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This research deals with a highly efficient, selective, low-cost, and recyclable adsorbent for the fast removal of lead (Pb)(II) ions from aqueous solutions, and an investigation of the related adsorption mechanisms. Three types of materials were prepared from pea peels waste using simple, energy-efficient and environmentally friendly treatment. Obtained adsorbents were characterized by elemental analysis, infrared spectroscopy, scanning electron microscopy, Boehm titration, and the main parameters were determined. The highest adsorption capacity was observed for the biochar prepared by heating of pea peels at 600°C for 30 minutes. The uptake of Pb(II) ions on pea peels-derived samples was examined as a function of pH, contact time, and initial Pb2+ concentration. Obtained results from adsorption experiments of Pb(II) ions on the biochar surface indicate high adsorption capacity, and the possibility of its preconcentration and selective removal in the presence of zinc(II) and cadmium(II) ions. This confirms a potential application of such materials in water remediation.

Effective purification of natural and wastewater from heavy metals is a relevant environmental and national-economic problem. It can be solved by using plant-waste-derived biosorbents in water treatment technologies. They are formed in large quantities by agricultural and food enterprises. Taking into consideration data on the peculiarities of mechanical and thermal effects on the components of plant biomass, the techniques have been substantiated to obtain biosorbents from pea processing waste. It has been shown that the dehydration of the waste, its carbonization, and the crushing of char can produce biosorbents with different sorption properties. The nature of influence exerted by the process parameters of the Cu(II) and Fe(III) ions biosorption from model aqueous solutions on a change in the concentration of the solution, the value, and adsorption uptake has been established. In particular, the effect of the process duration, the type and initial content of metal in the solution, dosage, and a biosorbent production technique was studied. It has been shown that 38 to 98 % of heavy metals can be removed from solutions at their initial concentration between 2 and 20 mg/dm 3 and a biosorbent dosage between 1 and 30 g/dm 3. It was found that char is more efficient at removing heavy metals. It was also determined that the biosorbents made from pea processing waste are better at removing the Cu(II) ions from aqueous solutions than the Fe(III) ions. The generalization of the results of kinetic research is represented in the form of a multifactor regression equation. The equation makes it possible to calculate a change in the concentration of heavy metal in the solution depending on its initial concentration, the duration of the biosorption process, and the dosage of a biosorbent. For the mathematical notation of the experimental adsorption isotherms, values of the coefficients in a Langmuir equation have been determined. The derived equations could make it possible to optimize the technological parameters of the process

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