Nanoparticles and nano-sized materials created by nanotechnology (NT) have been considered unique and sole solutions to overcome the limitations of other technologies and widen their applications. Although these materials have been widely used in environmental technology (ET), most environmental applications of nanoparticles were limited to the fabrication of nano-sensors for the detection of volatile organic compounds (VOC) and as nano-sized catalysts for air purification systems. As a result, the use of nanoparticles for the direct removal of pollutants from contaminated soil and wastewater has seldom been reported. However, environmental processes for soil remediation, wastewater treatment, and air purification strongly need innovative new materials to highly improve their performance and efficiency. So, demands for materials created by NT in ET are stronger than ever.