Water is one of the main problems of humanity. It is vital to identify new methods to purify water and to decontaminate and reuse wastewater, at lower costs than current ones, and minimizing the use of energy, the use of chemical agents, and the environmental impact of the decontamination process itself.
Solar photocatalysis has shown enormous potential for the disinfection and detoxification of wastewater. It is an environmentally benign and sustainable process, which makes use of minimal energy and material resources, and which is capable of eliminating both microorganisms and persistent organic compounds, without introducing chemical agents or additional toxic substances. The process allows the total elimination of pollutants (mineralizing them to CO 2 and water), with a minimum production of sludge or other by-products, the elimination of which represents an added problem in conventional treatment techniques.
Due to this great potential, demonstrators and pilot plants have been built which, however, have not reached commercial viability due to two fundamental barriers:
The lack of cheap, efficient photocatalysts that are easy to produce on a large scale. There are efficient photocatalysts, but they are synthesized by high cost processes, very difficult to industrialize and reproduce on a large scale, and require expensive and scarce materials. Current efficiency requires long photocatalyst-pollutant contact times and, therefore, long residence times in the photoreactor (> 1h) that are unfeasible in large-scale industrial treatment plants.
The difficulty of recovering the catalyst from the medium at the end of the process. Solar reactors keep the photocatalyst in suspension within the medium to be treated, and require expensive and complex processes to separate it after treatment.
The NANOBAC project aims to overcome these two barriers. It revolves around the development of new technologies for the large-scale production of nanostructured materials using low-cost, high-productivity techniques. The ultra-reactive faces doping and stabilization strategies will allow the obtaining of efficient materials, with accelerated degradation kinetics that reduce the residence time of the contaminants in the reactor, placing it at values compatible with profitable commercial exploitation. The technology aims to achieve the self-assembly of nanoparticles in larger, hollow and porous structures that allow easy separation of the reaction medium. Additionally, economic techniques for deposition and immobilization of the photocatalyst on various substrates will be developed, which allow the design of reactors based on impregnated walls, much simpler to operate.
With this starting photocatalyst, the design of a complete wastewater treatment system will be undertaken, based on an efficient and economical solar photoreactor. A system of commercial characteristics will be demonstrated, in which both the photocatalyst and the photoreactor will be multifunctional in nature, capable of fully degrading and mineralizing a wide range of contaminants.
The techniques developed have a strong transversal character. From the point of view of market orientation and commercial exploitation, the project can be considered articulated around two axes: a direct axis, which leads to the development of commercial wastewater treatment plants, operated by Alquimia, and an axis transversal, which will exploit the materials and production techniques developed at NANOBAC in all those markets that are directly accessible for the new photocatalyst material (associated with its low cost / high productivity manufacturing path). In the transversal axis, the construction markets (photocatalytic glass and ceramics for windows, coatings of buildings, and pavements), biomedical applications (especially biosensors), and energy (through the production of photocatalytic solar hydrogen), as well as others are attacked. Environmental applications other than water treatment: in particular, the treatment of confined atmospheres (eg aircraft cabins) and the purification of air in domestic applications are markets in strong growth, which demand an increasing amount of photocatalyst.