Recent research has focused on modifying 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 to enhance its use in environmental applications, particularly in anaerobic digestion—a process that breaks down organic matter to produce methane, a valuable biofuel. This study by Jiang et al., delves into how modifying algal biochar with quinone functional groups affects methane production.  

Biochar’s ability to influence anaerobic digestion is linked to its various properties, with redox properties taking center stage. Quinone groups, a type of oxygen-containing functional group, play a crucial role in biochar’s redox activity by facilitating electron transfer between microorganisms.  

In this study, the researchers modified algal biochar by immobilizing anthraquinone-2-sulfonate (AQS), a quinone compound, onto its surface. They then compared the methane production from glucose anaerobic digestion with the modified biochar (ABC-AQS) against raw algal biochar (ABC) and a control group.  

The results showed that the modified biochar had a higher electron-donating capacity, suggesting enhanced redox activity. Interestingly, while the modified biochar increased the rate of acid production (acidogenesis), it inhibited methane production. The researchers attribute this inhibition to the strong acid pretreatment used in the modification process, which likely caused 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 imbalances and the release of inhibitory substances.  

This study underscores the importance of considering the side effects of biochar modification methods on microbial processes like anaerobic digestion. While modifying biochar can enhance certain properties, it’s crucial to carefully evaluate potential unintended consequences that could hinder the overall process.  

SOURCE: Jiang Q, Zhou W, Chen Y, Peng Z, Li C (2025) Impacts of the quinone-functionalized biochar on anaerobic digestion: Beyond the redox property of biochar. PLoS ONE 20(4): e0322275.