Photooxidation of bisphenol A (BPA) in water in the presence of ferric and carboxylate salts

In this work, the photooxidation of bisphenol A (BPA), a suspected endocrine disruptor (ED), in water in the presence of ferric and oxalate ions was investigated in a concentric reactor under a 125 W high-pressure mercury lamp (lambda> or = 365 nm). The photooxidation efficiencies were dependent on the pH values and ferric/oxalate concentration ratios (Fe(III)/Ox) in the water, with higher efficiency at pH 3.50+/-0.05 and Fe(III)/Ox 10.0/120.0 micromol l(-1). The initial rate of photooxidation increases with increasing the initial concentration of BPA from 2.0 to 5.0 mg l(-1) while do not change at 5.0 and 10.0 mg l(-1). However, higher removal efficiency of BPA is archived at lower BPA initial concentration over range of 2.0 to 10.0 mg l(-1). For 2.0 mg l(-1) BPA, the initial rate of photooxidation is 0.06 mg l(-1)min(-1). By using UV-Vis spectrum and LC-MS techniques, the predominant photooxidation product BPA-o-catechol was identified and the mechanisms for the oxidative degradation were proposed. When BPA reacted with OH radicals, C atoms in 3-position were added with OH radicals followed by O2 peroxidation and HO2 radical escape. Then catechol derivatives were produced. After that, the two H atoms on the hydroxy group were extracted in two individual steps to form intermediates semiquinone radical and o-quinone. The intermediates underwent further oxidation, benzene ring cleavage and decarboxylation, up to mineralization ultimately.     

Biodegradation of natural and synthetic estrogens by nitrifying activated sludge and ammonia-oxidizing bacterium Nitrosomonas europaea

This report describes the uses of nitrifying activated sludge (NAS) and ammonia-oxidizing bacterium Nitrosomonas europaea to significantly degrade estrone (E1), 17beta-estradiol (E2), estriol (E3), and 17alpha-ethynylestradiol (EE2). Using NAS, the degradation of estrogens obeyed first-order reaction kinetics with degradation rate constants of 0.056 h(-1) for E1, 1.3 h(-1) for E2, 0.030 h(-1) for E3, and 0.035 h(-1) for EE2, indicating that E2 was most easily degraded. Then, we confirmed that E2 was degraded via E1 by NAS. With/without the ammonia oxidation inhibitor, it was observed that ammonia-oxidizing bacteria in conjunction with other microorganisms in NAS degraded estrogens. Using N. europaea, the degradation of estrogens reasonably obeyed zero-order reaction kinetics, and no remarkable difference is present among the four estrogens degradation rates and it was found that E1 was not detected during E2 degradation period. We suggested that E2 was degraded to E1 in NAS could be caused by other heterotrophic bacteria, not by ammonia-oxidizing bacteria.     

Removal and degradation characteristics of natural and synthetic estrogens by activated sludge in batch experiments

The removal and degradation characteristics of natural and synthetic estrogens by activated sludge were investigated by a series of batch experiments using the activated sludge samples of four actual wastewater treatment plants and synthetic wastewater spiked with estrogen. The rapid removal and degradation of 17β-estradiol (E2) and estrone (E1) were observed by the activated sludge samples of the oxidation ditch process which operated at higher solids retention time (SRT). On the other hand, E1 tended to remain both in the water phase and the sludge phase in the activated sludge samples of the conventional activated sludge process which operated at lower SRT. The anoxic condition was considered to be not favorable to the effective removal of estrogens as compared with the aerobic condition. The removal and degradation of EE2 showed the lag phase, which neither E2 nor E1 showed, but EE2 was finally removed and degraded completely after 24 h. The removal of estrogens in the water phase did not follow the first-order-rate reaction because a large part of the spiked estrogen was immediately removed from the water phase to the sludge phase by adsorption.     

Direct photolysis of estrogens in aqueous solutions

Direct photolysis of two estrogens 17beta-estradiol (E2) and estrone (E1) in aqueous solutions radiated by UV-light and UV-Vis-light was studied preliminarily. The results suggest that the photolysis of E2 in aqueous solutions occurs under irradiation with UV disinfection lamp (lambda = 254 nm, 30 W), while E1 can also undergo photolysis under irradiation with a high-pressure mercury lamp (lambda > or = 365 nm, 125 W). The photolysis reactions of E2 and E1 at the concentration of 3.0-20 mgl(-1) in aqueous solutions were all in accordance with pseudo-first-order law. The photolysis rate of estrogens in aqueous solutions reached the lowest value at pH approximately 5.0, while the highest at pH 8.0 over the range of 2.0-8.0. The higher the initial concentration of the two estrogens, the lower the rate of photolysis.     

Anaerobic biotransformation of estrogens

Estrogens are important environmental contaminants that disrupt endocrine systems and feminize male fish. We investigated the potential for anaerobic biodegradation of the estrogens 17-alpha-ethynylestradiol (EE2) and 17-beta-estradiol (E2) in order to understand their fate in aquatic and terrestrial environments. Cultures were established using lake water and sediment under methanogenic, sulfate-, iron-, and nitrate-reducing conditions. Anaerobic degradation of EE2 (added at 5 mg/L) was not observed in multiple trials over long incubation periods (over three years). E2 (added at 5 mg/L) was transformed to estrone (E1) under all four anaerobic conditions (99-176 microg L-1 day-1), but the extent of conversion was different for each electron acceptor. The oxidation of E2 to E1 was not inhibited by E1. Under some conditions, reversible inter-conversion of E2 and E1 was observed, and the final steady state concentration of E2 depended on the electron-accepting condition but was independent of the total amount of estrogens added. In addition, racemization occurred and E1 was also transformed to 17-alpha-estradiol under all but nitrate-reducing conditions. Although E2 could be readily transformed to E1 and in many cases 17-alpha-estradiol under anaerobic conditions, the complete degradation of estrogens under these conditions was minimal, suggesting that they would accumulate in anoxic environments.     

A thermodynamic analysis on adsorption of estrogens in activated sludge process

The adsorption behaviors of estrone (E1), 17beta-estradiol (E2), estriol (E3), 17 alpha-ethinylestradiol (EE2), and equol were studied with a deactivated sludge subjected to heat treatment at 80 degrees C for 30 min. The heat-treatment hardly changed the adsorption features of activated sludge (AS). The adsorption equilibrium of all estrogens was approached within 10 min at 20 degrees C, and a high removal of estrogens was achieved simultaneously. The equilibrium data were well fitted by a Freundlich isotherm. The adsorption behaviors of E1, E2, E3 and EE2 in the AS system were independent of their Kow values. Thermodynamic analysis revealed that the adsorption behaviors of E1, E2, E3 and EE2 could be considered as an exothermic, physical and reversible process, resulting in their higher adsorption capacities at lower temperature. Regarding equol, its adsorption was an endothermic, chemical and irreversible process.     

Fe2O3有机物光催化降解有机染料的研究进展

探讨了Fe2O3/H2O2体系在可见光下降解有机染料的研究进展,采用Fe2O3/H2O2体系,对大红4BS、甲基橙等染料进行了光氧化降解实验,得出Fe2O3/H2O2/太阳光体系和Fe2O3/H2O2/UV体系在不同pH值条件下的光降解效率。     

Photochemical induced changes of in vitro estrogenic activity of steroid hormones

Steroid estrogens are endocrine disrupting contaminants frequently detected in natural waters. Because these estrogens can elicit significant biological responses in aquatic organisms, it is important to study their rates and pathways of degradation in natural waters and to identify whether the transformation products retain biological activity. Photochemical kinetics experiments were conducted under simulated solar light for the hormones 17β-estradiol (E2), 17α-ethinylestradiol (EE2), estrone (E1), equilin (EQ), and equilenin (EQN) under direct and indirect photolysis conditions. All of these hormones were susceptible to direct photodegradation, with half-lives ranging from 40 min for E1 to about 8 h for E2 and EE2. Indirect photolysis experiments with added Suwannee River fulvic acid (SRFA) lead to faster degradation rates for E2, EE2, and EQ. Added SRFA caused slower photodegradation rates for E1 and EQN, indicating that it acts primarily as an inner filter for these analytes. The well-established yeast estrogen screen (YES) was used to measure the estrogenicity of the analytes and their photoproducts. Results of YES assay experiments show that only the direct photolysis of E1 gave estrogenic products. Lumiestrone, the major E1 direct photolysis product, was isolated and characterized. It formed in 53% yield and exhibited moderate estrogenic activity. When photolysed in the presence of perinaphthenone, a potent synthetic sensitizer, E1 degraded via an indirect photolysis pathway and did not produce lumiestrone or any other active products. These results suggest that under typical natural water conditions photochemical reactions of E2, EE2, EQ, and EQN are expected to produce inactive products while E1 will give the estrogenic product lumiestrone in moderate yield.     

Fate simulation and risk assessment of endocrine disrupting chemicals in a reservoir receiving recycled wastewater

A fugacity based model was applied to simulate the distribution of three endocrine disrupting chemicals (EDCs), namely estrone (E1), 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) in a reservoir receiving recycled wastewater in Australia. At typical conditions, the majority of estrogens were removed by degradation in the water compartment. A sensitivity analysis found that the simulated concentrations of E1, E2 and EE2 were equally sensitive to the parameters of temperature (T), reservoir water volume (V) and equivalent biomass concentration (EBC), but E1 was more sensitive to estrogen concentration in the recycled water (C_e) and recycling rate (F_r). In contrast, all three estrogens were not sensitive to reservoir water releasing rate (F_d). Furthermore, a probabilistic health risk assessment showed that the simulated concentrations were below fish exposure threshold value (ETV) and human public health standard (PHS). Human equivalent dose of EDCs from fish consumption was about 10 times higher than that from drinking water consumption. The highest risk quotient among the three estrogens was found for EE2 with less than 9.5 × 10⁻², implying negligible health risks.     

High estrogen concentrations in receiving river discharge from a concentrated livestock feedlot

Environmental estrogenic chemicals interrupt endocrine systems and generate reproductive abnormalities in wildlife, especially natural and synthetic estrogenic steroid hormones such as 17β-estradiol (E2), estrone (E1), estriol (E3), 17α-ethynylestradiol (EE2), and diethylstilbestrol (DES). Concentrated animal feedlot operations (CAFOs) are of particular concern since large amounts of naturally excreted estrogens are discharged into aquatic environments. This study investigated E2, E1, E3, EE2, and DES with high performance liquid chromatography/tandem mass (HPLC-MS/MS) analyses along Wulo Creek in southern Taiwan, near a concentrated livestock feedlot containing 1,030,000 broiler chickens, 934,000 laying hens, 85,000 pigs, and 1500 cattle. Sampling was performed from December 2008 to May 2009, in which 54 samples were collected. Experimental results indicate that concentrations of EE2 were lower than the limit of detection (LOD), and concentrations of DES were only detected twice. Concentrations ranged from 7.4 to 1267 ng/L for E1, from not detected (ND) to 313.6 ng/L for E2, and from ND to 210 ng/L for E3. E1 had the highest average mass fraction (72.2 ± 3.6%), which was significantly higher than E3 (16.2 ± 1.7%) and E2 (11.5 ± 2.6%). Additionally, the mean E2 equivalent quotient (EEQ) ranged from 17.3 to 137.9 ng-E2/L. Despite having a markedly lower concentration than E1, E2 more significantly contributed (52.4 ± 6.0%) EEQ than E1 (19.7 ± 3.5%). Moreover, the concentrations of E2, E1, and E3 upstream were significantly higher than concentrations downstream, suggesting a high attenuation effect and fast degradation in the study water. Most concentrations in winter season were higher than those of spring season due to the low dilution effect and low microbial activity in the winter season. Based on the results of this study, we recommend further treatment of the wastewater discharge from the feedlot.     

Photodegradation of 2,4-dichlorophenoxyacetic acid in various iron-mediated oxidation systems

The oxidation of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by different iron-mediated processes, with or without the presence of ultraviolet (at 253.7 nm) and oxalate, was investigated and compared. The initial decay rate and the overall removal percentage were used as the performance indexes. To extensively explore the associated processes, the following combinations or blank systems were investigated: UV radiation only, Fe(2+)/H(2)O(2), Fe(2+)/H(2)O(2)/UV, ferrous oxalate/H(2)O(2), ferrous oxalate/H(2)O(2)/UV, Fe(3+)/H(2)O(2), Fe(3+)/H(2)O(2)/UV, ferrioxalate/H(2)O(2), and ferrioxalate/H(2)O(2)/UV. This study showed that the degradation of 2,4-D by sole UV or dark processes (without UV) is generally slow, except by the conventional Fenton's process (Fe(2+)/H(2)O(2)). However, these slow reactions can be accelerated by exposure to UV irradiation, which can increase the initial 2,4-D decay rate from ten to more than one hundred times. Furthermore, if the reaction is initiated by ferrous oxalate or ferrioxalate instead of Fe(2+) or Fe(3+) ions, the rates can be further improved, because of the higher light sensitivity of the organometallic complexes. These reactions were also found sensitive to the initial hydrogen peroxide concentration. The competition of hydroxyl free radicals by the primary intermediate, 2,4-dichlorophenol, was also observed.     

Photodegradation of estrone and 17beta-estradiol in water

The TiO(2)-assisted photodegradation of two natural female hormones, estrone (E1) and 17beta-estradiol (E2), was investigated in two UV-photo-reactors, followed by solid-phase extraction and analysis by gas chromatography-mass spectrometry (GC-MS). The degradation of E1 and E2 in both reactors followed the pseudo-first-order kinetics. In reactor 1 (150W), 97% of compounds were degraded within 4h of irradiation. Even more rapid degradation was observed in reactor 2 (15W) where 98% of both compounds disappeared within 1h, due to the shorter wavelength of UV-light in reactor 2 (fixed at 253nm) than reactor 1 (238-579nm). The influences of different initial chemical concentrations, pH value, the presence of dissolved organic matter and hydrogen dioxide, and the catalyst concentration on the degradation rate of E1 and E2 in aqueous solutions were investigated. The results show that the extent of photo-induced degradation of E1 and E2 strongly depends on the water constituents in solution. The degradation rate was increased when pH value was increased from 2 to 7.6, beyond which the degradation rate started to decrease. The presence of humic acid enhanced the degradation of E1 and E2 in both reactors as a result of photosensitisation effect of humic acid chromophore. The degradation rate increased with an increase in H(2)O(2) concentration. The degradation rate was also enhanced by increasing catalyst concentration up to 2g/l. The findings therefore suggest that photocatalysis can be a very effective method of rapidly removing certain EDCs from water.     

pH effect on OH radical production in photo/ferrioxalate system

In wastewater treatment using the Fenton and photofenton processes, pH is one of the critical operating parameters, due to the fact that the Fenton reaction can work only under acidic pH conditions. It is hoped that Ferric iron complexed with oxalate (Fe(III)-oxalate; ferrioxalate) will provide an alternative to the traditional Fenton process with its limited range of pH conditions, since its high solubility in aqueous media can broaden the available pH range of the Fenton reaction up to the near neutral pH regime. In this study, we investigated the pH dependency of OH production in the photo/ferrioxalate system, in the presence and absence of externally supplied H(2)O(2), where 2,4--D was used as the probe compound for OH production at a wide range of pH values (1.2--7.4). In the absence of externally supplied H(2)O(2), the 2,4--D degradation was considerably enhanced with increasing pH, whereas it was reduced with increasing pH in the presence of an excess amount of H(2)O(2). These variations in the degradation of 2,4--D were thus found to be precisely related to the formation of H(2)O(2), a factor to which little attention was paid in previous studies. In the absence of H(2)O(2) addition, the in situ formation of H(2)O(2) is facilitated with increasing pH by the reaction of Fe(II) with O(2)(-), which increases with pH, augmenting the production of OH and thereby leading to the faster degradation of 2,4--D. This same reaction can also provide an explanation for the opposite pH dependence of 2,4--D degradation in the presence of H(2)O(2).     

北京污水厂进、出水中内分泌干扰物的分布

以三种酚类化合物(4-OP、4-n-NP、BPA)、五种雌激素(E1、E2、E3、17α-E2、EE2)为目标物,对其在北京市三个污水处理厂进、出水中的浓度及工艺流程中的分布、迁移进行了研究.结果表明,污水处理厂出水中浓度最高的物质是BPA、EE2,分别为(56～140)、(78～115)ng/L.BPA和天然雌激素(17α-E2除外)主要被生物降解去除,而对EE2的去除主要发生在初级处理过程,去除率约为63%.两种烷基酚在污水处理厂并不能被有效去除.与欧美国家、日本等相比,北京市污水处理厂进、出水中的内分泌干扰物浓度偏高,尤其是出水中的雌激素浓度较高,具有一定的环境风险.     

Effects of bacterial activity on estrogen removal in nitrifying activated sludge

The effects of bacterial activity on the degradation of estrone (E1), estradiol (E2), estriol (E3) and ethinylestradiol (EE2) in nitrifying activated sludge (NAS) were studied with different substrates and organic loading rates (OLRs) and low temperature conditions. Heterotroph was shown to have utilized glucose prior to E1 for metabolism. The co-metabolism of ammonia oxidizing bacteria (AOB) dominated the degradation of E1, E2 and EE2 in NAS. The higher the organic loading, the higher the rate of organic matter transformation, with less ammonia oxidation and less degradation of E1, E2 and EE2. The degradation of E3 in NAS was shown to be largely due to heterotroph metabolism. On the basis of the difference of apparent activity between heterotroph and AOB at 4 degrees C, the process of estrogen degradation via the co-metabolism of AOB was able to be identified.     

Determining estrogenic steroids in Taipei waters and removal in drinking water treatment using high-flow solid-phase extraction and liquid chromatography/tandem mass spectrometry

River water and wastewater treatment plant (WWTP) effluents from metropolitan Taipei, Taiwan were tested for the presence of the pollutants estrone (E1), estriol (E3), 17beta-estradiol (E2), and 17alpha-ethinylestradiol (EE2) using a new methodology that involves high-flow solid-phase extraction and liquid chromatography/tandem mass spectrometry. The method was also used to investigate the removal of the analytes by conventional drinking water treatment processes. Without adjusting the pH, we extracted 1-L samples with PolarPlus C18 Speedisks under a flow rate exceeding 100 mL/min, in which six samples could be done simultaneously using an extraction station. The adsorbent was washed with 40% methanol/60% water and then eluted by 50% methanol/50% dichloromethane. The eluate was concentrated until almost dry and was reconstituted by 20 microL of methanol. Quantitation was done by LC-MS/MS-negative electrospray ionization in the selected reaction monitoring mode with isotope-dilution techniques. The mobile phase was 10 mM N-methylmorpholine aqueous solution/acetonitrile with gradient elution. Mean recoveries of spiked Milli-Q water were 65-79% and precisions were within 2-20% of the tested concentrations (5.0-200 ng/L). The method was validated with spiked upstream river water; precisions were most within 10% of the tested concentrations (10-100 ng/L) with most RSDs<10%. LODs of the environmental matrixes were 0.78-7.65 ng/L. A pre-filtration step before solid-phase extraction may significantly influence the measurement of E1 and EE2 concentrations; disk overloading by water matrix may also impact analyte recoveries along with ion suppression. In the Taipei water study, the four steroid estrogens were detected in river samples (ca. 15 ng/L for E2 and EE2 and 35-45 ng/L for E1 and E3). Average levels of 19-26 ng/L for E1, E2, and EE2 were detected in most wastewater effluents, while only a single effluent sample contained E3. The higher level in the river was likely caused by the discharge of untreated human and farming waste into the water. In the drinking water treatment simulations, coagulation removed 20-50% of the estrogens. An increased dose of aluminum sulfate did not improve the performance. Despite the reactive phenolic moiety in the analytes, the steroids were decreased only 20-44% of the initial concentrations in pre- or post-chlorination. Rapid filtration, with crushed anthracite playing a major role, took out more than 84% of the estrogens. Except for E3, the whole procedure successfully removed most of the estrogens even if the initial concentration reached levels as high as 500 ng/L.     

The aqueous degradation of bisphenol A and steroid estrogens by ferrate

The aqueous reactivity of five prominent endocrine disrupting chemicals (EDCs) with potassium ferrate has been studied. The degradation kinetics and reaction pathways for bisphenol A (BPA) have been considered in detail, and the reaction rate constants for 17alpha-ethynylestradiol (EE2), estrone (E1), beta-estradiol (E2), and estriol (E3) have been determined, from tests carried out in the pH range of 8-12 and at different reactant molar ratios. The rate constants were determined by a kinetic model incorporating the various species equilibria for the EDC compounds and ferrate, using observations of the temporal reduction in EDC and ferrate concentrations. In agreement with other studies, the oxidation of the EDCs was found to be greater for mono-protonated ferrate, HFeO(4)(-), than for non-protonated ferrate, FeO(4)(2-). Among the five EDCs, all of which have phenol moieties, the ferrate oxidation of the four steroid estrogens (each incorporating the cyclopentanoperhydrophenanthrene ring) had higher reaction rates than BPA. The by-products of BPA degradation by ferrate were analyzed by liquid chromatography/mass spectrometry-mass spectrometry (LC/MS-MS) and gas chromatography/mass spectrometry-mass spectrometry (GC/MS-MS) and nine specific compounds were identified, including p-isopropylphenol, 4-isopropanolphenol, p-isopropenylphenol, and some dicarboxylic acids, etc. It is concluded that ferrate oxidation could be an effective treatment method for the purification of waters containing these particular EDCs.     

Photochemical oxidation of As(III) by vacuum-UV lamp irradiation

In this study, vacuum-UV (VUV) lamp irradiation emitting both 185 and 254 nm lights has been investigated as a new oxidation method for As(III). Laboratory scale experiments were conducted with a batch reactor and a commercial VUV lamp. Under the experimental conditions of this study, the employed VUV lamp showed a higher performance for As(III) oxidation compared to other photochemical oxidation methods (UV-C/H(2)O(2), UV-A/Fe(III)/H(2)O(2), and UV-A/TiO2). The VUV lamp oxidized 100 microM As(III) almost completely in 10 min, and the reaction occurred mainly due to OH radicals which were produced by photo-splitting of water (H(2)O+hv (lambda=185 nm)-->OH.+H.). There was a little possibility that photo-generated H(2)O(2) acted as a minor oxidant of As(III) at alkaline pHs. The effects of Fe(III), H(2)O(2), and humic acid (HA) on the As(III) oxidation by VUV lamp irradiation were investigated. While Fe(III) and H(2)O(2) increased the As(III) oxidation efficiency, HA did not cause a significant effect. The employed VUV lamp was effective for oxidizing As(III) not only in a Milli-Q water but also in a real natural water, without significant decrease in the oxidation efficiency. Since the formed As(V) should be removed from water, activated alumina (AA) was added as an adsorbent during the As(III) oxidation by VUV lamp irradiation. The combined use of VUV lamp irradiation and AA was much more effective for the removal of total arsenic (As(tot)=As(III)+As(V)) than the single use of AA. The As(tot) removal seemed to occur as a result of the pre-oxidation of As(III) and the subsequent adsorption of As(V) on AA. Alternatively, the combination of VUV lamp irradiation and coagulation/precipitation with FeCl(3) was also an effective removal strategy for As(tot). This study shows that vacuum-UV (VUV) lamp irradiation emitting both 185 and 254 nm lights is a powerful and environmentally friendly method for As(III) oxidation which does not require additional oxidants or catalysts. The As(III) oxidation by VUV lamp irradiation was tested not only in a batch reactor but also in a flow-through quartz reactor. The As(III) oxidation rate became much faster in the latter reactor.     

Natural and synthetic hormone removal using the horseradish peroxidase enzyme: temperature and pH effects

The primary objective of our research was to establish the technical feasibility of using the horseradish peroxidase (HRP) enzyme for natural and synthetic estrogens-estrone (E1), 17beta-estradiol (E2), estriol (E3), and 17alpha-ethinylestradiol (EE2)-removal. The effects of temperature and pH on enzymatic treatment kinetics were investigated. Residual estrogen concentrations were quantified by liquid chromatography, coupled with mass spectrometry analysis. In a synthetic solution at pH 7 and 25+/-1 degrees C, the HRP enzyme-catalyzed process was capable of achieving 92-100% removal of E1, E2, E3, and EE2 within 1h of treatment with an HRP activity of 0.017 U/ml. The influence of the pH (5-9) and temperature (5-35 degrees C) on estrogen removal was observed to be significant, with the optimum pH near neutral conditions. The results also showed that wastewater constituents significantly impact the HRP-catalyzed estrogen removal. The experimental research proved that the HRP-catalyzed system is technically feasible for the removal of the main estrogens present in the environment at low concentrations.     

Solar photocatalytic degradation of reactive blue 4 using a Fresnel lens

The heterogeneous photocatalytic degradation of reactive blue 4 dye (RB4) solutions under Fenton reagent and TiO(2) assisted by concentrated solar light irradiation using a Fresnel lens has been studied. Multivariate experimental design was applied to study the kinetic process. The efficiency of photocatalytic degradation was determined from the analysis of color and total organic carbon (TOC) removal. Factorial experimental design allowed to determine the influence of four parameters (pH and initial concentrations of TiO(2), Fe(II) and H(2)O(2)) on the value of the decoloration kinetic rate constant. Experimental data were fitted using neural networks (NNs). The mathematical model reproduces experimental data within 86% of confidence and allows the simulation of the process for any value of parameters in the experimental range studied. Also, a measure of the saliency of the input variables was made based upon the connection weights of the neural networks, allowing the analysis of the relative relevance of each variable with respect to the others. Results showed that acidic pHs (pH=3.6) are preferred for the complete dye decoloration. The optimum catalyst concentration is 1.2g TiO(2)/l. The use of a low cost catalyst and its activation using a Fresnel lens to concentrate solar energy significantly accelerates the degradation process when compared with direct solar radiation alone and can offer an economical and practical alternative for the destruction of environmental organic compounds.