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International audience; Diiron complexes mimicking the H-cluster of [FeFe]-hydrogenases have been extensively studied as (electro-)catalysts for proton reduction under homogeneous conditions. The incorporation of such complexes as "active sites" within macromolecular scaffolds such as organic polymers is receiving increasing attention as this strategy allows controlling the environment, that is, the outer coordination sphere, around the molecular catalytic center, to tune its performance as well as its stability. Here, we report on the synthesis and characterization of a library of metallo-copolymers featuring a bioinspired diiron active site and internal proton relays based on a previous report [Brezinski et al. Angew. Chem. Int. Ed. 2018, 57, 11898-11902]. The polymers are further functionalized with various amounts of pyrene groups for efficient noncovalent anchoring onto multi-walled carbon nanotubes (MWNTs), enabling the preparation of molecularly engineered electrode materials. The addition of pyrene anchors resulted in improved activity and stability, with a pyrene loading of about similar to 8% corresponding to an optimized balance between polymer hydrophilicity and surface affinity. The best material displayed an average turnover frequency (TOFH2) of 4.3 +/- 0.6 s(-1) and a conservative turnover number for H-2 production (TONH2) of 3.1 +/- 0.4 x 10(5) after 20 h of continuous bulk electrolysis in aqueous conditions at 0.39 V overpotential. Interestingly, comparing such activities with an analogous diiron site deprived from polymeric scaffold revealed that latter could only show TONH2 of similar to 4 +/- 2 x 10(3) and TOFH2 of 0.06 +/- 0.02 s(-1) in 20 h under the same conditions. Post operando analysis of the modified electrodes suggests that electrode inactivation occurs via leaching of the diiron core from MWNT. In addition, a life cycle assessment was carried out to evaluate the performance of the engineered electrode materials not only from a technical perspective but also from an environmental point of view.

Environmental pollution, resource scarcity, and freshwater shortage are critical world challenges facing humanity. Process industry produces large amounts of brine, a waste water with a high salinity level and often critical raw materials. This study applies the social life cycle assessment (S-LCA) to quantify societal benefits and risks in developing brine treatment systems. S-LCA is implemented for hotspot and site-specific levels on four case studies of the Zero Brine project. Hotspot analysis focused on the major commodities. Social Hotspot Database was used as source for data and endpoint indicators. In addition, site-specific analysis regarded the social performance of the case studies companies; interviews and questionnaires were performed with representatives of the four case studies. The collected data were converted to scores with subcategory assessment method and performance reference points. The results show that for all case studies “Labor rights and decent work” and “Health and safety” indicators result in the largest impacts due to imports of commodities from developing countries. Site-specific results show that the overall social sustainability performance of the case study companies is at a good level. The only potential areas for improvement are the “Occupational accidents” and “Contribution to the local community”. The former are minimally higher for silica plant and higher for coal mine in relation to these sectors average accidents rates. Furthermore, the coal mine company can contribute more to the local community and reduce conflicts concerning environmental impacts at the city level. Common identified hotspots among the case studies are: China, India and Congo. Reducing imports from these countries will significantly improve the societal performance of the brine systems.

Technological developments are opening new avenues to facilitate the circular economy through resource recovery from industrial wastewater. This paper presents the use of Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) in the development of technology solutions for the treatment of brine wastewater and recovery of by-products. Four industrial case studies are assessed that apply different innovative technology configurations, to treat the brines and recover the water, salts and mineral compounds. The assessment focusses on identifying hotspots and potential design improvements for the four case studies. In addition, the development of a unified approach for prospective LCA and LCC is illustrated to promote robustness and consistency in the analysis of the four systems. The analysis reveals that the impact and cost of treatment is highly dependent on the wastewater composition. Critically, whether the recovery of compounds and deionised water can counteract the impact and cost of the treatment systems. The early analysis suggests that this is possible for two of the cases studies. Estimates of the GHG emissions for the initial system analysis, range from 10 to 17 kg CO2e/m3, whilst costs range from €10/m3 to €25/m3. However, both are expected to decrease at full scale and are sensitive to costs of energy, chemicals and revenue from recovered by-products. The LCA's highlight chemical and energy consumption as critical hotspots. Design considerations therefore focus on the reduction of chemicals, reuse or switching to lower impact chemicals, and maximising by-product recovery, and using renewable energy.

MSocial Life Cycle Assessment (S-LCA) uses a life cycle perspective to assess social impacts of products, and the S-LCA guidelines describe developing the system boundaries based on a factory-level perspective. However, such a perspective may exclude stakeholders with a negative social performance which are cooperating with a factory but are not directly involved with the product under study, and it can result in a step back on corporate social responsibility (CSR). Our study aimed to align S-LCA with the CSR concept. Therefore, we designed a case study for the manufacturing sector in which we practiced expanding the system boundaries of S-LCA. Our results showed larger social risks after expanding the system boundaries due to subsidiary and supplier companies located in countries with less strict regulations than the Netherlands, which is where the main organizations and parent company existed. We conclude that system boundaries expansion can result in more complete picture of the involved organizations, and lead practitioners to approach S-LCA with the goal of improving social conditions and identify companies which deserve excellent or poor social scores. Its usefulness is mostly expected when S-LCA practitioners aim to identify social hotspots in supply chains in socially sensitive markets.