treatments with 17.5% and 9.45% NaOH solutions. A chlorite oxidation was carried out on a sample which had undergone water and ethanol-benzene extractions to measure the total water-insoluble carbohydrate content, since the ClO 2 formed in the process does not target polysaccharides (Ahlgren and Goring, 1971). Sheet forming and testing The conventional sheet-former method (ISO 5269-1) was used. Sheets from D. dichotoma pulps have low values of mechanical properties. For quality paper, pulp from brown algae was mixed in different proportions with an unbleached pine kraft pulp (PKP) obtained from the wood of Pinus pinaster Ait., from industrial origin. Agitation was done by hand, with a standard stirrer. Couch weights and standard plates were used to collect the handsheets. Sheets were left at 23ºC and 50% RH, while pressed by drying rings, for 24 h. The grammage of the handsheets was 60 g/m 2 . The tensile test for the breaking length and stretch, the burst test and the tear test were performed by means of appropriate testing machines from Houns ¦ eld, Metrotec and Messmer, respectively, and in accordance to the ISO standards 1924, 1974 and 2470 (ISO TC/6, 2011). Brightness was determined by means of a spectrophotometer from Lorentzen & Wettre, following ISO 2470 (ISO TC/6, 2011). Between 5 and 10 repetitions were carried out for mechanical properties and between 10 and 20 repetitions were performed for brightness. Results And Discussion Chemical characterization The results of the characterization of Dictyota dichotoma dead biomass, not being a lignocellulosic material, have to be taken with caution. In this case, the TAPPI standards commonly used to estimate the chemical composition of plant biomass do not give out percentages of lignin, α -cellulose and hemicellulose, but insights into the technological feasibility of using this material for papermaking. During the process, the biomass is involved in treatments with hot water, alkaline media, etc., and the end product is expected to be free from proteins and lipids. Table 2 displays the results of the tests. The amplitude of con ¦ dence intervals is four times the standard deviation. The ethanol:benzene extractables, hot water solubles and ashes, however, are qualitatively similar to what can be expected from vascular plants, allowing for a more comprehensive comparison. Wood is known to have very low contents of lipophilic compounds, not exceeding 2.6 % in Pinus pinaster and 1.2 % in Eucalyptus globulus (Jiménez et al., 2008). The high value detected in Dictyota dichotoma (7.2 ± 1.1%) can be explained by the abundance of lipids, mainly diacylglycerol derivatives, and the presence of pigments of the algae highlighting different types of chlorophyll, fucoxanthin and beta-carotene (Ryabushko et al., 2019). In any case, similar or even larger amounts of lipophilic compounds, as found in date palm rachis (6.3% in ethanol–toluene) (Khiari et al., 2010), Arundo donax (7.3%), sorghum stalks (8%) (Jiménez et al., 2008) or Tunisian vine stems (11.3%) (Mansouri et al., 2012), have not made researchers refrain from proposing those alternative materials for papermaking.
Page 5/14
Made with FlippingBook - Online magazine maker