**1.9 Nanoparticles**

A nanoparticle or ultrafine particle is usually defined as a particle of matter that is between 1 and 100 nm in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions.


#### **Table 1.**

*Various types of nanoparticles dimensions.*

Nanotechnology is the technology of inventing, synthesizing, and applying materials on the nanoscale. Nanotechnology produces materials with some specific properties and functions, which are different types from their counterparts. Nanomaterials can be classified according to their size in the range of different dimensions [17] as mentioned in **Table 1**.

Nanoparticles have several advantages over their mass particles, such as surfaceto-volume ratio, which results in more significant heat treatment, better mass transfer paths, dissolution rate, and catalytic activity. In addition, nanoparticles have different functions and they are easy to function. Surface active sites have increased electrical, optical properties and improved absorption capacity.
