Wenjie Ding,Xiaolong Fu,Jingwei Hou,Junyan Wang,Mao Yang,Yu Gong,Chengjian Xiao,Hongwen Huang,Heyi Wang
A metal-organic frameworks (MOFs) modified interface with superhydrophilic and superaerophobic properties was successfully prepared via the solution process for tritiated nuclear wastewater (HTO) treatment. The superwetting performance of the packing surface which facilitated the liquid phase catalytic exchange was discussed in detail for the hydrogen-water isotope exchange reaction. Superhydrophilic property originated from the microporous hydrophilic nature of MOFs resulting in a rapid spreading and phase-transfer process of the tritiated water droplet, and superaerophobic property accompanied by superhydrophilic water thin film favored the effective exchange between gaseous reactants. Computational fluid dynamic (CFD) simulations revealed the influence of contact angle and liquid flow rate on the gas-liquid two-phase interface and catalytic performance. High performance with the lowest height equivalent to a theoretical plate (HETP) and long-term stability is achieved for this superwetting packing, which holds promise for the detritiation of nuclear wastewater with higher performance and stability.
Lei Yue,Linjie Zhao,Jingwei Hou,Junyan Wang,Jiamao Li,Chengjian Xiao
Large amounts of tritiated water (HTO) will be produced during the operation of nuclear power plants and fusion devices, which is harmful to the environment and human due to its radioactivity and toxicity. So, the tritium concentration of tritiated water must be reduced to a very low value before discharge. Hydrogen-water isotope exchange reaction (H 2 + HTO→H 2 O + HT) based on palladium membrane reactor has been proposed to process tritiated water. However, a comprehensive study about the influence of operation parameters on the membrane reactor performance is insufficient, which is not conducive to the design of reactor in practical application. Moreover, the commonly used Pt/Al 2 O 3 or Ni/SiO 2 catalysts are not active for tritiated water dissociation, so the catalytic activity of these catalysts is not high. In order to process tritiated water more effectively, a two-stage membrane reactor has been designed and established in this work, and Pt/TiO 2 catalyst with rich oxygen vacancies is used to catalyze the hydrogen-water isotope exchange reaction for the first time. The membrane reactor performance shows an approximate linear relationship with a new combined parameter S 0.5 P 1.5 R / F 2 ( S is membrane area , F is water flow rate , P is vapor partial pressure, R is swamping ratio), which can be used predict the membrane performance . The isotope exchange reaction activity of Pt/TiO 2 is better than that of Pt/Al 2 O 3 due to its good ability for water dissociation and the hydrogen spillover effect. At last, a tritiated water processing experiment by using two-stage membrane reactor with Pt/TiO 2 catalyst with rich oxygen vacancies has been carried out. The tritium decontamination factor reaches 40588, which is the highest experimental value so far. The results indicate that the two-stage Pd membrane reactor based on hydrogen-water isotope exchange reaction is an efficient technology for tritiated water processing.
Run Li,Denggao Guan,Ming Wen,Xin Zhang,Min Chen,Haowei Yang,Cigang Xu
Separation of light water/tritiated water (H 2 O/HTO) is an important process in the nuclear energy sector to treat tritium-containing radioactive wastewater, for which H 2 O/D 2 O separation is usually used as a research model to minimize safety concerns. Recently Graphene oxide (GO)-based membrane distillation processes have demonstrated high separation factor, however, the permeation flux is low to affect the overall separation performance. In this study, the approach of tuning interlayer spacing and structure of GO membranes was explored to enhance the separation performance through two ways: (i) GO membrane was intercalated using cations (Na + , or Ca 2+ ), or cationic surfactant-cetyltrimethylammonium bromide (CTAB) to vary interlayer spacing, and the resulting GO-Ca membrane gave the highest permeation flux of 0.87 kg·m −2 ·h −1 among the intercalated GO membranes with a separation factor of 4.6% to deliver higher separation performance than the pristine GO membrane; (ii) GO-framework (GOF) membrane was prepared by cross-linking GO nanosheets with cations (Ca 2+ , or Al 3+ ) to prepare GOF@Ca and GOF@Al membrane, and GOF@Al membrane achieved a separation factor of 4.9% and a permeation flux of 0.9 kg·m −2 ·h −1 , both higher than that of the pristine GO membrane. Furthermore, the up-to-date H 2 O/D 2 O separation data from different GO-based membrane distillation processes were summarized to understand the correlation between the permeation flux and the separation factor of processes. The results of this study suggested that tuning interlayer spacing and structure of GO membranes can be a good approach to enhance the overall separation performance by simultaneously improving permeation flux and separation factor for the separation of H 2 O/D 2 O, which can guide for future development of low-cost and efficient H 2 O/HTO separation processes needed in the nuclear energy field.
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