Sung-Chan Jang

Porous three-dimensional graphene foam/Prussian blue composite for efficient removal of radioactive 137Cs

In this study, a simple one-step hydrothermal reaction is developed to prepare composite based on Prussian blue (PB)/reduced graphene oxide foam (RGOF) for efficient removal of radioactive cesium (137Cs) from contaminated water. Scanning electron microscopy and transmission electron microscopy show that cubic PB nanoparticles are decorated on the RGO surface. Owing to the combined benefits of RGOF and PB, the composite shows excellent removal efficiency (99.5%) of 137Cs from the contaminated water. The maximum adsorption capacity is calculated to be 18.67 mg/g. An adsorption isotherm fit-well the Langmuir model with a linear regression correlation value of 0.97. This type of composite is believed to hold great promise for the clean-up of 137Cs from contaminated water around nuclear plants and/or after nuclear accidents.

Pd nanospheres decorated reduced graphene oxide with multi-functions: Highly efficient catalytic reduction and ultrasensitive sensing, of hazardous 4-nitrophenol pollutant

We illustrate a facile approach for in situ synthesis of Pd-gum arabic/reduced graphene oxide (Pd-GA/RGO) using GA as the reducing agent, which favors the instantaneous reduction of both Pd ions and GO into Pd nanoparticles (NPs) and RGO. From the morphological analysis of Pd-GA/RGO, we observed highly dispersed spherical 5nm Pd NPs decorated over RGO. The as-synthesized Pd-GA/RGO composite was employed for the catalytic reduction and the electrochemical detection of 4-nitrophenol (4-NP), respectively. The catalytic reduction of 4-NP was highly pronounced for Pd-GA/RGO (5min) when compared to Pd NPs (140min) and Pd/RGO (36min). This enhanced catalytic activity was attributed to the synergistic effect of Pd NPs and the presence of various functional groups of GA. Significantly, the fabricated sensor offered a low detection limit (9fM) with a wider linear range (2-80 pM) and long-term stability. The simple construction technique, high sensitivity, and long-term stability with acceptable accuracy in wastewater samples were the main advantages of the developed sensor. The results indicated that the as-prepared Pd-GA/RGO exhibited better sensing ability than the other graphene-based modified electrodes. Therefore, the proposed sensor can be employed as a more convenient sensing platform for environmental and industrial pollutants.

Removal of Radioactive Cesium Using Prussian Blue Magnetic Nanoparticles

Radioactive cesium (137Cs) has inevitably become a human concern due to exposure from nuclear power plants and nuclear accident releases. Many efforts have been focused on removing cesium and the remediation of the contaminated environment. In this study, we elucidated the ability of Prussian blue-coated magnetic nanoparticles to eliminate cesium from radioactive contaminated waste. Thus, the obtained Prussian blue-coated magnetic nanoparticles were then characterized and examined for their physical and radioactive cesium adsorption properties. This Prussian blue-coated magnetic nanoparticle-based cesium magnetic sorbent can offer great potential for use in in situ remediation.

A highly facile and selective Chemo-Paper-Sensor (CPS) for detection of strontium

Chemosensors have attracted increasing attention for their usefulness on-site detection and monitoring. In this study, we elucidated a novel, facile, and highly selective Chemo-Paper-Sensor (CPS) for detection and monitoring of strontium (Sr(2+)) ions, which means a potent colorimetric sensor based on a Chrysoidine G (CG)-coated paper strip. The CPS for highly selective colorimetric detection of strontium ion was handily analyzed to determine the red-green-blue (RGB) value using portable devices such as desktop digital scanner and mobile phone camera, quantitatively. Interestingly, an orange to dark orange color transition was observed when the aqueous and solid paper colorimetric sensor was introduced to Sr(2+) ion, respectively. It was demonstrated that the value of the signal has a linear relationship with concentrations of the strontium in the 500 ppm to 100 ppb range with a detection limit of 200 ppb. We believe that a newly developed Chemo-Paper-Sensor will be useful in a wide range of sensing applications.

Synergistically strengthened 3D micro-scavenger cage adsorbent for selective removal of radioactive cesium.

A novel microporous three-dimensional pomegranate-like micro-scavenger cage (P-MSC) composite has been synthesized by immobilization of iron phyllosilicates clay onto a Prussian blue (PB)/alginate matrix and tested for the removal of radioactive cesium from aqueous solution. Experimental results show that the adsorption capacity increases with increasing the inactive cesium concentration from 1 ppm to 30 ppm, which may be attributed to greater number of adsorption sites and further increase in the inactive cesium concentration has no effect. The P-MSC composite exhibit maximum adsorption capacity of 108.06 mg of inactive cesium per gram of adsorbent. The adsorption isotherm is better fitted to the Freundlich model than the Langmuir model. In addition, kinetics studies show that the adsorption process is consistent with a pseudo second-order model. Furthermore, at equilibrium, the composite has an outstanding adsorption capacity of 99.24% for the radioactive cesium from aqueous solution. This may be ascribed to the fact that the AIP clay played a substantial role in protecting PB release from the P-MSC composite by cross-linking with alginate to improve the mechanical stability. Excellent adsorption capacity, easy separation, and good selectivity make the adsorbent suitable for the removal of radioactive cesium from seawater around nuclear plants and/or after nuclear accidents.

Porous 3D Prussian blue/cellulose aerogel as a decorporation agent for removal of ingested cesium from the gastrointestinal tract

In the present study, we successfully synthesized a porous three-dimensional Prussian blue-cellulose aerogel (PB-CA) composite and used it as a decorporation agent for the selective removal of ingested cesium ions (Cs+) from the gastrointestinal (GI) tract. The safety of the PB-CA composite was evaluated through an in vitro cytotoxicity study using macrophage-like THP-1 cells and Caco-2 intestinal epithelial cells. The results revealed that the PB-CA composite was not cytotoxic. An adsorption study to examine the efficiency of the decorporation agent was conducted using a simulated intestinal fluid (SIF). The adsorption isotherm was fitted to the Langmuir model with a maximum Cs+ adsorption capacity of 13.70 mg/g in SIF that followed pseudo-second-order kinetics. The PB-CA composite showed excellent stability in SIF with a maximum Cs+ removal efficiency of 99.43%. The promising safety toxicology profile, remarkable Cs+ adsorption efficacy, and excellent stability of the composite demonstrated its great potential for use as an orally administered drug for the decorporation of Cs+ from the GI tract.

Cesium-induced inhibition of bacterial growth of Pseudomonas aeruginosa PAO1 and their possible potential applications for bioremediation of wastewater

Radioactive isotopes and fission products have attracted considerable attention because of their long lasting serious damage to the health of humans and other organisms. This study examined the toxicity and accumulation behavior of cesium towards P. aeruginosa PAO1 and its capacity to remove cesium from waste water. Interestingly, the programmed bacterial growth inhibition occurred according to the cesium environment. The influence of cesium was analyzed using several optical methods for quantitative evaluation. Cesium plays vital role in the growth of microorganisms and functions as an anti-microbial agent. The toxicity of Cs to P. aeruginosa PAO1 increases as the concentration of cesium is increased in concentration-dependent manner. P. aeruginosa PAO1 shows excellent Cs removal efficiency of 76.1% from the contaminated water. The toxicity of cesium on the cell wall and in the cytoplasm were studied by transmission electron microscopy and electron dispersive X-ray analysis. Finally, the removal of cesium from wastewater using P. aeruginosa PAO1 as a potential biosorbent and the blocking of competitive interactions of other monovalent cation, such as potassium, were assessed. Overall, P. aeruginosa PAO1 can be used as a high efficient biomaterial in the field of radioactive waste disposal and management.

Versatile poly(diallyl dimethyl ammonium chloride)-layered nanocomposites for removal of cesium in water purification

In this work, we elucidate polymer-layered hollow Prussian blue-coated magnetic nanocomposites as an adsorbent to remove radioactive cesium from environmentally contaminated water. To do this, Fe3O4 nanoparticles prepared using a coprecipitation method were thickly covered with a layer of cationic polymer to attach hollow Prussian blue through a self-assembly process. The as-synthesized adsorbent was confirmed through various analytical techniques. The adsorbent showed a high surface area (166.16 m2/g) with an excellent cesium adsorbent capacity and removal efficiency of 32.8 mg/g and 99.69%, respectively. Moreover, the superparamagnetism allows effective recovery of the adsorbent using an external magnetic field after the adsorption process. Therefore, the magnetic adsorbent with a high adsorption efficiency and convenient recovery is expected to be effectively used for rapid remediation of radioactive contamination.

Facile fabrication of paper-based analytical devices for rapid and highly selective colorimetric detection of cesium in environmental samples

Cesium (Cs), a radioactive contaminant of the ecosystem, causes a major risk to human health and environments. Till now, the cesium sensor fabrication methods have been reported with the usage of expensive chemicals that are complex and time-consuming. In this work, we have fabricated a paper-based colorimetric device impregnated with a chrysoidine G (CG) as chemo-indicator which is simple, rapid, low-cost, and portable using a naked-eye quantitative technique for the detection and monitoring of inactive cesium in environmental analysis. This chemo-indicator is designed to exhibit a powerful detection capability featuring high selectivity and sensitivity to inactive Cs, by means of color discrimination from light yellow to red orange. Interestingly, a portable smart phone camera, which determined the relative red/green/blue (RGB) values within 3 s, provided us with further information on environmental pollution. Using our new colorimetric reusable sensor (CRS) platform, the CRS shows excellent detection linearity (R2 = 0.99) of inactive Cs from the contaminated water. Our results will pave the way for portable and versatile sensors and, in turn, for the detection and monitoring of toxic inactive cesium in contaminated water samples.