**1. Introduction**

Environmental degradation is attributable to improper industrial wastewater disposal, a situation that has caused serious contamination problems in many countries worldwide. Global consumption of potable water doubles every twenty years due to an exponential increase in world population (Han et al., 2009).

Industrial processes can create a wide variety of chemicals that pollute the air and water, with adverse impacts to ecosystems and humans. These impacts are caused by the polluting compounds that have toxic, carcinogenic, and also mutagenic properties (Busca et al., 2008). The treatment of wastewater containing phenolic compounds can be accomplished using applied principles of chemical oxidation, settling, membrane filtration, osmosis, ion, precipitation, and coagulation among other methods (Lin; Juang, 2009).

The treatment of hazardous wastes and reducing the presence of aqueous organic pollutants have placed focus on the use of alternatives to the standard environmental practices, such as the use of Advanced Oxidation Processes (AOPs), especially for the wastewater treatment (Segura et al., 2009).

AOPs are considered a highly effective means of water treatment contributing to the effective removal of organic pollutants that, otherwise, are untreatable whether are adopted the traditional methods (Oller; Malato; Sanchez-Pérez, 2011).

The study of riverine water quality by countries has recently become problematic due to the progressive scarcity of resources (Ongley, 1998). The monitoring water quality and making-

decisions based on qualitative data is a challenge for field researchers engaged in sample collection, storage, analysis, and the interpretations of results (Lermontov et al., 2008).

Multivariate Analysis in Advanced Oxidation Process 65

The treatment of hazardous waste and the presence of organic pollutants in water have increased the use of alternatives to environmental matrices such as the use of advanced

According to Kusic, and Koppivanac Srsan (2007), the high standard reduction potential of the hydroxyl radical enables the oxidation of a wide variety of organic compounds to CO2,

According to Domenech et al. (2001), hydroxyl radicals can be produced by various advanced oxidation processes and heterogeneous and homogeneous systems, divided into two groups: non-photochemical and photochemical processes. Table 2 shows the procedures

Compound E0 Reduction (V, 25 ºC)1

Fluorine(F2) 3,03

Hydroxyl Radical (•OH) 2,80 Atomic Oxygen (O2) 2,42 Ozone(O3) 2,07

Hydrogen peroxide (H2O2) 1,78 Radical Perhydroxyl (HO2•) 1,70

Hypochlorous acid (HCLO) 1,49

Chlorine dioxide 1,57

Chlorine (Cl2) 1,36 Bromine (Br2) 1,09 Iodine (I2) 0,54

With Irradiation Without Irradiation

O3/UV O3/H2O2 H2O2/UV O3/OH-H2O2/Fe2+/UV H2O2/Fe2+

\*Sc/O3/UV Eletro-Fenton

\*Sc/H2O2/UV - \*Sc/UV -

oxidation processes (AOPs) in the treatment of wastewater (Segura et al., 2009).

H2O and inorganic ions from heteroatoms.

1 Potential refers to the standard hydrogen electrode.

**Table 1.** Reduction potential of some compounds

**Table 2.** Exploited systems to produce hydroxyl radical

Source: Domenech et al. (2001)

Homogeneous Systems

Heterogeneous Systems

\*Sc: semiconductor (ZnO, TiO2, etc.)

Source: Morais (2005)

described above for the production of the hydroxyl radical.

This study demonstrates the application of Multivariate Analysis (MA) in effluent treatment of polyester resin by using advanced oxidation processes (heterogeneous photocatalysis - UV/TiO2). Exploring the relationship between methodologies and computational chemistry, the use of MA can modify the industrial processes and simplify experimental conditions, with a consequent improvement of processes, products, and the resolution of environmental issues.
