The feasibility of immobilizing strontium in cement–bentonite matrices was investigated by studying the effect of mineralogical phase development on mechanical and containment performances. Within this context, the chemical composition and physical properties of bentonite were determined. Different cement–bentonite waste matrices were prepared and analyzed using XRD technique to trace the changes in phases during the curing period. The mechanical performance of these matrices was evaluated by measuring the compressive strength throughout their curing period and the containment performance was determined by conducting long-term static leaching test then the experimental results were checked against some regulatory limits. The results indicated that the presence of strontium and bentonite did not lead to formation of new hydrated phases. The mechanical performance of the matrices is acceptable and the enhanced compressive strength was attributed to the progression in the formation of cement hydrated phases and the pozzolanic reaction between bentonite and lime in cement–bentonite matrices. The speciation data and phase structures analysis indicated that Sr2+ containment in cement might be due to Ca substitution in Ettringite structure and cations exchange on Montmorillonite lattice. The mathematical analysis of the long-term leaching results indicated that strontium leaching resulted from a combination of first order reaction and diffusion mechanisms.

Abstract Binding mechanisms and leaching characteristics of cesium from different cement–
bentonite immobilization matrices were investigated. The effect of Sr presence as a
competitive contaminant in the matrices was studied by investigating the binding and
leaching mechanisms in binary contaminant matrices that contains both Cs and Sr solutions.
Binding investigations aimed to trace Cs binding mechanisms by calculating the distribution
of contaminant and major structural elements aqueous complexes in the mixing solution ...

The aim of the present work was to develop controlled release, gastroretentive device
using superporous hydrogel composite (SPHC). Furosemide was chosen as good
candidate for such system due to its narrow absorption window, low bioavailability
and short half-life. Plain hydrogel was evaluated with respect to swelling ratio,
apparent density and floating time. Scanning electron micrographs of SPHC showed
large interconnected pores and extensive capillary insertion. Prepared Microspheres
were tested for drug content, and tablets evaluated with respect to quality control
tests. All loaded formulae inside SPHC were tested for drug release profile.
Microspheres, tablets and drug solutions were tested for loading inside SPHC. Kinetic
treatment of release data revealed that soaked drug solution was unable to control
drug release, where it gave a t1/2(0.5hrs) very similar to that of the free drug (0.6hrs).
Loaded microspheres showed only a slight retardation in release t1/2 to 1.06 hrs along
with a high percent of flush (~30mg %). However, loaded tablet demonstrated a
promising sustained effect corresponding to a release t1/2= 6hrs and a low percent of
initial flush (~1.2mg %). Therefore, the applicability of SPHC as a controlled release
device proved to be largely dependent on the type of dosage form included.