Multifunctional Nanocomposites for Environmental Remediation

Abstract

The ever-increasing disposal of municipal solid waste (MSW) has caused serious environmental problems in the past few decades. Landfilling, incineration, and recycling are currently the major options for MSW treatment. However, landfilling poses environmental risks due to the chemical inertness of plastics and limited available space, a serious drawback of this method. Incineration, not widely used primarily because of the potential generation of toxic gaseous products and ash, only shifts a solid waste issue to an air pollution problem. Recycling plastic waste yields great benefits in terms of environmental concerns and economic feasibility, which include reducing the need for landfilling and incineration, preventing the pollution caused by the manufacturing of products from raw materials, decreasing greenhouse gas emissions, and conserving natural resources such as timber, water, and minerals. Much more effort is still required to recycle plastics due to the very low recycling rate for some types of plastic wastes. For instance, polypropylene accounted for 13.6% of the total plastic waste in the United States in 2000, but only about 0.3% was recycled. Being aware of the current challenges in recycling plastic wastes, how to efficiently recycle polymer nanocomposites (PNCs) becomes even more challenging due to complex components and unpredictable degradation species with the existence of nanofillers. In this chapter, a comprehensive and sustainable waste-free process of PNC recycling will be discussed in which magnetic carbon nanocomposites (MCNCs) decompose and produce useful chemical species that can be utilized as feedstock in the petrochemical industry. Moreover, these MCNCs can serve as novel adsorbents with large adsorption capacity and high removal efficiency to remove heavy metals such as Cr(VI) from wastewater. Large saturation magnetization (32.5 emu/g) of these novel MCNCs allows fast recycling of both the adsorbents and the adsorbed Cr(VI) from liquid suspension in a more energetically and economically sustainable way by simply applying a permanent magnet. The high kinetics of the treatment to remove Cr(VI) makes these MCNCs promising for efficient removal of heavy metals from wastewater. In addition to the aforementioned MCNCs, other multifunctional nanocomposites, including conducting polymers and graphene nanoplatelets, will also be discussed as nanocomposite matrix choices, especially with regard to their application to the remediation of heavy metals and arsenic species from water resources. Kinetics and related mechanisms will be elaborated as well. In summary, the synergistic process and advantages of applying multifunctional nanocomposites to environmental remediation including solid wastes, heavy metals, arsenic, and organic dyes are backed and confirmed by the sound research work published by our team and others in this chapter.