Comparative study of adsorption of Pb(II) on native garlic peel and mercerized garlic peel

A comparative study using native garlic peel and mercerized garlic peel as adsorbents for the removal of Pb²⁺ has been proposed. Under the optimized pH, contact time, and adsorbent dosage, the adsorption capacity of garlic peel after mercerization was increased 2.1 times and up to 109.05 mg g^?1. The equilibrium sorption data for both garlic peels fitted well with Langmuir adsorption isotherm, and the adsorbent–adsorbate kinetics followed pseudo-second-order model. These both garlic peels were characterized by elemental analysis, Fourier transform infrared spectrometry (FT-IR), and scanning electron microscopy, and the results indicated that mercerized garlic peel offers more little pores acted as adsorption sites than native garlic peel and has lower polymerization and crystalline and more accessible functional hydroxyl groups, which resulted in higher adsorption capacity than native garlic peel. The FT-IR and X-ray photoelectron spectroscopy analyses of both garlic peels before and after loaded with Pb²⁺ further illustrated that lead was adsorbed on the through chelation between Pb²⁺ and O atom existed on the surface of garlic peels. These results described above showed that garlic peel after mercerization can be a more attractive adsorbent due to its faster sorption uptake and higher capacity.