Physicochemical characterization of a waste from argentine agriculture: Soybean Hull as potential tool for bioadsorption applied to the downstream processes of enzymes

MARIA EMILIA BRASSESCO; CAROLINE IVANNE LE ROY; GUILLERMO PICÓ; PAULA JÁUREGUI

Salamanca

Congreso; Congreso Iberoamericano de Biotecnología- BioIberoamérica 2016; 2016

Argentine produce 60 millions of tons of soybean/years, 7% represents the hull, a waste which is used as food supplement for cow or is discarded in the environment, producing a negative impact on it. In previous work we have recovered peroxidase from soy bean hull, however the non soluble fraction on this, is formed by polysaccharides with a great porosity which make a material with potential uses in adsorption process. The goal of this work was to evaluate the potential of soybean hull to be used as an absorbent matrix for macromolecules found in water waste. The matrix was chemically modified using four independent treatments: water washed (control), NaOH, citric and tartaric acids. The chemical structure modifications implied by the treatments (using Infra Red measurements), the number of carboxyl group present, the pH of electrical charge zero and the pKa were evaluated. Finally we evaluated the ability of soya hull to retain water and to absorb macromolecules.The pKa for both acid treatments were higher and contain in average five times more carboxyl group per gram de soya hull than the control and base washed batch. In addition IR displayed modification of the chemical group found at the surface of the hull. Three zones of transmittance were modified : between 1600 and 1800 cm-1 (that can be assigned to carboxylic acid group) where an increase in the transmittance was observed for the NaOH treatment and between 2400 and 2700 cm-1 and at 2100 cm-1 where transmittance augment and decrease respectively for both acidic treatment. NaOH was the treatment that induced the highest water retention level, approximately two times more than for both acid treatments. Finally, we demonstrated that soybean hull was able to absorb macromolecules (positively electrical charge like lysozyme) regardless of treatment but that optimum absorption was reached at pH 5.0 with the NaOH batch, also it showed a mayor water retention ability. These results show the potential application of this waste in the separation of macromolecules and other small molecules at scaling up level.