# Tailored Biochar–Pseudomonas chlororaphis Composites for Triclocarban Removal: A Feedstock-Dependent Structure–Interface–Metabolism Study

## TL;DR

This study explores how different biochar materials affect microbial activity in removing a contaminant called triclocarban.

## Contribution

The study introduces a new framework linking biochar structure, interface properties, and microbial metabolism for contaminant removal.

## Key findings

- Biochar composites improved triclocarban removal compared to free cells.
- Corn cob-derived biochar showed the highest contaminant removal efficiency.
- Immobilization altered microbial redox metabolism and interfacial electron exchange.

## Abstract

Biochar provides a porous scaffold, conductive carbon framework and redox-active surface functional that can promote microbial attachment and extracellular electron flow. However, how feedstock-dependent biochar properties regulate the biochar–cell interface and microbial metabolism during contaminant removal remains insufficiently understood. Here, biochar derived from rice husk, corn straw and corn cob was used to immobilize Pseudomonas chlororaphis for triclocarban removal in batch microcosms. Multiscale analyses, including scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), (electrochemical impedance spectroscopy (EIS) and liquid chromatography–mass spectrometryLC-MS, were combined to link the biochar structure, interface and extracellular metabolism signatures with triclocarban (TCC) removal. Compared with free cells, all composites enhanced TCC removal and exhibited altered interfacial functional-group features together with substantially reduced fitted charge-transfer resistance, indicating facilitated interfacial electron exchange. Untargeted metabolomics further revealed consistent remodeling of extracellular redox-associated metabolite signatures upon immobilization, with increased quinone/polyphenol-associated features and pathway-level shifts related to redox homeostasis. Among feedstocks, the corn cob composite showed the highest triclocarban removal. Overall, this work proposes an evidence-supported “structure–interface–metabolism” framework for interpreting how agricultural-residue biochars modulate biofilm interfaces and redox-related metabolic signatures to improve triclocarban removal, providing guidance for designing biochar-supported bioprocesses for halogenated micropollutants.