As modern civilization progresses, several types of pollutants are released into the environment as a result of human and industrial processes. There are many air pollutants, such as particulate matter (PM2.5, particles with a diameter of 2.5 μm or less; PM10, particles with a diameter of 10 μm or less), gases (carbon dioxide, CO2; carbon monoxide, CO; formaldehyde, HCHO), biological molecules (bacteria, viruses), and so forth. Meanwhile, severe water pollution containing organic dyes and pesticides, inorganic metal ions, and biological pollutants (bacteria, viruses, and algae) are widespread. Environmental pollution and the energy crisis are thwarting society's long-term growth and have a negative impact on the world's quality of life.

Remediation of the environment has grown exceedingly challenging. In 2017, the United Nations set out an urgent call for action for all countries in its Sustainable Development Goals, recognizing that ending poverty goes hand-in-hand with improving health, the environment, and the economy to reduce inequality in all areas. Nanotechnology delivers revolutionary, game-changing discoveries and inventions that may bring solutions to aid our society and planet. Energy, environmental protection, resource management, and healthcare are among the areas where nanotechnology breakthroughs are making a difference through the creation of smart materials and linked devices. Practical and environmentally benign technologies for nanomaterials synthesis are a vital milestone. Top-down and bottom-up techniques are used in the biosynthesis of nanoparticles. Chemical, biological, and physical processes are used to synthesize these nanoparticles. These approaches require hazardous substances, harsh environments, and specialized instrumentation. Biological methods are more cost-effective and eliminate the use of such harmful substances. Due to the many uses of nanomaterials, nanotechnology is a tremendously popular subject of research that covers practically all technological fields. Nanomaterials can be prepared from a variety of sources, including plant/agricultural/household waste, polymers, metals, waste plastics, and so on. This will aid in the achievement of the SDGs as well as the circular economy (CE).

The aim of this Special Issue is to publish the most recent findings in the field of green/sustainable nanomaterial synthesis and its applications in environmental and medicinal domains. We seek review articles and original research on these topics, with a focus on long-term sustainability.

Potential topics include but are not limited to the following:

• Functionalization of metal/metal oxide NPs with organic/inorganic components for photocatalysis, antimicrobial, heavy metal ion sensing
• Sustainable synthesis of nanomaterials using plant materials, microorganisms, bacteria, algae, and various biowastes, including vegetable waste, fruit peel waste, eggshell, agricultural waste
• Core-shell/bimetallic nanomaterials for water purification and biological applications
• Carbon-based nanomaterials for environmental and biological applications
• Polymer and based nanomaterials
• Waste to wealth materials
• Toxicity assessment of nanomaterials Role of nanotechnology/nanomaterials to attain sustainable development goals and circular economy
• Antimicrobial, anticancer applications
• Nanosafety measures