Green purification of heavy metal pollution from aquatic environment by biorefinery waste biomass of Nigella sativa L.: A novel and effective treatment agent

Abstract

Nigella sativa L. biorefinery waste biomass with antioxidant and antimicrobial properties was used as a novel biosorbent material for the green treatment of heavy metal pollution from water environment in this work. Manganese, one of the most widely used heavy metals, was used as a model to test the biosorption behavior of novel biosorbent. The main variables of biosorption operation such as pH, biosorbent amount (m), heavy metal concentration (Ci), and time (t) were optimized by the batch-type test system. The typical features of process of heavy metal biosorption were displayed by the characterization, kinetics, equilibrium, and thermodynamics studies. The characterization studies indicated that the biosorbent material possessed a heterogeneous surface morphology including many protuberances and cavities, and a rich profile of functional group. pH of 6, m of 10 mg, Ci of 30 mg L−1, and t of 120 min were determined to be the optimum variables values of biosorption process. The experimental data of heavy metal biosorption followed the kinetics model of Elovich and the isotherm model of Freundlich. The biosorption of heavy metal from aquatic medium was a spontaneous, favorable, and physical operation (ΔG∘: -7.27–3.55 kJ mol−1 and EDR: 0.90 kJ mol−1). The biosorbent material exhibited higher heavy metal biosorption performance (91.53 mg g−1) than many other sorbent materials reported in the literature. Thus, the current study showed that the biorefinery waste biomass of N. sativa L. could be used as an effective biosorbent for the biosorption of heavy metal from water environment, in addition to its use as an antimicrobial and antioxidant agent for multidirectional treatment of aquatic medium.