Metal oxide nanomaterials are unique materials due to their electronic structure and optical, electronic, and magnetic properties. In addition, the ability to create nanomaterials with a given structural and phase organization makes it possible to obtain a wide variety of functional products due to the possibility of controlling the size and morphology of particles, specific surface features and porosity, acid-base characteristics, and surface chemistry. This is especially important when creating environmental nanomaterials, such as adsorbents, heterogeneous catalysts, membranes, and antibacterial agents, as well as sensors for water quality monitoring. Particular attention when creating new metal oxide nanomaterials should be given to their safety, design, and reusability.

It is expected that the use of nanomaterials will allow for the development of non-reagent green technologies for water purification, which will be more efficient and less energy consuming; both very important for sustainable water treatment technologies. It is also equally important to create closed and technologically innovative water treatment systems that will change the methods of water treatment, distribution and usage, and, ultimately, water reusage. The development of such approaches will create high-performance, safe and sustainable water treatment technologies.

The purpose of this Special Issue is to present original research and review articles on the synthesis of metal oxide nanomaterials with desirable properties, their effective application in water treatment technologies and their environmental safety, which will lead to the creation of sustainable water treatment technologies and water quality monitoring. Particular attention is paid to green methods of synthesis of metal oxide nanomaterials and technologies that will be safe, closed, and sustainable in management of water treatment and water treatment systems.

Potential topics include but are not limited to the following:

• New routes for the synthesis of metal oxide nanomaterials for environmental purposes based on green chemistry principles
• Study of the effect of particle sizes, their morphology, specific surface area, porosity, and surface chemistry on the adsorption and catalytic properties of metal oxides
• Strategies for the sustainable reuse of metal oxide nanostructured adsorbents, heterogeneous catalysts, membranes, and other multifunctional materials
• Features of the synthesis of antibacterial agents for use in water treatment
• Development of sensors for the continuous monitoring of water quality based on metal oxide nanomaterials
• Innovative new high-performance closed water treatment systems using metal oxide nanomaterials
• Development of safe and sustainable features of current and new water treatment technologies
• Case studies or applications of metal oxide nanomaterials for water treatment
• Comprehensive and critical reviews on the application of metal oxide nanomaterials for water treatment