Electrochemical behaviour of titanium supported spinel type anodes

Studies on the cobalt based spinel compounds coated titanium anodes (for example, cobalt-nickel and cobaltzinc systems) by galvanostatic polarisetion technique have been carried out under various experimental conditions. The influence of the incorporation of nickel or zinc as oxidea to cobalt spinel has also been studied and the rewh compared. In addition, data obtained from x-ray and SEM studii are presented

Anodes for electrowinning - polarisation characteristics

Study is made on oxygen evolving ekctrock from the stend point of the devdopment of ektmdea based on the we of nobk metd oxickrlrpind type oxider &her singly or pintly cwtsd over titanium having a witable inner byer. The aipificencs of h pmrt pbysd by oxygen evolving dectmcatalyets is examined

Evaluation of stable catalytic anodes for oxygen evolution in sulphuric acid

The electrochemical activity and stability of Ti/(Ru02 -Ti02)/ (Ru02- Mn02) anodes have been characterised employing steady state, cyclic voltammetric and galvanostatic accelerated polarization techniques in 0.5M H2SO4. Their dependence on composition of Ru02-Mn02 has been highlighted based on the comparison of the data obtained by the above techniques. Attempt has also been made to derive 'Stability index' and 'Activity' from cyclic voltammetry dat

Treated titanium anodes for the production of emd

The application of treated titanium anodes with special reference to the process know-how on Electrolytic Manganese Dioxide (EMD) is briefly described. The know-how has been developed on a pilot plant scale, using manganese salt solutions and graphite or treated titanium anodes. The results obtained with titanium anodes as well as thesignificance of employment of chloride route, with specialemphasis on the characteristics of the final product, are also presented. Furthermore, the various steps involved in the treatment of titanium anode so as to make it suitable for high current density and high acidity operations in EMD preparation and their significance have been highlighted

A process for the preparation of highly pure manganse sulphate electrolyte useful for electrodeposition of highly pure electrolytic manganese dioxide(HPEMD")

The invention relates to a process for the preparation of highly pure manganese sulphate electrolyte useful for electrodeposition of highly pure electrolytic manganese dioxide (HPEMD). In the process of the present invention the manganese sulphate solution containing monovalent cations, in particular K and Na are removed as a complex, viz. jarosite, which is highly crystalline and insoluble from manganese sulphate under optimum conditions. This has been done by digesting the manganese sulphate solution containing monovalent cations with ferric sulphate, at a pH of 1.5 to 3.0, for a duration of 15 to 180 minutes. The temperature being maintained between 80 to 100°C. Bringing about precipitation with suitable addition of seeding. Allowing to cool, followed by filtration. Subsequently treating either with CaO or calcine to raise the pH. The present invention thus provides a process for the preparation of highly pure manganese sulphate electrolyte by the removal of monovalent metal ions from manganese sulphate solution, which is a precursor for the electrodeposition of highly pure electrolytic manganese dioxide (HPEMD)

Performance characteristics of different anode systems in EMD deposition

A comparison has been made of the behavior of variety of pretreated/activated anodes, viz., Ti, expanded Ti, Ti/RuO2-TiO2, Ti/MnO2, expanded Ti/MnO2 during deposition of EMD from sulphate and chloride electrolyte and compared with that of conventional ones, i.e., graphite, bare Ti and platinum with special reference to energy consumption and cell voltage. It is found that cell voltage increases with increase in sulphuric acid concentration in the bath, indicating passivation of the substrate. Ti/RuO2-TiO2 anode exhibits a lower cell voltage than bare Ti or Ti/MnO2 due to lower contact drop between the deposit and the substrate. The employment of expanded Ti/MnO2 exhibits a cell voltage comparable to that of Ti/RuO2-TiO2. In chloride electrolytes, in general Ti/RuO2-TiO2 behaves similar to Ti/MnO2 except that it exhibits a lower cell voltage by about 400-500 mV. Smooth platinum performs poorly due to lower overpotential for chloride evolution. Chemical manganese dioxide coated anode is more attractive for employment as anode for MnO2 deposition from either electrolyt

Electrochemical behavior of Ti-supported cobaltite anode in sulphuric acid

Titanium electrodes coated with Co3O4-IrO2 have been characterized for their electrochemical activity and stability employing transient, cyclic voltammetric and accelerated polarization studies. Incorporation of IrO2 in Co3O4 increases the life of the anode upto 70 atom%. The influence of intermediate layer of ‘mixed-crystal oxides’ of Ru and Ti introduced in between the titanium substrate and the outer layer (Co3O4-IrO2) has also been studied and compare

Electrolytic manganese dioxide from chloride electrolyte: Anode potential measurements

683-686In the preparation of electrolytic manganese dioxide (EMD) the dependence of anode potentials on conditions of electrolysis,viz. ,temperature, anodic current density and concentration of hydrochloric acid, has been studied and the behaviour of uncoated and MnO2 coated graphite in HCI, H2SO4 and MnCI2-HCI electrolyte has been compared. It is observed that above 70°C, below an anode current density of 100 Am-2 and below a concentration of 20 g/L hydrochloric acid, the deposition of manganese dioxide takes place preferentially. Among the probable electrochemical reactions EMD deposition, oxygen evolution and chlorine evolution occur under the present experimental conditions. The data collected employing an all- glass apparatus also confirm the results

Spinel oxide coated titanium anodes-preparation and characterization

Cobalt oxide based spinel anodes containing NiO or ZnO as the secondary component have bee coated over titanium substrate by pyrolysis technique. The conditions of preparation were optimized. Electrochemical and structural properties were studied using X-ray diffraction (XRD), cyclic voltammetry (CV) and galvanostatic polarization techniques and the results are discusse

Studies on the preparation of pure ammonium para tungstate from tungsten alloy scrap

Ammonium paratungstate was prepared from tungsten alloy swarf employing anodic dissolution in sodium hydroxide using a packed bed configuration followed by chemical conversion into ammonium tungstate through tungstic acid. The alkaline tungstate solution was dialysed to recover sodium hydroxide, which could be recycled to the electrolytic dissolution. The influence of anodic current density and other parameters on dissolution/recovery was studied and discussed. It was observed that a current density of 600 mA/100 g scrap could be applied when the concentration of NaOH was maintained around 2.5 M. The energy consumption for anodic dissolution was 2.14 kWh/kg W with more than 90% recovery achieved. XRD studies indicated that the exhausted scrap contained an alloy of nickel and iron with a very low percentage of tungsten. APT sample prepared through anodic dissolution in NaOH was characterized