The performance of different nanofiltration (NF) membranes for the treatment of strontium-containing radioactive wastewater was investigated. The effects of the initial strontium concentration, solution pH and complexation phenomena on strontium removal were described. For all the three membranes, the strontium rejection increased with decreasing initial strontium concentration. Meanwhile, the strontium rejection was minimum at the membrane isoelectric point (pH 5) primarily due to decreased co-ion electrostatic repulsion. In the presence of a complexing agent (polyacrylic acid or ethylenediamine tetraacetic acid disodium salt), the strontium rejection was generally higher than those obtained without a complexing agent for NF 270 and XN 45. Membrane cleaning experiments were also conducted to recover the performance of the membranes, which exhibited degradation during long-time filtration. The performance of the membranes after cleaning was close to that of the virgin membranes, especially for XN 45, whose recovery percentage was nearly 100%.
Siyi Wang,Pengcheng Zhang,Enzhao Ma,Suwen Chen,Zijie Li,Liyong Yuan,Jianhua Zu,Lin Wang,Weiqun Shi
The removal and recovery of radioactive Sr(II) from wastewater and seawater has been of great concern due to the negative environmental impacts of nuclear energy development and the potential risk of nuclear accidents. Herein, a facile molten salt synthesis strategy was developed to systematically investigated the reaction of different types of MXenes with nitrates. Among the products, K + intercalated hierarchical titanate nanostructures (K-HTNs) obtained from the direct chemical transformation of multilayered Ti 3 C 2 T x exhibited unique layered structures, good physicochemical properties, and outstanding adsorption performance for Sr(II). The maximum adsorption capacity of Sr(II) by K-HTNs reached 204 mg·g −1 at ambient temperature, and the good regeneration and reusability of the titanate was also demonstrated. K-HTNs showed preferential selectivity for Sr(II) in different environmental media containing competing ions, and the removal efficiency of Sr(II) in real seawater was as high as 93.3 %. The removal mechanism was elaborated to be the exchange of Sr 2+ with K + /H + in the interlayers of K-HTNs, and the adsorbed Sr(II) had a strong interaction with Ti−O − termination on the titanate surface. Benefiting from the merits of rapid and scalable synthesis and excellent adsorption performance, MXene-derived K-HTNs have broad application prospects for the purification of 90 Sr-contaminated wastewater and seawater.
Na Yang,Xu Guo,Jing Yu,Hongsen Zhang,Rumin Li,Lele Wang,Qi Liu,Jun Wang
The effective removal of radioactive Sr 2+ and Cs + ions from wastewater is crucial for environmental remediation. Herein, a novel solar-enhanced adsorption platform based on a CoS 2 /MoS 2 /P-MXene/C composite aerogel has been developed that can efficiently remove Sr 2+ and Cs + ions. The constructed CoS 2 /MoS 2 heterointerface provides abundant active regions, while the hierarchical porous structure of the aerogel promotes the rapid transfer of ions and water molecules. In particular, the superior photothermal conversion ability of the CoS 2 /MoS 2 /P-MXene/C makes it capable of capturing solar energy for local heating effect, thereby increasing ion diffusion and accelerating mass transfer. This photothermal feature can greatly enhance the adsorption kinetics through the evaporation of the solution and the ion concentration at adsorption sites. The equilibrium of both Sr 2+ and Cs + was reached within 1 h under one-sun illumination. The measured maximum adsorption capacities were 98.7 and 150.6 mg/g for Sr 2+ and Cs + ions, respectively. In addition, it has excellent selectivity and recyclability as well as high performance in high-salinity solution. The CoS 2 /MoS 2 /P-MXene/C also shows promising potential in the fields of solar-driven seawater desalination and purification of wastewater containing dyes due to the multi-functionality. This work not only engineers an efficient adsorbent for treating nuclear wastewater, but also presents a generic design strategy for multifunctional adsorption system enhanced by external fields for environmental applications.
危险品化学品经营许可证（带存储）