SIMULTANEOUS DETERMINATION OF BIO-INHIBITORS IN SULFITE LIQUOR BY ATTENUATED TOTAL REFLECTION (ATR) ULTRAVIOLET SPECTROSCOPY

This work presents an attenuated total reflection ultraviolet (ATR-UV) spectroscopic method for simultaneously measuring the contents of lignosulfonates and furfural substances in spent liquor during acidic sulfite process of lignocellulose. The ATR-UV spectra of lignosulfonates, furfural and HMF exhibit similar features with the well-known UV absorption spectra. The spectral intensity at 215 nm can be used for determination of lignosulfonates. Dual-wavelength calibration using absorptions at 220 and 286 nm provides more accurate quantification of lignosulfonates and total furfural substances. A simplified tri-wavelength technique was built to determine the individual concentration of furfural and HMF in liquor. The interference of inorganic substances can be ignored as the three calibrations were carried out. This ATR-UV spectroscopic method facilitates the study on kinetic degradation of lignosulfonates during an acidic sulfite process.