Papers by Keyword: Electrolysis

Abstract: Nicosulfuron is a kind of sulfonylurea herbicide used for controlling weeds in corn. In order to solve the problem of plant water with agrochemical, electrolysis was investigated for the treatment of nicosulfuron from dilute aqueous solutions. The operating varieles of time, chlorine anion, pH were experimented and the electrolytic decomposition mechanism of nicosulfuron was suggested. Acid solution was effective for the decomposition of the nicosulfuron and the existence of chloride ions lead to the formation of electrolytic reaction products, which regarded as chloronicosulfuron by HPLC-MS. The reaction is similar to free radical reaction.

Abstract: Used fixing reagent, from X-ray laboratories of hospitals is often contaminated with numerous chemicals. Silver (Ag (I)) ion is the major contaminant present in used fixing reagent. This work determined the Ag (I) ion and chemical oxygen demand (COD) in used fixing reagent of X-ray laboratory. The removal of Ag (I) ion was done by electrolysis and followed with the adsorption onto crab shell chitosan (CSC) and black rice husk ash (BRHA). The Ag (I) ions in an used fixing reagent was analyzed by flame atomic absorption spectrophotometry (FAAS) at λ = 540 nm. The COD was measured by reflux technique and the results indicated that the initial concentrations of Ag (I) ions and COD values were 5,634.66 ± 179.74 mg L^-1 and 182,821.28 ± 5759.04 mg L^-1, respectively. The optimum voltage and time for electrolysis were 2 volts and 10 hrs. After the electrolysis had been done, 82.28% of the Ag (I) ions were removed, while the COD was reduced by 51.76%. After the adsorption experiment was applied, 72.16% of the Ag (I) ions were adsorbed onto CSC and 51.83%. onto BRHA. The COD was reduced 37.04% and 34.08% by CSC and BRHA, respectively. Therefore, these two techniques, electrolysis and adsorption, are appropriated techniques for Ag (I) ions recovery and the COD reduction of the used fixing reagent discharged from X-ray laboratories.

Abstract: In this report, synthesis and characterization of gold nanoparticles (AuNPs) from gold leaf by electrolysis in two different media (gel and paper) in presence of sodium chloride (NaCl), glucose (C₆H₁₂O₆) and polyvinyl pyrrolidone (PVP) at room temperature were investigated. Graphite was used as two electrodes, NaCl was used as an electrolyte, C₆H₁₂O₆ was used as reducing agent and PVP was used as stabilizer to control the aggregation of the nanoparticles. UV-Visible spectroscopy (UV-Vis) and scanning electron microscopy (SEM) were used to confirm the characteristics and morphologies of the synthesized AuNPs.

Abstract: The method of electrochemical reduction utilizes electrons as agent to achieve the reduction of indigo, vat dyes and pollution emissions, as well as the recycling of electrolyte. In this study, Ca²⁺-Fe³⁺-triethanolamine (TEA) redox system was used as the mediator to achieve the indirect electrochemical reduction of indigo. The optimization of parameter was analyzed by reduction efficiency (RE) and current efficiency (CE). The result showed that indigo could be reduced by electrochemical method and the best optimization recipe was 20 g/L NaOH + 5 g/L Fe₂(SO₄)₃ + 30 g/L TEA + 5 g/L Calcium gluconate + 3 g/L indigo in 1 A·dm^-2 current density at 50°C. This work suggested that Ca²⁺-Fe³⁺-TEA redox system in reduction of indigo was an effective way with higher CE (75.9 %).

Abstract: During the test of DC(direct current) abrasive magnetic fluid technology,many bubbles and noises were generated near the graphite electrode , and the yellow green liquid was produced, which affected the further test.Through the study of graphite electrode, it was found that NaCl solution magnetic fluid produced hydrogen and chlorine gas after electrolysis. At the same time, chlorine gas dissolved in water to form yellow green liquid.The magnetic field of neodymium boron permanent magnet was equivalent to a mechanical stirring, which inhibited the production of chlorine gas.According to the difference of impressed current system, the abrasive magnetic fluid jet technology was divided into DC and AC(alternating current) .There was no electrode in AC abrasive magnetic fluid jet technology, so no gas or noise would be produced.The rotating magic ring permanent magnet produced alternating magnetic field, acting on the abrasive magnetic fluid to form an induced current.Under the action of the magnetic field, the electromagnetic force was applied to move along the circumferential direction to promote the motion of the abrasive magnetic fluid.

Abstract: The porous structure of copper-cadmium oxide system produced by electrochemical synthesis using alternating current in ammonium chloride solutions with concentrations of 3 and 25 wt% was studied. It was shown that the composition of electrolysis products is represented by oxides of copper (I) and (II), hydroxides of cadmium; it depends on the current density and the solution concentration. The products of joint electrochemical oxidation of copper and cadmium obtained in ammonium chloride solution with concentrations of 3 and 25 wt% and current densities of 1 and 3 A/cm² are characterized by mesoporous structure.

Abstract: The porous structures of nanoparticles of copper and cadmium prepared by AC electrochemical synthesis in solutions of acetate of sodium, chlorides of ammonium and sodium were studied. It is established that at current density of 1A/cm² and concentration of NaCl 3 % wt. with the highest specific surface area (8.23m²/g), maximum pore volume (0.029 cm³/g) are formed, and the largest volume of the particles is characteristic of the nominal pore diameter - 62 nm. The values of specific surface area and total pore volume with increase in the temperature of calcination decrease, and the pores are slightly enlarged in diameter. Thus, the obtained data allow predicting operating parameters of the electrolysis to obtain copper - cadmium oxide system a predetermined porous structure.

Abstract: Joint electrochemical oxidation of copper and aluminum using alternating current (AC) was performed. The electrolysis products were dried on air (method carbonate) and at the residual pressure of 3-5 kPa (oxide method). Cu-Al layered double hydroxide (Cu-Al/LDH) are formed at air carbonization. Oxide method saves copper (I) oxide. Heat treatment causes the decomposition of LDH to CuO and Al₂O₃ as well as Cu₂O oxidation to CuO. Copper-aluminum spinel (CuAl₂O₄) is the product of solid-phase interaction of copper and aluminum oxides. Infrared spectra revealed that oxide method provides the boehmite dehydration and metal oxides interaction at lower temperature despite the fact that the poorly crystallized copper (II) oxide is formed at LDH decomposition.

Abstract: Water is a chemical compound with chemical formula H₂O. By the electrolysis proses, water can be split constituent elements, namely hydrogen (H₂) and oxygen (O₂). In this study, an electrolyze system used six pieces of electrodes which made from 304L SS for electrolysis process for both of distilled water and adding catalyst NaHCO3 (Sodium Bicarbonate) on distilled water. The results indicated that electrolysis process on distilled water consumed power of 353.52 Watts to produce Brown’s gas of 0.00123 l/s. Whenever, NaHCO3 was added into distilled water with the mass fraction of 1.33% consumed power decrease of 27.89 Watts and Browns gas was produced 0.0017 l/s. The efficiency of distilled water had the greatest efficiency only 5.53% by using current of 2 Ampere and power reached 31.043Watts. While the addition of catalysts had the greatest efficiency reached 40.29% in the use of mass fraction of catalyst 1.5%, 6 Ampere currents and power of 19.829 Watts.

Abstract: Hydrometallurgical routes of copper recovery from smelted low-grade e-waste are presented. Electronic scrap was smelted to produce Cu–Zn–Ag-Sn alloys of various phase compositions. The alloys were then treated in the following ways: (a) anodic dissolution with simultaneous metal electrodeposition using ammoniacal solutions with various ammonium salts (chloride, carbonate, sulfate). This resulted in the separation of metals, where lead, silver and tin accumulated mainly in the slimes, while copper was transferred to the slime, electrolyte and then recovered on the cathode. (b) leaching in ammoniacal solutions of various compositions and then copper electrowinning. Alloy was leached in chloride, carbonate, sulfate and thiosulfate baths. This resulted in the separation of the metals, wherein copper and zinc were transferred to the electrolyte, while metallic tin and silver as well as lead remained in the slimes. Copper was selectively recovered from the ammoniacal solutions by the electrolysis, leaving zinc ions in the electrolyte. The best conditions of the alloy treatment were obtained, where the final product was copper of high purity (99.9%) at the current efficiency of 60%. Thiosulfate solution was not applicable for the leaching of the copper alloy due to secondary reactions of the formation of copper(I) thiosulfate complexes and precipitation of copper(I) sulfide.