ABSTRACT
Figure 5.1 Number of annual patents on amphiphilic polymer nanoparticle related to pollutant removal technology. (Searched at US Patent Office, World Intellectual Property Organization (WIPO), European Patent Office and UK Patent Office; Key words: amphiphilic nanoparticle, water and hydrocarbon; Search on Oct. 30, 2009.)
received intensive interests from industries over the last couple of decades. Figure 5.1 shows that the number of patents on pollutant removal applications has increased exponentially and exceeded 50 articles in 2008. However, these polymers are very expensive and can be obtained only by extremely difficult synthetic processes, which make their practical application limited. In this chapter, a new ultrafiltration process is presented for removal of pollutants from water using designed amphiphilic polymer nanoparticles. 5.2 AMPHIPHILIC POLYMER NANOPARTICLE
as a nano-absorbentContamination of soil and groundwater by hydrophobic organic carbons (HOCs) is caused by leakage from storage tanks, spillage, or improper disposal of wastes. Once in the soil matrix, HOCs are a source of dissolved contaminants [19-23]. Among HOCs, polyaromatic hydrocarbons (PAHs) are of special interest because they are strongly sorbed onto soil or sediment. Consequently, sorbed PAHs may act as a long-term source of groundwater contamination. Many researchers have been using surfactants to enhance the desorption of sorbed PAHs from soil through solubilization of sorbed PAHs in surfactant micelles [24-31]. However, surfactant-enhanced remediation techniques have some disadvantages because of micelle breakage and loss of surfactant through sorption to soil. Therefore, surfactant-enhanced desorption and washing are effective only when the surfactant dose is much greater than its critical micelle concentration (CMC) [26-29, 32-34]. As a result, recent research has been directed toward the design of a surfactant that minimizes such losses and also toward the development of surfactant recovery and recycling techniques. Amphiphilic polymers, which have hydrophilic and hydrophobic moieties on the same carbon backbone, have been widely used in various fields. In fact, parallels can be drawn between typical surfactants and amphiphilic polymers, and both materials have been used as emulsifiers, dispersants, foamers, thickeners, rinse aids, and compatibilizers [35-37]. The CMC of amphiphilic polymers is extremely low and their dispersion efficiency is retained even at extremely high dilution, hence amphiphilic polymers can be used as an alternative for the removal of absorbed hydrophobic pollutants
from the soil. There are several types of amphiphilic polymers, such as nonionic, anionic, or cationic homopolymers, random copolymers, and diblock-copolymers. It has been generally recognized that amphiphilic block or graft copolymers are very effective and versatile. In this chapter, a new process is suggested for the enhanced desorption of sorbed phenanthrene (PAHs), which uses amphiphilic polyurethane (APU) nanoparticles that had been synthesized via soap-free emulsion polymerization of amphiphilic urethane acrylate nonionomer chains (UAN) or amphiphilic urethane acrylate anionomer chains (UAA). Unlike surfactant molecules that completely dissolve in water below its CMC, UAN and UAA chains cannot be dissolved in water but are just dispersed in water to form nano-aggregates (APU nanoparticles) even at extremely low concentrations, because whole UAN and UAA chains are insoluble in water.
