Abstract
This study aimed to develop a low‐cost, multifunctional material with both antimicrobial and antioxidant properties by modifying zinc‐derived biochar (BC) from coconut husks. The coconut husk BC was produced through oxygen‐limited pyrolysis at 450°C and was subsequently modified using a zinc nitrate ion‐exchange treatment to create zinc‐modified biochar (Zn‐BC). Characterization techniques such as X‐ray diffraction, scanning electron microscopy, Fourier‐transform infrared spectroscopy, and Raman spectroscopy demonstrated the retention of the carbonaceous BC matrix along with zinc‐containing crystalline domains identified as ZnO. While unmodified BC showed no detectable antimicrobial activity within the tested range (minimum inhibitory concentration [MIC] > 1 mg·mL
−1
), Zn‐BC inhibited all tested bacterial and fungal strains at an MIC of 0.5 mg·mL
−1
. Zn‐BC exhibited enhanced radical‐scavenging activity compared to BC, achieving 67.0 ± 1.5% inhibition of DPPH radicals at 5 mg·mL
−1
and 57.6 ± 5.2% inhibition of ABTS radicals at 25 mg·mL
−1
. Integration of waste‐derived coconut husk BC with zinc modification results in a material that combines broad‐spectrum antimicrobial activity with measurable antioxidant properties. These findings indicate the need for further evaluation of Zn‐BC in water treatment, environmental applications, and the development of antimicrobial surfaces.