Mining iron from stainless steel pickling wastewater to produce quasi-MIL-100(Fe) for boosted photocatalytic peroxymonosulfate activation

In the current context of global resource scarcity, resource recovery is of strategic importance. A team led by Prof. Chong-Chen Wang of Beijing University of Civil Engineering Architecture, Novel Materials & Technology for Environmental Remediation, has successfully developed a method for the preparation of high value-added MOFs based on the resource utilization of industrial wastewater. The research team prepared quasi-MIL-100(Fe) (Q350-MIL-100(Fe)) with hierarchical pores and abundant oxygen vacancies through modification of MIL-100(Fe) from resource recovery. The experimental results showed that Q350-MIL-100(Fe) exhibited significantly enhanced catalytic performance in advanced oxidative degradation of organic pollutants compared with the conventional MIL-100(Fe). This study not only proposes a new strategy for industrial wastewater recycling, but also provides opportunities for the low-cost, large-scale production of environmental functional materials, successfully realizing the synergistic effect of pollution control and resource recovery.

The team published their research paper in Nano Research on April 15, 2025.

“In this study, we provide a method to prepare high value-added Quasi-MOFs from stainless steel pickling wastewater using microwave-assisted method to mining useful resources, which can also solve the discharge of hazardous waste and is undoubtedly an important embodiment of the 3Rs principle (reduce, reuse, recycle).”said Chong-Chen Wang, corresponding author of the paper, director of Beijing Key Laboratory of Functional Materials for Building Structure and Environment Remediation. Prof. Wang is also the deputy secretary general of Chinese Materials Research Society, the deputy secretary general of Beijing Chemical Society.

Metal-organic frameworks (MOFs) are porous inorganic organic functional materials formed by the coordination and self-assembly of polydentate organic ligands and metal ions, which have witnessed rapid development in recent years. At present, commercial metal salts are generally used as metal sources to produce MOFs, which might increase the production cost. Using metallic wastewater to synthesize MOFs can not only reduce the cost, but also realize the harmless disposal of wastewater. A moderate number of defects in a photocatalyst can modulate energy bands, electronic structure and material properties enhancing its photocatalysis activity and charge separation efficiency. Quasi-MOF, characterized by its metastable state with controlled ligand dissociation-induced defects, can preserves the intrinsic merits of the pristine MOFs like high specific surface area, structural versatility and tunable functionality. Quasi-MOF can synergistically integrate the benefits of defect engineering to achieve superior performance to its parent MOF counterpart.

The research team prepared high-value-added MIL100(Fe) economically and quickly using stainless steel pickling wastewater by relatively mild microwave method, which was used to yield quasi-MOF (Q350-MIL-100(Fe)). In the Q350-MIL-100(Fe) construction, the skeletal structure of pristine MIL-100(Fe) was largely retained, forming a hierarchical pore structure which ensures the reactants are accessible to the exposed active sites (Fe sites and oxygen vacancies) and can diffuse in a timely and effective manner. The results showed that Q350-MIL100(Fe) has an efficient degradation ability of ATZ through the photocatalytic activation of the PMS process, which is 41.56-fold higher than the MIL-100(Fe). The ATZ degradation process is a radical-dominated process, which was facilitated by the exposure of more Fe sites and the existence of oxygen vacancies. Moreover, the degradation solution exhibits low biotoxicity and the continuous removal of ATZ for at least 96.0 h was achieved in a homemade reactor, which strongly demonstrated the potential of Q350-MIL-100(Fe) for practical applications. This research offers a valuable reference for exploring resource recovery from wastewater to synthesize high-value-added functional materials. The materials can be further applied to eliminate pollutants, aligning with the goals of both pollutant reduction and carbon reduction.

This work was supported by the National Natural Science Foundation of China (Nos. 52370025 and 22176012) and BUCEA Post Graduate Innovation Project (No. PG2024086).

About Nano Research

Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 7,000 articles. In 2024 InCites Journal Citation Reports, its 2024 IF is 9.0 (8.7, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.