Periodic Reporting for period 1 - MagMD (Magneto-responsive hydrophobic membrane and membrane distillation: insight into the real-time fouling and wetting mitigation mechanism)
Reporting period: 2023-07-01 to 2025-06-30
Water scarcity and pollution are the key global threats, they are the internal driving force for water/wastewater research, treatment, and application in chasing od the sustainable development goals (SDGs) and carbon neutrality. Membrane technology plays a crucial role in water-energy nexus in terms of seawater desalination, water reuse, and industrial wastewater treatment and zero liquid discharge (ZLD). However, the membrane fouling remains the key Achilles' heel for membrane process, driving the quest for fouling mitigation to achieve long end-of-life, low operation costs, and low carbon footprint. Specially, scaling is the main fouling mechanism during hypersaline wastewater desalination. In this project, the scaling mechanisms in both temperature- and pressure-driven membrane process were demonstrated and compared with a goal to promote the application of membrane in hypersaline treatment. A 3-stage flux decline mechanism in vacuum membrane distillation (VMD) was identified, in where the bulk crystallization was the dominating mechanism. However, the surface crystallization and following pore-blocking prevailed in NF, and the combination of Si and Mg showed a significant impact on cake layer formation. Meanwhile, the role of organic matters and the key scalants in scaling was revealed in membrane process. By which we proposed a mixed scaling mechanism in hypersaline desalination, it could offer scientific support to the desalination world. Secondly, we investigated the combination of magnetic nanoparticles and magnetic field in MD, to mitigate the membrane fouling and pore wetting issue with a new perspective. The multiple effects of magnetism including the vibration, nano-heating, anti-scaling, anti-biofouling effects were envisioned as combined with membrane. Then, a one-pot hydrothermal method was developed to synthesize metal-organic frameworks (MOFs) with high water (0.4 g·g⁻¹ at 20% RH) and ammonia adsorption capacities. Magnetic nanoparticles (Fe₃O₄) were prepared via solvothermal synthesis, exhibiting strong magnetism and dispersibility. Composite membranes integrating these nanoparticles and MOFs showed enhanced hydrophobicity, reduced flux decline, and improved ammonia adsorption, leading to stable long-term MD performance. Furthermore, we studied the effect of magnetic field on the MD process for Urine treatment. A low-frequency magnetic field integrated with MD mitigated fouling, slowed flux decline, and delayed organic/nitrogen accumulation. Composite membranes with magnetic MOFs further improved performance, achieving >99% rejection of TOC, TP, and PO₄³⁻, and >90% rejection of TN and ammonia in 24-hour runs. This work will pave a new way for hydrophobic/ Janus membrane preparation by bring in the magnetism, and shape a new road to the hypersaline wastewater desalination and resource recovery for the proposing of new MagMD process and the demonstration of mixed scaling mechanism.
Dring the project, we study the scaling mechanisms in MD and NF and proposed a mixed scaling mechanism for membrane-based desalination process. Meanwhile, the impacts and role of the scalants and organic matters were also investigated. Then, the potential of magnetism on the MD process was reviewed and discussed. After that we prepared 3 types of magMEMs with the MNPs and the magnetic modified MOFs. Then the self-built magMD setup was used to test the performance of magMD in urine treatment. The magMD showed more stable long-term performance and the membrane fouling of magMD was also investigated and studied. We had published 3 papers in Water Research within this project, and I also coauthored other 5 papers with the teams in RCEES, Beijing forestry university, and KU LEUVEN during the project. We also did lots of work for communication, technique exchange, and dissemination. Joined 4 internation conferences including the conference of membrane in chemical engineering, MEMDES2023, 2024 Qingdao International Water Conference & Expo, ISPT 2024, and so on. Meanwhile, we hold the 2nd Europe-China Eco-Envionmental Forum for Yong Scientists in KU LEUVEN under the supports of the department of chemical engineering, build a relationship with the young scientists in Europe. I also shared our research results in Research center for eco-environmental sciences, institute of urban environmental, Jiangxi academy of sciences, and Renmin University. To promote the application of our project, we joined more than 10 technique exchanges with more than 7 companies to expand our knowledge to the industrial world. Among them, we had some ongoing application cooperation with two companies. I also try my best to introduce the MSCA and MCAA during this project in China. I had joined the MCAA China chapter, and act as the board member in the committee. I participate the organization of the first and second annual conference of MCAA China chapter and participated many activities. On behalf of the MCAA, I joined the World Young Scientist Summit 2024 and detailed introduce the MCAA, MCAA China Chapter, and MSCA project, which enhance the impact of MSCA.
In this project, we mainly focus on the magMD process with the magMEMs preparation and magMD setup construction, as well as the scaling mechanism in membrane desalination. The key finding of the project including 4 parts. Firstly, we discussed the potential of magneto-responsive membranes with special and switchable wettability on the membrane process, especially on the MD. In the perspective paper, we systematically reviewed the research status and dilemmas of MD, and had a detailed conclusion and discussion of the magneto-responsive membrane, and their role in membrane science. Then we discuss the role of the magnetic nanoparticles as incorporated in the membrane, as well as the responsive membranes for future application in MD Finally, we discussed the mechanisms of the effects and functions of the magneto-responsivity, focus on magMEM preparation methods. Secondly, we developed the MNPs, MOF, and the magnetic-modified MOF with simple method. Then the magMEMs was prepared by introducing of the MNPs into the PVDF membrane. The membrane showed high stability and permeate quality for the combination of adsorption, membrane rejection, and magnetic effects. Thirdly, we demonstrated the scaling mechanism and proposed the mixed scaling mechanism for membrane desalination process. The scaling process was deconstructed with a cascade strategy by stepwise changing the composition of the synthetic desulfurization wastewater, and a 3-stage scaling mechanism was reported. Heterogeneous nucleation was found the main incipient scaling mechanism, and the bulk crystallization was the key scaling mechanism in VMD. However, the bulk crystallization of CaSO4 and Mg-Si complexes and the resultant pore blocking and cake formation under high pressure were the main scaling mechanisms in NF. We also reported the high impact of Mg-Si hydrates and the permeate drag force to the dense cake formation. And the two-way impact of DOM was illuminated for enhancing incipient scaling but inhibiting bulk crystallization at the later stage. Finally, we built the magMD setup with a low-frequency magnetic field generator. The variation of urine properties during storage and the effect of pretreatment agents was investigated before MD process. Then the performance and stability of magMEM in magMD was proceed, which showed significantly fouling mitigation effect with a higher permeate quality. Meanwhile, the membrane fouling of magMD was explored and will be continuing studied in the future.