Design and development of smart advanced materials and sustainable technologies for water treatment

Within the actual “One Health” perspective, the health and well-being of humans and other living species, together with the Earth ecosystems protection, are inextricably linked to clean water sources preservation. Unfortunately, because of anthropogenic activities, urbanization, expanding global population and climate changes, sources of safe and potable water are becoming less safe and more and more limited. In this scenario, significant attention has to be paid to more efficient and sustainable treatment/recycling/recovery of water (wastewater and underground water) for its reclamation and (re)use, in order to manage a global water shortage and the development of “water-smart” cities. Unfortunately, today conventional methods of wastewater treatment still lack in the removal of the so-called “emerging contaminants”, such as pharmaceuticals, cosmetics, pesticides, personal and home care products, organic dyes, etc.; actually, there is not a real and defined European legislation fixing their acceptable and allowed concentration limits in the environment. One of the most challenging tasks of the 21st century is therefore to develop new eco-friendly, sustainable, and economically-sound technologies to remediate the water from the presence of contaminants. In this regard, as discussed in the First Chapter, nanotechnologies and new advanced nanostructured materials represent the potential for the development of green and smart products/techniques for a wide series of sustainable applications, as well as environmental remediation and waste/underground water treatment. The research activity of this PhD thesis aims to explore the design and synthesis of smart, nano/micro-structured hybrid materials opportunely functionalized and blended with suitable (bio)polymers with the aim to develop by means of different synthetic and deposition techniques, new sustainable solutions and technologies useful in the landscape of the water remediation from emerging contaminants. The main goal of these studies, as described in the three Chapters 2−4, is to investigate and evaluate the effect of different hybrid, polymeric and organic additives to implement and tune the properties of the final systems, obtained as powders, beads and membranes. In particular, this thesis explores the proper design and synthesis of the functional additives, the final adsorbent/filtering material preparation, the chemical-physical-mechanical-morphological characterization techniques and, in particular, their application and test, as systems for the treatment of contaminated water. In particular, the Second Chapter concerns the design and development of sustainable bio-polymeric blends based on polyamide 11 and chitosan biopolymers and doped with functional hybrid halloysite derivatives, employed to produce different electrospun nanofiber membranes and composite membranes through electrospinning technique. Their retention performances towards two model organic dyes are investigated through a dead-end filtration cell. The Third Chapter focuses on the use of secondary-raw bio-based materials and natural waterborne sources for the development of innovative cellulose-derived opportunely functionalized products, which are employed as dopant agents for water-based polyvinyl alcohol solutions and to obtain different electrospun nanofiber composite membranes. The developed bio-based and eco-friendly membranes are tested in a dead-end filtration cell for the gravity-driven removal of two model organic dyes. The Fourth Chapter refers to the design and development of new polyether sulfone smart blends by its combination with new innovative smart polymers combining the responsiveness of poly[2-(dimethylamino)ethyl methacrylate] polymer and the host-guest properties of the covalently linked pillararene macrocycles. The systems in the form of functional beads are tested towards the selective adsorption of two model organic dyes, i.e. MO and MB, whose kinetics and performances were studied. The described results (see Chapter 5) emphasize how important it is to develop materials with implemented mechanical, thermal, and different pollutant retention properties, through the rational design of the starting polymeric blends with appropriate nano, micro-fillers, or functional doping agents. The bio-based or water-based formulations, obtained within this PhD thesis, could open the way to the employment of innovative and sustainable nanotechnological approaches for the development of proof-of-concept, PoC, filtration membranes to be employed for real-case treatment and commitment of industrial, municipal, agriculture and other wastewaters, as well as contaminated groundwater reserves, thus rationally and more efficiently substituting the traditional fossil-based filtration technologies. Finally, thanks to the presence of the Industrial Supervisor, and the interest of stakeholder and startup belonging to the Environmental Technology sector, these advanced products and technologies could be scale-up into large-scale industrial applications framework.