Figure 2

IR and Raman spectra comparison for pure mellitic acid, \(10\) wt\(\%\) mellitic 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 (b) the partial redshift of the \(1153 \, {\text{cm}}^{-1}\) band due to interaction between mellitic acid and hydrated magnesium sulfate via carboxyl groups is shown. In panel (c) a partial blueshift of the \(982 \, {\text{cm}}^{-1}\) band due to the mineral dehydration is shown. Legend: \({\nu }_{s}\) symmetric stretching vibrations; \({\delta }_{p}\) in-plane bending vibrations\(.\)