Preparation And Properties Of Calcium Alginate Composite Fiber And Porous Sponge

Materials manufactured from renewable marine biomass through environmentally friendly and low-cost processes have attracted great attentions.The cell wall in brown algae is primarily consisted of sodium alginate,and its content in kelp is as high as 30-40%.Sodium alginate is the most important natural renewable polysaccharide due to its specific advantages,such as biocompatibility,nontoxicity,biodegradability.In this paper,sodium alginate was used as raw materials to systematically study the structure and property of fiber and porous material.The results were summarized as follows:Two samples of acid-hydrolyzed nanocellulose and two samples of TEMPO-oxidized nanocellulose were separately prepared from cotton liner pulp and microcrystalline cellulose,and dispersed in water.Sodium alginate,which was extracted from brown seaweed,was dissolved in the nanocellulose suspensions and wet spun in a calcium chloride bath to form four kinds of alginate/nanocellulose composite fibers.The structures and properties of the obtained nanocellulose and composite fibers were investigated and compared.Results showed that all of the nanocellulose samples exhibited a needle shape with slightly different sizes.The incorporation of nanocellulose increased the opacity of the spinning dopes but improved the mechanical properties of the alginate fibers.The optimum adding amount for all of the nanocellulose was 5wt%(based on the weight of sodium alginate).The TEMPO-oxidized nanocellulose produced from cotton liner pulp had the greatest influence on the strength of the fibers.All the composite fibers had an irregular cross section with dense and uniform structure,indicating the good compatibility between nanocellulose and alginate.In addition,the introduction of nanocellulose slightly improved the thermal stability of the alginate fibers.Calcium alginate porous sponge was prepared from pure sodium alginate by freeze-dried method,and investigated its structure and capacity of methylene blue(MB)adsorption.Alginate sponge exhibited stratiform-porous shape with outstanding mechanical compression property.Benefiting from large specific surface area,multiple porosity and sufficient active sites,the alginate sponge adsorbent showed ultrahigh adsorption capacity(1279 mg/g)for MB removal,which was higher than the MB adsorbents in previous reported.For its controlled shape,alginate sponge can be used as a column-packed device,achieving fast removal of MB with adsorption capacity of 1100 mg/g within 50 min.Such efficient,low cost and eco-friendly adsorbent has potential applications.