Fourier transform near infrared analysis of waste paper with the addition of cereal bran biodegraded by Ascomycetes fungi

The goal of this work was to develop a Fourier transform near infrared (FT-NIR)-based methodology for estimating the biodegradation rate of recycled paper. Two types of fungi, Chaetomium globosum Kunze et Fr. and a mixture of Aspergillus niger van Tieghem, Trichoderma viride Persoon ex. S.F. Gray aggr. and Penicillium funiculosum Thom. were used as biotic cultures. Paper sheets made of recycled fibres with the addition of 0%, 3%, 5% and 10% of cereal bran, were used as test samples. Tests of breaking length (according to PN-EN ISO 1924-1:1998) and the degree of fungal infestation were performed on the 2nd, 4th, 7th, 10th, 14th and 21st days after infestation to quantify the resistance of the paper to biodegradation. The surface of each sheet of paper was scanned using a FT-NIR spectrometer. It was found that the addition of wheat bran increased susceptibility to fungal colonisation, compared to the samples without any bran. Degradation of paper colonised by Ch. globosum was more advanced. FT-NIR analysis revealed that spectra displayed the most significant difference in the wavenumber bands 4280 cm-1, 4404 cm-1 and 4620-4890 cm-1, which correspond to CH, CH2 and OH functional groups of cellulose. Differences in FT-NIR spectra were in good agreement with the reference methods and, therefore, this technique has the potential for monitoring the paper biodegradation process.