The Dynamic and Leaching Study of Gold in Treated Sludge from Nonferrous Metal Smelting Waste Water

2011 ◽  
Vol 281 ◽  
pp. 228-232
Author(s):  
Hong Liang Guan ◽  
Xun Min Yu ◽  
Qing Xin Li
Keyword(s):  
Waste Water ◽  
Activation Energy ◽  
Dynamic Behavior ◽  
Noble Metals ◽  
Nonferrous Metal ◽  
Copper Anode ◽  
Rare Metals ◽  
Reaction Velocity ◽  
Secondary Sludge ◽  
Leaching Efficiency

Copper anode sludge was a byproduct produced during the refinery of copper. The sludge contained amount of noble metals and rare metals, and also was an important resources for recovering noble metals. In this paper, ammonium thiocyante was used as leaching reagent for extracting gold from arsenic-free anode sludge (secondary sludge). Under the optical conditions, the leaching efficiency was up to 85.1%, while the dynamic behavior of gold leaching was studied, the activation energy of the system Eα=20.093kJ•mol-1, and reaction velocity constant k=4.084e-20093/RT. The treatment of copper sludge could greatly reduce the potential contamination to the environment.

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: VII. THE DECOMPOSITION OF ETHYLIDENE DIBUTYRATE AND HEPTYLIDENE DIACETATE

1937 ◽  
Vol 15b (6) ◽  
pp. 247-253 ◽  
Author(s):  
C. C. Coffin ◽  
J. R. Dacey ◽  
N. A. D. Parlee
Keyword(s):  
Activation Energy ◽  
Homologous Series ◽  
Reaction Velocity ◽  
Vapor State ◽  
Specific Reaction ◽  
First Order ◽  
Gas Reactions

Ethylidene dibutyrate and heptylidene diacetate decompose in the vapor state at temperatures between 200° and 300 °C. to form an aldehyde and an anhydride. The reactions are homogeneous, unimolecular, and complete. The activation energy is the same as that previously found for other members of this homologous series. Ethylidene dibutyrate decomposes at the same rate as ethylidene diacetate, and thus provides further evidence that the specific reaction velocity is independent of the size of the anhydride radicals. Heptylidene diacetate decomposes at the same rate as butylidene diacetate. This indicates that after the aldehyde radical has attained a certain size (three or four carbon atoms) the addition of –CH2− groups leaves the specific reaction velocity unchanged. The velocity constants are given by the equations[Formula: see text]

Potentiodynamic examination of electrode kinetics for electroactive adsorbed species: applications to the reduction of noble metal surface oxides

1969 ◽  
Vol 310 (1503) ◽  
pp. 541-563 ◽  
Keyword(s):  
Noble Metals ◽  
Reaction Rate ◽  
Substrate Surface ◽  
Intrinsic Property ◽  
Surface Heterogeneity ◽  
Surface Oxide ◽  
Rate Equations ◽  
Quasi Equilibrium ◽  
Linear Potential ◽  
Reaction Velocity

The relation between reaction rate and potential (or time) for electrochemical surface processes occurring under potentiodynamic control (linear potential-time programme) has been investigated with particular reference to the behaviour of thin surface oxide films on noble metals. The kinetics of processes involving adsorbed electroactive species are treated for several model cases; the rate equations are developed for mechanisms involving various reaction orders or for processes involving adsorbed reactant interactions and surface heterogeneity effects. By examination of the dependence of the reaction rate (current) with time and the effect of potential scan rate, v , on the maximum reaction velocity and the potential at which it occurs, the models may be distinguished. In this manner, the inter­dependence of v and the reaction velocity constants k a and k c for the anodic oxidation and the cathodic reduction processes respectively, can be quantitatively established. The relation between quasi-equilibrium situations where the reverse reaction is significant and irreversible situations where it is not can be demonstrated. Heterogeneity terms introduced into the kinetic relations express deviations from Langmuir adsorption behaviour and may be an intrinsic property of the substrate surface or a property of the adsorbed reactant (induced heterogeneity). Applications of the treatment are made to reduction of surface oxide species at the noble metals and the significance of hysteresis and time effects in the processes of electrochemical formation and reduction of surface oxide at platinum, rhodium, iridium and palladium is investigated.

THE KINETICS OF CUPRENE GROWTH

1950 ◽  
Vol 28b (7) ◽  
pp. 358-372
Author(s):  
Cyrias Ouellet ◽  
Adrien E. Léger
Keyword(s):  
Nitric Oxide ◽  
Activation Energy ◽  
Carbon Monoxide ◽  
Apparent Activation Energy ◽  
Copper Catalyst ◽  
Maximum Velocity ◽  
Static System ◽  
Reaction Velocity ◽  
First Order ◽  
Kinetics Of

The kinetics of the polymerization of acetylene to cuprene on a copper catalyst between 200° and 300 °C. have been studied manometrically in a static system. The maximum velocity of the autocatalytic reaction shows a first-order dependence upon acetylene pressure. The reaction is retarded in the presence of small amounts of oxygen but accelerated by preoxidation of the catalyst. The apparent activation energy, of about 10 kcal. per mole for cuprene growth between 210° and 280 °C., changes to about 40 kcal. per mole above 280 °C. at which temperature a second reaction seems to set in. Hydrogen, carbon monoxide, or nitric oxide has no effect on the reaction velocity. Series of five successive seedings have been obtained with cuprene originally grown on cuprite, and show an effect of aging of the cuprene.

Activation energy of hydrogen in Al and the noble metals

1983 ◽  
Vol 13 (7) ◽  
pp. 1449-1455 ◽  
Author(s):  
S Mahajan ◽  
N Singh ◽  
S Prakash
Keyword(s):  
Activation Energy ◽  
Noble Metals

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: VIII. THE DECOMPOSITION OF TRICHLORETHYLIDENE DIACETATE AND TRICHLORETHYLIDENE DIBUTYRATE

1937 ◽  
Vol 15b (6) ◽  
pp. 254-259 ◽  
Author(s):  
N. A. D. Parlee ◽  
J. R. Dacey ◽  
C. C. Coffin
Keyword(s):  
Activation Energy ◽  
Experimental Error ◽  
Acid Anhydride ◽  
Exchange Energy ◽  
Reaction Velocity ◽  
First Order ◽  
Measurable Rate ◽  
Gas Reactions

Trichlorethylidene diacetate and trichlorethylidene dibutyrate have been found to decompose at temperatures between 200° and 290 °C. at a measurable rate to give chloral and an acid anhydride. The reactions are homogeneous and of the first order, and have the same specific velocity in both the liquid and vapor states. The activation energy is identical (within experimental error) with that previously found for non-chlorinated members of this series of esters. The two compounds decompose at the same rate, in agreement with the hypothesis that the anhydride radicals do not easily exchange energy with the bonds that break. This reaction velocity, which is somewhat smaller than that of ethylidene diacetate at any temperature, is given by the equation [Formula: see text].

scholarly journals Effect of Noble Metal Addition on the Disorder Dynamics of Ni3Al by Means of Monte Carlo Simulation

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4832
Author(s):  
J.J. Ramos-Hernandez ◽  
C.D. Arrieta-Gonzalez ◽  
J.G. Chacon-Nava ◽  
E. Porcayo-Palafox ◽  
M. Sanchez-Carrillo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Noble Metal ◽  
Noble Metals ◽  
Activation Energies ◽  
Time Constants ◽  
Metal Addition ◽  
L12 Structure

In this work, the effect of the addition of noble metals on the order–order disorder process of the L12 structure corresponding to the intermetallic Ni3Al is analyzed. Stoichiometric, nonstoichiometric, and quasi-binary compositions doped with noble metals such as Ag, Au, Pd, and Pt (1 at%) were analyzed. It was observed that depending on the composition, there is a modification in the activation energies calculated from the two time constants that characterize the disorder process. The statistic of atomic jumps was typified based on the configuration of the window to be crossed and, with this, it was identified that the origin of the negative activation energy of the long disorder process is due to an increase in the corresponding energy of the AlAl-Ni jump through unnatural windows.

Hydrogen–Water Deuterium Exchange over Graphon Supported Group VIII Noble Metals

1973 ◽  
Vol 51 (24) ◽  
pp. 4031-4037 ◽  
Author(s):  
Norman Henry Sagert ◽  
Rita Mary Louise Pouteau
Keyword(s):  
Activation Energy ◽  
Atomic Number ◽  
Noble Metals ◽  
Activation Energies ◽  
Group Viii ◽  
Surface Exchange ◽  
Hydrogen Water ◽  
Temperature Range ◽  
The Third ◽  
Specific Activities

Specific activities of Group VIII noble metals supported on Graphon have been determined for hydrogen–water deuterium exchange. Metal surface areas, which are required to calculate specific activities, were measured by hydrogen chemisorption, and by reaction of hydrogen with chemisorbed oxygen. For the second triad metals, ruthenium, rhodium, and palladium, and in the temperature range 140 to 225 °C, the variation of activity was Ru < Rh > Pd. For the third triad metals, osmium, iridium, and platinum, the variation of activities was Os < Ir < Pt in the same range of temperature. Apparent activation energies were measured over this temperature range, and orders of reaction with respect to hydrogen and water were measured at 160 °C (200 °C for Pt). From these data, activation energies for the surface exchange reaction were calculated. In the second triad the activation energies decrease slightly with increasing atomic number, but in the third triad they decrease quite markedly with increasing atomic number. A good correlation was obtained between the activation energy for surface exchange and the thermionic work function of the metal. This supports our earlier suggestion that Graphon is able to donate electrons to the metal and thus lower the activation energy for the surface exchange.

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: VI. THE DECOMPOSITION OF METHYLENE DIACETATE, METHYLENE DIPROPIONATE, AND METHYLENE DIBUTYRATE

1937 ◽  
Vol 15b (5) ◽  
pp. 229-236 ◽  
Author(s):  
C. C. Coffin ◽  
W. B. Beazley
Keyword(s):  
Activation Energy ◽  
Experimental Error ◽  
Pressure Change ◽  
Reaction Rates ◽  
Reaction Velocity ◽  
First Order ◽  
Exact Position ◽  
Gas Reactions ◽  
Homogeneous Decomposition ◽  
Large Experimental Error

The homogeneous decomposition of methylene diacetate vapor to formaldehyde and acetic anhydride at temperatures between 220° and 305 °C. and at pressures ranging from several centimetres of mercury to several atmospheres has been studied. Reaction rates were determined by analytical and by pressure change methods. The first order decomposition is opposed by a second order recombination. A secondary reaction makes it impossible to determine the exact position of the resulting equilibrium. Within the rather large experimental error, methylene diacetate has the same activation energy (33,000 cal.) as its homologues. Its specific reaction velocity is smaller than that of the ethylidene esters. Methylene dipropionate and dibutyrate decompose at the same rate as the diacetate. These facts are in accord with the hypothesis that the extent to which a radical can contribute to the energy of activation is dependent upon its position in the molecule. Veolcity constants are given by the equation [Formula: see text]

scholarly journals Leaching Kinetics of Selenium, Tellurium and Silver from Copper Anode Slime by Sulfuric Acid Leaching in the Presence of Manganese(IV) Oxide and Graphite

2021 ◽  
Vol 3 (1) ◽  
pp. 16
Author(s):  
Kurniawan Kurniawan ◽  
Jae-chun Lee ◽  
Jonghyun Kim ◽  
Rina Kim ◽  
Sookyung Kim
Keyword(s):  
Activation Energy ◽  
Sulfuric Acid ◽  
Chemical Reaction ◽  
Acid Leaching ◽  
Anode Slime ◽  
Surface Chemical ◽  
Copper Anode ◽  
Surface Chemical Reaction ◽  
Sulfuric Acid Leaching ◽  
Copper Anode Slime

Sulfuric acid leaching of copper anode slime (CAS) in the presence of manganese(IV) oxide (MnO2) and graphite was investigated for Se, Te and Ag recovery. The study reveals that the leaching of Se, Te and Ag was facilitated by the galvanic interaction with MnO2, and graphite played the role of a catalyst. The leaching process could yield 81.9% Se, 90.8% Te, and 80.7% Ag leaching efficiency when the conditions were maintained as 500 rpm, 2.0 M H2SO4, 0.8/0.8/1 MnO2/graphite/CAS, and 90 °C temperature. The kinetic study showed that Se leaching followed the surface chemical reaction at all the tested temperature range (25–90 °C) with the activation energy of 27.7 kJ/mol. Te and Ag leaching at temperature 25–50 °C followed the mixed and surface chemical reaction models, respectively, and changed to fit the diffusion and mixed control models, respectively, in the temperature range 60–90 °C with the corresponding activation energy of 17.8 and 12.2 kJ/mol.

Behind the Quantum and Size Effects: Broken-Bond-Induced Local Strain and Skin-Depth Densified Quantum Trapping of Charge and Energy

2010 ◽  
Vol 444 ◽  
pp. 17-45 ◽  
Author(s):  
Li Kun Pan ◽  
Ming Xia Gu ◽  
Gang Ouyang ◽  
Chang Q. Sun
Keyword(s):  
Dynamic Behavior ◽  
Noble Metals ◽  
Magnetic Transition ◽  
Local Strain ◽  
Joint Effect ◽  
Skin Depth ◽  
Effect Of Temperature ◽  
Defect Sites ◽  
Energy Quantum ◽  
Low Dimensional

Shrinking the size of a solid down to nanometer scale is indeed fascinating, which makes all the otherwise constant physical quantities to be tunable such as the Young’s modulus, dielectric constant, melting point, etc. The variation of size also generates novel properties that can hardly be seen in the bulk such as the conductor-insulator and nonmagnetic-magnetic transition of noble metals at the nanoscale. Although the physics of materials at the nanoscale has been extensively investigated, the laws governing the energetic and dynamic behavior of electrons at such a scale and their consequences on the tunable physical properties of nanostructures have not been well understood [C. Q. Sun, Prog Solid State Chem 35, 1-159 (2007); Prog Mater Sci 54, 179-307 (2009)]. The objective of the contribution is to update the recent progress in dealing with the coordination-resolved energetic and dynamic behavior of bonds in the low-dimensional systems with consideration of the joint effect of temperature and pressure. It is shown that the broken-bond-induced local strain and the associated charge and energy quantum trapping at the defect sites perturbs the atomic cohesive energy, electroaffinity, the Hamiltonian and the associated properties of entities ranging from point defects, surfaces, nanocavities and nanostructures. Application of the theories to observations has led to consistent understanding of the behavior of nanometer-sized materials and the interdependence of these entities as well as the means of determining the bond energy through the temperature-dependent measurements.

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