Moringa oleifera Seed Protein Adsorption to Silica: Effects of Water Hardness, Fractionation, and Fatty Acid Extraction.

Motivated by the proposed use of cationic protein-modified sand for water filtration in developing nations, this study concerns the adsorption of Moringa oleifera seed proteins to silica surfaces. These proteins were prepared in model waters of varying hardness and underwent different levels of fractionation, including fatty acid extraction and cation exchange chromatography. Adsorption isotherms were measured by ellipsometry, and the zeta potentials of the resulting protein-decorated surfaces were measured by the rotating disk streaming potential method.

Antimicrobial sand via adsorption of cationic Moringa oleifera protein.

Moringa oleifera (Moringa) seeds contain a natural cationic protein (MOCP) that can be used as an antimicrobial flocculant for water clarification. Currently, the main barrier to using Moringa seeds for producing potable water is that the seeds release other water-soluble proteins and organic matter, which increase the concentration of dissolved organic matter (DOM) in the water. The presence of this DOM supports the regrowth of pathogens in treated water, preventing its storage and later use.

Specific counterion effects on the competitive co-adsorption of polyelectrolytes and ionic surfactants.

Counterions affect not only the bulk and interfacial self-assembly of ionic surfactants but also their competitive adsorption with similarly charged polyelectrolytes. Here, we explore the specific effects of bromide, chloride, and the bulky, somewhat hydrophobic tosylate counterion on the adsorption of hexadecyltrimethylammonium surfactants (CTA(+)), the adsorption of polylysine (PL), and the co-adsorption of CTA(+) and PL on negatively charged silica surfaces. Similar to bulk self-assembly, increasing the micellar binding affinity of the counterion from chloride to bromide to tosylate promoted interfacial self-assembly in the absence of polylysine.