Figure 1

IR and Raman spectra comparison for pure phthalic acid, \(10\) wt\(\%\) phthalic acid adsorbed on hydrated magnesium sulfate and epsomite blank in (a) IR \(8000-3500{\text{ cm}}^{-1}\) spectral range; (b) IR \(3500-500{\text{ cm}}^{-1}\) spectral range; (c) Raman \(65-2000 \, {\text{cm}}^{-1}\) spectral range. In panels (a,b) only adsorbed phthalic acid bands (black spectrum) with shifts greater than the resolution of the instrument (\(>4 \, {\text{cm}}^{-1}\)) with respect to the pure phthalic acid (red spectrum) are shown. In panel (c) the shifts of the hydrated magnesium sulfate (black spectrum) with respect to the epsomite blank \(463 \, {\text{cm}}^{-1}\) and \(982 \, {\text{cm}}^{-1}\) bands (blue spectrum) are highlighted. Legend: \({\nu }_{s}\) symmetric stretching vibrations; \({\nu }_{as}\) asymmetric stretching vibrations; \({\delta }_{p}\) in-plane bending vibrations; \({\delta }_{op}\) out-of-plane bending vibrations.