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In order to solve the problems of poor stability and low decontamination efficiency of foam detergent in the process of removing surface radioactive contamination in a low-temperature environment, MXene (Ti 3 C 2 T x) was prepared by LiF/HCl etching, the MXene was modified by hydroxylation to obtain Alk-MXene, and the Alk-MXene was hydrophobically modified by octadecylamine (ODA) to obtain Alk-MXene@ODA. MXene, Alk-MXene, and Alk-MXene@ODA were characterized by SEM, XRD, FTIR, BET, and a contact angle measuring instrument. The effects of the addition of Alk-MXene@ODA on the foam stability, foaming ability of the foam detergent, foam liquid-film thickness, liquid-film decay rate, viscosity at the same shear rate, and spraying and wall-hanging properties were investigated. The decontamination properties of the Alk-MXene@ODA-stabilized biomass-based antifreeze foam detergent were also investigated. The results show that Alk-MXene has a large interlayer spacing, a large specific surface area, and abundant –OH on its surface. Alk-MXene exhibits full absorption of water, and the hydrophobicity of Alk-MXene@ODA after graft modification with ODA increased and the wetting contact angle increased to 89.07°. Via Alk-MXene@ODA synergistic foam stabilization, the drainage half-life of the foam increased from 40.81 min to 66.89 min, the average thickness of the foam liquid film increased from 47.065 µm to 53.162 µm, the liquid-film decay rate reduced from 0.956 µm/min to 0.544 µm/min, and the viscosity of the foam detergent solution increased at different shear rates. The foam detergent is sprayable, and the wall-hanging time can reach 80 min on a vertical tile surface. At −10 °C, the α decontamination factors of the Alk-MXene@ODA-stabilized biomass-based antifreeze foam detergent on glass, painted board, ceramic tile, and stainless steel were improved by 23.89, 23.77, 23.01, and 22.53, the β decontamination factors were improved by 15.48, 17.12, 15.03, and 14.42, respectively, relative to ordinary foam. The adsorption and coordination of uranyl ions with Alk-MXene@ODA promoted the improvement in the decontamination factor of the foam detergent. Alk-MXene@ODA combined with biomass-based antifreeze foam detergent can achieve dual functions of stabilizing foam and increasing decontamination efficiency. Biomass-based antifreeze foam detergent with increased stability and decontamination efficiency by Alk-MXene@ODA can efficiently and quickly remove surface radioactive contamination in a low-temperature environment. [Display omitted] [ABSTRACT FROM AUTHOR]

The environmentally friendly antifreeze foam detergent was synthesized from the biomass-based surfactants alkyl polyglucoside (APG), tea saponin (TAS), waterborne polyurethane (WPU), tartaric acid (TA), and sodium chloride (NaCl) in order to remove radioactive contamination on the surface of nuclear emergency and decommissioning facilities in low temperature environment. Additionally, the composition of foam detergent was optimized by response surface methodology. The foaming, stability, wall-hanging property of antifreeze foam detergent and its decontamination properties of simulated radioactive pollution under low temperature environment were studied. The surface tension, viscosity, and wettability of antifreeze foam detergent and the decontamination mechanism at low temperature were analyzed. The results show that at the low temperature of − 10 ºC, the foaming multiple of the foam detergent is 14.37, the half-life is 44.43 min, and the wall-hanging time on the surface of vertical ceramic tile is 60 min. Within 30 min, the decontamination factors of simulated radioactive contamination on the surface of the glass, ceramic tile, stainless steel, and lacquered board by antifreeze foam detergent are 17.83, 12.82, 12.03, and 14.83, respectively. Environmentally friendly antifreeze foam detergent with high foaming property, outstanding wall-hanging property, and decontamination ability has broad application prospects in nuclear emergency and decommissioning of nuclear facilities in low temperature environments in winter. [Display omitted] [ABSTRACT FROM AUTHOR]

Conventional water-based foam decontaminants used for the removal of radionuclides lose their efficacy in winter at temperatures below 0 °C. To address this problem, an antifreeze foam, with characteristics of good stability, high decontamination efficiency, less liquid waste generation, and excellent biodegradability, was developed using a biomass-based surfactant, a polysaccharide foam stabilizer, and an antifreeze agent. Furthermore, the surface tension, solution viscosity, foam stability, and decontamination of simulated radionuclides on different plates of a xanthan gum (XG)-stabilized antifreeze foam at temperatures ranging from −10 °C to 10 °C were investigated. Especially, the bulk-phase performance and stabilizing mechanism of the antifreeze foam were analyzed. Compared with the antifreeze foam without stabilizer, the half-life of the XG-stabilizing foam increases from 30.5 min to 2785 min, and the initial drainage time increases from 5 min to 383.5 min at −10 °C, which considerably extends the decontamination time and is conducive to improving the decontamination efficiency. Furthermore, the foam stability and bulk viscosity of the foam solution at a low shear rate exhibited a significant positive correlation. As a result, with decreasing the temperature, the viscosity of the XG-stabilized antifreeze foam solution increased leading to a better stability of foam at a lower temperature. The stabilizing mechanism of the XG stabilizer would possibly be the rigid chain structure of the XG molecule, which could lightly resist the contraction and bending of the molecular chain caused by Na+ originated from the surfactant sodium alpha-olefin sulfonate (AOS) and H+ originated from acidic chelator citric acid (CA) in the decontamination foam. Another probable stabilizing mechanism would be that the electrostatic repulsion generated by the negatively charged groups on the XG molecular chains could prevent the molecular aggregation and precipitation. Moreover, surface decontamination results revealed that the XG-stabilized antifreeze foam can remove >90% of the radionuclide contamination physically attached to surfaces of glass, stainless steel, white paint, green paint, and tile plate below 0 °C. Therefore, the antifreeze foam detergent exhibits good application potential for the decontamination of surface radioactive contamination in winter due to its excellent stability, high decontamination efficiency, and biodegradability. [Display omitted] [ABSTRACT FROM AUTHOR]