Characterization of three non-product materials from a bleached eucalyptus kraft pulp mill, in view of valorising them as a source of cellulose fibres

This paper is a contribution of scientific knowledge on the characteristics of several by-product materials from a bleached eucalyptus kraft pulp mill. In fact, three industrial wastes arising from bleached hardwood kraft pulps, namely: unbleached screen rejects (USR), effluent treatment (ETW), and eucalyptus bark (EB) were analyzed with the aim of their possible valorization as an alternative source of cellulose. Pure powder cellulose, CEAL, from Aldrich was also analyzed, as a reference. The structural, thermal, and morphological study of these raw materials were carried out by Fourier transform infrared spectroscopy (FTIR), energy dispersion spectrometry (EDS), X-ray diffraction (XRD), thermogravimetry (TG), temperature modulated differential scanning calorimetry (TMDSC) and scanning electron microscopy (SEM). Their morphological properties were determined using MorFi apparatus. For this study the sample bleached kraft pulp, BKP, was analyzed as a reference. Lignin and carbohydrate contents were also quantified. These by-products were studied as such (i.e. without careful purification) because we intended to find rational and low-cost way of valorization. In fact any additional operation will induce an over cost. The results obtained indicate that these industrial wastes can be potential raw material in fibre-based applications (paper, composites, …), since they contain a high proportion of cellulose with preserved fibrillar morphology and good thermal stability. Some of these materials have low lignin and inorganic residue contents.