PhD opening (2022-2025)

Innovative hybrid mineral-organic composites for the remediation of polluting metal ions

Hosting laboratories : CIRIMAT (Toulouse) and Institut Charles Gerhardt de Montpellier (ICGM), Montpellier

1- Context and objectives

The depollution of industrial wastewaters containing various metal

cations is a major issue. Retention by sorption is a key approach but it

requires performing adsorbents for the efficient and fast

decontamination of multicomponent solutions. In this context, the

original approach envisioned in this PhD work aims at elaborating hybrid

multifunctional solids combining chelating polymers and optimized

calcium phosphate substrates (stability, performances) to address actual

industrial needs.

2- PhD program

The objective of this PhD thesis is to combine the performances of

mineral and organic absorbents by developing hybrid mineral-organic

systems. The challenge is to associate the two components to develop

materials allowing for the efficient elimination of target pollutants

(fast sorption kinetics, high sorption amounts more or less selective

versus the target wastewaters), while remaining environment-friendly

(low-energy process, bio-inspired components…). We will associate

apatitic calcium phosphates (expertise of the CIRIMAT lab) with

chelating copolymers in link with a detailed physicochemical

investigation (specialties of ICGM).

While the calcium phosphate component will confer mechanical support to

the whole system as well as a porous network aiming at increasing the

contact surface with the surrounding liquid medium, the chelating

polymer moiety will ensure the retention of metal cations, aiming

effective depollution kinetics in conditions close to actual industrial

use. The association between the mineral and organic components will be

provided by functionalization of the polymers by functional groups known

to adsorb efficiently on apatitic surfaces. A challenge will be to

combine the two components without being deleterious to their respective

properties, to ensure the stability of the hybrid materials and to

maintain an optimal retention efficacy of the chelating organic

functions in the supported form. The shaping and costs of the hybrid

materials will also have to be optimized.

The materials will be evaluated on all the criteria to envision in the

depollution process, first in terms of sorption capacity and kinetics,

especially via ITC calorimetry (Isothermal titration Calorimetry,

expertise of ICGM) with the view to identify the most efficacious

systems. A first challenge will be in obtaining an efficient retention

of various metal cations. A second challenge will consist in

demonstrating the non-alteration of the polymer performances once

supported on a calcium phosphate matrix. The hybrid materials will be

characterized (before and after sorption) by different techniques

including XRD, IR/Raman, SEM and chemical titrations. We will then

explore the possible recyclability of the sorbents.

Keywords : depollution, chelating polymers, calcium phosphates, processing/shaping, adsorption