High-efficiency continuous enrichment of cesium ions using CuFC composite microspheres: dynamic adsorption and mechanism analysis

Cesium adsorption from an aqueous medium for environmental remediation: A comprehensive analysis of adsorbents, sources, factors, models, challenges, and opportunities

Considering the widespread and indispensable nature of nuclear energy for future power generation, there is a concurrent increase in the discharge of radioactive Cs into water streams. Recent studies have demonstrated that adsorption is crucial in removing Cs from wastewater for environmental remediation. However, the existing literature lacks comprehensive studies on various adsorption methods, the capacities or efficiencies of adsorbents, influencing factors, isotherm and kinetic models of the Cs adsorption process. A bibliometric and comprehensive analysis was conducted using 1179 publications from the Web of Science Core Collection spanning from 2014 to 2023. It reviews and summarizes current publication trends, active countries, adsorption methods, adsorption capacities or efficiencies of adsorbents, tested water sources, influencing factors, isotherm, and kinetic models of Cs adsorption. The selection of suitable adsorbents and operating parameters is identified as a crucial factor. Over the past decade, due to their notable capacity for Cs adsorption, considerable research has focused on novel adsorbents, such as Prussian blue, graphene oxide, hydrogel, and nanoadsorbents (NA). However, there remains a need for further development of application-oriented laboratory-scale experiments. Future research directions should encompass exploring adsorption mechanisms, developing new adsorbents or their combinations, practical applications of lab-scale studies, and recycling radioactive Cs from wastewater. Drawing upon this literature review, we present the most recent research patterns concerning adsorbents to remove Cs, outline potential avenues for future research, and delineate the obstacles hindering effective adsorption. This comprehensive bibliometric review provides valuable insights into prevalent research focal points and emerging trends, serving as a helpful resource for researchers and policymakers seeking to understand the dynamics of adsorbents for Cs removal from water.

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.

Enhanced removal of cesium from hydrobiotite using polyacrylonitrile (PAN)-based nickel ferrocyanide beads

The desorption of cesium (Cs) from contaminated clay minerals remains challenging because of the restricted efficiency of the removal process. Therefore, in the present study, a bead-type adsorbent was added during the conventional acid washing process to improve the removal of Cs⁺ from a clay mineral. As the Cs⁺ adsorbent, polyacrylonitrile-based nickel potassium hexacyanoferrate (NiFC-PAN) was used to selectively adsorb Cs⁺ in a strongly acidic solution containing competing ions. To prevent erosion of the adsorbent under harsh environmental conditions and to facilitate the separation of clay particles, PAN was deliberately constructed as large beads. The synthesized adsorbent (NiFC/PAN in a 2:1 ratio) showed high selectivity for Cs⁺, with a maximum capacity for Cs⁺ adsorption of 162.78 mg/g in 0.5 M HNO₃ solution. Because the NiFC-PAN demonstrated greater Cs⁺ selectivity than the clay mineral (hydrobiotite, HBT), the addition of NiFC-PAN during the acid washing significantly increased Cs⁺ desorption (73.3%) by inhibiting the re-adsorption of Cs⁺ on the HBT. The radioactivity of ¹³⁷Cs-HBT was substantially decreased from 209 to 27 Bq/g by the acid treatment in the presence of NiFC-PAN, corresponding to a desorption efficiency of 87.1%. Therefore, these results suggest that the proposed technique is a potentially useful and effective method for decontamination of radioactive clay.

Highly selective cesium(I) capture under acidic conditions by a layered sulfide

Radiocesium remediation is desirable for ecological protection, human health and sustainable development of nuclear energy. Effective capture of Cs+ from acidic solutions is still challenging, mainly due to the low stability of the adsorbing materials and the competitive adsorption of protons. Herein, the rapid and highly selective capture of Cs+ from strongly acidic solutions is achieved by a robust K+-directed layered metal sulfide KInSnS4 (InSnS-1) that exhibits excellent acid and radiation resistance. InSnS-1 possesses high adsorption capacity for Cs+ and can serve as the stationary phase in ion exchange columns to effectively remove Cs+ from neutral and acidic solutions. The adsorption of Cs+ and H3O+ is monitored by single-crystal structure analysis, and thus the underlying mechanism of selective Cs+ capture from acidic solutions is elucidated at the molecular level.