Physico-chemical studies of pH-sensitive surfactants for the development of solid supports in the context of treated wastewater reuse

Located on the campus of the National Institute of Applied Sciences of Toulouse (INSA), the public research laboratory TBI—supported by INSA Toulouse, CNRS, and INRAE—combines fundamental and applied research in the field of biotechnology.

The SOFTMAT laboratory, Chemistry of Colloids, Polymers & Complex Assemblies, is dedicated to research in the chemistry of soft matter. It focuses on organized systems composed of surfactants, polymers, biomolecules, or nanoparticles.

.

Ensuring good water quality is emerging as one of the major challenges of the coming decades to preserve both human health and ecosystems. Among advanced wastewater treatment processes, membrane bioreactors (MBRs) are considered one of the most efficient technologies. However, membrane fouling significantly increases operating costs. Recently, biological methods have been explored by the scientific community [1] to mitigate this phenomenon.

Quorum Quenching (QQ) has emerged as an innovative solution to control fouling by interfering with Quorum Sensing (QS), a mechanism partially responsible for its occurrence. One approach to implementing QQ involves using porous solid supports capable of entrapping bacteria that can disrupt the QS signaling pathway. The supports used in this project are beads made of a bio-based material, sodium alginate (ALG), and a polymer, polyvinyl alcohol (PVA) [2].

To meet sustainability requirements, the project aims to develop a silica coating with controlled porosity on the surface of the beads using a sol-gel process. Mesoporosity is achieved through a templating effect induced by surfactants. In this internship, a mixture of a pH-sensitive surfactant (TD) and a cationic surfactant will be used. The structures formed by the TD/CTAB (cetyltrimethylammonium bromide) mixture have been reported in the literature [3], but those involving cetyltriethylammonium bromide (CTEAB) have not yet been described.

Replacing CTAB with CTEAB is expected to significantly reduce the amount of surfactant required for the sol-gel process. The objective of the project is therefore to perform a physicochemical characterization of TD/CTEAB assemblies as a function of pH. These assemblies will be analyzed by tensiometry, DLS, SAXS, NTA, and fluorescence spectroscopy. During the internship, they will be incorporated into the sol-gel process to develop more resistant beads, in the presence or absence of bacteria.

[1] Bouayed, N. Process-Oriented Review of Bacterial Quorum Quenching for Membrane Biofouling Mitigation in Membrane Bioreactors (MBRs). Membranes (Basel), 2016, 6(4), E52.
[2] Preparation and Characterization of Novel Polyvinyl Alcohol–Alginate Beads for Quorum Quenching Application in Membrane Bioreactors. J. Polym. Environ., 2024, 32, 5837. https://doi.org/10.1007/s10924-024-03304-7

We are looking for a student interested in organic synthesis, material synthesis, and the physicochemical characterization of surfactants. The internship start date is flexible, between January and March, depending on availability.