Selective Capture Of metals by Polymeric spongEs (SCOPE)
Descrizione
The ability to recycle heavy metals from wastewater is of fundamental importance to build a sustainable economy. Current recycling methods struggle to extract them from water and do not allow for material recovery. A possible solution for both problems is provided by nanomaterials, as their high specific surface area confers them unique properties that can be exploited for adsorption at the nanoscale. In particular, polymeric nanoparticles like PolyOxazoline-based multi-arms Star-Polymers (POSP) have recently been shown to possess a high adsorption capability for heavy metal ions in water [1,2] and to be biocompatible and thermoresponsive [3], allowing to recycle both the adsorbate and the adsorbent. These characteristics make POSP a very promising basis for the development of reusable nano-adsorbers, provided one is able to design and synthesize them at scale.
The SCOPE project aims at developing a multi-step strategy to engineer, synthesize, and test polyoxazoline based star-like nano-adsorbers, optimized for specific industrial applications. To reach this end, we will consider a specific case study relevant to green energy production: lead adsorption from the recycling of perovskite solar panels.
Frequent communication and feedback between the groups, will allow to establish a concurrent, iterative workflow, testing new polymer architectures and improving simulations based on the best nano-adsorbers identified in the lab on one side and screening the most promising components based on simulation results on the other. The feasibility of the approach is based on the close collaboration between different groups, including experts in computational physics, chemical design and synthesis and in the management of scientific networks. The SCOPE project will have a profound impact both on fundamental science and on technology, as it will provide
A well defined strategy for the rational design of smart nano-adsorbers, starting from chemical details up to the level of a whole complex macromolecule, to be conceptually implemented, in the future, at the production level.
An in depth characterization of how the chemical composition, geometrical, and topological properties of star-like polymers affect their adsorption of heavy metals.
A class of nano-adsorbers optimized for the recovery of lead from the recycling of perovskites-based solar cells.
Finalità
To achieve its goal, SCOPE will be divided into four objectives
Objective 1 : Characterize a large set of different polyoxazoline-based “arms” for the assembly of star polymers .
Objective 2 : Develop a Coarse-Graining (CG) scheme to map atomistic details to ad-hoc CG potentials suitable for large scale simulations.
Objectives 3 : Develop a computational protocol to characterize the physico-chemical properties of star-like systems with different geometries and topologies.
Objective 3 : Assemble and test the nano-adsorbers in the lab to demonstrate their effectiveness (WP4).
Risultati attesi
Action A1.1: Characterization of the thermal responsiveness and solvophilicity/solvophobicity of polyoxazolines with different side groups. (Completed)
Action A1.2: Characterization, by means of advanced techniques (ICP-MS, HR-TEM) of Pb2+ ions selective binding by polyoxazoline candidates with different side groups (Completed)
Action A1.3 Ensemble of optimal polyoxazoline polymers candidates to be used as building block of star-polymers for the adsorption of Pb2+ ions (Completed)
Action A2.1: Derivation of the general chemico/physical properties of polyoxazolines as a function of hydrophilicity or hydrophobicity of the general nature (length/ chemistry) of the local functionalisation: influence of the local structure on the general scalable properties of the molecule (Ongoing)
Action A2.2 Library of effective interactions between fragments of polyoxazolines, and between fragments and ions (Not Completed)
Action A2.3: Simulation pipeline (python, C++) for the derivation of CG potentials. (Not Completed)
Action A3.1: ] Identification of the optimal physical parameters for the selected architectures using a generic model (Completed)
Action A3.2: Identification of the optimal assembling strategy for spherical ring brushes (Completed)
Action A3.3: Computational pipeline, employing the potentials from WP2, to select optimal polyoxazoline star polymer-like nano-adsorbers (Ongoing)
Action 4.1 Assembled POSPs and polyoxazoline-based spherical ring brushes (Not Completed for the ring brushes – we have full characterisation of spherical linear brushes)
Action 4.2 Physico-chemical characterization of the assembled nano-adsorbers (Not Completed)
Action 4.3 Experimental assessment of the adsorption properties of the assembled nano-adsorbers and comparison with theoretical prediction (Ongoing)
Stato dell’arte
Currently, about 3% of the total amount of water on earth is freshwater and, of this, only about 0.007% is available for human consumption[4]. Water scarcity has been historically restricted to developing countries, but nowadays it has become of high concern also for developed countries. Along with the increasing production of wastewater (a byproduct of human activities), reduced river flows, lowered levels of groundwater and drying wetlands are globally reported and, altogether, significantly reduce water availability and quality, which are essential for the sustainment of life [5].
Specifically, the flourishing industrialization pace has vandalized water reservoirs with malicious pollutants like heavy metal ions, which have been a significant cause of distinct severe diseases. These metals have a tendency to accumulate in the environment and, as a result, are hard to remove from the food chain and they can thus exert a heavy toll on human health.[6,7]
Possible sources of heavy metal ions include mining, vehicular emission, agricultural runoff, industrial waste, burning of fossil fuels and, perhaps surprisingly, new technologies for renewable energy production. Indeed, newer generations of photovoltaic (PV) require the presence of toxic materials to function: for example, halide perovskites, which emerged as record breaking material in terms of efficiency [8], requires lead, a heavy metal very well known for its toxicity. While solar PV is by far the most promising renewable energy, we argue that water pollution from lead can hardly be overlooked while aiming for a true sustainable economy. In this perspective, the capture of heavy metals from water is a problem of present as well as future relevance.
Over the years, many research groups have focused their efforts on the development of new technologies for water remediation against the heavy metals, such as chemical precipitation, ion exchange, coagulation, flocculation, electrochemical treatment and/or the deployment of nanomaterials as adsorbent species. In particular, exploiting adsorption at the nano scales presents a series of advantages. Nanoparticle functionalization can be done both chemically – for example by choosing specific functional groups when designing the macromolecules [2], or physically – by affecting their geometry [9]. Polymeric macromolecules have also shown to be an extremely promising system in the adsorption/release framework, allowing recovery and reuse of both adsorbate and adsorbent compounds. For this reason, in recent years, synthesis and investigations of polymeric properties have focused on the design of macromolecules, able to perform predetermined tasks and sensitive to external stimuli. Specifically, the ability of the adsorbing macromolecules to react to chemo-physical changes – such as temperature, pH gradients, and magnetic fields, renders them as a promising and tunable material for controlled adsorption and release at the nanoscale.
Within the macromolecular class of polymers, Poly(2-alkyl/aryloxazoline)s (PAOx) have recently gained significant interest due to their biocompatibility, stealth behavior, and thermosensitivity: among others, poly(2-isopropyl-2-oxazoline) or PiPrOx and poly(amino-2-oxazoline)s or PAmOx and their derivatives are able to change the interaction with media by tuning the temperature, as well as to exploit electrostatic and hydrophilic interaction with defined cargo in solution.
In turn, amongst polymeric assemblies, star diblock copolymers, i.e. macromolecules made by a number of diblock copolymers tethered on a central core, have shown to be efficient adsorbers at the nanoscale. Indeed, recently [1,2,3] different poly(2-oxazoline)s were used to realize block copolymer-coated nanoparticles which a) are able to interact / adsorb with heavy metals, b) are biocompatible, and c) show a thermoresponsive behavior in aqueous solution.
Points a) and b) guarantee the possibility to design an environment-friendly system using polyoxazoline-based star-polymers (POSP). The fact that POSPs are thermoresponsive and undergo a solubility phase transition induced by temperature provides the opportunity to design star polymers whose solubility and adsorption strength can be tuned dynamically in order to retrieve the metal ions and reuse both them and the adsorbent polymer. If an optimal adsorber has to be designed and engineered, to be fully sustainable it has to retain 4 different characteristics: i) high capture efficiency, ii) low operation costs, iii) small environmental footprint, iv) tunable reversibility of the adsorption process. Polymeric nano-adsorbers can thus be engineered to satisfy these requirements.
Riferimento: PRIN 2022 PNRR – Codice progetto: 2022RYP9YT – CUP: F53D23001130006
Investimento totale del progetto: € 208.592
Partner/proponente: Università degli Studi di Padova (Coordinatore), Università degli Studi di Trento, CNR, Università degli Studi Roma Tre
Coordinatore dell’UdR Università degli Studi Roma Tre: Barbara Capone
