Mechanistic Insights into Biochar@PVA-SA Composite Fillers for Enhanced Biopurification of Isohexane in Biotrickling Filters

• • CG@PVA-SA composite filler achieved a water retention of 358 mg·g−1, a 27.9% improvement over the control (280 mg·g−1), directly enhancing the moisture environment critical for microbial activity in biotrickling filters. • • The filler exhibited a saturated adsorption capacity of 201.02 mg·kg−1 for isohexane, 76% higher than the control (114.24 mg·kg−1), which accelerates pollutant capture and mitigates mass transfer limitations. • • Rhodococcus ruber ZYH-ZY survival on CG@PVA-SA reached 79.0%, more than double the control (37.2%), demonstrating superior biocompatibility and biofilm support, essential for sustained biodegradation. • • Static degradation tests achieved 96.59% removal of 10 μL isohexane within 24 h, confirming the synergistic adsorption-biodegradation efficiency of the composite, which is pivotal for industrial BTF applications.