Tailoring of Organically Modified Silicas for the Solid−Liquid Extraction of Actinides

Abstract

Hybrid materials with complexing properties toward lanthanides(III), americium(III), and plutonium(IV) are described. These new silica-based materials, containing malonamide ligands, have been prepared by sol-gel hydrolysis and condensation of a silylated tetraethylmalonamide in the presence of tetraethoxysilane (TEOS). A family of these hybrid materials was obtained by varying the amount of TEOS, the catalyst, and the R w ratio (amount of water added per Si-O bonds). The porous hybrids exhibited BET surface areas up to 300 m 2 g -1 with the average pore diameter ranging from 30 to 90 Å. The new hybrids were used as solid phase extractants in batch experiments for the extraction of americium and plutonium from high-level liquid wastes. The hybrids were shown to be highly efficient materials in solid-liquid extraction, exhibiting distribution coefficients up to 10 4 and loading capacities up to 0.46 mequiv/g. They compared favorably to related silica-based material containing malonamide immobilized by classical techniques. The sol-gel approach allows one to adjust the ligand loading and to achieve some control and some tuning of the ligand environment since the oxide matrix is built around the complexing moieties. The use of templating techniques was also studied to enhance the extracting properties.

Bioinspired control of colloidal silica in vitro by dual polymeric assemblies of zwitterionic phosphomethylated chitosan and polycations or polyanions

“…There are several other scientific areas, where silicates and silica play a central role, such as geochemistry [56,57], general medicine [58], orthopaedics [59], nutrition [60,61], cement technology [62], nanoparticle technology [63], water treatment [64], and others. Scientists working at the interface of different research areas have been utilizing each other's knowledge and expertise, not only to get deeper insight into complex biochemical processes involved in natural systems, but also to design novel materials that may be biomimetic analogs of complex systems found in Nature.…”

Exceptional Affinity of Nanostructured Organic–Inorganic Hybrid Materials towards Dioxygen: Confinement Effect of Copper Complexes

“…Therefore, application of the chelate-functionalized silicas can lead to promising materials in many areas such as catalysis; [42] metal-ion separation processes, especially for transition metals, [43][44][45] heavy metals [46][47][48] and actinides; [36] as well as chemical [49] and optical sensors. [50,51] Despite the growing interest in functionalized sol-gel materials, only a few examples are known for gas separation through the formation of chemical bonds between gas molecules and coordination complexes immobilized in an inorganic matrix by way of chemisorption, [39, 40, 52 53] and their use as gas sensors is still scarce.…”

Separation of lanthanides(III) by inorganic nanofiltration membranes using a water soluble complexing agent

“…Although liquid/liquid [1] or solid/liquid [2] processes have been widely developed for the An(III)/Ln(III) separation, alternative technologies such as membrane processes have been investigated [3,4]. In this process no organic solvent is used.…”