Lignin coating of Alginate aerogel particles
Biopolymer aerogels are nanoporous lightweight materials with high surface area and very low density (0.15 g/cm3). The properties made them well desired in diverse applications such as insulation, catalysts, and drug delivery systems. However, one main drawback of the biopolymer aerogels is their hydrophilic surface and the open pore structure of aerogels which permits the penetration of moisture or reactive molecules into the inner part of the materials and may cause damage of the pores. The conventional approaches comprise of a subsequent modification step either by: (1) a hydrophobic post-modification of aerogel inner surfaces, or (2) an application of a protective coating to the aerogel outer surfaces. This research work investigates an alternative solution which introduces the possibility of one-step simultaneous gelation and coating of alginate aerogels using lignin as the coating material. In this study, lignin particles are mixed with the alginate solution subsequently the lignin alginate hydrogel particles are produced via dripping method in calcium chloride solution to facilitate ions-induced gelation. Thereafter, aerogel particles are evaluated in terms of particle morphology and porous structure, While the coating layer is evaluated in term of homogeneity and thickness. The preliminary results showed the formation of porous lignin layer as an outer shell of alginate aerogel particles as validated by SEM images, the addition of lignin up to 50% wt dry mass basis did not negatively influence the porous structure (Sv up to 350 m2/g). The targeted application for the developed lignin coated alginate aerogel particles is as thermal insulation material for building elements using blow in technique.
Lignin coating of Alginate aerogel particles.pdf