Nanoparticles as Sorbents for Removal of Heavy Metal Ions from Aqueous Solutions - Nanotechnologies for Water Environment Applications - page 137

CHAPTER 6

Nanoparticles as Sorbents for Removal of Heavy Metal
Ions from Aqueous Solutions

K.H. Wee and Renbi Bai

6.1

Introduction

6.1.1 Heavy Metal Pollution

Environmental pollution remains an important issue attracting great global
attention despite many efforts being put in place worldwide. As a result of massive
anthropogenic activities, numerous harmful substances have been released from
unsustainable industrial hubs, agriculture and municipalities into various fresh water
reservoirs, such as groundwater, lakes and rivers. Consequently, about 1 billion of the
world population has been reported to have no access to clean water supply (UNESCO-
WWAP, 2006). Besides, the modernized society also continues to put stress on current
water treatment and sanitation systems that have faced a challenge in providing a world
population of 2.6 billion with clean water. The situation deteriorates further due to the
increasing demand of clean water consumption as well as the rapid growth of the world
population.

The pollutants in water may include a wide spectrum of substances, such as
endocrine disrupters, anti-oxidants, plasticizers, heavy metals, fire retardants, insect
repellents, solvents, insecticides, herbicides, fragrances, food additives, drugs and
pharmaceuticals. Upon entering the surface and ground water, many of these harmful
pollutants, for instance atrazine, trihalomethanes, polychlorinated biphenyls and heavy
metals, would greatly burden the water treatment need and cause considerable concerns
over their long-term fate and transport in the environment (Schwarzenbach et al . , 2006).

In particular, the anthropogenic inputs of heavy metals, such as zinc, chromium,
nickel, lead, copper, cadmium, mercury to the aquatic environment could amount up to

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