Novel synthesis of algae-derived mesoporous magnetic nanomaterial for sustainable removal of Pb and Cr(VI) from synthetic and industrial wastewater

In this study, mesoporous iron oxide magnetic nanoparticle was fabricated using Oscillatoria sp. (OsIONP) for the adsorption of Cr(VI) and Pb from aqueous solution and to treat industrial wastewater. The magnetic nanoparticle was characterized using different techniques like XRD, SEM, TEM, XPS, etc. BET analysis revealed their mesoporous nature with a pore diameter of 15.749 nm. From the experimental results the optimum conditions were found to be pH 4, 90 ppm and 50 ppm concentration of Pb and Cr(VI), 0.16 g/L and 0.17 g/L OsIONP dosage for Pb and Cr(VI), respectively. The nanomaterial follows the Langmuir adsorption isotherm model better than the Freundlich isotherm model, with an adsorption efficiency of 108.343 mg/g for Cr(VI) and 316.456 mg/g for Pb. The synthesized magnetic adsorbent exhibits high stability and reusability without any considerable changes in the material up to seven cycles. The OsIONP is applied to the industrial wastewater collected from a local industrial area in the Rohtak district of Haryana, India and analyzed using excitation-emission fluorescence spectroscopy. From the initial concentrations of 185.117 ppb and 7.122 ppb for Cr(VI) and Pb, the concentrations were reduced to 1.02 ppb and 0.931 ppb, respectively for Cr(VI) and Pb after the adsorptive treatment. The adsorptive treatment showed strong adsorption affinity and efficient purification with 99.45 % removal of Cr(VI) and 86.90 % removal of Pb, indicating high efficiency of the nanoparticle against industrial wastewater treatment. The results showed that OsIONP can be effectively used as a low-cost adsorbent for the removal of heavy metals both from synthetic and industrial wastewater.