Valorizing the biosorptive potential and bioactivity of Anabasis articulata Sahara plants

Finding new affordable biosorbents for the remediation of toxic inorganic pollutants is a great challenge. This challenge arises from the need for biosorbents with functional groups that can efficiently chelate heavy metals and facilitate their removal from water. The present study examines the application of the local Egyptian Sahara medicinal plant Anabasis articulata, in both raw (ANA) and NaOH-modified (ANAS) forms, as biosorbents for removing Pb(II) ions from aqueous solutions. The characterization of both biosorbents was conducted using multiple analytical techniques, such as Fourier-transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) surface area analysis, Boehm titration, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The effects of experimental variables on Pb(II) biosorption, including initial Pb(II) concentration, pH, biosorbent dosage, contact duration, and the presence of foreign ions, were systematically investigated. To ensure the reliability of the kinetic and isotherm adsorption models, error functions, including χ², SSE, and MSE, were used as validation tools. Analysis of adsorption equilibrium data demonstrated that the Langmuir model most accurately described the process, yielding maximum capacities of 76.38 ± 0.26 mg/g and 46.74 ± 0.21 mg/g for ANA and ANAS, respectively. A measurable enhancement in adsorption was observed following mercerization, which altered the dominant Pb(II) binding mechanism. Thermodynamic analysis revealed that Pb(II) biosorption on ANA and ANAS was exothermic and endothermic, respectively. The ANA extract exhibited significant antioxidant activity as determined by the DPPH radical scavenging assay. Furthermore, the methanolic extract of ANA showed potential antimicrobial activity against both Gram-negative and Gram-positive bacteria. The mechanism of Pb(II) biosorption onto ANA and ANAS biosorbents is elucidated. The ANAS biosorbent, produced via a simple, environmentally friendly process, offers a sustainable solution for wastewater treatment in arid regions.