Of

There is a burgeoning interest in reliably characterizing the intrinsic reactivity of metallic iron materials (Fe0) or zero-valent iron materials (ZVI) used in the water treatment industry. The present work is a contribution to a science-based selection of Fe0 for water treatment. A total of eight (8) granular ZVI materials (ZVI1 to ZVI8) were tested. Fe0 dissolution in ethylenediaminetetraacetic acid (EDTA test) and 1,10-Phenanthroline (Phen test) is characterized in parallel experiments for up to 250 h (10 days). 50 mL of each solution and 0.1 g of each Fe0 material are equilibrated in quiescent batch experiments using 2 mM EDTA or Phen. Results indicated a far higher extent of iron dissolution in EDTA than in Phen under the experimental conditions. The tested materials could be grouped into three reactivity classes: (i) low (ZVI4, ZVI6, ZVI7, and ZVI8), (ii) moderate (ZVI1 and ZVI5) and (iii) high (ZVI2 and ZVI3). The order of reactivity was the same for both tests: ZVI2 ≅ ZVI3 > ZVI1 ≅ ZVI5 > ZVI4 ≅ ZVI6 ≅ ZVI7 ≅ ZVI8. Phen results revealed for the first time the time-dependent variation of the kinetics of iron corrosion (corrosion rate) in short-term batch experiments. Overall, the results demonstrated the superiority of the Phen test for evaluating the initial stage of Fe0 dissolution. Long-term column experiments are recommended to deepen the acquired knowledge.

scholarly journals A Novel and Facile Method to Characterize the Suitability of Metallic Iron for Water Treatment

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2465 ◽  
Author(s):  
Mesia Lufingo ◽  
Arnaud Igor Ndé-Tchoupé ◽  
Rui Hu ◽  
Karoli N. Njau ◽  
Chicgoua Noubactep
Keyword(s):  
Ascorbic Acid ◽  
Water Treatment ◽  
Metallic Iron ◽  
Ethylenediaminetetraacetic Acid ◽  
Complexing Agents ◽  
Iron Corrosion ◽  
Dissolved Iron ◽  
The One ◽  
Intrinsic Reactivity ◽  
Dissolved O2

Metallic iron (Fe0) materials have been industrially used for water treatment since the 1850s. There are still many fundamental challenges in affordably and reliably characterizing the Fe0 intrinsic reactivity. From the available methods, the one using Fe0 dissolution in ethylenediaminetetraacetic acid (EDTA—2 mM) was demonstrated the most applicable as it uses only four affordable chemicals: Ascorbic acid, an ascorbate salt, EDTA and 1,10-Phenanthroline (Phen). A careful look at these chemicals reveals that EDTA and Phen are complexing agents for dissolved iron species. Fe3-EDTA is very stable and difficult to destabilize; ascorbic acid is one of the few appropriate reducing agents, therefore. On the other hand, the Fe2-Phen complex is so stable that oxidation by dissolved O2 is not possible. This article positively tests Fe0 (0.1 g) dissolution in 2 mM Phen (50 mL) as a characterization tool for the intrinsic reactivity, using 9 commercial steel wool (Fe0 SW) specimens as probe materials. The results are compared with those obtained by the EDTA method. The apparent iron dissolution rate in EDTA (kEDTA) and in Phen (kPhen) were such that 0.53 ≤ kEDTA (μg h−1) ≤ 4.81 and 0.07 ≤ kPhen (μg h−1) ≤ 1.30. Higher kEDTA values, relative to kPhen, are a reflection of disturbing Fe3 species originating from Fe2 oxidation by dissolved O2 and dissolution of iron corrosion products. It appears that the Phen method considers only the forward dissolution of Fe0. The Phen method is reliable and represents the most affordable approach for characterizing the suitability of Fe0 for water treatment.

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.

Long-Term Traces of Tachistoscopic Word Perception

1967 ◽  
Vol 25 (1) ◽  
pp. 25-35
Author(s):  
Lee E. Doerries ◽  
E. Rae Harcum
Keyword(s):  
Critical Word ◽  
Word Perception ◽  
Experimental Task ◽  
Control Groups ◽  
Experimental Conditions ◽  
Consolidation Effect ◽  
First Time ◽  
Positive Effect ◽  
Special Control

Threshold durations were determined by the Method of Limits for a series of 8-letter nonsense words. For experimental Os the threshold for a critical word was obtained a second time after threshold determinations for 0, 1, 2, 4, or 8 different filler-words had intervened. For control Os no word was repeated in the series. Instructions introduced a set against seeing any word again after its threshold had been obtained the first time. The second threshold for a critical word was lower than the first for all experimental conditions; this effect could not be attributed to practice. The greatest effect occurred when 2 filler-words intervened. The positive effect after 8 words had intervened indicates that the trace was still present after 7 min. Greater threshold decrements for special control groups, for whom the interpolated activity was unrelated to the experimental task, indicate a consolidation effect on the trace under those conditions.

scholarly journals Steel Wool for Water Treatment: Intrinsic Reactivity and Defluoridation Efficiency

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 265 ◽  
Author(s):  
Benjamin Hildebrant ◽  
Arnaud Igor Ndé-Tchoupé ◽  
Mesia Lufingo ◽  
Tobias Licha ◽  
Chicgoua Noubactep
Keyword(s):  
Bearing Steel ◽  
Fluoride Removal ◽  
Batch Experiments ◽  
Steel Wool ◽  
Column Leaching ◽  
Leaching Experiments ◽  
Series Of Experiments ◽  
Intrinsic Reactivity

Studies were undertaken to characterize the intrinsic reactivity of Fe0-bearing steel wool (Fe0 SW) materials using the ethylenediaminetetraacetate method (EDTA test). A 2 mM Na2-EDTA solution was used in batch and column leaching experiments. A total of 15 Fe0 SW specimens and one granular iron (GI) were tested in batch experiments. Column experiments were performed with four Fe0 SW of the same grade but from various suppliers and the GI. The conventional EDTA test (0.100 g Fe0, 50 mL EDTA, 96 h) protocol was modified in two manners: (i) Decreasing the experimental duration (down to 24 h) and (ii) decreasing the Fe0 mass (down to 0.01 g). Column leaching studies involved glass columns filled to 1/4 with sand, on top of which 0.50 g of Fe0 was placed. Columns were daily gravity fed with EDTA and effluent analyzed for Fe concentration. Selected reactive Fe0 SW specimens were additionally investigated for discoloration efficiency of methylene blue (MB) in shaken batch experiments (75 rpm) for two and eight weeks. The last series of experiments tested six selected Fe0 SW for water defluoridation in Fe0/sand columns. Results showed that (i) the modifications of the conventional EDTA test enabled a better characterization of Fe0 SW; (ii) after 53 leaching events the Fe0 SW showing the best kEDTA value released the lowest amount of iron; (iii) all Fe0 specimens were efficient at discoloring cationic MB after eight weeks; (iv) limited water defluoridation by all six Fe0 SW was documented. Fluoride removal in the column systems appears to be a viable tool to characterize the Fe0 long-term corrosion kinetics. Further research should include correlation of the intrinsic reactivity of SW specimens with their efficiency at removing different contaminants in water.

scholarly journals The Suitability of Methylene Blue Discoloration (MB Method) to Investigate the Fe0/MnO2 System

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 548
Author(s):  
Viet Cao ◽  
Ghinwa Alyoussef ◽  
Nadège Gatcha-Bandjun ◽  
Willis Gwenzi ◽  
Chicgoua Noubactep
Keyword(s):  
Methylene Blue ◽  
Time Dependent ◽  
Diffusive Transport ◽  
Mass Loading ◽  
Batch Experiments ◽  
Present Communication ◽  
Iron Corrosion ◽  
Typical Time ◽  
Blue Discoloration

The typical time-dependent decrease of the iron corrosion rate is often difficult to consider while designing Fe0-based remediation systems. One of the most promising approaches is the amendment with manganese dioxide (Fe0/MnO2 system). The resulting system is a very complex one where characterization is challenging. The present communication uses methylene blue discoloration (MB method) to characterize the Fe0/MnO2 system. Shaken batch experiments (75 rpm) for 7 days were used. The initial MB concentration was 10 mg L−1 with the following mass loading: [MnO2] = 2.3 g L−1, [sand] = 45 g L−1, and 0 < [Fe0] (g L−1) ≤ 45. The following systems where investigated: Fe0, MnO2, sand, Fe0/MnO2, Fe0/sand, and Fe0/MnO2/sand. Results demonstrated that MB discoloration is influenced by the diffusive transport of MB from the solution to the aggregates at the bottom of the test-tubes. Results confirm the complexity of the Fe0/MnO2/sand system, while establishing that both MnO2 and sand improve the efficiency of Fe0/H2O systems in the long-term. The mechanisms of water decontamination by amending Fe0-based systems with MnO2 is demonstrated by the MB method.

scholarly journals Densification Kinetics of Multi-Doped Zirconia Ceramic Body with Organic Coating Powders

2018 ◽  
Author(s):  
Y.G. Hoo ◽  
Yusheng Shi ◽  
Wenzhong Lu
Keyword(s):  
Solid Oxide Fuel Cells ◽  
Ceramic Body ◽  
Equivalent Strain ◽  
Organic Coating ◽  
Zirconia Ceramic ◽  
Sintering Process ◽  
Zirconia Ceramics ◽  
Initial Stage ◽  
First Time ◽  
Kinetics Of

Abstract: This work for the first time investigated the densification of multi-doping zirconia ceramic body with organic coating powders for solid electrolyte of solid oxide fuel cells via online imaging technology. The densification results show the initial stage plays a key role in the sintering. It can be found the covered organic PVA (polyvinyl acetate) supplies a potential kinetics to the initial densification during sintering. As a result, a kinetic function of densification in the initial stage was suggested. Furthermore, a novel sintering model with six sub-stages is developed for polycrystalline zirconia ceramics. The findings would be a valuable reference for predicting final temperature of sintering, the equivalent strain during the sintering process, as well as optimizing the densification behavior.

scholarly journals Long-term incubation with CXCL2, but not with CXCL1, alters the kinetics of TRPV1 receptors in cultured dorsal root ganglia neurons

2017 ◽  
Vol 69 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Antonia-Teona Deftu ◽  
Alexandru-Florian Deftu ◽  
Violeta Ristoiu
Keyword(s):  
Dorsal Root Ganglia ◽  
Dorsal Root ◽  
Ionic Channels ◽  
Homologous Sequence ◽  
Trigeminal Ganglia ◽  
Experimental Conditions ◽  
Trpv1 Receptors ◽  
Dorsal Root Ganglia Neurons ◽  
Kinetics Of

CXCL1 and CXCL2 are homologous chemokines that can be upregulated in different pathological conditions, affecting among other targets, neuronal ionic channels or receptors. TRPV1 is a polymodal nociceptor expressed in both dorsal root and trigeminal ganglia neurons. According to existing data, short-term incubation with CXCL1 can reduce TRPV1 desensitization, however, the long-term modulatory effect of both CXCL1 and CXCL2 on this receptor is less known. In the present study we investigated the influence of overnight incubation with 1.5 nM CXCL1 or CXCL2 on the functioning of TRPV1 receptors expressed in cultured dorsal root ganglia neurons. Calcium imaging and patch-clamp recordings showed that under the same experimental conditions and at the same concentration, only CXCL2 significantly decreased the TRPV1 current and increased its desensitization rate, whereas CXCL1 had no effect. This study proposes a different contribution of CXCL1 and CXCL2 to the modulation of TRPV1-mediated processes, in spite of their highly homologous sequence.

scholarly journals Characterization of Temperature-Dependent Kinetics of Oculocutaneous Albinism-Causing Mutants of Tyrosinase

2021 ◽  
Vol 22 (15) ◽  
pp. 7771
Author(s):  
Samuel A. Wachamo ◽  
Milan H. Patel ◽  
Paul K. Varghese ◽  
Monika B. Dolinska ◽  
Yuri V. Sergeev
Keyword(s):  
Trichoplusia Ni ◽  
Oculocutaneous Albinism ◽  
Size Exclusion ◽  
Temperature Dependent ◽  
Experimental Conditions ◽  
Rate Limiting Step ◽  
Its Gene ◽  
Exclusion Chromatography ◽  
First Time ◽  
Kinetics Of

Human tyrosinase (Tyr) is a glycoenzyme that catalyzes the first and rate-limiting step in melanin production, and its gene (TYR) is mutated in many cases of oculocutaneous albinism type phenotype in patients with OCA1 have only began to be examined and remain to be delineated. Here, we analyze the temperature-dependent kinetics of wild-type Tyr (WT) and two OCA1B mutant variants (R422Q and P406L) using Michaelis–Menten and Van’t Hoff analyses. Recombinant truncated human Tyr proteins (residues 19–469) were produced in the whole insect Trichoplusia Ni larvae. Proteins were purified by a combination of affinity and size-exclusion chromatography. The temperature dependence of diphenol oxidase protein activities and kinetic parameters were measured by dopachrome absorption. Using the same experimental conditions, computational simulations were performed to assess the temperature-dependent association of L-DOPA and Tyr. Our results revealed, for the first time, that the association of L-DOPA with R422Q and P406L followed by dopachrome formation is a complex reaction supported by enthalpy and entropy forces. We show that the WT has a higher turnover number as compared with both R422Q and P406L. Elucidating the kinetics and thermodynamics of mutant variants of Tyr in OCA1B helps to understand the mechanisms by which they lower Tyr catalytic activity and to discover novel therapies for patients.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Somatic Embryogenesis and In vitro Plant Regeneration in Vigna trilobata (L.) Verd. - A Potential Pasture Legume

1970 ◽  
Vol 19 (1) ◽  
pp. 89-99
Author(s):  
K. Choudhary ◽  
M. Singh ◽  
M. S. Rathore ◽  
N. S. Shekhawat
Keyword(s):  
Somatic Embryogenesis ◽  
Growth Regulators ◽  
Somatic Embryos ◽  
Basal Medium ◽  
Long Term Study ◽  
Continuous Application ◽  
First Time ◽  
Pasture Legume

This long term study demonstrates for the first time that it is possible to propagate embryogenic Vigna trilobata and to subsequently initiate the differentiation of embryos into complete plantlets. Initiation of callus was possible on 2,4-D. Somatic embryos differentiated on modified MS basal nutrient medium with 1.0 mg/l  of 2,4-D and 0.5 mg/l  of Kn. Sustained cell division resulted in globular and heart shape stages of somatic embryos. Transfer of embryos on to a fresh modified MS basal medium with 0.5 mg/l of Kn and 0.5 mg/l of GA3 helped them to attain maturation and germination. However, the propagation of cells, as well as the differentiation of embryos, were inhibited by a continuous application of these growth regulators. For this reason, a long period on medium lacking these growth regulators was necessary before the differentiation of embryos occurred again. The consequences for improving the propagation of embryogenic cultures in Vigna species are discussed. Key words: Pasture  legume, Vigna trilobata, Globular, Heart shape, somatic embryogenesis D.O.I. 10.3329/ptcb.v19i1.4990 Plant Tissue Cult. & Biotech. 19(1): 89-99, 2009 (June)

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