scholarly journals The recovery of metallic cadmium from the cadmium containing residue in a electrolytic zinc plant

2015 ◽  
Vol 5 (2) ◽  
pp. 26-32
Author(s):  
Manh Hung Luong ◽  
Ngoc Vuong Tran

This report presents a process for recovery and purification of metallic cadmium from a residue of the purification process for zinc sulphate solution in Thai Nguyen electrolytic zinc plant. The cadmium containing residue was digested by sulfuric acid of 140 g/l at a temperature of 700C for 4h, the obtained solution will be purified for removal of some impurities such as iron, copper, etc. The purified solution with concentration 50 g/l of Cd,  120 g/l of sulphuric acid and 0.1 g/l of gelatin as an additive will be subjected to an electrolysis process with current density of 50 A/m2 for recovery of metallic cadmium. The temperature of electrolyte is lower 400C. Overall recovery of cadmium is 90%,  purity of the obtained metalic cadmium  is up to 99.0%.

As long ago as 1899, Caspari showed that the condition that zinc should dissolve in an acid solution with evolution of hydrogen may be expressed in the form— Single potential of metal + overvoltage < single potential of hydrogen electrode. ( a ) The single potential of zinc in a normal zinc sulphate solution is —0⋅493 volt, and that of a hydrogen electrode in normal sulphuric acid is +0⋅277 volt. If a mixture of zinc sulphate and sulphuric acid be taken, the potential of the zinc will become more positive as the concentration of zinc sulphate increases, and the potential of the hydrogen electrode more negative as the concentration of the acid decreases. Since the overvoltage of pure zinc is about 0⋅7 volt, conditions may be easily adjusted in this way so that solution is exactly arrested and the statement above ( a ) then becomes an equation. If a definite solution is used for a series of experiments, then the potential of the hydrogen electrode is constant, and the tendency of the metal to dissolve will be measured by the fixed potential of this hydrogen electrode minus the sum of the overvoltage and the potential of the metal.


Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 405
Author(s):  
Marlon L. Mopon ◽  
Jayson S. Garcia ◽  
Dexter M. Manguerra ◽  
Cyril John C. Narisma

Sulfuric acid anodization is one of the common methods used to improve corrosion resistance of aluminum alloys. Organic acids can be added to the sulfuric acid electrolyte in order to improve the properties of the anodized aluminum produced. In this study, the use of gallic acid as an additive to the sulfuric acid anodization of AA1100 was explored. The effect of varying anodization current density and gallic acid concentration on the properties of anodized aluminum samples was observed using electrochemical impedance spectroscopy, linear polarization, and scanning electron microscopy. It was observed that the corrosion resistance of samples anodized in gallic-sulfuric acid solution at 10 mA·cm−2 is lower than samples anodized in sulfuric acid. It was also observed that higher anodization current density can lead to lower corrosion resistances for aluminum samples anodized in gallic-sulfuric acid solution. However, samples anodized at 5 mA·cm−2 and at a gallic acid concentration of 5 g·L−1 showed better corrosion performance than the samples anodized in sulfuric acid only. This suggests that the use of low amounts of gallic acid as an additive for sulfuric acid anodization can lead to better corrosion resistances for anodized aluminum.


Author(s):  
B. G. Abdulov ◽  
A. A. Hasanov

The purification process of polycyclic aromatic hydrocarbons was carried out by extraction of diesel fraction from the primary oil refining using the effect of magnetic field. A mixture of N-methylpyrrolidone with sulfuric acid was used as an extractant. The content of aromatic hydrocarbons in the diesel fraction decreased by 39.8% under normal conditions and by 50.8% under the influence of magnetic field after extraction. The samples were investigated by infrared (IR) spectroscopy method before and after extraction. Vibartional modes corresponding to different atomic bonds have been observed. Deodorization of diesel was determined by interpreting obtained modes.


1996 ◽  
Vol 199 (11) ◽  
pp. 2531-2535 ◽  
Author(s):  
S Benvenuti ◽  
A Gagliardo

Pigeons were made anosmic by unilateral treatment of their olfactory mucosa with a zinc sulphate solution and by plugging the contralateral nostril. In a series of releases at unfamiliar sites, 55&shy;79 km from the home loft, the experimental birds' homing behaviour was compared with that of two control groups: unmanipulated control birds, and birds subjected to unilateral zinc sulphate treatment and equipped with an ipsilateral nasal plug. The experimental pigeons exhibited homing behaviour &shy; in terms of both homeward initial orientation and homing performance &shy; significantly poorer than that of both unmanipulated and treated control pigeons. In addition, the homing behaviour of the treated controls turned out to be only slightly, and not significantly, poorer than that of the unmanipulated birds. The results show that the impaired homing capabilities of the zinc-sulphate-treated birds are due to the lack of navigational information and not to non-specific brain damage caused by the experimental treatment.


1970 ◽  
Vol 52 (2) ◽  
pp. 481-494
Author(s):  
J. F. SKIDMORE

1. Damage to the gill epithelium occurs when hatched fish are killed rapidly by solutions of zinc sulphate. 2. The rate of routine oxygen uptake by lightly sedated, quiet, rainbow trout did not alter on exposure to a rapidly toxic solution of zinc sulphate. However, oxygen utilization decreased seven-fold, gill ventilation volume increased six-fold, heart rate was halved, coughing rate increased 18-fold and the Po2 of dorsal aortic blood declined. 3. Unsedated trout usually struggled on exposure to zinc. The survival time of struggling fish was reduced and oxygen uptake increased, but other physiological changes were similar to those in quiet fish. 4. The respiratory changes in poisoned trout were generally similar to changes observed earlier in the same fish under hypoxia. 5. The osmotic concentration and the concentrations of sodium, potassium, calcium, magnesium and zinc in blood were largely unaffected by immobilization in zinc sulphate solution. Trout survived a four-fold increase in zinc concentration in the blood by injection. 6. The results suggest that epithelial damage decreased the permeability of the gills to oxygen, and did not increase their permeability to cations. Zinc was not a rapid internal poison. Death was probably caused by tissue hypoxia, when maximum gill ventilation was no longer sufficient to supply the oxygen needs of the fish.


Sign in / Sign up

Export Citation Format

Share Document