Toxicological assessment and adsorptive removal of lead (Pb) and Congo red (CR) from water by synthesized iron oxide/activated carbon (Fe3O4/AC) nanocomposite

Heavy metals and dyes are the persistent pollutants causing harmful effects on living organisms in different ecosystems. In current study, removal of Lead (Pb) and Congo Red (CR) from water was performed using Iron oxide/Activated Carbon (Fe3O4/AC) nanocomposite. Ferromagnetic behavior of the nanocomposite is the crucial advantage in separation of nanocomposite after biosorption process. The biosorbent was thermally stable till 800 °C of temperature. The synthesized biosorbent was polycrystalline in nature comprising of elements like C, O, Fe. The influence of various experimental conditions was optimized through batch study with the biosorption capacity of 144.92 mg/g (Pb) and 122.22 mg/g (CR) at pH 5–6, Fe3O4/AC dosage (0.04 g) for 40 mg/L of Pb and CR. Toxicological assessment was performed using Danio rerio and seeds to evaluate the harmful effects of pollutants on these organisms. The phytotoxicity results revealed that growth inhibition of seeds lies between 85.64% and 55.92% (Pb) and 77.94%–51.85% (CR). The LC50 value of Pb on the Danio rerio was found to be 20.98 mg/L. In contrast, we observed significant increase in LC50 value about 86.82 mg/L after biosorption of Pb onto biosorbent. [Display omitted] •Effective biosorptive removal of Pb and CR by Fe3O4/AC nanocomposite was reported.•Characterization of Fe3O4/AC nanocomposite by various microscopic and spectroscopic techniques.•Maximum biosorption capacity was found to be 144.92 mg/g for Pb and 122.22 mg/g for CR.•Toxicological assessment viz. Seed and Fish toxicity of Pb and CR were evaluated.