The team of Professor Zheng Qiang of Zhejiang University and Associate Professor Zhu Fengbo of Taiyuan University of Technology: Fly ash "turns waste into treasure" to create a new solution for the industrialization of strong hydrogels

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The team of Professor Zheng Qiang of Zhejiang University and Associate Professor Zhu Fengbo of Taiyuan University of Technology: Fly Ash "turns waste into treasure" to create a new solution for the industrialization of strong hydrogels 2026-03-02 Recently, the team of Professor Zheng Qiang of Zhejiang University and Associate Professor Zhu Fengbo of Taiyuan University of Technology has made breakthrough progress in the field of composite hydrogels (CHs). By innovatively using fly ash (FA), a solid waste from coal combustion, as a low-cost and sustainable filler, they have developed a new composite hydrogel system that can be prepared quickly and on a large scale at room temperature. The relevant research results, titled "Alkali-activated fly ash catalyzed sustainable and scalable production of tough composite hydrogels toward versatile applications", were published in the internationally authoritative journal "Chemical Engineering Journal" (DOI: 10.1016/j.cej.2026.174270). The first author of the paper is master student Shi Xiaowen, and the corresponding authors are Professor Zheng Qiang and Associate Professor Zhu Fengbo. This research work obtained * * Supported by the Natural Science Foundation of China and the Shanxi Provincial Natural Science Foundation. Traditionally, the design of composite hydrogels for industrial applications (such as drilling sealing, rapid bonding) has faced two major challenges.: It is difficult to produce on a large scale, and the production process usually requires high energy consumption methods such as external heating or ultraviolet irradiation. The core innovation of this research is to use "fly ash", an industrial solid waste with a global annual output of over one billion tons but a utilization rate of less than half, to cleverly solve the above problems. core breakthrough: Without the need for external energy, the "one-button trigger" room temperature curing research team found that after mixing alkali (NaOH)-activated fly ash with monomers, cross-linking agents and conventional thermal initiator KPS, the mixture can spontaneously and rapidly undergo free radical polymerization in normal temperature air, and the entire process does not require any external energy input. Ultra-fast gel speed: Taking the acrylamide (AAm) system as an example, the precursor solution containing alkali-activated FA can gel within 5 minutes and completely gel within 10 minutes. Excellent scale scalability: This method is insensitive to oxygen and successfully achieves linear scale-up preparation from 7 ml to 7 liters, demonstrating its huge industrial-scale production potential. Significant contrast: The control group without FA or alkali was unable to achieve this rapid spontaneous polymerization, indicating that the synergistic effect of FA and alkali is the key. ⚙️ Reveal the dual mechanism behind: Release of Heat + Catalytic Free Radical Team used isothermal calorimetry, electron paramagnetic resonance and other analytical methods to reveal the mechanism of rapid catalytic polymerization of fly ash excited by alkali: “Self-generated heat” drive: Alkali solution can dissolve the oxide layer on the surface of FA particles, and this process will release a large amount of heat. This part of the heat directly reduces the energy barrier required for the decomposition of the initiator KPS. Catalyze free radical generation: The trace metal elements (such as Fe, Ti, etc.) contained in FA itself can effectively promote the decomposition of KPS in the alkali activation state, thereby generating a large number of free radicals in the system. It is the dual effects of "thermal release energy barrier reduction" and "catalytic promotion of decomposition" that trigger the high-speed free radical polymerization of vinyl monomers at room temperature. Even more ingeniously, researchers can precisely control the gelation time of the system (ranging from 2 minutes to 20 minutes) by simply adjusting the concentration of NaOH. The combination of strength and beauty: Significant jump in performance and strong reversibility In addition to the catalytic function, the addition of fly ash also greatly enhances the bulk mechanical properties of the hydrogel. Compared with the pure gel (PAAm network), the FA composite gel increased the fracture strain by 5 times (reaching 756%). In the two key mechanical indicators of fracture stress and tear energy, it has achieved an order of magnitude improvement of nearly 10 times (reaching 207 kPa and 210 J/m² respectively). This is due to the physical interaction formed between FA particles and polymer network chains, which can provide additional energy dissipation capabilities when the gel deforms, making the material extremely strong. For example, composite gels can withstand more than 95% compressive strain and quickly return to their original shape after the external force is removed. Broad application potential: From Adhesives to Mine Safety Thanks to its room temperature operation, rapid curing, ease of scale-up, and excellent bulk properties, this fly ash-based composite gel system has shown great application potential in multiple industrial scenarios. High performance environmentally friendly adhesive: The gel precursor can be directly coated on the surface of wood, metal, glass and other substrates to achieve fast and strong bonding at room temperature. Soil Solidification and Geological Engineering: Injected into a loose sand mold, it cements and firmly holds soil or rock particles in place. Quick sealing of drilled holes: Especially suitable for engineering scenarios such as coal mining. The gel precursor liquid can be quickly solidified in situ after being injected into the pores, and a near-vacuum sealing environment can even be quickly established in the transparent pipeline experimental model, showing extremely high practical value. Conclusion and Outlook This research "turns waste into treasure" by transforming fly ash, a bulk industrial solid waste, into an efficient and low-cost catalytic filler and reinforcing phase for preparing high-performance composite hydrogels. It not only provides a new high-value resource utilization path to solve the global fly ash disposal problem, but more importantly, it provides a highly inspiring innovative design paradigm for the green, sustainable, and controllable production of high-performance hydrogel materials for large-scale industrial applications. This work is expected to promote the in-depth application and industrialization of composite hydrogels in construction, mining, environmental protection and other industrial fields. The research team firmly believes that this strategy can have a profound impact on the development and application of next-generation functional composite materials.