Relationship between the diffusion rate constant and rate constant of triplet-triplet annihilation for porphyrins in liquid solutions

1996 ◽  
Vol 63 (4) ◽  
pp. 514-521
Author(s):  
V. V. Sapunov
Keyword(s):  
Rate Constant ◽  
Diffusion Rate ◽  
Liquid Solutions ◽  
Diffusion Rate Constant ◽  
Triplet Triplet Annihilation

Diffusional Fluorescence Quenching of Aromatic Hydrocarbons

2003 ◽  
Vol 57 (5) ◽  
pp. 538-544 ◽  
Author(s):  
Clelia Canuel ◽  
Sophie Badre ◽  
Henning Groenzin ◽  
Markus Berheide ◽  
Oliver C. Mullins
Keyword(s):  
Fluorescence Quenching ◽  
Molecular Oxygen ◽  
Rate Constant ◽  
Aromatic Hydrocarbons ◽  
Diffusion Rate ◽  
Energy Difference ◽  
Quenching Rate ◽  
Quenching Rate Constant ◽  
Diffusion Rate Constant ◽  
Organic Fluorophore

The quenching of the fluorescence of five aromatic hydrocarbons by three halogenated organics and by molecular oxygen has been measured. Both fluorescence intensity and fluorescence lifetime measurements have been employed to validate results and interpretation; linear Stern–Volmer analyses are shown to apply throughout. The fluorescence quenching rate constant of molecular oxygen for the five aromatic hydrocarbons is essentially equivalent to the diffusion rate constant independent of the fluorophore excitation energy. The halogenated organic–fluorophore rate constants vary by a factor of 965 and are shown to correlate roughly with the energy difference between the quencher and fluorophore excited electronic states in accord with a standard model of quantum two-level mixing. The value of the coupling interaction energy is ∼2500 cm−1.

scholarly journals Characterization of hydroxybenzoic acid chelating resins: Equilibrium, kinetics, and isotherm profiles for Cd(II) and Pb(II) uptake

2011 ◽  
Vol 76 (6) ◽  
pp. 903-922 ◽  
Author(s):  
Bhavna Shah ◽  
Ajay Shah ◽  
Ritesh Tailor
Keyword(s):  
Rate Constant ◽  
Metal Ion ◽  
Diffusion Rate ◽  
Ion Concentration ◽  
Particle Diffusion ◽  
Specific Rate ◽  
Hydroxybenzoic Acid ◽  
Sorption Data ◽  
Intra Particle Diffusion ◽  
Diffusion Rate Constant

Chelating ion-exchange resins were synthesized by polycondensation of ortho/para hydroxybenzoic acid with resorcinol/catechol employing formaldehyde as cross-linking agent at 80?5?C in DMF. The resins were characterized by FTIR and XRD. The uptake behaviour of synthesized resins for Cd(II) and Pb(II) ions have been studied depending on contact time, pH, metal ion concentration and temperature. The sorption data obtained at optimized conditions were analyzed by the Langmuir and Freundlich isotherms. Experimental data of all metal-resin system were best represented by the Freundlich isotherm. The maximum obtained sorption capacity for cadmium was 69.53 mg g-1 and 169.32 mg g-1 for Lead. The adsorption process follows first order kinetics and the specific rate constant Kr was obtained by the application of the Lagergan equation. Thermodynamic parameters ?Gads, ?Sads and ?Hads were calculated for the metal-resin systems. The external diffusion rate constant (Ks) and the intra-particle diffusion rate constant (Kid) were calculated by the Spahn-Schlunder and Weber-Morris models, respectively. The sorption process was found to follow an intra-particle diffusion phenomenon.

scholarly journals Removal of Grey BL from Dye Wastewater by Derris (Pongamia Glabra) Leaf Powder by Adsorption

2010 ◽  
Vol 7 (4) ◽  
pp. 1454-1462 ◽  
Author(s):  
T. Mugugan ◽  
A. Ganapathi ◽  
R. Valliappan
Keyword(s):  
Rate Constant ◽  
Freundlich Isotherm ◽  
Mean Value ◽  
Batch Adsorption ◽  
First Order Kinetics ◽  
Pongamia Glabra ◽  
Adsorbate Concentration ◽  
Leaf Powder ◽  
Diffusion Rate Constant ◽  
Isotherm Equations

The dye, Grey BL was adsorbed on an adsorbent prepared from mature leaves of the Pungan tree (Pongamia glabra). A batch adsorption study was carried out with variable adsorbate concentration, adsorbent amount and pH. Ninety three percent of the dye could be removed by 2 g of the derris leaf powder from 1 L of an aqueous solution containing 25 mg of the dye at 300 K. The adsorption followed pseudo first order kinetics with a mean rate constant of 3.73 ×10-3min-1and an intraparticle diffusion rate constant of 6.36 x10-2mg g-1min-0.5. A possible mechanism of adsorption was suggested on the basis of concurrently operating surface adsorption and pore diffusion. The experimental data yielded excellent fits with Langmuir and Freundlich isotherm equations. The Langmuir monolayer capacity had a mean value of 8.27 mg g-1. The results indicated that the dye, Grey BL, strongly interacts with a biomass-based adsorbent, the Derris (Pongamia glabra) leaf powder.

scholarly journals Kinetic Modeling for Photo-Assisted Penicillin G Degradation of (Mn0.5Zn0.5)[CdxFe2-x]O4 (x ≤ 0.05) Nanospinel Ferrites

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 970
Author(s):  
Omar Alagha ◽  
Noureddine Ouerfelli ◽  
Hafedh Kochkar ◽  
Munirah A. Almessiere ◽  
Yassine Slimani ◽  
...  
Keyword(s):  
Visible Light ◽  
Rate Constant ◽  
Spinel Ferrite ◽  
Penicillin G ◽  
X Ray Diffraction ◽  
Order Model ◽  
Manganese Zinc ◽  
Model Molecule ◽  
Diffusion Rate Constant ◽  
New Generation

Penicillin G is an old and widely used antibiotic. Its persistence in the environment started to appear in many environmental samples and food chains. The removal of these emerging pollutants has been a challenging task for scientists in the last decades. The photocatalytic properties of Cd2+ doped Manganese- Zinc NSFs with chemical formula (Mn0.5Zn0.5)[CdxFe2−x]O4 (0.0 ≤ x ≤ 0.05) NSFs are herein evaluated. The Manganese- Zinc N.S.F.s nanomaterials were deeply characterized, utilizing UV-Vis (reflectance) spectroscopy, X-ray diffraction, N2 adsorption isotherm measurements, and S.E.M., SEM-EDX mapping, and T.E.M. The Kinetic model for the photodegradation of penicillin G (as a model molecule) is investigated using visible light as a source of energy. The kinetic study shows that our results fit well with the modified pseudo-first-order model. The Pen G degradation are 88.73%, 66.65%, 44.70%, 37.62% and 24.68% for x = 0.5, 0.4, 0.3, 0.2 and 0.1, respectively, against 14.68% for the free Cd spinel sample. The pseudo-rate constant is bandgap dependent. From the intra-diffusion rate constant (Kd), we developed an intra-diffusion time (τ) model, which decreases exponentially as a function of (x) and mainly shows the existence of three different domains versus cadmium coordination in spinel ferrite samples. Hence, Cadmium’s presence generates spontaneous polarization with a strong opportunity to monitor the charge separation and then open the route to a new generation of “assisted” photocatalysts under visible light.

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