Performance Evaluation of Modified Biochar as a Polycyclic Aromatic Hydrocarbon Adsorbent and Microbial-Immobilized Carrier

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Abstract
Herein, biochars derived from corn stalks, rice husks, and bamboo powder were modified by nitric acid oxidation and sodium hydroxide alkali activation to identify efficient and cost-effective polycyclic aromatic hydrocarbon-adsorbent and microbial-immobilized carriers. The surface characterization and adsorption investigation results suggested that acid/alkali modification promoted the phenanthrene removal ability in an aqueous solution of biochars via facilitating π–π/n–π electron donor–acceptor interactions, electrostatic interactions, hydrogen bonds, and hydrophobic interactions. Subsequently, the degrading bacteria Rhodococcus sp. DG1 was successfully immobilized on the rice husk-derived biochar with nitric acid oxidation (RBO), which exhibited the maximum phenanthrene adsorption efficiency (3818.99 µg·g−1), abundant surface functional groups, and a larger specific surface area (182.6 m2·g−1) and pore volume (0.141 m3·g−1). Degradation studies revealed that the microorganisms immobilized on RBO by the adsorption method yielded a significant phenanthrene removal rate of 80.15% after 30 days, which was 38.78% higher than that of the control. Conversely, the polymer gel network-based microenvironment in the microorganism-immobilized RBO by the combined adsorption–embedding method restricted the migration and diffusion of nutrients and pollutants in the reaction system. This study thus introduces an innovative modified biochar-based microbial immobilization technology characterized by a simple design, convenient operation, and high adsorption efficiency, offering valuable insights into material selection for PAH contamination bioremediation.
Funding Information
  • National Natural Science Foundation of China (52400218, ZR2023QD063, X24078, GW202301, TJKLAST-PT-2022-03)
  • Natural Science Foundation of Shandong Province (52400218, ZR2023QD063, X24078, GW202301, TJKLAST-PT-2022-03)
  • Doctoral Research Fund of Shandong Jianzhu University (52400218, ZR2023QD063, X24078, GW202301, TJKLAST-PT-2022-03)
  • Open Project Program of Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education of China (52400218, ZR2023QD063, X24078, GW202301, TJKLAST-PT-2022-03)
  • Research Fund of Tianjin Key Laboratory of Aquatic Science and Technology (52400218, ZR2023QD063, X24078, GW202301, TJKLAST-PT-2022-03)

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