Homogeneous succinylation of cellulose acetate: Design, characterization and adsorption study of Pb(II), Cu(II), Cd(II) and Zn(II) ions

In this study, the removal of Pb(II), Cu(II), Cd(II), and Zn(II) ions from aqueous solutions was investigated using succinic anhydride modified cellulose monoacetate. In the first part, the cellulose acetate was successfully succinylated in a homogenous medium of DMF using 4-dimethylaminopyridine (DMAP) as a catalyst. The obtained material (AcS) was analyzed by FTIR and CP/MAS 13C NMR Spectroscopy, thermogravimetry analysis and DRX patterns. The titration method was used to determinate the degree of hydroxyl group substituted by carboxyl group (DS) and was found to be 1.36. In the second part, the Bach technique was used to study the effects of pH, contact time, concentration of metals, ionic selectivity and regeneration. Maximum sorption capacities of AcS for Pb(II), Cu(II), Cd(II), and Zn(II) were 241.81, 133.76, 156.61 and 73,58 mg.g-1, respectively. The Langmuir isotherm and the pseudo second order kinetic models provided best fit to the experimental data of metal ion sorption. The nature of the adsorption process was exothermic and spontaneous in nature with negative values of ΔG° and ΔH°. Regeneration of the modified cellulose acetate was accomplished using nitric solution and showed high stability and good recyclability.

A Study of Ni & Cu Surface Status in a Supercritical Carbon Dioxide into a Microemulsion Using QCM

A set of Quartz Crystal Microbalances (QCM's) was used to observe the film removal characteristics of three different CO2-nitric acid microemulsions. QCM's electroplated with nickel or copper were used as specimens. F-AOT, NP-4 and the synthesized Proline Surfactant-1 were used as surfactants to create microemulsions. While the F-AOT microemulsion yielded a relatively low removal rate, that of the Proline Surfactant-1 completely removed the Cu metal film within a short period of time. The NP-4 microemulsion removed the metal surface. However, removal rate measurements per QCM were not possible due to the instability of the microemulsion when Cu ions were present in the nitric solution. The reaction kinetics and metal removal capabilities of microemulsion formed by the different surfactants are explained along with the characteristics of reverse micelles.

The Effect of Radiation Damage on Zirconolite Dissolution

ABSTRACTPolished tiles (7×7×2 mm3) of Nd-bearing zirconolite were fabricated and then some were irradiated on both large faces with 3 MeV or 2 MeV Au2+ ions (total fluence of ≥ 1 × 1015 ions/cm2) in order to render the zirconolite amorphous and so simulate displacement damage caused by alpha decay. Both the irradiated and non-irradiated tiles were then subjected to static dissolution tests in 0.01M nitric solution (pH2) at 90 C, for periods of 0–1, 1–7, 7–14 and 14–28 days. It was found that radiation damage did not affect the dissolution rate of zirconolite as indicated by the elemental leach rates of Nd, Ti, Ca and Al. The results of solution analyses are consistent with those obtained from X-ray Photoelectron Spectroscopy (XPS) in that the Ca, Nd, Ti and Al concentrations in the top surface layer (< 5 nm) all decreased with respect to that of Zr after dissolution testing, and the leached surface composition of the non-irradiated zirconolite is very similar to that of the two irradiated specimens. The implications of these results are discussed in the context of previous work.

Europium and Cesium Ion Immobilization in Crystalline Hosts with Magnetoplumbite or Related Type Structures

ABSTRACTThis study deals with the incorporation of Eu3+ ions in aluminates with magnetoplumbite (MP) or mixed β alumina - MP type structure. The synthesis procedure is the coprecipitation from a nitric solution. Partial substitution of Eu3+ byLa3+ increases the thermal stability range of the phases. In these structuresEu3+ occupies several sites and in the case of Na+ containing phases, Eu3+ and Na+ coexist at some mirror planes. Some results concerning Cs+ ion immobilization in mixed β - MP structures, by ionic exchange in molten salt are also reported.