Globally, environmental challenges have been recognised as a matter of concern. Among these challenges are the reduced availability and quality of drinking water, and greenhouse gases that give rise to change in climate by entrapping heat, which result in respirational illness from smog and air pollution. Globally, the rate of demand for the use of freshwater has outgrown the rate of population increase; as the rapid growth in town and cities place a huge pressure on neighbouring water resources. Besides, the rapid growth in anthropogenic activities, such as the generation of energy and its conveyance, release carbon dioxide and other greenhouse gases, warming the planet. Polymer nanocomposite has played a significant role in finding solutions to current environmental problems. It has found interest due to its high potential for the reduction of gas emission, and elimination of pollutants, heavy metals, dyes, and oil in wastewater. The revolution of integrating developed novel nanomaterials such as nanoparticles, carbon nanotubes, nanofibers and activated carbon, in polymers, have instigated revitalizing and favourable inventive nanotechnologies for the treatment of wastewater and gas separation. This review discusses the effective employment of polymer nanocomposites for environmental utilizations. Polymer nanocomposite membranes for wastewater treatment and gas separation were reviewed together with their mechanisms. The use of polymer nanocomposites as an adsorbent for toxic metals ions removal and an adsorbent for dye removal were also discussed, together with the mechanism of the adsorption process. Patents in the utilization of innovative polymeric nanocomposite membranes for environmental utilizations were discussed.

In many parts of the world, the availability of clean water is almost an impossible task owing to the intrusion of contaminants in flowing or stagnant streams which renders them unsafe for use by man. Water pollution is a serious environmental problem that poses serious dangers to humans, the environment and aquatic life. Also, the recent rise in the spate of emerging contaminants as well as bacteria in waters recovered from process streams, manufacturing and other production activities, have resulted in unforeseen consequences including environmental pollution, health related sicknesses (diarrhoea, dysentery, cholera, skin irritations, lung infection, etc.) as well as loss and extinction of aquatic lives, hence, the need to consider viable methods of treating waste waters so as to render them safe for use by these organisms. This will in turn preserve life below water- SDG 14 as well as promote the use of clean water and a healthy environment- SDG 6. Among the several existing nanotechnologies tailored towards the treatment of wastewater, a couple of inorganic toxic nanomaterials/nanosubstances have been adopted which render such treated waters as potential risks to humans and aquatic lives. However, green nanoparticles are considered potent and viable means of treating these waters, especially when literature has it that some nanomaterials are toxic in nature. Furthermore, the paper also reports on some unpopular but very potent emerging green nanomaterials, alongside recent advances, applications, related challenges and ways to address them. Information on future prospects of green nanoparticles as potential long-term sustainable water purification and wastewater treatment technologies are also included; therefore, this study is focused on addressing issues related to SDGs 3 (ensure healthy lives and promote wellbeing), 6 (clean water and sanitation), 12 (responsible consumption and production) and 14 (life below water).