Enhanced dispersion stability and heavy metal ion adsorption capability of oxidized starch nanoparticles

- Modified starch nanoparticles (SNPs) were prepared with sodium hypochlorite.
- Zeta-potential of modified SNPs increased significantly from −13 to −31 mV.
- The dispersion stability of SNPs was remarkably improved by oxidation modification.
- The rates of heavy metal ion (Pb2+ and Cu2+) adsorption by modified SNPs increased.

Starch nanoparticles (SNPs) have attracted much research interest recently due to their biodegradability and biocompatibility. However, practical utilization of SNPs is generally restricted due to their weak colloid stability and reduced functionality. In this work, SNPs were functionally modified by sodium hypochlorite (1-5% active chlorine based on dry SNPs weight). The degree of modification, particle size, stability, and adsorption characteristics of the SNPs were systematically investigated. The results showed that as the active chlorine concentration increased, the carbonyl and carboxyl contents increased to 0.150% and 0.855%, respectively. Compared with SNPs, the zeta potential value of SNPs modified with 5% active chlorine increased significantly (p < 0.05) from −13 to −31 mV and the dispersion stability of modified SNPs was remarkably improved. Moreover, modified SNPs exhibited high adsorption capacities for Pb2+ and Cu2+, suggesting that they could be employed as a novel absorbent for removal of heavy metal ions.