(%) Prop.
Y (%) TI (Nm 2 /g) ST (%) BI (kN/g) BL (km) BR (%)
NaClO 1 75:25 83.4 6.6
0.22 1.09
9.1
46.3
3
76.5 7.5
0.36 1.22
9.5
45.6
6
57.5 8.2
0.77 2.62
29.6
66.4
1 25:75 83.4 8.2
0.35 1.03
9.7
58.2
3
76.5 9.0
0.50 1.47
10.2
57.2
6
57.5 13.5
0.80 2.91
37.5
62.4
HW 1 75:25 82.5 4.1
0.25 0.78
8.2
47.9
1 25:75 82.5 4.7
0.28 0.80
8.2
55.7
Both treatments lead to lower yields at higher reagent concentrations. However, from 9% the decrease on yield percentage is less abrupt (Figure 2a). Tear index, burst index and stretch increase at higher concentrations of caustic soda or sodium hypochlorite during pulping and no signi ¦ cant differences were found with both reagent (Figure 2b-e). Brightness is independent from the concentration of NaOH and increases with the concentration of NaClO, owing to the latter’s capability to oxidize pigments (Figure 2f). Conclusions Phaeophyceae seaweed from coastal residues could not be used alone for papermaking, due to its low cellulose content and the abundance of lipophilic compounds. However, after easily extracting most proteins, lipids and pigments, the carbohydrate-rich product from brown algae constitutes a good addition to long cellulosic ¦ bers, allowing for acceptable paper strength even when the percentage of conventional pulp was as low as 25%. Sheets formed after extractions with NaOH or NaClO presented higher quality than those obtained with hydrogen peroxide or hot water. While brightness of paper sheets was higher after NaClO treatments, hydroxide and hypochlorite extractions differed little in mechanical properties, as both produced a four-fold increase in tensile strength. These results indicate that dead biomass from these brown algae, naturally occurring along coastlines and currently needing to be treated, can be successfully reused to partially replace wood pulp in the manufacturing of non-graphical papers. Declarations Ethics approval and consent to participate
Not applicable. No studies involving humans and/or animals.
Consent for publication
Not applicable.
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