Ultra-fast adsorption of radioactive technetium (99mTc) by using mining waste clay samples, Abu-Tartur, Egypt

In this study, we have opened a great route to fabricate a high-performance nanocomposite for various functional applications based on the composite of a natural stone. A clay sample (black shale (B.Sh)) was collected from the Abu-Tartur area in Egypt. The black shale was organically modified with organic materials in our laboratory, which is called organo-black shale (O-B.Sh). The samples were characterized by XRD, FTIR, SEM, and XRF. These techniques confirmed that the samples have multi-oxide phases with approximately SiO2 at 54.1%, Al2O3 at 24.73%, Fe2O3 at 6.02%, K2O at 1.12%, MgO at 1.09%, and Na2O of 0.09%, as calculated by XRF. The two samples were applied to the adsorption processes of the radioactive technetium materials, which have been used for the medical treatment of the cancer institute of Upper Egypt. The adsorption processes were performed at various concentrations of the radioactive material and various amounts of clay samples. The as-collected B.Sh sample showed an adsorption activity of 65%, however, the organically modified materials showed a high adsorption rate toward technetium reaches to 100% in a very short time and without any further process. The present collected materials are very promising to withdraw the radioactive materials from the saline solution to save human and environmental health. We believe these multi-compound composites may open a new approach for creating new fabric composites with high performance for various applications.

Inorganic Sorbents for Wastewater Treatment from Radioactive Contaminants

The article presents the distribution coefficient (Kd) values of 137Cs and 90Sr tracer radionuclides in solutions of sodium and calcium salts for a wide range of commercially available inorganic sorbents: natural and synthetic aluminosilicates, manganese, titanium and zirconium oxyhydrates, titanium and zirconium phosphates, titanosilicates of alkali metals, and ferrocyanides of transition metals. The results were obtained using a standard technique developed by the authors for evaluating the efficiency of various sorption materials towards cesium and strontium radionuclides. It was shown that bentonite clays and natural and synthetic zeolites are the best for decontaminating low-salt natural water from cesium radionuclides, and ferrocyanide sorbents are the choice for decontaminating high-salt-bearing solutions. The manganese (III, IV) oxyhydrate-based MDM sorbent is the most effective for removing strontium from natural water; for seawater, the barium silicate-based SRM-Sr sorbent is the first-in-class. Results of the study provide a possibility of making a reasonable choice of sorbents for the most effective treatment of natural water and technogenic aqueous waste contaminated with cesium and strontium radionuclides.

Investigation of materials for reactive permeable barrier in removing cadmium and chromium(VI) from aquifer near a solid domestic waste landfill

The sorption characteristics of raw and biofilm-coated materials: vermiculite, lightweight expanded clay aggregate (LECA), perlite, zeolite, and shungite toward Cd and Cr(VI) ions were investigated to evaluate the possibility of their use as filtration barrier in the aquifer near a solid domestic waste landfill. The effectiveness of Cr(VI) removal by the raw materials changed in the following order: shungite > zeolite > perlite > vermiculite > LECA and for Cd: zeolite > shungite > vermiculite > perlite > LECA. After biofilm formation on the surface of the materials, the sorption capacity increased in some (perlite, LECA), while in others (zeolite) it was reduced. Four kinetic models were used to describe the experimental data. Mechanisms of metal removal were proposed: for Cr(VI), a characteristic combination of sorption processes was suggested, while the removal of Cd ions could occur by ion exchange and by complexation on the surface of the sorbent. Cr(VI) reduction by living bacterial cells forming a biofilm on the sorbent surface was assessed.

Investigation of interaction behaviours of cesium and strontium ions with engineering barrier material to prevent leakage to environmental

This study deals with performance of removal of cesium (Cs⁺) and strontium (Sr²⁺) ions from synthetic aqueous solution using amino pyridine sulfone amid resin as a barrier material for nuclear waste storage areas to reduce environmental risk. The effects of adsorbate concentration, temperature and contact time on the efficiencies of the engineering barrier material for Cs⁺ and Sr²⁺ ions were investigated and evaluated. It was found that total adsorption capacity was higher for cesium ions than strontium ions. Dubinin-Radushkevich (D-R) isotherm model was well fitted to the adsorption data for both ions. The micropore capacity of the barrier material was found as 4.20 mg for strontium ions and 5.40 mg for cesium ions. ΔH values were indicated that the interaction process is exothermic for both ions. The positive value of entropy for both ions show that randomness at the solid-solution interface increased. Pseudo-second-order model was well fitted the kinetic data.