Competitive sequestration behavior and mechanism of Cd2+, Pb2+and Ni2+ ions from single, binary and ternary metal laden solution by Hevea brasiliensis wood sawdust (HBS)

Abstract

HeveaBrasiliensis wood sawdust (HBS), a lignocellulosic material, was employed for the eradication of Cd(II), Pb(II), and Ni(II) from synthetic single and multi-metalsystem. In the realm of multimetal adsorption, HBS exhibited the most substantial adsorption capacities for heavy metals, in the order: Pb(II) > Cd(II) > Ni(II). Experiments involving batch process were carried out to explore the rolesofpH, contact duration, HBS quantity, and preliminary metal concentrations on the adsorption capacity. Optimal conditions for biosorption of metal ions were determined as pH 5.0, dosage of 7 gL−1, and an equilibrium time of 90 min. The pseudo-second-order kinetics andLangmuirisotherm had a favorable alignment with the biosorption of all individual metal ions. Adsorption capacity was 8.45, 13.01 and 6.04 mg g− 1 for Cd, Pb and Ni respectively in single metal system. In binary and ternary system the capacity and adsorption percentages decreases significantly due the presence of competitive metal ions. HBS demonstrated effectiveness in treating real wastewater containing Cd2+, Pb2+and Ni2+ ionsin both single and mixed metal solutions, highlighting the necessity of thoroughly considering the impact of competitive adsorption. SEM with EDS results indicated single metal fixing in a multi-ion solution followed complex mechanisms. The surface area and functional group studies were conducted utilizing BET and a FTIR Spectrometer. Electrostatic attraction and complexation mechanisms were identified as responsible factor for capturing metal ions to the active surfaces of the bio sorbent. Cost analysis reflected the adsorbent cost was $0.021 per liter of mixed contaminated ternary effluent (30 mg L−1).