scholarly journals Copper Electropolishing in Phosphoric Acid under Normal and Forced Convection Conditions in Presence of Some Pharmaceutical Drugs

2020 ◽  
Vol 32 (4) ◽  
pp. 912-922
Author(s):  
Fatma M. Abouzeid ◽  
Sultanah Alshammery
Keyword(s):  
Forced Convection ◽  
Pharmaceutical Compounds ◽  
Copper Surface ◽  
Limiting Current ◽  
Pharmaceutical Drugs ◽  
Rotating Disc ◽  
Surface Appearance ◽  
Copper Dissolution ◽  
Pharmaceutical Compound ◽  
Increasing Temperature

Some pharmaceutical drugs namely valsartan, hydrocholorothiazide, erythromycin thiocynate and diclofenac potassium were studied as chemical additions for enhancing the finished copper surface attained. Anode potential-limiting current relationship was measured and comparing of gradually increasing pharmaceutical compound concentrations (from 1 × 10-4 to 7 × 10-4 M). Copper dissolution behaviour in presence of pharmaceutical compounds was studied under natural convection [rotating cylinder (RCE) and rotating disc electrode (RDE)] as forced convection. The limiting current was found to diminish with enlarging additives concentration and increase with increasing temperature (293-313 K). Activation energies values confirm that reaction rate was diffusion controlled. The results showed that the improvement produced in electropolishing in presence of pharmaceutical compounds occurs through adsorption of their molecules above metal surface. All the pharmaceutical compounds adsorption process obey kinetic-thermodynamic model. The data under different conditions were controlled by dimensionless correlations viz. Sherwood, Schmidt and Reynolds numbers. Surface morphology also confirmed that an addition of pharmaceutical compound to copper dissolution bath enhance surface appearance and its texture quality to great extent.

Evaluating two new Schiff bases synthesized on the inhibition of corrosion of copper in NaCl solutions

RSC Advances ◽  
2015 ◽  
Vol 5 (19) ◽  
pp. 14804-14813 ◽  
Author(s):  
Yang Zhou ◽  
Shenying Xu ◽  
Lei Guo ◽  
Shengtao Zhang ◽  
Hao Lu ◽  
...  
Keyword(s):  
Schiff Bases ◽  
Copper Surface ◽  
Nacl Solution ◽  
Organic Film ◽  
Copper Dissolution

An AND or DSM organic film can be formed onto a copper surface in 3% NaCl solution and acts as a barrier to copper dissolution and O2reduction.

Fibrinogen Induces Changes In Platelet Membrane Potential

1981 ◽  
Author(s):  
H Vainer ◽  
A Caprani
Keyword(s):  
Membrane Potential ◽  
Conformational Changes ◽  
Human Albumin ◽  
Human Platelets ◽  
Platelet Membrane ◽  
Limiting Current ◽  
Transmembrane Transport ◽  
Membrane Glycoproteins ◽  
Rotating Disc ◽  
Experimental Conditions

Changes in platelet membrane potential (MP) reflecting ion transmembrane transport accompany the platelet activation by various stimuli. We have studied the platelet MP and the effect of fibrinogen on its expression, using an electro-chemical method. The MP determination is based on the evaluation of the transmembrane partition coefficient (PC) (Ci/Ce) of an electroactive tracer, such as the ferro- cyanid anion. Washed human platelets are incubated with the tracer solution ; the amount of tracer in the supernatant (Ce) and in the acellular lysate of SDS-treated platelet pellet (Ci) is measured as the diffusion limiting current corresponding to the tracer oxidation at the surface of a rotating disc electrode. The kinetics for the PC evaluation have been studied in order to standardize the experimental conditions which allow to express the MP by the Nernst equation : Vi-Ve = RT/4F. Log Ci/Ce.The mean value ± SD (N = 9) of the platelet MP in saline is -5.5 ± 0.5 mV (PC = 0.445 ± 0.020). When fibrinogen replaces the saline, a MP of -8.83 mV (PC = 0.257) is observed. While it contrasts sharply with the MP of platelets in saline, it is comparable to the MP of platelets in plasma, which is : -8.63 mV (PC=0.266). We have also measured the effect of human albumin and gamma globulins on the MP ; both these plasmatic proteins cause a much smaller decrease of MP, as compared to fibrinogen (or plasma), all used at physiological concentrations in saline and without the platelet pretreatment with any agent.The results suggest that a relationship might exist between the marked decrease of platelet MP caused by fibrinogen - possibly via mediators of the transmembrane transport- and/or some of the platelet membrane glycoproteins which appear to function as binding sites for fibrinogen and must undergo (conformational) changes that allow fibrinogen to bind.

scholarly journals The Effects ofCassia SiameaLam. Root Extract on the Corrosion and Kinetics of Corrosion Process of Copper in Alkaline Solutions

2011 ◽  
Vol 8 (4) ◽  
pp. 1708-1713
Author(s):  
A. I Onen ◽  
B. T. Nwufo ◽  
E. E. Ebenso
Keyword(s):  
Copper Surface ◽  
Alkaline Solutions ◽  
Root Extract ◽  
Adsorption Model ◽  
Free Energy Of Adsorption ◽  
First Order Kinetics ◽  
Absorbance Difference ◽  
Increasing Temperature ◽  
Kinetics Of ◽  
Kinetic Treatment

The effect ofCassia siamealam. (CSL) root extract as a corrosion inhibitor of copper in 0.50 M NaOH solutions was investigated using absorbance difference technique at 30 °C and 40 °C. CSL root extract inhibited the corrosion of copper in 0.50 M NaOH solutions and the inhibition efficiency (% IE) increased to a maximum of 78.3±2.3% with increasing concentration of the extract but decreased with increasing temperature. The adsorption of CSL root extract on copper surface followed the Langmuir adsorption model with the average heat of adsorption, Qadsand free energy of adsorption, ΔGadsof -8.98 kJmol-1and -8.70 kJmol-1respectively. A kinetic treatment of the data revealed a first order kinetics with respect to copper in the presence and absence of the extract.

Spectral-Directional Emittance of CuO at High Temperatures

2005 ◽  
Vol 128 (4) ◽  
pp. 382-388 ◽  
Author(s):  
Peter D. Jones ◽  
George Teodorescu ◽  
Ruel A. Overfelt
Keyword(s):  
Cupric Oxide ◽  
Polar Angle ◽  
Copper Surface ◽  
Emission Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Direct Emission ◽  
Increasing Temperature ◽  
Directional Emittance ◽  
Good Agreement

Spectral-directional emittance measurements for cupric oxide (CuO) are presented. The data cover polar angles of 0-84deg from the surface normal, wavelengths between 1.5 and 8μm, and temperatures between 400 and 700°C. The data were generated using a radiometric, direct emission measurement method. The oxide was grown on a very clean, smooth, and mirror-like copper surface, heated in air at 700°C until emission measurements became constant (270h). X-ray diffraction and EDS analyses were performed to characterize the spatial and molecular composition of the copper oxide layer. It is generally found that CuO emittance decreases with increasing polar angle, increases with increasing wavelength, and increases with increasing temperature. Spectral-directional emittance values calculated from the Fresnel relations show good agreement with the measurements up to polar angles of 72deg.

Theory of Copper-Electrolyte Slimes Decoppering in the Presence of Hydrogen Peroxide

2019 ◽  
Vol 946 ◽  
pp. 585-590
Author(s):  
V.G. Lobanov ◽  
K.D. Naumov ◽  
A.A. Korolev
Keyword(s):  
Hydrogen Peroxide ◽  
Dissolution Rate ◽  
Rate Constant ◽  
Chemical Transformations ◽  
Composition Effect ◽  
Rotating Disc ◽  
Copper Dissolution ◽  
Copper Leaching ◽  
Copper Electrolyte ◽  
Dissolution Rate Constant

The problem of copper leaching from copper-electrolyte slimes is discussed. To intensify the long and costly process, it is proposed to use a leaching system containing sulfuric acid and hydrogen peroxide as an oxidizing agent. The chemical transformations possible variants at the treatment of slime under the specified conditions and the thermodynamic parameters of the predicted reactions are considered. Solution composition effect on the copper dissolution rate at room temperature was studied in the presence of hydrogen peroxide using the rotating disc technique. It is found that dissolution rate constant at using hydrogen peroxide slightly inferior to dissolution rate constant under autoclaved conditions in an oxygen atmosphere.

scholarly journals Effect of Temperature on Diluate Water in Batch Electrodialysis Reversal

Separations ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 229
Author(s):  
Germán Eduardo Dévora-Isiordia ◽  
Alejandra Ayala-Espinoza ◽  
Luis Alberto Lares-Rangel ◽  
María Isela Encinas-Guzmán ◽  
Reyna Guadalupe Sánchez-Duarte ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Significant Degree ◽  
Operating Conditions ◽  
Limiting Current ◽  
Effect Of Temperature ◽  
Input Concentration ◽  
Limiting Current Density ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
The Cost

A high percentage of the agricultural wells in the state of Sonora are overexploited, thus generating a significant degree of saline intrusion and abandonment by nearby communities. In this paper, the effect of temperature on the final concentration of diluted water was evaluated with variations in voltage and input concentration in a batch electrodialysis reversal (EDR) process in order to find the optimal operating conditions, with an emphasis on reducing the energy consumption and cost of desalinated water. Thirty-six samples were prepared: eighteen samples of 2000 mg/L total dissolved solids (TDS) and eighteen samples of 5000 mg/L TDS; brackish well water of 639 mg/L TDS and synthetic salt were mixed to obtain these concentrations. Three different temperatures (25, 30, and 35 °C) and two different voltages (10 and 20 V) were tested for each sample after evaluating the limiting current density. The best salt removal occurred in the 20 V sets, with 18.34% higher removal for the 2000 mg/L TDS experiments and 25.05% for the 5000 mg/L experiments (average between the 25 to 35 °C tests). The temperature positively affected the EDR, especially in the experiments at 10 V, where increasing by 10 °C increased the efficiency by 10.83% and 24.69% for 2000 and 5000 mg/L TDS, respectively. The energy consumption was lower with increasing temperature (35 °C), as it decreased by 1.405% and 1.613% for the 2000 and 5000 mg/L TDS concentrations, respectively (average between the 10 and 20 V tests), thus decreasing the cost per m3 of water.

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