**2. Phenolic compounds**

In the last times, phenolic compounds have attracted a great interest, because they have several applications indispensable in our daily life. The phenolic compounds are present in adhesives, foams, emulsifiers and detergents, insecticides, dyes, explosives, flavors and rub‐ ber chemicals, self‐assembly to nanomaterials, resins and so on, in other different applica‐ tions. All these products have great economic importance in many industries such as food, medicine, petrochemical, agriculture, chemical synthesis and polymer chemistry, among oth‐ ers [1]. Thus, there is a great environmental interest in the removal of phenolic compounds. Phenolic compounds are among the most important contaminants present in the environ‐ ment. On the other hand, phenolic compounds are not only generated by human activity, but they are also formed naturally, the phenols are present in soils and sediments and therefore these compounds produce the contamination of groundwater. Some organizations such as the European Union and the US Environmental Protection Agency (EPA) have included as priority contaminants, some of the phenolic compounds due to their high toxicity and persis‐ tence in the environment [2]. The structures of eleven phenols considered priority pollutants by the EPA are shown in **Figure 1**.

**Figure 1.** Phenolic compounds structures considered priority contaminants by US EPA. Reprinted with permission from Mahugo‐Santana et al. [2]. Used under Creative Commons Attribution 3.0 Unported (CC BY 3.0) (https://creativecommons. org/licenses/by/3.0/).
