Selective removal of cesium ions from aqueous solutions by zinc hexacyanoferrate functionalized magnetic carbon nanotube composites as adsorbent

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.

Simultaneous selective removal of cesium and cobalt from water using calcium alginate-zinc ferrocyanide-Cyanex 272 composite beads

Composite beads consisting of Ca alginate mixed with zinc ferrocyanide (ZnFC) and Cyanex 272 were synthesized in order to selectively adsorb Cs⁺ and Co²⁺ from water. Their physicochemical properties of the synthesized composite beads were characterized using various techniques, including FESEM, EDX, FTIR, and TGA. The ZnFC/Cyanex 272/alginate (ZCA) composite beads were then tested as an adsorbent for the selective removal of Cs⁺ and Co²⁺ from an aqueous solution. The adsorption capacity increased with increasing ZnFC and Cyanex 272 contents. The adsorption process followed the Langmuir model and pseudo-second-order kinetics. The ZCA composite beads exhibited excellent selectivity toward Cs⁺ and Co²⁺ even in the presence of competitive cations (K⁺, Na⁺, Fe²⁺, and Ni²⁺). The adsorption capacity of the ZCA composite beads for Cs⁺ and Co²⁺ was almost maintained after three times of adsorption-desorption process.

Ecofriendly, selective removal of radioactive strontium ions in aqueous solutions using magnetic banana peels

Radionuclide Sr²⁺ in aqueous solution was removed using a large amount of banana peel (BP). Magnetized BP, mag@BP, was synthesized for recovery after the adsorption process. The synthesis was a very simple process of precipitation of BP with a magnetic substance. The synthesized adsorbent was thoroughly examined by performing Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction analysis, and vibration sample magnetometer analysis. Moreover, mag@BP has a Sr²⁺ maximum adsorption capacity of 23.827 mg/g according to isothermal adsorption, which is the best fit for the Langmuir isotherm model. In the pH effect experiment, the highest Sr²⁺ adsorption capacity was found at pH 9, and it has a spontaneous adsorption mechanism through experiments on temperature, time, and selectivity, and it reaches adsorption equilibrium within a short time and has high selectivity through competitive adsorption with Na⁺. In addition, an adsorption mechanism accompanied by ion exchange with K⁺ on the surface of BP, bonding with various functional groups, and electrical attraction were established. Therefore, mag@BP is suitable for use an environmentally friendly, low cost, and recoverable adsorbent for magnetic removal of Sr²⁺ from aqueous solutions. Further, unlike other carbon-based adsorbents, it does not cause cytotoxicity.