area-based cultivation productivity of brown algae is higher than that of red and green algae (Lee and Lee, 2016), likely due by a higher photon absorption rate during photosynthesis (Thompson et al., 2019). The main components in the cell walls from brown algae (up to 45% of algal dry weight) are anionic polysaccharides such as alginates and fucoidans (Kloareg and Quatrano, 1988). In some brown algae, alginate constitutes up to 60% of the total sugars (Lee and Lee, 2016). Intertidal and supratidal brown algae, including Dictyota dichotoma (Terauchi et al., 2012), roughly present an average weight ratio of 3:1:1 in alginates, fucoidans and cellulose, respectively (Kloareg and Quatrano, 1988). Siddhanta et al. (2011) found little variation in cellulose content among six brown algae investigated, including three different orders ( Dictyotales , Fucales and Scytosiphonales ), accounting for values around 10%. This little amount of cellulose changes the strategy of the papermaking approach for valorization. In order to use the ¦ brillar cell walls with an acceptable yield and without severely damaging their structure, extraction requires particularly mild processes that, while removing most materials which hinder ¦ ber dispersion and sheet formation, do not seek to isolate cellulose. In fact, the paper industry uses plenty of polysaccharides other than cellulose, including starch and, precisely, alginates (Bai et al., 2017). Carrageenan from red algae, which shares similarities with fucoidans, has been proven to strengthen both paper (Liu et al., 2017) and plastic ¦ lms (Sudhakar et al., 2021). Hence, there are reasons to hypothesize that biomass from Phaeophyceae , when combined with conventional cellulosic ¦ bers, can lead to the production of paper of good quality. The purpose of this study is to valorize dead biomass from brown algae as a new supporting material to be added to a conventional pulp, once enriched in carbohydrates by sulfur-free and preferably mild chemical extraction methods. With this objective in mind, D. dichotoma was subjected to the key composition tests in papermaking. Moreover, mild extraction processes with hydrogen peroxide (alone and combined with hydrochloric acid or sodium perborate), sodium hydroxide, sodium hypochlorite and hot water were carried out. The characterization of the paper sheets fabricated with the resulting pulps was done. As far as we know, this is the ¦ rst study on the production of pulp and paper including brown marine algae, and not a particular extract from them. Experimental Harvesting and cooking Tidal wastes were harvested from “Playa de Costacabana” in the south of Spain (Almería). Samples were exhaustively washed with freshwater and screened in order to remove sand and other macroscopical impurities. Brown algae were selected from a mixture of marine plants and other algae, identi ¦ ed and dried at 40 ºC during 3 days such shown in Figure 1 that schematizes the sequence of experiments. Clean, dried brown algae were homogenized, crushed (size < 5mm), and cooked to do the extraction. Cooking was performed in a stainless steel batch reactor. Liquor to solid ratio was held at 8. Cooking liquor consisted of hydrogen peroxide, hydrogen peroxide–sodium perborate (SPB; 0.5% w/w), hydrogen
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