Lead and cadmium biosorption from contaminated water using <i>Tagetes erecta</i> L. flower waste proven through langmuir and freundlich models

The discharge of wastewater containing toxic pollutants, such as lead [Pb(II)] and cadmium [Cd(II)], into water bodies is one of the most critical challenges nowadays. Apart from this, the daily generation of organic waste like vegetable, fruit, and flower waste in cities is increasing constantly. Therefore, a novel approach was adopted in this study that used flower waste (<i>Tagetes erecta</i> L. marigold) for the metal removal from polluted water with a view to manage flower waste and metal contaminants simultaneously. The characterization of prepared waste of <i>T. erecta</i> flowers and its biosorption capacity for Cd and Pb were investigated through various techniques viz., atomic absorption spectrophotometer (AAS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared analysis (FTIR). Experiments for adsorption isotherm were carried out at the room temperature and the performance was determined using Langmuir and Freundlich adsorption models. Equilibrium data was confirmed to follow pseudo second order kinetics. The maximum adsorption capacities of flower waste for Cd(II) and Pb(II) were 52.6 and 21.74 mg g^-1, respectively. The study findings indicated that the optimum pH and time for the most effective elimination were pH 6 and 150 min, respectively, for Pb (80%) and Cd (91.8%).