**4. Advanced oxidation process**

Advanced oxidation processes UV/TiO2, UV/H2O2, UV/H2O2/Fe, O3, O3/Fe, O3/TiO2, UV-O3/H2O2/Fe, are widely used in the degradation of effluents. These processes are characterized by the generation of free radicals in the organic matter degraded, and so are the polluting compounds mineralized or they are converted into a lower-chain or a less harmful process, in order to be subjected to a biological treatment subsequently (Thiruvenkatachari et al., 2007).

Oxidation processes are based on the generation of reactive species such as hydroxyl radical (OH). These radicals are highly reactive, non selective and may be used to degrade a wide range of organic pollutants. The OH radical is unstable and must be continuously generated *in situ*, by chemical or photochemical (Oliver; Hyunook; Pen-Chi, 2000). Table 1 shows reduction potential of various chemicals, and it can be observed that after fluorine, the hydroxyl radical is the one with higher oxidation potential (Domènech et al., 2001).

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

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, H2O and inorganic ions from heteroatoms.

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 described above for the production of the hydroxyl radical.


1 Potential refers to the standard hydrogen electrode. Source: Domenech et al. (2001)

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


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

Source: Morais (2005)

64 Multivariate Analysis in Management, Engineering and the Sciences

non-renewable sources (Abrafati, 1995; Weiss, 1997).

significant amount of solvents (Metcalf; Eddy, 1991).

**4. Advanced oxidation process** 

(Thiruvenkatachari et al., 2007).

impact of these industries on ecosystems (Nedhi; Sumner, 2003).

**2. Polyester resin** 

**3. Dye industry** 

decisions based on qualitative data is a challenge for field researchers engaged in sample

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.

Polyesters and alkyd resins represent a class of polymers used in the manufacture of solvent-based paints due to the reduced cost and its versatility. These resins are the condensation products of polyols (e.g., glycerol, pentaerythritol), polybasic acids or their anhydrides (most phthalic anhydride) and monobasic fatty acids or oils. The term is typically restricted to polyester resins with acid or hydroxyl functional groups, which are relatively free of oil mixtures. The alkyd resins, a type of polyester resin, can be synthesized from renewable resources, i.e., vegetable oils as soybean oil, but most oils are coming from

Effluents from industries are highly complex dyes so they are not treated by conventional methods. Alternative matrices; AOPs; have been used to minimize the environmental

Industrial waste is classified into three main categories: wastewater, solid waste and air pollutants. Greater attention is given to wastewater since studies revealed content of

Advanced oxidation processes UV/TiO2, UV/H2O2, UV/H2O2/Fe, O3, O3/Fe, O3/TiO2, UV-O3/H2O2/Fe, are widely used in the degradation of effluents. These processes are characterized by the generation of free radicals in the organic matter degraded, and so are the polluting compounds mineralized or they are converted into a lower-chain or a less harmful process, in order to be subjected to a biological treatment subsequently

Oxidation processes are based on the generation of reactive species such as hydroxyl radical (OH). These radicals are highly reactive, non selective and may be used to degrade a wide range of organic pollutants. The OH radical is unstable and must be continuously generated *in situ*, by chemical or photochemical (Oliver; Hyunook; Pen-Chi, 2000). Table 1 shows reduction potential of various chemicals, and it can be observed that after fluorine, the

hydroxyl radical is the one with higher oxidation potential (Domènech et al., 2001).

collection, storage, analysis, and the interpretations of results (Lermontov et al., 2008).

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