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The objective of this study was to investigate sorption, desorption, and immobilization of Pb in the clay and calcareous loamy sand soils treated with inorganic ligands (NO3−, Cl− and H2PO4−). Pb sorption was also determined in the presence of oxalate and citrate. The maximum Pb sorption capacities (q) ranged from 42.2 to 47.1 mmol kg−1 for the clay soil, and from 45.2 to 47.0 mmol kg−1 for loamy sand soil. It was observed that the binding energy constant (k) for Pb sorbed onto loamy sand soil (528–1061) is higher than that for clay soil (24.38–55.29). The loamy sand soil-sorbed greater quantities of Pb compared to the clay soil when initial pH was ≥ 3. However, it had lower sorption capacity at the lowest initial pH of 2. Additionally, the greatest Pb sorption and immobilization occurred in the soil treated with H2PO4. In the clay soil, the sorption of Pb was depressed at 0.1 mol kg−1 of Cl−, as compared with other ligands. Concerning organic acids, citrate ligand showed the highest decrease in Pb sorption. It could be concluded that the nature of Pb sorption can depend on the type and quantity of ligands present, as well as the soil type.

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The influence of repeated and continuous dry heat treatments on structural, physicochemical, and digestive properties of sweet potato starch was investigated. The results showed that the original A-type crystallinity of sweet potato starch remained unchanged after dry heat treatments. The light transmittance, gelatinization temperature, and pasting temperature of sweet potato starch increased; while the pasting viscosities, swelling power, and solubility decreased after dry heat treatments. Relative crystallinity, solubility, swelling power, light transmittance, and thermal parameter values (To, Tp, Tc, ΔT) were found to be significantly higher for the continuous dry heat (CDH) treated starch than those of the repeated dry heat (RDH) treated starch after treatment for the same duration. However, CDH treated starch samples showed lower paste viscosity and digestibility than those of RDH treated samples after treatment for the same duration. In addition, the CDH treatment highly influenced the structure of starch granule surface compared with the RDH treatment. Generally, it can be concluded that RDH treatment highly influenced structural, physicochemical, and digestive properties of sweet potato starch compared with CDH treatment.

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