Rubidium and Cesium Ion Adsorption by a Potassium Titanium Silicate-Calcium Alginate Composite Adsorbent

Constructing porous ZnFC-PA/PSF composite spheres for highly efficient Cs+ removal

Radioisotope leaking from nuclear waste has become an intractable problem due to its gamma radiation and strong water solubility. In this work, a novel porous ZnFC-PA/PSF composite sphere was fabricated by immobilization of ferrocyanides modified zinc phytate into polysulfone (PSF) substrate for the treatment of Cs-contaminated water. The maximum adsorption capacity of ZnFC-PA/PSF was 305.38 mg/g, and the removal efficiency of Cs+ was reached 94.27% within 2 hr. The ZnFC-PA/PSF presented favorable stability with negligible dissolution loss of Zn2+ and Fe2+ (< 2%). The ZnFC-PA/PSF achieved high-selectivity towards Cs+ (Kd = 2.24×104 mL/g) even in actual geothermal water. The adsorption mechanism was inferred to be the ion-exchange between Cs+ and K+. What's more, ZnFC-PA/PSF worked well in the fixed-bed adsorption (E = 91.92%), indicating the application potential for the hazardous Cs+ removal from wastewater.

Radioactive cesium ion removal from wastewater using polymer metal oxide composites

Radioactive cesium ion (Cs-137) removal from wastewater was investigated by novel composite adsorbents, chitosan-bone powder (CS-KT) and chitosan-bone powder-iron oxide (CS-KT-M) at 25 and 50 °C. The characterization of adsorbents was performed by Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Brunauer-Emmett-Teller and Barrett-Joyner-Hallenda (BET-BJH), and Atomic Force Microscopy (AFM) analyses. While BET surface areas of CS-KT and CS-KT-M adsorbents were found to be 131.5 and 144.9 m²/g, respectively, average pore size and pore volume values were 4.69 nm/0.154 cm³/g and 7.49 nm/0.271 cm³/g, respectively. Amongst Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) models, Langmuir model fits well for Cs⁺ ion sorption by these adsorbents. The maximum adsorption capacity obtained from Langmuir adsorption isotherm was 0.98 × 10^-4 mol/g at 25 °C, and 1.16 × 10^-4 mol/g at 50 °C for CS-KT; it was found to be 1.79 × 10^-4 mol/g at 25 °C and 2.24 × 10^-4 mol/g at 50 °C for CS-KT-M. FT-IR analyses showed that Cs⁺ sorption occurs by its interaction with CO₃^2-, PO₄^3- and -NH₂ groups. The average adsorption energy "E" was calculated as ca.11 kJ/mol from D-R adsorption isotherm. The adsorption kinetics was interpreted well by pseudo-second order model.

The Incorporation of Strontium in a Sodium Alginate Coating on Titanium Surfaces for Improved Biological Properties

Orthopedic implant failure is mainly attributed to the poor bonding of the implant to bone tissue. An effective approach to minimize the implant failure would be modifying the surface of the implant. Strontium (Sr) can stimulate the proliferation and differentiation of osteoblasts and reduce the activity of osteoclasts. In this study, a titanium (Ti) surface was successively functionalized by covalently grafting dopamine, sodium alginate (SA), and Sr²⁺ via the electrostatic immobilization method. The as-prepared coatings on the Ti surface were characterized by using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and contact angle. The results indicated that the Sr-incorporated coatings were successfully prepared and that Sr distributed uniformly on the surface. A long-lasting and sustained Sr release had been observed in Sr²⁺ release studies. The Ti/DOPA/SA/Sr exhibited little cytotoxicity and a robust effect of Sr incorporation on the adhesion and spreading of MG63 cells. The proliferation and alkaline phosphatase (ALP) activity of MG63 cells were enhanced by immobilizing Sr²⁺ on the SA-grafted Ti. The Sr-containing coatings, which displayed excellent biocompatibility and osteogenic activity, may provide a promising solution for promoting the tissue integration of implants.