Polydopamine-modified foam iron for hydrogen production from herbal medicine residues via dark fermentation

To address the critical challenges of clean utilization of herbal medicine residues, this study developed a polydopamine-modified foam iron (PDA-FI) material and systematically evaluated its enhancement effects and metabolic regulatory mechanisms during dark fermentation hydrogen production. Optimal process conditions were identified by combining single-factor experiments with an Extreme Learning Machine-Bayesian Optimization algorithm. The results showed that under optimal conditions, the cumulative hydrogen production was increased by 25.1% compared to the control group with the introduction of PDA-FI. Microbial community analysis revealed a 24.8% increase in the relative abundance of hydrogen-producing Clostridium_sensu_stricto_1 in the PDA-FI group compared to the control. Meanwhile, the proliferation of lactate-producing Escherichia-Shigella was markedly suppressed. Additionally, PDA-FI significantly activated key metabolic genes associated with butyrate synthesis and hydrogenase activity. Economic simulations demonstrated that PDA-FI exhibits favorable cost-effectiveness. Therefore, PDA-FI, as a highly efficient functional carrier material, holds broad application prospects in the field of dark fermentation.