scholarly journals Influence of flow rate on the transport of nTiO2 and phosphate and its modeling

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Gang Feng ◽  
Gang Feng ◽  
Nan Xu ◽  
Zuling Li ◽  
Zuling Li ◽  
...  
Keyword(s):  
Flow Rate ◽  
Ion Concentration ◽  
Rate Coefficients ◽  
Soluble Phosphate ◽  
Attachment Rate ◽  
First Order ◽  
Zeta Potentials ◽  
Rapid Flow ◽  
Attachment Model ◽  
Titanium Dioxides

We studied Zeta potentials of nanoparticles titanium dioxides （nTiO2） in different concentration of NaNO3 and phosphate (P) solutions. In addition, the effect of flow rate on the transport of nTiO2 in P was investigated at pH＝6.5. Experimental results show that the Zeta potential of nTiO2 is compressed with the increasing ion concentration (IC) of NaNO3 at pH＝6.5. The negative charge increases with the augment of P. Therefore, the high P and low NaNO3 induce the stabilization of nTiO2 aggregates. The transport experiments suggest that the rapid flow rate is favorable for the transportability of nTiO2 and soluble phosphate. The breakthrough transport curves (BTCs) of nTiO2 in sand columns can be fitted well with two-site kinetic attachment model. The modeling results suggest that the values of first-order attachment rate coefficients (k2) and detachment rate coefficients (k2d) on site 2 and first-order attachment rate coefficients (k1) on site 1 are responsible to the attaching efficiency of nTiO2 on sands and their transportability.

MODELLING NITROGEN PROCESSES IN SOIL: MATHEMATICAL DEVELOPMENT AND RELATIONSHIPS

1976 ◽  
Vol 56 (2) ◽  
pp. 71-78 ◽  
Author(s):  
D. R. CAMERON ◽  
C. G. KOWALENKO
Keyword(s):  
Time Dependent ◽  
Rate Coefficients ◽  
Nitrification Rate ◽  
Order Kinetic ◽  
Nitrogen Flow ◽  
First Order ◽  
Interaction Term ◽  
Flow Pathways ◽  
Adsorption Desorption ◽  
Temperature Water

A small subsystem model was developed to simulate the major nitrogen flow pathways in an unsaturated soil treated with ammonium sulphate. A nonlinear Freundlich equilibrium model and a Langmuir kinetic model were used to describe mathematically the adsorption–desorption of soluble NH4+ to the exchangeable and clay-fixed phases, respectively. Time dependent, microbial mediated first-order kinetic models were used to quantify the ammonification and nitrification processes. The subsystem model was then used as a research tool to derive ammonification and nitrification rate coefficients for a preceding incubation experiment conducted using different soil moisture contents and temperatures. The model yields reasonably good fits to the observed data. A subsequent regression analysis relating the coefficients to temperature and moisture pointed out the importance of the temperature–water content interaction term in quantifying microbial mediated processes.

Models to Determine First-Order Rate Coefficients from Single-Well Push-Pull Tests

Ground Water ◽  
2006 ◽  
Vol 44 (2) ◽  
pp. 275-283 ◽  
Author(s):  
Martin H. Schroth ◽  
Jonathan D. Istok
Keyword(s):  
Rate Coefficients ◽  
First Order ◽  
Order Rate ◽  
Single Well ◽  
Pull Tests

The comparative chemistry of ammine and methylamine complexes of rhodium(III) and cobalt(III)

1977 ◽  
Vol 55 (17) ◽  
pp. 3166-3171 ◽  
Author(s):  
Thomas Wilson Swaddle
Keyword(s):  
Ionic Strength ◽  
Spectral Data ◽  
Electron Donor ◽  
Dissociation Constants ◽  
Base Hydrolysis ◽  
Acid Dissociation ◽  
Rate Coefficients ◽  
Acid Dissociation Constants ◽  
First Order ◽  
Kinetics Of

For the aquation of (CH3NH2)5RhCl2+, the first order rate coefficients are represented by ΔHaq* = 101.9 kJ mol−1 and ΔSaq* = −50.2 JK−1 mol−1 in 0.1 M HClO4, while for base hydrolysis the rate is first order in [(CH3NH2)5RhCl2+] and [OH−] at ionic strength 0.10 M and the rate coefficients (in M−1 s−1) are represented by ΔHOH*> = 108.6 kJ mol−1 and ΔSOH* = 74.1 J K−1 mol−1. Acid dissociation constants are reported for (RNH2)5MOH23+ (R = H or CH3; M = Rh or Co), and these, combined with spectral data, show CH3NH2 to be a poorer electron donor than NH3 in complexes of this type, contrary to expectations. The comparative kinetics of reactions of (RNH2)5MCl2+ support the assignment of an Ia mechanism to aquation when M = Rh or Cr, Id to aquation when M = Co, and Dcb for base hydrolysis in all these cases.

Chelating agents in high temperature aqueous chemistry. 1. The kinetics of the thermal decomposition of aqueous nitrilotriacetate (NTA), iminodiacetate (IDA), and N-methyliminodiacetate (MIDA)

1977 ◽  
Vol 55 (10) ◽  
pp. 1762-1769 ◽  
Author(s):  
Meindert Booy ◽  
Thomas Wilson Swaddle
Keyword(s):  
Chelating Agents ◽  
Nuclear Reactors ◽  
Rate Coefficients ◽  
Aqueous Mixtures ◽  
Hydrothermal Conditions ◽  
Good Thermal Stability ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of ◽  
Thermal Stability Of

Aqueous H3NTA, H2MIDA, H2IDA, and their anions decompose under hydrothermal conditions (400–580 K) according to first order kinetics by successive decarboxylations, oxidation by O2 being unimportant except at the highest temperatures. In the presence of added H+, the species H4NTA+ and, to a lesser extent, H3MIDA+ (but not H3IDA+), provide significant decomposition pathways through elimination of a —CH2COO— group (deacetylation). For HnNTA(3−n)−, first order rate coefficients kn for decomposition are k0 = 4.5 × 10−7, k1 ∼ 1 × 10−6, k2 ∼ 7 × 10−5, k3 = 2.1 × 10−4, and k4 = 1.0 × 10−2 s1, at 503 K and ionic strength 2.0 m, the spread in rates being due to differences in ΔS* rather than ΔH*. H2MIDA and H2IDA are comparable in reactivity to H3NTA, while their anions are much less reactive than the NTA species of the same charge. The good thermal stability of aqueous NTA commends it as a reagent for boiler servicing and for decontamination of water-cooled nuclear reactors. A potentiometric method for the estimation of mono-, di-, and tribasic aminoacids in aqueous mixtures of these is described.

Temporal Response of Porous Glass Electroosmotic Pumps

2002 ◽  
Author(s):  
Shuhuai Yao ◽  
Shulin Zeng ◽  
Juan G. Santiago
Keyword(s):  
Flow Rate ◽  
Maximum Flow ◽  
Ion Concentration ◽  
Temporal Response ◽  
Short Term ◽  
Cooling Systems ◽  
Sintered Glass ◽  
Rate Capacity ◽  
Bioanalytical Applications ◽  
Electroosmotic Pumps

Sintered glass electroosmotic pumps have been fabricated that provide maximum flow rates and pressure capacities exceeding 14 ml/min and 1.4 atm, respectively, at 150 V, with an active pumping volume of less than 2 cm3. These compact devices with no moving parts have the potential to impact a variety of applications including microelectronics cooling systems and bioanalytical applications. We present here a preliminary a study of the response of the pumps to changes in fluidic load, including their short-term transient performance. A 0.5 mM borate buffer (pH = 9.2) is used to stabilize pump performance, with nearly optimal flow rate capacity. The experiments are conducted for working electrolytes of varying ion concentration. These performance characteristics are critical to applications that aim to use feedback control of flow rate and pressure over varying conditions.

scholarly journals Neutralization Dialysis for Phenylalanine and Mineral Salt Separation. Simple Theory and Experiment

Membranes ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 171 ◽  
Author(s):  
Anton Kozmai ◽  
Elena Goleva ◽  
Vera Vasil’eva ◽  
Victor Nikonenko ◽  
Natalia Pismenskaya
Keyword(s):  
Amino Acid ◽  
Flow Rate ◽  
Solution Concentration ◽  
Exchange Capacity ◽  
Ion Concentration ◽  
Solution Flow Rate ◽  
Strong Electrolyte ◽  
Mineral Salts ◽  
Solution Flow ◽  
Hydrodynamic Mode

A simple non-steady state mathematical model is proposed for the process of purification of an amino acid solution from mineral salts by the method of neutralization dialysis (ND), carried out in a circulating hydrodynamic mode. The model takes into account the characteristics of membranes (thickness, exchange capacity and electric conductivity) and solution (concentration and components nature) as well as the solution flow rate in dialyzer compartments. In contrast to the known models, the new model considers a local change in the ion concentration in membranes and the adjacent diffusion layers. In addition, the model takes into consideration the ability of the amino acid to enter the protonation/deprotonation reactions. A comparison of the results of simulations with experimental data allows us to conclude that the model adequately describes the ND of a strong electrolyte (NaCl) and amino acid (phenylalanine) mixture solutions in the case where the diffusion ability of amino acids in membranes is much less, than mineral salts. An example shows the application of the model to predict the fluxes of salt ions through ion exchange membranes as well as pH of the desalination solution at a higher than in experiments flow rate of solutions in ND dialyzer compartments.

scholarly journals Adsorption of Cu (II) and Ni (II) Ions from Solution onto Calcium Alginate Beads

2020 ◽  
Vol 24 (2) ◽  
pp. 329-333
Author(s):  
D.O. Jalija ◽  
A . Uzairu
Keyword(s):  
Contact Time ◽  
Calcium Alginate ◽  
Alginate Beads ◽  
Second Order ◽  
Ion Concentration ◽  
Order Kinetic ◽  
Calcium Alginate Beads ◽  
First Order ◽  
Pseudo Second Order ◽  
Pseudo First Order

The objective of this study was to investigate the biosorption of Cu (II) and Ni (II) ions from aqueous solution by calcium alginate beads. The effects of solution pH, contact time and initial metal ion concentration were evaluated. The results showed that maximum Cu (II) removal (93.10%) occurred at pH of 9.0, contact time of 120 minutes and initial ion concentration of 10 mg/L while that of Ni (II) was 94.6%, which was achieved at pH of 8.0, contact time of 120 minutes and initial ion concentration of 10 mg/L. The equilibrium data fitted well to the Langmuir Isotherm indicating that the process is a monolayer adsorption. The coefficients of determination, R2, values for the Langmuir Isotherm were 0.9799 and 0.9822 respectively for Cu (II) and Ni (II) ions. The values of the maximum biosorption capacity, Qo, were 10.79 and 6.25 mgg-1 respectively. The kinetic data also revealed that the sorption process could best be described by the pseudo – second order kinetic model. The R2 values for the pseudo – second order kinetic plots for Cu (II) and Ni (II) were 0.9988 and 0.9969 respectively. These values were higher than those for the pseudo – first order plots. The values of the biosorption capacity qe obtained from the pseudo – second order plots were very close to the experimental values of qe indicating that the biosorption process follows the second order kinetics. This study has therefore shown that calcium alginate beads can be used for the removal of Cu (II) and Ni (II) ions from wastewaters. Keywords: Keywords: Adsorption, Calcium alginate, Isotherm, Langmuir, Pseudo- first order, Pseudo-second order

scholarly journals Properties of thin ZnS:Mn films sprayed by improved method: The role of Mn2+ ion concentration

2017 ◽  
Vol 35 (2) ◽  
pp. 291-302 ◽  
Author(s):  
Rangnath V. Zaware ◽  
Ratan Y. Borse ◽  
Bhiva G. Wagh
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Doping Concentration ◽  
Ion Concentration ◽  
Solution Flow Rate ◽  
Mn Doping ◽  
Spray Solution ◽  
Yellow Orange ◽  
Mn Doped ◽  
Zns Films

Abstract Undoped and Mn-doped thin ZnS films were deposited on ordinary glass substrates at temperature of 450 °C by an improved spray pyrolysis (ISP) method. The ISP parameters, such as carrier gas flow rate, solution flow rate and substrate temperature, were controlled with accuracy ±0.25 Lpm, ±1 mL/h and ±1 °C, respectively. A pulse-spray mode of the method was used to spray the precursor solution. Thin film samples were prepared for Mn-doping with the concentrations of 0 at.%, 1 at.%, 3 at.%, 6 at.%, 8 at.% and 12 at.% relative to Zn in the spray solution. The Mn-doping concentration dependent chemical composition, surface morphology, and structural, optical and photoluminescence (PL) properties were studied. All the thin films were well adherent, nearly stoichiometric, dense, uniform, and possessed cubic crystal structure with preferential orientation along h〈1 1 1〉 direction. A slight enhancement in structural properties, an increase in band gap, and a decrease in refractive index and dielectric constant with Mn-doping concentration were observed. The PL spectra of Mn-doped thin ZnS films at room temperature exhibited both the 490 nm blue defect-related emission and the 590 nm yellow-orange Mn2+ ion related emission. The observed yellow-orange emission intensity was maximum for 3 at.% of Mn-doping concentration in the spray solution.

EXCHANGE BETWEEN THALLOUS AND THALLIC IONS IN THE PRESENCE OF SULPHATE ION

1958 ◽  
Vol 36 (1) ◽  
pp. 167-170 ◽  
Author(s):  
D. R. Wiles
Keyword(s):  
Exchange Reaction ◽  
Higher Order ◽  
Transfer Mechanism ◽  
Ion Concentration ◽  
First Order ◽  
Order Dependence

The rates of the exchange reaction between thallous and thallic ions have been measured as a function of sulphate ion concentration, at constant acidity. At high sulphate concentrations, the results agree with those of Brubaker and Mickel, indicating second- and higher-order dependence of the rate on sulphate ion concentration. At low sulphate concentrations, pure first-order dependence on sulphate is found. The inhibitive effect found in some systems is absent. A bridge-transfer mechanism is suggested.

Response of Backflow to Flow Rate Fluctuations

2006 ◽  
Vol 129 (3) ◽  
pp. 350-358 ◽  
Author(s):  
Xiangyu Qiao ◽  
Hironori Horiguchi ◽  
Yoshinobu Tsujimoto
Keyword(s):  
Angular Momentum ◽  
Flow Rate ◽  
Three Dimensional ◽  
Low Frequency ◽  
Gain Factor ◽  
Numerical Calculations ◽  
Positive Mass ◽  
First Order ◽  
Rate Fluctuation ◽  
Cavity Development

The response of backflow at the inlet of an inducer to the flow rate fluctuation is studied by using three-dimensional numerical calculations based on the k-ϵ turbulence model for the discussion of its effect on cavitation instabilities. It is first shown that the size of the backflow region can be correlated with the angular momentum in the upstream and the phase of the backflow significantly delays behind the quasi-steady response even at a very low frequency. It is then shown that the conservation relation of angular momentum is satisfied with minor effects of the shear stress on the boundary. The supply of the angular momentum by the negative flow is shown to be quasi-steady due to the fact that the pressure difference across the blade causing the backflow is quasi-steady at those frequencies examined. A response function of the angular momentum in the upstream to flow rate fluctuation is derived from the balance of the angular momentum and the results of the numerical calculations. This clearly shows that the backflow responds to the flow rate fluctuation as a first-order lag element. The effects of the backflow cavitation on cavitation instabilities are discussed assuming that the delay of cavity development is much smaller than the delay of the backflow. It was found that the backflow cavitation would destabilize low frequency disturbances due to the effects of the positive mass flow gain factor but stabilize high frequency disturbances due to the effect of the cavitation compliance.

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