Synthesis of porous starch xerogels modified with mercaptosuccinic acid to remove hazardous gardenia yellow

• Potato starch is modified with MSA under moderate conditions (freeze-drying).
• PSX/MSA exhibits a porous structure due to the existence of MSA in the starch chains.
• MSA hinders the self-aggregation of starch chains during the freeze-drying process.
• The qe of PSX/MSA is greatly enhanced due to pore diffusion and newly formed H-bonds.
• Adsorption of GY fits Freundlich isotherm and pseudo-second-order kinetic model.

Mercaptosuccinic acid (MSA) molecules were inserted into potato starch, leading to the breaking of intrinsic H-bonds within macromolecular chains of starch and the formation of intermolecular H-bonds between MSA and starch, which could be verified by Fourier transform infrared spectroscopy (FT-TR). MSA modified porous starch xerogels (PSX/MSA) were obtained after freeze-drying the MSA modified starch, and they were characterized by field emission scanning electron microscopy (FESEM), exhibiting the intriguing porous structure due to the separation of starch chains by MSA molecules. The PSX/MSA were then used as the adsorbents to remove gardenia yellow (GY), a natural colorant with genotoxicity. Due to the porous structure of PSX and the introduced carboxyl groups from MSA, the adsorption capacity of the PSX/MSA was much higher than that of the starch xerogels alone (SX). The adsorption behaviors of GY by the PSX/MSA fitted both the Freundlich isotherm model and the pseudo-second-order kinetic model, and the efficient adsorption of GY suggested that the PSX/MSA might be potential adsorbents for the removal of dyes from contaminated aquatic systems.