Phytofabrication of Spondias dulcis derived silver nanoparticles as sustainable nanocatalysts for removal of organic dyes and p-nitrophenols

Industrial effluents containing recalcitrant organic pollutants pose escalating threats to freshwater ecosystems and public health, necessitating the development of efficient, sustainable remediation strategies. Green synthesis of silver nanoparticles (AgNPs) using plant-derived bioreductants offers a promising avenue, combining environmental compatibility with potent catalytic performance. This study reports, for the first time, the synthesis and characterization of biocompatible AgNPs from the aqueous extracts of four different parts of Spondias dulcis, a species for which cross-part comparative AgNP synthesis, bark- and stem-mediated nanoparticle synthesis, and catalytic wastewater remediation applications remain undocumented. UV–Vis spectroscopy confirmed successful AgNP synthesis from bark and stem extracts at 90 °C for 45 min. Characterization revealed 30–60 nm cuboidal, with 84.8% silver composition, −32.8 mV zeta potential and 56.94 nm average diameter for Bark_AgNP. Cytotoxicity assessment via the brine shrimp lethality assay demonstrated 100% viability at concentrations of 200 and 800 mg/L, establishing the biocompatibility of the synthesized nanoparticles. Catalytic reduction of p-nitrophenol to p-aminophenol in the presence of NaBH₄ was most efficiently accomplished by Bark_AgNPs, achieving a rate constant of 1.056 ± 0.0080 min⁻¹ at 266.67 mg/L, a value exceeding those reported for comparable plant-derived AgNP systems. Photocatalytic evaluation under solar irradiation demonstrated that the addition of 4000 mg/L Bark_AgNPs with NaBH₄ accelerated methyl orange degradation at a rate of 0.4499 ± 0.0162 min⁻¹, markedly outperforming NaBH₄-free conditions. These findings establish S. dulcis Bark_AgNPs as highly effective, biocompatible nanocatalysts with significant potential for the remediation of phenolic and azo dye contaminants in industrial wastewater.