Several kinds of spherical cysteine grafted cobalt/manganese imprinted crosslinking chitosan spheres were synthesized for Mn2+ and Co2+ removal, in which Mn2+ and Co2+ were used separately or together as imprinting ions. Structures of the adsorbents were analyzed utilizing the techniques of SEM and FTIR. The effects of initial pH, contact time, presence of other cations, initial Mn2+ and Co2+ concentration on adsorption were investigated. Furthermore, adsorption kinetics and isotherm were studied, which showed sorption data fitted to pseudo-second-order and Langmuir models for both Mn2+ and Co2+. The overall results indicated the possibility of using Cys–Co/Mn–CCTS–2 for efficient removal of Mn2+ and Co2+ from dilute low-level radioactive liquid waste.
The feasibility of using nonwoven polypropylene fiber (NWPP) as the filter media to treat oil-in-water emulsion was studied. Both static adsorption experiments and dynamic filtration in coalescence bed were made. Due to the hydrophobic property of NWPP, the oil adsorption happened immediately when contacted with NWPP. The equilibrium was achieved after 50min adsorption. The Freundlich isotherm fits the experimental data well. The data was analyzed with three adsorption kinetic models: the pseudo first order, second order adsorption kinetics as well as the intra-particle diffusion models. The results showed that the second order adsorption kinetic was more accurate to correlate the experimental data. After the dynamic filtration processes using 4.0g NWPP, the oil removal efficiency could achieve 95%. It also found that the low flow rates would be better to treat oil-in-water emulsion in dynamic condition using NWPP as the filter media.
A large amount of hydrogen would be generated because of zirconium-water reaction during serious accidents in nuclear power plant (NPP). Hydrogen could be combusted or explode under certain conditions, resulting in damage of the containment integrity and releasing radioactive substances into surrounding environment. Therefore, hydrogen elimination inside the NPP containment is an important subject. According to the requirements of NNSA (National Nuclear Security Administration), enough passive hydrogen recombiners (PHR) had been installed in unit 3&4 of Qinshan phase II NPP to prevent the hydrogen explosion in a serious accident. Additionally, new PHRs for unit 1&2 were also added. This article introduces the practical experience for the PHR modification, the comparisons between unit 1&2 and unit 3&4.
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