In a recent study published in BiocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More, Hui Zhang, Zi Cheng, Kai Hu, Boxiong Shen, Honghong Lyu, and Jingchun Tang explore how the atmosphere during ball milling can significantly impact the performance of iron ore/biochar composite nanomaterials. Their research provides crucial insights into optimizing these materials for environmental remediation, particularly for degrading persistent organic pollutants like phenol.

Soil and water contamination by persistent organic pollutants poses a significant environmental challenge. Traditional remediation methods are often insufficient, prompting the search for more effective and sustainable solutions. Advanced Oxidation Processes (AOPs), which use highly reactive radicals to break down pollutants, are a promising avenue. Iron-based catalysts, especially those containing Fe(II), are excellent activators for peroxydisulfate (PS), a common oxidant in AOPs, generating powerful sulfate radicals (SO4−​) that can degrade various organic contaminants. Combining iron ore with biochar, a carbon-rich material from biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More, can further enhance catalytic performance due to biochar’s large surface area and electron-donating functional groups.

Ball milling is a high-efficiency, environmentally friendly, and economical method for modifying materials. While previous studies focused on adjusting milling parameters, the influence of the milling atmosphere has been underexplored. This new research systematically investigates how different ball milling atmospheres—air, nitrogen, and vacuum—affect the physicochemical properties of siderite/biochar composites (BM-SD/BCs) and their catalytic performance in phenol removal.

The results are striking: the composites prepared under nitrogen atmosphere (N/BM-SD/BC) demonstrated exceptional catalytic performance, achieving a phenol removal efficiency of 90.3%. This was significantly higher than composites prepared under air (A/BM-SD/BC) at 73.8% and vacuum (V/BM-SD/BC) at 81.3%. This superior performance is linked to marked changes in the composites’ surface morphology and structural properties. Under a nitrogen atmosphere, the ball-milled composites exhibited smaller particle sizes, a larger specific surface area and a richer distribution of surface functional groups and Fe(II) species. These characteristics collectively enhanced their redox activities and increased the active sites, thereby improving their ability to activate persulfate.

The active species responsible for phenol degradation were identified as hydroxyl radicals (OH), which contributed 50.7% to phenol removal, and superoxide radicals (O2−​), contributing 25.3%. This highlights the crucial role of these reactive radicals in the efficient breakdown of phenol. Furthermore, the N/BM-SD/BC/PS system proved its adaptability by effectively degrading phenol across a broad pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More spectrum, particularly within the typical pH range of actual wastewater, suggesting strong potential for practical application.

The study delves into the mechanisms behind these improvements. The nitrogen atmosphere was more conducive to particle fracture and bonding, exposing more functional groups and preserving the material’s structure from excessive oxidation. This led to a higher ratio of carbon-carbon double bonds, which are crucial for activating PS. Critically, the nitrogen and vacuum atmospheres also helped retain a higher proportion of Fe(II) (73.4% in N/BM-SD/BC compared to 62.8% in A/BM-SD/BC). This is significant because Fe(II) is a highly efficient electron donor that readily activates persulfate. The conversion of Fe(II) to Fe(III) during the reaction further confirmed its active participation in phenol oxidation.

Overall, the untreated biochar and siderite alone showed low phenol removal efficiencies. However, the combination of ball-milled siderite/biochar with persulfate demonstrated a significant synergistic effect, drastically improving phenol degradation. The N/BM-SD/BC composite’s excellent performance was attributed to its optimized surface area, pore volume, and uniform dispersion of iron particles, maximizing interaction with pollutants and oxidants.

This research underscores the pivotal role of the ball milling atmosphere in modulating the physicochemical properties and reactivity of nanomaterials. It provides theoretical support for designing highly efficient environmental catalysts for various applications. Future research can leverage these findings to further optimize the synthesis and application of similar composites for broader environmental challenges.

Source: Zhang, H., Cheng, Z., Hu, K., Shen, B., Lyu, H., & Tang, J. (2025). Atmosphere regulation: unraveling effective strategies for creating high-performance iron ore/biochar composite nanomaterials in ball milling processes. Biochar, 7(82).