scholarly journals An Electrochemical Process Comparison of As(III) in Simulated Groundwater at Low Voltage in Mixed and Divided Electrolytic Cells

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1126 ◽  
Author(s):  
Yanyan Qin ◽  
Yanping Cui ◽  
Lidan Lei ◽  
Ya Gao ◽  
Zhengwei Zhou ◽  
...  
Keyword(s):  
Low Voltage ◽  
Electrochemical Process ◽  
First Order ◽  
Electrolytic Cells ◽  
Process Comparison ◽  
First Order Kinetics ◽  
Simulated Groundwater ◽  
High Arsenic ◽  
High Arsenic Groundwater

A relatively low voltage can be favor of e- transfer and peroxide generation from dominant 2e--reduction of O2 on carbon materials as cathode, with low energy loss. In this study the conversion of As(III) in simulated high arsenic groundwater at low voltage was compared in a mixed and a anode–cathode separated electrolytic system. With applied voltages (the potential difference between cathode and anode) from 0.1 V to 0.8 V, As(III) was found to be efficiently converted to As(V) in the mixed electrolytic cells and in separated anodic cells. The complete oxidation of As(III) to As(V) at 0.1–0.8 V was also achieved on graphite in divided cathodic cells which could be long-running. The As(III) conversion process in mixed electrolytic cells, anodic cells and cathodic cells all conformed to the pseudo first-order kinetics equation. The energy consumed by As(III) conversion was decreased as the applied voltage declined. Low voltage electrolysis is of great significance for saving energy consumption and improving the current efficiency and can be applied to in-situ electrochemical pre-oxidation for As(III) in high arsenic groundwater.

Modified ferron assay for speciation characterization of hydrolyzed Al(III): a precise k value based judgment

2009 ◽  
Vol 59 (4) ◽  
pp. 823-832 ◽  
Author(s):  
Ye Changqing ◽  
Wang Dongsheng ◽  
Wu Xiaohong ◽  
Qu Jiuhui ◽  
John Gregory
Keyword(s):  
Kinetic Constant ◽  
Nonlinear Least Squares ◽  
Precise Determination ◽  
K Value ◽  
First Order ◽  
First Order Kinetics ◽  
Parallel Reactions

The speciation of Al-OH complexes in terms of Ala, Alb and Alc could be achieved by traditional ferron assay and Alb is generally considered as Al13, however, the inherent correlation between them remains an enigma. This paper presents a modified ferron assay to get precise determination of Al13 using nonlinear least squares analysis, and to clarify the correlation between Alb and Al13. Two parallel reactions conforming to pseudo-first-order kinetics can simulate the complicate reactions between polynuclear complexes and ferron successfully. Four types of experimental kinetic constant (k value) of Al-OH complexes can be observed by this method when investigating three typical aluminium solutions. Comparing with the results of 27Al NMR, the species with moderate kinetics around 0.001 s−1 can be confirmed to resemble to Al13 polycation. The other types of kinetics are also well-regulated in partially neutralized aluminium solutions with various OH/Al ratios (b values) in the range 0 ∼ 2.5. It would provide potential means to trace the in-situ formation of Al13 in dilute solutions such as coagulation with Al-based coagulants

scholarly journals A side-by-side comparison of the solidification dynamics of quasicrystalline and approximant phases in the Al–Co–Ni system

2019 ◽  
Vol 75 (2) ◽  
pp. 281-296 ◽  
Author(s):  
Insung Han ◽  
Xianghui Xiao ◽  
Haiping Sun ◽  
Ashwin J. Shahani
Keyword(s):  
Driving Forces ◽  
Nucleation And Growth ◽  
Experimental Investigations ◽  
X Rays ◽  
Decagonal Quasicrystal ◽  
First Order ◽  
First Order Kinetics ◽  
Complex Crystal ◽  
Widespread Interest

Quasicrystals and their approximants have triggered widespread interest due to the challenge of solving their complex crystal structures as well as their possibly exceptional properties. The structural motifs of approximants are similar to those of the corresponding quasicrystals, but to what extent are their crystallization pathways the same? Unfortunately, there have been very few in situ experimental investigations to answer this question. Here, by leveraging the high penetrating power of hard X-rays, synchrotron-based X-ray tomography was conducted in order to capture the nucleation and growth of a decagonal quasicrystal and its related approximant. The combination of data-driven computational analysis with new thermodynamic databases allowed the characterization, with high precision, of the constitutional and kinetic driving forces for crystallization. The experimental results prove that the growth of both crystals from a liquid is dominated by first-order kinetics. Nevertheless, and somewhat surprisingly, significant differences were observed in their rates of nucleation and growth. The reasons for such divergent behaviours are discussed in light of contemporary theories of intermetallic crystallization.

scholarly journals In situ chemichromic studies of interactions between a lutetium bis-octaalkyl-substituted phthalocyanine and selected biological cofactors

2011 ◽  
Vol 9 (66) ◽  
pp. 183-189 ◽  
Author(s):  
C. Pal ◽  
A. N. Cammidge ◽  
M. J. Cook ◽  
J. L. Sosa-Sanchez ◽  
A. K. Sharma ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Nicotinamide Adenine Dinucleotide ◽  
Reduction Rate ◽  
Lithium Perchlorate ◽  
Linear Increase ◽  
First Order ◽  
Glass Substrates ◽  
First Order Kinetics ◽  
Neutralization Process

Spin-coated films, approximately 100 nm thick, of a newly synthesized bis[octakis(octyl)phthalocyaninato] lutetium(III) complex on ultrasonically cleaned glass substrates exhibit pronounced chemichromic behaviour with potential application in healthcare. In situ kinetic optical absorption spectroscopic measurements show that the phthalocyanine Q-band is red shifted by 60 nm upon oxidation arising from exposure to bromine vapour. Recovery to the original state is achieved by the treatment of the oxidized films with nicotinamide adenine dinucleotide and l -ascorbic acid (vitamin C) in an aqueous solution containing 1.5 M lithium perchlorate. The neutralization process is found to be governed by first-order kinetics. The linear increase of the reduction rate with increasing concentration of cofactors provides a basis for calibration of analyte concentrations ranging from 3.5 mM down to 0.03 mM.

In-situ electrochemical ESR: First-order kinetics and transient signals

1984 ◽  
Vol 163 (1-2) ◽  
pp. 65-75 ◽  
Author(s):  
Richard G. Compton ◽  
David J. Page ◽  
George R. Sealy
Keyword(s):  
Transient Signals ◽  
First Order ◽  
First Order Kinetics

scholarly journals Electrochemical conversion pathways and existing morphology of arsenic(III) in anode-cathode separated electrolytic cells

2020 ◽  
Author(s):  
Yanyan Qin ◽  
Yanping Cui ◽  
Zhengwei Zhou ◽  
Ya Gao ◽  
Lidan Lei ◽  
...  
Keyword(s):  
Electrochemical Oxidation ◽  
Low Voltage ◽  
Electrolytic Cell ◽  
Alkaline Media ◽  
Acid Electrolyte ◽  
Electrolytic Cells ◽  
Electrochemical Conversion ◽  
Theoretical Support ◽  
Platinum Anode

Abstract To explore the electrochemical conversion of arsenic at different voltages and pH, an open separated electrolytic cell with a platinum anode and a graphite cathode was selected for this paper. The form and concentration of arsenic in the anodic cell and cathodic cell were detected. Experimental results proved that at 40.0 V, As(III) in an acid electrolyte in the cathodic cell was firstly mainly reduced to AsH3 with trace As(0) as intermediate. As the electrolysis time arrived at 27 min, pH in the cathodic cell jumped suddenly from acidity to alkalinity, accompanied by the majority of the remaining As(III) converting to As(V) for an instant. As time went on, As(III) and As(V) remained almost unchanged at the ratio of 1:3, and the reduction of As(III) became extremely weak in the alkaline environment. When pH in the cathodic tank was adjusted to keep it acid, As(III) was eventually converted to AsH3. Compared with high voltage, at a low voltage of 1.0 V the cathode failed to achieve the potential of As(III) reduction and As(III) was eventually oxidized to As(V) in the acid catholyte. Electrochemical oxidation of As(III) in the open cathodic cell was likely caused by in-situ generation of peroxide from electrochemical reduction of O2. Theoretical support for electrochemical oxidation of As(III) on a carbon cathode in neutral and weak alkaline media is provided in this study.

Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 167-178 ◽  
Author(s):  
Xin Tong ◽  
Jiao Li ◽  
Jun Ma ◽  
Xiaoquan Chen ◽  
Wenhao Shen
Keyword(s):  
Degradation Rate ◽  
Southern China ◽  
Catalytic Degradation ◽  
Pulp And Paper ◽  
Gaseous Pollutants ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methyl Orange ◽  
Solution Ph ◽  
Vanadium Concentration ◽  
Limiting Behavior ◽  
First Order ◽  
First Order Kinetics ◽  
Ph Range ◽  
Kinetic Pattern ◽  
Triton X ◽  
Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

Biodegradation rates of aromatic contaminants in biofilm reactors

1995 ◽  
Vol 31 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Jean-Pierre Arcangeli ◽  
Erik Arvin
Keyword(s):  
Aromatic Hydrocarbons ◽  
Competitive Inhibition ◽  
Removal Rate ◽  
First Order ◽  
Biofilm Reactors ◽  
First Order Kinetics ◽  
Reducing Conditions ◽  
Low Concentrations ◽  
Degradation Rates ◽  
Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

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