**5. Solar treatment for carbamazepine**

The carbamazepine (CBZ) is widely used as antiepileptic and mood stabilizer, worldwide, and the consumption is about 1014 ton year<sup>−</sup><sup>1</sup> . The CBZ shows high stability and low biodegradability, and the removal percentage for conventional water treatment process is less than 10%. Almost all consumed CBZ is discharged as sewage in the water environment causing adverse effects on the surface water quality, ecosystem, and human health [6].

The CBZ photodegradation process catalyzed by TiO2 and ZnO nanoparticles generates three derivatives: carbamazepine epoxide, acridine, and acridone. TiO2 is effective in degrading CBZ and carbamazepine epoxide. Considering the acridine and acridone, no significant differences were found between those two catalysts. The CBZ and carbamazepine epoxide photodegradation was affected by pH (especially in the presence of TiO2 as NPs) and natural organic matter [7]. In contrast, the acridine and acridone photodegradation was not affected by pH and organic matter. The TiO2 and ZnO catalysts present contrasted efficiency on CBZ decomposition when compared with its derivatives and the effect of environmental parameters on the CBZ as photodegradation efficiency of the derivatives' presence cannot be predicted based only on the parent molecule (CBZ) behavior. The indication of higher degradation efficiency was for higher initial concentrations with a degradation rate of 52 times greater than for lower initial concentrations, and the kinetics corresponds to pseudo-second-order.

The negatively charged CBZ is due to the presence of the amide bond, and the exposed surface of the semiconductor positively charged enhances the surface adsorption processes. The proton adsorption also improves the effectiveness of the catalyzed reaction under visible light radiation, promoting long-term stability and the catalyst reusability. The visible-light-driven photocatalytic activity enhancements are the synergetic effects, including a large absorption capacity, the promotion of the light harvestability, and high separation efficiency of photogenerated e<sup>−</sup> and h+ pairs.

The use of some scavengers as AgNO3 <sup>−</sup> for e<sup>−</sup>, HCOONa for h<sup>+</sup> , and butanol for ˙OH (radical) and the N2 purging to detect the function of O2 elucidate the main active species involved in the photodegradation process. The addition of NaHCO2 reduces the decomposition in 18% as an indication of the importance of the h+ radical in the reaction. The addition of n-butanol or N2 purging showed no different reaction efficiency; this effect implied the addition of O2 produces the ˙O2 radicals and increases the CBZ degradation confirming the domination of the degradation process by oxidation step with the ˙O2 <sup>−</sup> radical generation and partly by the direct h+ oxidation process.

The CBZ (A) oxidation reaction results in four intermediaries B, C, and D. The compounds B, C, and D are intermediaries with high decomposition rate (**Figure 1**). The attack of the CBZ oleofinic bond in a central heterocyclic ring forms compound B. The generation of radicals and the oleofinic bond of CBZ decomposed in C and D. The compound C uses a ring contraction reaction followed by an intramolecular cyclization mechanism resulting in intermediate compound F. Finally the formation of compound G was by intramolecular cyclization mechanism of compound D.

The primary concern about the pharmaceutical photodecomposition is the possible formation of the toxic intermediate and by-products. The literature cited as possible toxic intermediates for CBZ photodecomposition, the CBZ-10, 11-epoxide,

**73**

2–3 mg L <sup>−</sup><sup>1</sup>

**Figure 1.**

mineralization and proper discharge.

*The Carbamazepine degradation by-products.*

**6. Solar photodecomposition of hormones**

tertiary treatment study and photodecomposition improvement [8].

*Green Water Treatment for Pharmaceutical Pollution DOI: http://dx.doi.org/10.5772/intechopen.85116*

and acridine. The photodecomposition optimization indicates BiOCl removed about

The 17β-estradiol (E2) is the most natural estrogenic hormone occurring in sewagepolluted waters and also an intermediate key in the industrial synthesis of other estrogens. It is frequent in natural water environment with the high potential to hormonal disruption pathways in wildlife even in low nanogram concentrations. Recently, it was added to the watch list of priority substances in the EU Water Framework Directive. Many research projects use E2 as representative of emerging pollutant (EP) for water

There are many studies of immobilized TiO2-based composites, TiO2- and iron-exchanged zeolite of ZSM5 type (TiO2-FeZ), or another semiconducting material (TiO2-SnS2) and active solar photocatalysts. The solar-driven photocatalytic parameters as pH values, H2O2 concentration, and composite formulation, on the effectiveness of E2 degradation, allow the calculation of the surface modeling. The solar/TiO2-FeZ/H2O2 process achieved E2 degradation by 78.1%; it was higher in comparison with the reference process of TiO2 P25 with 41.3% of remotions and

intermediaries. Always there will be the possibility to keep the photodecomposition reaction for a longer time of solar radiation. The recommendation is the use of adsorbent material, and after the absorption, removing the pharmaceuticals from the reaction media, and the photodecomposition reaction can keep continuing until

of CBZ after 150 min of solar irradiation, more than 78% of no toxic

*Green Water Treatment for Pharmaceutical Pollution DOI: http://dx.doi.org/10.5772/intechopen.85116*

*Green Chemistry Applications*

mance catalyst for dye wastewater treatment.

**5. Solar treatment for carbamazepine**

quality, ecosystem, and human health [6].

corresponds to pseudo-second-order.

The use of some scavengers as AgNO3

process by oxidation step with the ˙O2

oxidation process.

worldwide, and the consumption is about 1014 ton year<sup>−</sup><sup>1</sup>

mixtures with Ag2O indicates no apparent photoreduction of Ag2O, and the solid material still consisted of pure Ag2O and can be used consequently as a high-perfor-

The carbamazepine (CBZ) is widely used as antiepileptic and mood stabilizer,

The CBZ photodegradation process catalyzed by TiO2 and ZnO nanoparticles generates three derivatives: carbamazepine epoxide, acridine, and acridone. TiO2 is effective in degrading CBZ and carbamazepine epoxide. Considering the acridine and acridone, no significant differences were found between those two catalysts. The CBZ and carbamazepine epoxide photodegradation was affected by pH (especially in the presence of TiO2 as NPs) and natural organic matter [7]. In contrast, the acridine and acridone photodegradation was not affected by pH and organic matter. The TiO2 and ZnO catalysts present contrasted efficiency on CBZ decomposition when compared with its derivatives and the effect of environmental parameters on the CBZ as photodegradation efficiency of the derivatives' presence cannot be predicted based only on the parent molecule (CBZ) behavior. The indication of higher degradation efficiency was for higher initial concentrations with a degradation rate of 52 times greater than for lower initial concentrations, and the kinetics

The negatively charged CBZ is due to the presence of the amide bond, and the exposed surface of the semiconductor positively charged enhances the surface adsorption processes. The proton adsorption also improves the effectiveness of the catalyzed reaction under visible light radiation, promoting long-term stability and the catalyst reusability. The visible-light-driven photocatalytic activity enhancements are the synergetic effects, including a large absorption capacity, the promotion of the light harvestability, and high separation efficiency of photogenerated e<sup>−</sup> and h+

˙OH (radical) and the N2 purging to detect the function of O2 elucidate the main active species involved in the photodegradation process. The addition of NaHCO2 reduces the decomposition in 18% as an indication of the importance of the h+ radical in the reaction. The addition of n-butanol or N2 purging showed no different reaction efficiency; this effect implied the addition of O2 produces the ˙O2 radicals and increases the CBZ degradation confirming the domination of the degradation

The CBZ (A) oxidation reaction results in four intermediaries B, C, and D. The compounds B, C, and D are intermediaries with high decomposition rate (**Figure 1**). The attack of the CBZ oleofinic bond in a central heterocyclic ring forms compound B. The generation of radicals and the oleofinic bond of CBZ decomposed in C and D. The compound C uses a ring contraction reaction followed by an intramolecular cyclization mechanism resulting in intermediate compound F. Finally the formation of compound

The primary concern about the pharmaceutical photodecomposition is the possible formation of the toxic intermediate and by-products. The literature cited as possible toxic intermediates for CBZ photodecomposition, the CBZ-10, 11-epoxide,

G was by intramolecular cyclization mechanism of compound D.

<sup>−</sup> for e<sup>−</sup>, HCOONa for h<sup>+</sup>

<sup>−</sup> radical generation and partly by the direct

stability and low biodegradability, and the removal percentage for conventional water treatment process is less than 10%. Almost all consumed CBZ is discharged as sewage in the water environment causing adverse effects on the surface water

. The CBZ shows high

pairs.

, and butanol for

**72**

h+

**Figure 1.** *The Carbamazepine degradation by-products.*

and acridine. The photodecomposition optimization indicates BiOCl removed about 2–3 mg L <sup>−</sup><sup>1</sup> of CBZ after 150 min of solar irradiation, more than 78% of no toxic intermediaries. Always there will be the possibility to keep the photodecomposition reaction for a longer time of solar radiation. The recommendation is the use of adsorbent material, and after the absorption, removing the pharmaceuticals from the reaction media, and the photodecomposition reaction can keep continuing until mineralization and proper discharge.
