Radioactive wastewaters purification using titanosilicates materials: State of the art and perspectives

Titanosilicates in cation adsorption and cation exchange – A review

Ion exchange is a proven process for radioactive wastewater decontamination, where inorganic sorbents are ideal due to their thermal, chemical and radiation stability. This review focuses on the removal of Cs+ by inorganic exchangers, viz. zeolites, titanosilicates, hexacyanoferrates metal oxides and hydrous metal oxides, bentonite/clays and the key family of ammonium phosphomolybdates (AMPs). The design of new selective composites is also addressed focusing on those based on AMPs, hexacyanoferrates and titanosilicates/zeolites. Future inorganic Cs+ exchangers will encompass promising solids, like lanthanide silicates, sodium titanates and metal sulfides. The sensing ability derived from the photoluminescence properties of lanthanide silicates and the efficiency of layered gallium-antimony-sulfide materials in acidic and basic solutions disclose considerable potential for real applications. The ion exchange systems are discussed in terms of sorbent capacity and selectivity (with competitors), pH, temperat...

Inorganic Ion Exchangers for Cesium Removal from Radioactive Wastewater

The sorption of the thallous ion from aqueous acidic solution (pH = 1.5) onto as-synthesized and modified ETS-10 titanosilicates was studied by using an isotope dilution method and a batch-mode technique. The present results show that the thallium(I) sorption was effective onto all three considered materials and is enhanced by the porosity and acidity modification of the ETS-10 titanosilicate. The best uptake performance was achieved by the meso-ETS-10. This behavior is explained based on the newly created additional mesoporous system and enriching the external surface with silanol groups. Also, the presence of phosphorus enhanced the inherent porosity allowing thus better internal diffusion properties of crystalline material. However, the chemically modified surface seems to have a negative contribution to the kinetic uptake of thallous ion as shown by the positive value of the activation energy E
 a, in comparison with the processes more favorable energetically for ETS-10 and meso-ETS-10 materials.

Sorption of thallous ion from acidic aqueous solutions onto ETS-10 titanosilicate

Harnessing the power of nuclear reactions has brought huge benefits in terms of nuclear energy, medicine, and defense, as well as risks including the management of nuclear wastes. One of the main issues for radioactive waste (RW) management is liquid RW (LRW). Different methods have been applied to remediate LRW, thereunder ion exchange and adsorption. Comparative studies have demonstrated that Na2Ti2O3SiO4·2H2O titanosilicate sorption materials are the most promising in terms of Cs+ and Sr2+ retention from LRW. Therefore, these TiSi materials became the object of this study. The recently developed in Ukraine sol–gel method of synthesizing these materials was chosen among the other reported approaches as it allows obtaining the TiSi materials in the form of particles with size ≥ 4 mm utilizing inexpensive and bulk stable inorganic precursors and yielded the materials with desirable properties by alteration of the comparatively mild synthesis conditions. The main aim of this study was to investigate the physicochemical properties of sol–gel synthesized titanosilicates for radionuclide uptake from aqueous solutions. The effect of synthesis conditions on the structural and sorption parameters of TiSi xerogels was planned to determine in order to obtain a highly efficient sorption material. The ability of the obtained TiSis to retain Cs+, Sr2+, and other potentially toxic metal cations from the synthetic and real aqueous solutions was intended to assess. To our expectations, abovementioned studies will illustrate the efficiency and profitability of the chosen synthesis approach, synthesis conditions, and the obtained materials. X-ray diffraction, low temperature adsorption/desorption surface area analysis, X-ray photoelectron spectroscopy, infrared spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy was used for xerogel characterization. The sorption capability of the synthesized TiSi gels was studied as a function of pH, adsorbent mass, initial concentration of target ion, contact time, temperature, composition, and concentration of the background solution. It was found that the applied sol–gel approach yielded materials with a poorly crystalline sodium titanosilicate structure under relatively mild synthesis conditions. The temperature of hydrothermal treatment has the strongest influence on the structure of the materials and consequently was concluded to be the control factor for the preparation of gels with the desired properties. The obtained materials proved to be effective and selective for both Sr2+ and Cs+ decontamination from synthetic and real aqueous solutions like drinking, ground, sea, and mine waters, blood plasma, and LRWs.

Sol–gel synthesized titanosilicates for the uptake of radionuclides

Mesoporosity of about 7 nm in ETS-10 titanosilicate was generated by postsynthesis treatment with hydrogen peroxide under microwave irradiation, resulting in an increased external surface area of the materials (55 m/g). The influence of titanosilicate porosity and its surface modification by phosphorus atoms (ET(P)S-10) on the retention of some nanoions (α-emitting radioactive U(VI) and Th(IV) ions) and biomolecules (the proteins cytochrome c, papain, and γ-globulin) was investigated.

On the influence of ETS-10 porosity and surface properties in retention of some nanoions and nanomolecules

Soil nutrients assessment has great importance in horticulture. Implementation of an information system for horticulture faces many challenges: (i) great spatial variability within farms (e.g., hilly topography); (ii) different soil properties (e.g., different water holding capacity, different content in sand, sit, clay, and soil organic matter, different pH, and different permeability) for different cultivated plants; (iii) different soil nutrient uptake by different cultivated plants; (iv) small size of monoculture; and (v) great variety of farm components, agroecological zone, and socio-economic factors. Advances in information and communication technologies enable creation of low cost, efficient information systems that would improve resources management and increase productivity and sustainability of horticultural farms. We present an information system based on different sensing capability, Internet of Things, and mobile application for horticultural farms. An overview on different techniques and technologies for soil fertility evaluation is also presented. The results obtained in a botanical garden that simulates the diversity of environment and plant diversity of a horticultural farm are discussed considering the challenges identified in the literature and field research. The study provides a theoretical basis and technical support for the development of technologies that enable horticultural farmers to improve resources management.

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IoT-Based Systems for Soil Nutrients Assessment in Horticulture

The use of Augmented Reality in mobile guide applications for natural parks and gardens enables compelling and memorable experiences that enrich visits. But the creation of these experiences is still riddled with several challenges concerning technology and content production. This paper presents guidelines for the development of AR experiences in mobile applications that support visits to gardens or natural parks, providing a list of technological and multimedia content elements that should be considered. We applied these guidelines in the development of a mobile application for a Botanical Garden, implemented for Android and iOS. We conducted a study with volunteers during visits to the garden and the results revealed high levels of perceived app usability and strong agreements about app features, which allow us to accept that the app was evaluated positively.

Stefan Postolache

Papers

On the influence of ETS-10 porosity and surface properties in retention of some nanoions and nanomolecules

IoT-Based Systems for Soil Nutrients Assessment in Horticulture

Enriching the Visit to an Historical Botanic Garden with Augmented Reality