**1.2. Nanofiber application methods**

**1. Introduction**

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**1.1. Nanotechnology to fibers**

pore distribution, fiber evenness, cross-sectional shapes, etc.

**Figure 1.** Comparison of nanofibers to conventional standard fibers.

Section 4 provides commentary for future applications.

Nanotechnology is a new technology which can make an ultimately fine material such as a fiber (see Figure 1) by controlling atoms and molecules as small as 10−9 m in size, and this technology can be widely used in many industrial situations. Among the many possible nanoproducts, nanofibers could be controlled for fiber length, diameter, surface properties,

Nanofibers are one of the most advanced materials which can be easily designed with highperformance materials having distinctive properties. New geosynthetic materials which have separation, filtration, and absorption functions and are specifically made could be developed in the field of geoenvironmental applications.(*Koerner, R. M., 2005*) In addition to fibers, nanoparticles (such as nanoclay) can be used to make unique formulations, which can, in turn, be used to make conventional fibers for geotextiles and yarn-type geogrids. As an example of nanocomposite geosynthetics in geoenvironmental applications, it is very important to eliminate the toxic and organic components of various waste leachate solutions. Such capa‐ bility is not found in the standard manufactured nonwoven geotextiles and hence the func‐ tional nonwoven geotextiles need to be manufactured which can absorb the toxic and organic

It is possible to manufacture these types of functional nonwoven geotextiles by using nano‐ technology. Section 2 describes nanofiber technology to gain insight into extremely small-scale manufacturing. Section 3 describes the objective of this study that introduces nanoclay into a polymeric formulation to manufacture a geotextile for use in geoenvironmental applications.

components that may be harmful to personal health and the environment.

Figure 2 shows various aspects of nanofiber manufacturing technology and productivity of nanofibers where it is seen that mass production of nanofibers is possible by modified electrospinning. Electrospinning is the general method used to manufacture nanofibers, which is similar to the melt-blown method, but the current problem is to increase mass productivity.

**Figure 2.** Fiber manufacturing technology and productivity.

In general, regular fibers are widely used to manufacture geotextiles and yarn-type geogrids, but filtration efficiency of microfibers and nanofiber geotextiles would be better than the standard fiber used to manufacture conventional geotextiles. To be considered, it is expected that nanofiber geosynthetics could provide the sustainable filtration function in geoenviron‐ mental applications by their composition structure as shown in Figure 3. If the numbers of filled fibers per unit area increases, the pore size among nanofibers is decreased. Therefore, fine pollutants cannot pass through pores made by nanofibers and the filtration efficiency will be improved. This means that ultrathin geosynthetic filters can be manufactured having a highquality filtration function to absorb fine impurities and toxic components in both polluted water media and polluted air media (Figure 4). Figure 5 shows the separation concept of a nanofiber air filter by pressure. To optimize this air filter, a higher particle collection and dust retention rate are required. Therefore, hybrid-type air filters must be the optimum, and Figure 6 shows such fiber materials versus fiber length. For hybrid membrane technology (HMT) and expanded PTFE materials, nanofiber layers are accumulated above the general fiber materials as a hybrid material. This is the important result of larger specific adsorption area in the surface of geosynthetics. Figure 7 shows the relationship between separation fields and separation membranes using fiber-related nanotechnology.

**Figure 3.** Fiber filling between microfiber and nanofiber per unit area.

**Figure 4.** Effect of using a nanofiber geotextile filter.

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**Figure 5.** Maintenance of filtration efficiency for nanofiber filters.

**2.5x109/cm2 2.5x105/cm2**

**1cm 1cm**

**Figure 3.** Fiber filling between microfiber and nanofiber per unit area.

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**Figure 4.** Effect of using a nanofiber geotextile filter.

**Figure 6.** Comparison of fiber diameter and surface area using nanofiber and other fibers.

**Figure 7.** Relationship between separation fields and separation membranes using nanotechnology.
