Sustainable mold biomachining for the manufacturing of microfluidic devices

Biomachining has been investigated as a sustainable and effective alternative to conventional prototyping techniques for molding polymeric materials for their subsequent use as microfluidic devices. A novel and simple process based on the combination of a Pressure Sensitive Adhesive mask and a varnish has been proposed for preparing metal workpieces as an alternative to photolithography, with the latter being the most widely used technique for protecting workpieces. As far as the bioprocess is concerned, it has been applied in successive mold-etching and oxidant bio-regeneration stages. Metal solubilization has proven to be repeatable in several consecutive mold-etching stages when using the regenerated oxidant solution. As a result, the lifespan of the biomachining medium has been prolonged, contributing to process sustainability. An equation with two restrictions has been proposed to predict the time required to obtain a mold with a fixed height, as metal solubilization evolves differently between the first and subsequent hours. Finally, the bio-engraved copper pieces have acted as effective molds in the fabrication of self-powered polydimethylsiloxane microfluidic devices. This new biomachining application is therefore an effective and ecofriendly process for producing microfluidic devices.This work was supported by the State Agency for Research (AEI) of the Spanish Government-European Regional Development Fund (FEDER-ERDF, EU) [grant number: CTM2016-77212-P], Spain’s Ministry of Science and Education [grant number: PID2020-120313 GB-I00/AIE/10.13039/501100011033], and the Basque Government’s Department of Education for the consolidation of research groups [grant number: IT1633-22]. Professor L. N. López de la Calle is acknowledged for his assistance with the copper samples

Metal Extraction and Recovery from Mobile Phone PCBs by a Combination of Bioleaching and Precipitation Processes

Bearing in mind the metal rich composition of printed circuit boards (PCBs), this material represents a secondary source of valuable metals and offers an entrepreneurial opportunity in the metal sales market. Based on the ability of microorganisms to regenerate and produce the chemical oxidants that are responsible for metal leaching, bioleaching has become an efficient and affordable alternative to conventional metal recycling technologies, although further research is still necessary before industrial implementation. This study focuses on the recovery of metals contained in mobile phone PCBs through a combined process. Two different PCB pre-treatments were evaluated: grinding the whole piece and removing the epoxy cover from the piece without grinding. The benefit of A. ferrooxidans activity on the metal solubilization rate was analyzed. Additional chemical leaching assays were also conducted for comparison purposes and the reagents ferric iron (Fe3+) and sulfuric acid (H2SO4) were selected for these experiments. The copper extraction results obtained in Fe3+ experiments with and without bacteria (A. ferrooxidans) were similar after 260 h of operation, indicating the need for alternative strategies to ensure a controlled and continuous metal biodissolution rate. The contribution of H2SO4 to the leaching processes for copper and nickel was almost negligible during the first 50 h, and more significant thereafter. The recovered metals were precipitated from a synthetic solution simulating a real ferric leaching by adding sodium hydroxide (NaOH) and sodium sulfide (Na2S). The combination of both precipitants allowed an effective removal of metals from the leachate.The authors wish to acknowledge the financial support received from the State Agency for Research (AEI) of the Spanish Government and the European Regional Development Fund (ERDF, EU) [Project CTM2016-77212-P]. The University of the Basque Country UPV/EHU (Spain) [GIU18/118] is also acknowledged

Creating a Green Chemistry Lab: Towards Sustainable Resource Management and Responsible Purchasing

The main goal of this project was to improve the efficiency and sustainability of the chemistry teaching laboratories of the Faculty of Engineering Vitoria-Gasteiz (University of the Basque Country (UPV/EHU)). With this aim, three different actions were developed. The first two actions aspired to achieve and maintain order and maximize efficiency within the facilities. With this in mind, the first phase involved carrying out an inventory, classifying, and rearranging all the chemical products in the warehouse using a computer storage system. Secondly, 5S lean methodology was implemented in the laboratories. The final phase included the development of a protocol for a joint purchasing strategy of chemical reagents that fostered a more responsible and sustainable acquisition and management of the substances used in various departments of the UPV/EHU. This protocol plays a key role in the transition towards the Circular Economy and its importance lies in the fact that it could be extended to other departments and faculties with similar needs. This project was developed during last two academic years (2017/2019) in the frame of the Campus Bizia Lab Programme, an initiative created to address sustainability challenges within the University.This research was funded by the University of the Basque Country (UPV/EHU) in the frame of Campus Bizia Lab Programme (CBL-17GALL and CBL-18GALL)

Copper solubilization strategies for mold biomachining and bioleaching from printed circuit boards

274 p.En los últimos años, los fundamentos de la solubilización de metales a partir de minerales empleando microorganismos se han aplicado al biomecanizado de piezas y a la revalorización de residuos eléctricos. A pesar de que estas aplicaciones son prometedoras y presentan ventajas frente a otras tecnologías, todavía existe la necesidad de estudiar ciertos aspectos operacionales que permitan diseñar e implantar procesos mejorados a escala productiva. El principal objetivo de esta tesis es proponer estrategias que permitan mejorar el rendimiento de cara a dos aplicaciones concretas: el biomecanizado de moldes para la fabricación de dispositivos microfluídicos y la recuperación de metales a partir de placas de circuito impreso (PCI) de teléfonos móviles en desuso. Con el fin de optimizar el proceso y contribuir a incrementar su sostenibilidad, se ha seleccionado la concentración de oxidante más adecuada para el crecimiento bacteriano y la movilización de cobre, se ha diseñado un proceso semicontinuo basado en la alternancia de etapas de tratamiento y bioregeneración del oxidante y, finalmente, se ha estudiado la ventaja operativa que supone emplear biomasa inmovilizada.Este proceso ha sido satisfactoriamente aplicado al biomecanizado de moldes de cobre, partir de los cuales se han fabricado estructuras microfluídicas funcionales. Así mismo, la extracción de cobre a partir de PCIs ha sido más eficiente en el medio biológico que en medio químico. La recuperación de este metal a partir de las disoluciones residuales generadas en ambas aplicaciones permite reintroducir en la cadena de valor este preciado metal

Gorbeialdeko Hondakinen Partzuergoak kudeatutako hiri-hondakin solidoen errefusaren karakterizazioa

The following research work includes the proposed methodology and the results obtained for the characterization of the mixed waste fraction of the urban solid waste managed by the consortium of Gorbea Foothills in Alava. In order to conform the samples of urban waste analysed, the routes to be carried out by the trucks were designed, and for these two variables were taken into account: the season (winter and summer) and the area (urban, rural or chalets origin). The analyses carried out show that these two variables have an effect on the composition of the mixed waste fraction, especially on the two major fractions: organic matter and other residues. Within the fraction analysed, more or less 65 % of the waste could be recycled or reused. In gen-eral, all the samples analysed show a great improvement margin in terms of selective collection of organic matter.; Ikerketa-lan honetan Arabako Gorbeialdeako Hondakinen Partzuergoak kudeatzen dituen hiri-hondakin solidoen (HHSen) errefusa frakzioa karakterizatzeko proposaturiko metodologia eta lorturiko emaitza nagusiak jaso dira. Aztertu diren laginak osatzeko, bilketa kamioiek egin beharreko ibilbideak diseinatu dira, eta horretarako aldagai orokor bi kontuan hartu dira: sasoia (negua eta uda) eta etxebizitza-mota (herrialdea, baserrialdea eta txaletak). Egindako analisiek adierazi dute bi aldagai horiek eragina dutela errefusa frakzioaren konposizioan, eta batez ere errefusa osatzen duten bi frakzio nagusietan: materia organikoa eta bestelako hondakinak. Nabarmentzekoa da errefus masa totalaren %65 (gutxi gorabehera) birzikla edota berrerabil daitezkeen materialek osatzen dutela. Oro har, aztertutako lagin guztiek hobetzeko hein zabala dute materia organikoaren bilketa selektiboan