Scarlet sage mediated green nano-phytoremediation of industrial sludge

Salvia splendens was used as a phytoremediator, with a particular emphasis on examining its capacity to mitigate industrial sludge pollution. The synergistic effects of iron and zinc nanoparticles, i.e., T0 (control), T1 (iron nanoparticles), T2 (zinc nanoparticles), T1 + T2 (iron + zinc nanoparticles) by growing the plants in industrial sludge (0, 10, 20, 30%) was examined. The experiment comprised three replicates, and the plants were harvested after 2 months of experiment. Soil analysis was performed before the transplanting of scarlet sage includes: pH (7.5–8.0), EC (618–796 dS cm−1), TDS (395–508 mg L−1), and heavy metals like Pb (27–284 mg kg−1), Ni (169–241 mg kg−1), and Pb (53–112 mg kg−1). After two-month of growth period, various morphological, physiological parameters and enzymatic and non-enzymatic antioxidant activities were checked along with various biochemical attributes. Roots and shoots of scarlet sage indicated a higher accumulation of heavy metals than shoots. The order of accumulation of heavy metal was Pb > Ni > Cd. The capacity of scarlet sage to absorb heavy metals exhibited a positive correlation with industrial sludge concentration, with lead being the most accumulated heavy metal. The maximum metal uptake was in 30% sludge and the combined application of iron and zinc nanoparticles significantly enhanced the heavy metals uptake. Morphological and physiological parameters, including plant height (up to 68 cm increase) and total chlorophyll content (up to 0.056 mg g−1 FW increase) in 10%, also improved under nanoparticle treatments. The goal of the study was to explore the role of scarlet sage and nanoparticles interaction on plant growth and metal accumulation to optimize the phytoremediation efficiency. Further research could focus on the potential benefits of nano-phytoremediation to achieve a more effective way for the removal of heavy metals from industrial sludge.