FIGURE 8.

Absorbance Fourier Transform Infra-Red spectra of γ-PGA obtained from different standard and complex waste substrates after tangential flow filtration. The peaks within the figure represent different functional groups of γ-PGA: C=O stretch (1739 cm⁻¹), the Amide I N-H bend (1643 cm⁻¹), the Amide II stretch (1585 cm⁻¹), the C=O symmetric stretch of γ-PGA in its sodium (1402 cm⁻¹) or calcium (1412 cm⁻¹) isoform, the C-N stretch (1162 cm⁻¹), the N-H bending (689 cm⁻¹), the O-H stretch (3449 cm⁻¹).