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.
Study on kinetics and thermodynamics of hypericin adsorbed by macroporous resin.
[Objective] To study the kinetics and thermodynamics characteristics of hypericin adsorbed by D101 macroporous resin.[Method] The pseudo-first-order kinetics model,pseudo-second-order kinetics model and Kannan equation of intra-particle diffusion were used to fit the kinetics process of hypericin adsorbed by D101 macroporous resin,and Langmuir model,Freundlich model,Temkin model and Origin soft were used to fit the thermodynamics process of hypericin.[Result] The adsorption of hypericin by D101 macroporous resin conformed to the pseudo-second-order kinetics equation,and it was demonstrated from the results of thermodynamics study that adsorption of hypericin by D101 macroporous resin conformed to Freundlich adsorption isotherm equation.The enthalpy changes △H0 indicated that the absorption was an exothermic process,and |△H | 20 kJ/mol revealed that the absorption process was physical adsorption.Meanwhile,the free energy changes △G0 indicated that the absorption was a spontaneous process;the entropy changes △S0 demonstrated that the absorption process was the process of entropy increase.[Conclusion] The study provides theoretical basis for industrial production of isolation and purification of hypericin through macroporous resin.
Diphonix® Resin: A Review of Its Properties and Applications
Abstract The recently developed Diphonix® resin is a new multifunctional chelating ion exchange resin containing geminally substituted diphosphonic acid ligands chemically bonded to a styrene-based polymeric matrix. Diphonix can be regarded as a dual mechanism polymer, with a sulfonic acid cation exchange group allowing for rapid access, mostly non-specific, of ions into the polymeric network, and the diphosphonic acid group responsible for specificity (recognition) for a number of metal cations. The Diphonix resin exhibits an extraordinarily strong affinity for actinides, especially in the tetra- and hexavalent oxidation states. Therefore the resin has potential for applications in TRU and mixed waste treatment and characterization, and in the development of new procedures for rapid actinide preconcentration and separation from environmental samples. Metal uptake studies have been extended to alkaline earth cations, to transition and post-transition metal species, and to metal sorption from neutral or ne...