Periodic Reporting for period 2 - HYSOLCHEM (A Hybrid Reactor for Solar CO2 and N2 Conversion Coupled to WasteWater Treatment)
Período documentado: 2022-07-01 hasta 2023-12-31
HYSOLCHEM focuses on the successful validation, at industrial level (TRL 5), of a new concept of low-cost flow photo-reactor prototype for the reduction of CO2 and N2 to produce fuels and chemicals (CH4, C2H4, C3H6 and NH3) coupled to the oxidation of microplastics and organic pollutants from wastewater treatment plants. To achieve this ground-breaking goal, an interdisciplinary consortium has been gathered to tackle the multiple involved challenges in a holistic manner: (i) Design and synthesis of highly efficient and stable photocathodes for CO2 and N2 reduction (ii) Development of low-cost and long-duration anodes for the electro-oxidation of microplastics and other organic pollutants in wastewater (iii) Design and fabrication of cost-effective, selective and photo-stable ion-exchange membranes (iv) Advanced characterisation of materials at different levels with state-of-the-art spectroscopic techniques (v) Integration of developed CO2/N2 reduction photocathodes, waste/microplastic oxidation anodes and ion-exchange membranes in a solar-powered flow reactor for simultaneous water detoxification and CO2/N2 valorisation (vi) Validation of the prototype in a wastewater treatment plant and (vii) study of the developed materials and devices from an environmental, economic and social point of view.
Objective 1 (O1). To integrate ‘design-synthesis’ efforts towards the design of innovative photocathodes. New hybrid organic/inorganic photocathodes based on Conjugated Porous Polymers and IOS have been successfully designed and synthesized. Their performance as photoelectrodes has been determined (i.e. photocurrent, photostabilities etc.). The photoreduction of CO2 by means of copper oxides has been successfully tested in lab scale. These photocathodes have been scaled up to face their implementation on the final PEC reactor.
O2. To develop efficient, low-cost and long-duration anodes for the electro-oxidation of microplastics and other organic pollutants in wastewater. An electrode composed by Ni foam decorated with a Ni-based oxide was selected as candidate to address the oxidation of wastewater/microplastics. The mechanism of the phenol degradation through electrooxidation using NiMnO3 as the active material was elucidated. Furthermore, the stability of the electrodes was improved by a dual approach. First by examining alternative electrode supports (graphite felts provide better performance than nickel foam), and second, by introducing reduced graphene oxide to achieve better electrode stability.
O3. To design and fabricate ion-exchange membranes. Membranes based on sulfonated polyether ether ketone (SPEEK) and polyvinyl alcohol (PVA) showed the most potential as self-supporting membranes. They were optimized in sulfonation and cross-linking degree, obtaining performances better than Nafion 117. The membrane concept was optimized in safety by using a less reactive catalyst and a green, non-hazardous solvent. The PVA membranes show superior fuel retention, but a lack in conductivity. A facile protocol to fabricate commercial competitive hierarchical ion exchange membrane was worked out. These membranes were optimized in mechanical properties by identifying and solving the rolling issue. In the end, the membranes of both concepts have made significant progress towards a successful scale-up.
O4. To determine the reaction mechanisms. Some points have been reached: 1) a liquid flow cell and an electro(photo)chemical flow cell for operando for synchrotron based XPS and NEXFFS measurements has been successfully designed, developed and use as tester of WP materials. 2) A protocol to study thin films photocathodes by TAS in order to determine the charge transfer mechanism has been developed.
O5. To integrate in a solar-powered flow reactor the developed CO2/ photocathodes, waste/microplastic oxidation anodes and ion-exchange membranes for simultaneous water detoxification and CO2/N2 valorisation. The upscaled prototype at TRL5 has already finished, consisting of a versatile pilot with two different cells (Photocathode/PV+EC with dark anode dual configuration and electrochemical cell). The procurement of the different elements has been started and pilot will be finished in April-May 2024
O6. To validate the prototype in a wastewater treatment plant to remove microplastics, urea and organic matter in general from wastewater, converting them from a residue to a fuel. The RP1 work has been focused on two main aspect: 1) to develop and optimise a method to analyse and quantify microplastics (MPs) present on waste water treatment plan (WWTP) based on the use of an optical microscope coupled with an FTIR spectrophotometer; 2) to evaluate the performance of the anode developed so far in the oxidation of pollutants in the prototype designed and built in the Objective 5. The RP2 work has been focused on two main aspects: 1) re-evaluation of the wastewater matrix to check for potential microplastics misidentification; 2) assessment of commercially available anodes for the anodic oxidation of polyethylene nanoplastics ; 3) development and optimisation of a method to analyse and quantify nanoplastics (NPs) by a pyrolyser coupled to a gas chromatograph and mass spectrometer (py-GC/MS).
O7. To study the performance of the developed materials and devices from an environmental, economic and social point of view. Life Cycle Assessment (LCA), social life cycle assessment (S-LCA) and Life cycle costing (LCC) data collection forms have been prepared, distributed among the project partners and compiled. Characterization of the environmental life-cycle profile and economic life-cycle profile of the HYSOLCHEM system and identification of its environmental hotspots across its whole supply chain has been completed. Definition of a representative supply chain of the HYSOLCHEM system and analysis of its geographical location, and environmental and economic benchmarking o with respect to competing technologies/processes have been started.
O2. To develop efficient, low-cost and long-duration anodes for the electro-oxidation of microplastics and other organic pollutants in wastewater. An electrode composed by Ni foam decorated with a Ni-based oxide was selected as candidate to address the oxidation of wastewater/microplastics. The mechanism of the phenol degradation through electrooxidation using NiMnO3 as the active material was elucidated. Furthermore, the stability of the electrodes was improved by a dual approach. First by examining alternative electrode supports (graphite felts provide better performance than nickel foam), and second, by introducing reduced graphene oxide to achieve better electrode stability.
O3. To design and fabricate ion-exchange membranes. Membranes based on sulfonated polyether ether ketone (SPEEK) and polyvinyl alcohol (PVA) showed the most potential as self-supporting membranes. They were optimized in sulfonation and cross-linking degree, obtaining performances better than Nafion 117. The membrane concept was optimized in safety by using a less reactive catalyst and a green, non-hazardous solvent. The PVA membranes show superior fuel retention, but a lack in conductivity. A facile protocol to fabricate commercial competitive hierarchical ion exchange membrane was worked out. These membranes were optimized in mechanical properties by identifying and solving the rolling issue. In the end, the membranes of both concepts have made significant progress towards a successful scale-up.
O4. To determine the reaction mechanisms. Some points have been reached: 1) a liquid flow cell and an electro(photo)chemical flow cell for operando for synchrotron based XPS and NEXFFS measurements has been successfully designed, developed and use as tester of WP materials. 2) A protocol to study thin films photocathodes by TAS in order to determine the charge transfer mechanism has been developed.
O5. To integrate in a solar-powered flow reactor the developed CO2/ photocathodes, waste/microplastic oxidation anodes and ion-exchange membranes for simultaneous water detoxification and CO2/N2 valorisation. The upscaled prototype at TRL5 has already finished, consisting of a versatile pilot with two different cells (Photocathode/PV+EC with dark anode dual configuration and electrochemical cell). The procurement of the different elements has been started and pilot will be finished in April-May 2024
O6. To validate the prototype in a wastewater treatment plant to remove microplastics, urea and organic matter in general from wastewater, converting them from a residue to a fuel. The RP1 work has been focused on two main aspect: 1) to develop and optimise a method to analyse and quantify microplastics (MPs) present on waste water treatment plan (WWTP) based on the use of an optical microscope coupled with an FTIR spectrophotometer; 2) to evaluate the performance of the anode developed so far in the oxidation of pollutants in the prototype designed and built in the Objective 5. The RP2 work has been focused on two main aspects: 1) re-evaluation of the wastewater matrix to check for potential microplastics misidentification; 2) assessment of commercially available anodes for the anodic oxidation of polyethylene nanoplastics ; 3) development and optimisation of a method to analyse and quantify nanoplastics (NPs) by a pyrolyser coupled to a gas chromatograph and mass spectrometer (py-GC/MS).
O7. To study the performance of the developed materials and devices from an environmental, economic and social point of view. Life Cycle Assessment (LCA), social life cycle assessment (S-LCA) and Life cycle costing (LCC) data collection forms have been prepared, distributed among the project partners and compiled. Characterization of the environmental life-cycle profile and economic life-cycle profile of the HYSOLCHEM system and identification of its environmental hotspots across its whole supply chain has been completed. Definition of a representative supply chain of the HYSOLCHEM system and analysis of its geographical location, and environmental and economic benchmarking o with respect to competing technologies/processes have been started.
Significant advances in wastewater treatment, as well as CO2 and N2 reduction have been performed in the last years. However, they mainly focus on TRL ≤ 3 developments. Thus, it is necessary to tack+le these technologies with a holistic approach to achieve progress in innovative CO2 valorisation and N2 fixation technologies. The key technological advancements of the project is focused on the development of novel materials with improved electro-oxidation properties (anodes) and light harvesting together with enhanced charge separation and transport (photocathodes), and highly selective and stable ion exchange membranes. This also includes their scale-up using innovative large scale techniques like 3D printing, miniemulsions, electro- and photo- polymerisation, etc. Advanced characterisation and modelling tools will be crucial to understand the reaction mechanisms and develop optimized materials. In this sense during the first RP of the project a new in situ XPS and NEXFFS devices has been designed , manufactured and tested. Regarding scalability, scarce examples of pilot-plant solar reactors have been assayed in real conditions to oxidize microplastics and other organic waste and to reduce CO2 or N2 to produce fuels and chemicals. Within the project this work in ongoing knowing that in key technical issues still remain unsolved in the process up-scaling for commercial use