**Application of Heterogeneous Catalysts in Dechlorination of Chlorophenols**

Fuchong Li, Yansheng Liu, Linlei Wang, Xu Li, Tianqiong Ma and Guangbi Gong

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.79134

#### **Abstract**

Chlorophenols (CPs) is a very important kind of basic organic chemical intermediates such as sanitizers, germicides, insecticides and so on; but CPs also constitutes a particular group of priority pollutants that widely distribute in wastewater and the polluted groundwater. Because of their acute toxicity, persistence and low biodegradability, their emissions have been progressively restricted by strong legal regulations. In this chapter, we focused on methods for degrading of CPs recent years, especially by using new heterogeneous catalytic hydrogenation methods to the dechlorination of CPs. The purpose is to introduce scientific research workers and companies to waste water treatments in order to inspire and further better protect the environment.-

**Keywords:** heterogeneous catalysts, dechlorination, chlorophenol, core-shell, environment

#### **1. Introduction**

The global water storage is up to 1.45 billion cubic kilometers (**Figure 1**), but the number of water storage can be produced and used directly by people is very less. Water is widely used in industries, agriculture, homes and so on, but keeping water quality becomes a major challenge for the coming decades. There are many factors that cause water damage. Industrial wastewater, agricultural wastewater, and domestic wastewater may be the main pollution sources (**Figure 2**).

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Figure 1.** Beautiful earth.

**Figure 2.** Chemical pollution is the largest source of pollution.

The development of chemical technology growing changed our lives. More and more food, medicine, cars, and appliance made by industries come to our lives. However, pollution problems were generating while we are enjoying our lives. Not only polluting the water and the air, but also seriously polluting the people's physical and health. Solving and treating the toxic organic compounds in wastewater are becoming an important project and research in recent years. It is becoming an important things for the government, companies, and academic research [1].

Chlorophenols (CPs) constitute a series of common organic compounds and intermediate involved in industrial processes such as fungicides, insecticides and dye precursors [2]. Chlorophenols (CPs) are also used in preservatives, papermaking and cosmetics industries. But because of acute toxicity, persistence and low biodegradability, chlorophenols especially such as chlorophenol, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and 5-chlorophenol are highly toxic substances [3]. Their emissions have been progressively restricted by strong legal regulations. (Most chlorophenol compounds can interfere with endocrine, may cause cancer, cell mutations or teratogenesis, are almost non-biodegradable and difficult- to remove from the environment. Therefore, they are a list of priority control pollutants by the US Environmental Protection Agency (EPA) and China Environmental Monitoring Center.)

In fact, chlorophenols and their derivatives may be produced by the chlorination of phenols. The phenol reacts with chlorination in the presence of high concentrations of chlorine and the toxicity of chlorophenols increases with its degree of chlorination and usually are difficult to degrade. These chlorophenols released into the natural environment can cause serious pollution, especially causing water pollution.

Conventional wastewater treatment based primarily on biological processes are not very efficient for the treatment of toxic or non-biodegradable and high-concentration wastewaters. Therefore, in order to protect our environment, it is necessary to develop efficient technologies for treating organic wastewater containing chlorine.
