Sustainable dual-functional lignin-Cr/Zn oxide nanocomposite for organic pollutant removal: A Box-Behnken approach

This study highlights the transformation of lignin, an agricultural byproduct, into a multifunctional material with significant environmental applications. A chromium-doped zinc oxide/lignin nanocomposite (L@CrZnO) was synthesized and characterized to evaluate its dual functionality in organic pollutant removal and antibacterial activity. Methylene blue (MB) was used as a model contaminant to assess photocatalytic performance under varying conditions of dosage (0.005-0.025 g/mL), reaction time (30-75 min), and temperature (25-40 °C). Optimization using the Box-Behnken design revealed a 94 % confidence level between predicted and experimental outcomes. Additionally, L@CrZnO exhibited superior antibacterial activity, with inhibition zones of 5.5 ± 0.3 cm for Staphylococcus aureus and 5.8 ± 0.1 cm for Escherichia coli. These results demonstrate the material's potential as a versatile tool for water purification and pathogen control. This work underscores the value of lignin in developing sustainable, high-performance materials for environmental remediation.