A thermodynamic and kinetic study of trace iron removal from aqueous cobalt sulfate solutions using Monophos resin
Background: High purity cobalt has many important applications, such as magnetic recording media, magnetic recording heads, optoelectronic devices, magnetic sensors, and integrated circuits, etc. To produce 5N or higher purity cobalt in an electro-refining process, one of the challenges is to effectively reduce the Fe content of aqueous cobalt salt solution before electrolysis. This paper describes thermodynamic and kinetic investigations of the Fe adsorption process of a new sulfonated monophosphonic resin with the trade mark Monophos. Methods: Five cobalt sulfate solutions of different Co concentrations were prepared. Fe ions were removed from the solutions by ion exchange method using Monophos resin. Chemical analysis was carried out using a Perkin Elmer ICP-OES. Results: The initial Fe concentrations of about 0.9–2.0 mg/L can be reduced to about 0.3–0.8 mg/L, which is equivalent to an Fe removal rate of 60–67%. The Langmuir isothermal adsorption model applies well to the Fe removal process. A second-order type based on McKay equation fits better with experimental data than other kinetic models. The kinetic curve can be divided into two sections. For t < 30 min, particle diffusion may act as the controlling step, whereas chemical reaction may control the Fe adsorption process in the section t > 30 min. Conclusions: Monophos resin is effective for the removal of trace Fe from cobalt sulfate solution. This ion exchange process obeys the Langmuir isothermal adsorption model and the McKay equation of second-order kinetics.
A comparison of various ion exchange resins for the removal of ferric ions from copper electrowinning electrolyte solutions part I: Electrolytes containing no other impurities
Abstract Column testing was performed on four commercially available ion exchange resins to evaluate their ability to remove ferric from a synthetic copper electrowinning electrolyte. Results from the loading test indicated that the sulphonated diphosphonic resin, Eichrom Diphonix, has significantly lower capacity than other resins tested. Stripping tests were performed using cuprous elution and showed that the aminophosphonic resin, LanXess Lewatit TP260, stripped more slowly than the two sulphonated monophosphonic resins, Purolite S957 and generic resin D416. Results from the various stripping tests indicate that the use of an ORP titration on the elution cycle appears to be an excellent indicator of the elution endpoint. Further stripping tests performed on the Purolite S957 resin indicate that total stripping time was approximately linear with the theoretical concentration of cuprous in solution, for theoretical cuprous concentrations between 0.4 and 0.8 g/L Cu+.
Dot arrays of L11 type Co–Pt ordered alloy perpendicular films
Magnetic properties of dot arrays of L11 type Co–Pt ordered alloy perpendicular films were studied. L11-Co–Pt films with a large uniaxial magnetic anisotropy Ku of the order of 107 erg/cm3 were fabricated at a substrate temperature of 360 °C using ultrahigh vacuum sputter film deposition. Dot patterns with dot diameters of 70–200 nm were made using high resolution e-beam lithography and reactive ion etching (RIE). The values of Ku were measured by the GST method using the Anomalous Hall Effect; we observed the averaged signals of 6000 dots. The values of Ku for dot arrays of 10-nm-thick L11-Co50Pt50 films deposited on MgO(111) substrates (single crystal films) and glass disks (polycrystalline films) were nearly the same as those of the original films independent of D, indicating no significant etching damage by the RIE process. Magnetic force microscopy images revealed that all dots were single domains in the present D region. The coercivity Hc of the dot arrays was 25.0 kOe [MgO(111) substrate, D=70 nm] ...