Production of oxidised starch-gelatine particles for heavy metal absorption via a one-step synthesis approach followed by spray

Amino starch materials have strong potential as adsorbents of heavy metal in water systems. Some of the current drawbacks in producing this form of composite material is the need to use relatively expensive periodate oxidizing agents (to form dialdehyde starch) and the need to separate the oxidizing step with the subsequent and complexation process with amino acids. This work explored an alternative cheaper one step synthesis process which does not require the formation of dialdehyde starch. Different mass ratios of oxidized starch to gelatin was evaluated in the synthesis of the materials ranging from 20:80 (starch:gelatin) to 80:20 (starch:gelatin). The resultant material was then spray dried with a counter current spray dryer into a powder form for easier handling, transportation and storage. Infrared spectroscopy (FT-IR) analysis showed significant Schiff-base characteristics particularly when the mass ratio of 20:80 (starch to gelatin) was used. This observation was complemented by viscosity measurement of the cross-linked material at that ratio, prior to spray drying, in which and increased in viscosity was observed. These observations suggest that there may be an optimal starch to gelatin ratio which may be determined by the available ‘site’ for crosslinking between the starch and gelatin. X-ray photoelectron spectroscopy (XPS) further revealed that the surface has a higher representation of gelatin when compared to the initial bulk composition. It is unclear at the moment if this is due to any possible surface activity of the gelatin or if this higher representation is caused by other mechanisms during spray drying. Work is currently underway evaluating the dissolution (or non-dissolution) behaviour of the material and its heavy metal absorption capability.

Keyword: Oxidized starch, Gelatine, Schiff base, heavy metal adsorption