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For the first time, simple and facile fabrication of a magnetic alginate microadsorbent via piezoelectric inkjet technology was developed for the selective removal of 137Cs via magnetic separation. Through the ejection of an alginate solution containing potassium ferrocyanide and magnetic nanoparticles (MNPs) into a Cu2+ solution via an inkjet device, the fabrication of a copper ferrocyanide-embedded magnetic alginate microadsorbent (CuFC-MAM) with an average size of 39.38 μm was easily achieved in a one-pot fabrication process; here, the Cu2+ ions acted as both a cross-linker for the gelation of alginate and a Cu source for the in situ synthesis of CuFC with potassium ferrocyanide. The Cs adsorption behavior of CuFC-MAM was effectively fitted by the pseudo-second-order kinetic model and Langmuir isotherm. Owing to the increased specific surface area of CuFC-MAM, its pseudo-second-order rate constant and maximum adsorption capacity were 76.54 and 1.486 times greater than those of CuFC-embedded magnetic alginate macroadsorbents fabricated without inkjet devices. Compared with other Cs adsorbents, CuFC-MAM presented the highest maximum capacity and K d value; these results were attributed to the high content of CuFC in CuFC-MAM (50.15%). In addition, our CuFC-MAM exhibited an excellent removal efficiency of radioactive Cs, exceeding 99% from seawater. A magnetic Cs micro-adsorbent, which has excellent Cs adsorption properties, was fabricated using piezoelectric inkjet technology for the first time. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract A simple one-step approach for fabricating copper ferrocyanide-embedded magnetic hydrogel beads (CuFC-MHBs) was designed, and the beads were applied to the effective removal of cesium (Cs) and then magnetically separated from water. The polyvinyl alcohol (PVA)-coated CuFC (PVA-CuFC) was first synthesized using PVA as a stabilizer and subsequently embedded in magnetic hydrogel beads made of a cross-linked network between the PVA and magnetic iron oxide nanoparticles that was prepared through the simple dropwise addition of a mixed solution of PVA-CuFC, PVA and iron salt into an ammonium hydroxide solution. The synthesis and chemical immobilization of the PVA-CuFC in the magnetic beads were simple, facile and achieved in one pot, and the process is scalable and convenient for the large-scale treatment of Cs-contaminated water. The resulting CuFC-MHBs showed effective Cs removal performance with a high K d value of 66,780 mL/g and excellent structural stability without the release of CuFC for at least 1 month and could be effectively separated from water by an external magnet. Moreover, the CuFC-MHBs selectively adsorbed Cs with high K d values in the presence of various competing ions, such as in simulated groundwater (24,500 mL/g) and seawater (8290 mL/g), and maintained their Cs absorption ability in a wide pH range from 3 to 11. The convenient fabrication method and effective removal of Cs from various aqueous media demonstrated that the CuFC-MHBs have great potential for practical application in the decontamination of Cs-contaminated water sources caused by nuclear accidents and radioactive liquid waste in various nuclear industry fields. Highlights • A facile one-pot synthesis of copper-ferrocyanide-embedded magnetic hydrogel beads was developed. • CuFC-MHBs can be fabricated in a large quantity, which is crucial for their practical applications. • The beads can remove Cs in a wide pH range from 3 to 11 with excellent structural stability for up to 1 month. • The beads exhibit excellent selectivity for Cs, even in the presence of competing ions such as in groundwater conditions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel PVDF membrane with selected properties for Cs was fabricated. • The SiO 2 and CuFC NPs are irreversibly fixed on the membrane surface. • CuFC/SiO 2 /PVDF membrane exhibits great flux and high stability. • Composite membrane owns high selectivity with the co-existing ions and organics. • Competitive adsorption and Donnan' effect govern the rejection of Cs. Abstract A novel polyvinylidene fluoride (PVDF) membrane was fabricated through chemical binding SiO 2 nanoparticles (NPs) and copper ferrocyanide (CuFC) layers onto a membrane surface simultaneously to improve the removal efficiency of Cs. The results indicated that the SiO 2 NPs were strongly deposited onto the membrane surface, and the CuFC layer was firmly attached on the surface of SiO 2 NPs and the membrane. CuFC/SiO 2 /PVDF membrane remained stable after the acidic solution and sonication stress treatments. CuFC/SiO 2 /PVDF membrane showed good permeate flux and high selectivity on removal of Cs, and adsorbing capacity reached 1440.4 mg m−2 for Cs. The membrane remained high rejections of Cs in a wide pH, and could be regenerated well by H 2 O 2 and N 2 H 4. Selective adsorption and electrostatic interaction govern the rejection of Cs. The coexisting cations decreased the rejection of Cs mainly in accordance to the order of cations' hydration radii as K+ > Na+ > Ca2+ > Mg2+. In addition, the rejection of Cs could still reach 99.4% in 8 h in the filtration of humic acid solution and natural surface water. The membrane could removal of Cs from water effectively by directly rapid filtration, suggesting it can be applied as promising technology for radioactive wastewater treatment. [ABSTRACT FROM AUTHOR]

Abstract: Copper ferrocyanide (CFCN) crystals, well known for its selectivity for Cs+ ions, have been synthesized within the pores of a polycarbonate track etched membrane (PTEM) by two compartment permeation method using CuSO4 and K4Fe(CN)6. The synthesized material has been characterized by X-ray Diffraction (XRD), Small Angle X-ray Scattering (SAXS), Energy Dispersive X-ray Fluorescence (EDXRF) and Transmission Electron Microscopy (TEM) techniques. X-ray techniques confirmed the presence of nanosized ferrocyanide particles (radius ∼40nm) within the pores of the PTEM. It has been observed from TEM analysis that the CFCN crystals are almost uniformly filling the conical shaped pores of the PTEM with the dimension of each conical shaped structure being ∼300nm diameter at surface and ∼140nm diameter inside. This CFCN loaded PTEM (CFCNm) has been used to study the selective transport of Cs+ over Na+ in presence of nitric acid. The rate of cation transport has been enhanced (∼300%) by application of electric field across the membrane. A cation exchange membrane (Nafion-1135) has been coupled with the CFCNm to protect the ferrocyanide crystals from early degradation. The transport behavior of the Nafion-CFCNm composite system under different experimental conditions has been studied and explanation has been given for the differential transport of Cs+ over Na+ through this membrane. The Cs+ transport rate of the membrane has been found to be limited by the ion exchange capacity of the CFCNm. [Copyright &y& Elsevier]

Abstract: Copper ferrocyanide (CuFC) was used as an adsorbent to remove cesium. Jar test results showed that the adsorption capacity of CuFC was better than that of potassium zinc hexacyanoferrate. Lab-scale tests were performed by an adsorption–microfiltration process, and the mean decontamination factor (DF) was 463 when the initial cesium concentration was 101.3μg/L, the dosage of CuFC was 40mg/L and the adsorption time was 20min. The cesium concentration in the effluent continuously decreased with the operation time, which indicated that the used adsorbent retained its adsorption capacity. To use this capacity, experiments on a countercurrent two-stage adsorption (CTA)–microfiltration (MF) process were carried out with CuFC adsorption combined with membrane separation. A calculation method for determining the cesium concentration in the effluent was given, and batch tests in a pressure cup were performed to verify the calculated method. The results showed that the experimental values fitted well with the calculated values in the CTA–MF process. The mean DF was 1123 when the dilution factor was 0.4, the initial cesium concentration was 98.75μg/L and the dosage of CuFC and adsorption time were the same as those used in the lab-scale test. The DF obtained by CTA–MF process was more than three times higher than the single-stage adsorption in the jar test. [Copyright &y& Elsevier]