Algae-water-silica interactions in low and high ionic strength environments

The interaction between algae and solid surfaces is of direct interest for the optimization of biofuel production technologies. Silica is particularly relevant due the use of solgel matrices for enhanced growth and ease of processing, where ionic strength variation is an important consideration. Here, an inverted fluorescence experiment is used to perform measurements of the distance between a silica surface and algae in solution. At low ionic strength, the average algae-silica distance is approximately 90 nm but increases to roughly 130 nm at 1 M NaCl, contradicting the prediction based on simple electrical double layer interaction models. These findings illustrate the role of biochemical and electrostatic interactions at charged aqueous interfaces of relevance to biofuel production. © 2023 Author(s).