Speaker
Description
Microbial resistance is increasing the global burden, and the search for non-antimicrobial products useful in environmental as well as biological applications continues. Coconut husk-derived biochar (BC) was synthesised by pyrolysis at 450 °C and then modified by zinc ion exchange to form zinc-loaded biochar (Zn-BC). The structural and morphological characterisation by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR) revealed the amorphous structure of carbon matrix loaded with adsorbed zinc-based crystalline domains, maintaining the porous microstructure of the biochar. Antimicrobial activity showed no inhibition to BC (MIC > 1 mg mL⁻¹) against all tested microorganisms. Zn-BC showed broad bactericidal and fungicidal activity of minimum inhibitory concentration (MIC) in all the examined organisms (0.5 mg mL⁻¹). Activity ratios (MBC/MIC ≤ 4) proved bactericidal and fungicidal. In addition, Zn-BC exhibited a moderate antioxidant activity compared to that of BC. Zn-BC exhibited up to 67.0 ± 1.5% radical scavenging in the DPPH assay at 5 mg mL⁻¹, and 61.7 ± 2.6% for unmodified biochar. In the ABTS assay, Zn-BC showed concentration-dependent scavenging with an inhibition of 57.6 ± 5.2% at 25 mg mL⁻¹, higher than that of unmodified BC. These findings indicate that zinc modification can convert coconut husk biochar into an effective and versatile material with high antimicrobial and moderate antioxidant activity.
