Visible light induced photocatalytic degradation of 2-nitrophenol at high concentration implementing rGOTiO2: mathematical modeling behavior.

This investigation implemented the nanomaterial rGOTiO2 for photodegradation of 2-nitrophenol solution at high concentrations. The 2-nitrophenol photodegradation was carried out in the presence of three kinds of light sources in the visible range spectrum. The results demonstrate that the nanomaterial rGOTiO2 is capable of pollutant degradation even in the low power light source (10 W), and have high activity under sunlight. The degradation of 2-nitrophenol was monitored by UV-vis spectroscopy, adjusting method by least squares for nonlinear functions. The equation represents the material photocatalytic activity under sunlight, which excludes climatic and variance factors. This equation predicts the pure rGOTiO2 behavior under sunlight; this will enable future research to develop more advanced processes.

Indirect photodegradation of the lampricides TFM and niclosamide.

3-Trifluromethyl-4-nitrophenol (TFM) and 2',5-dichloro-4'-nitrosalicylanilide (niclosamide) are lampricides used in tributaries of the Great Lakes to kill the invasive parasitic sea lamprey (Petromyzon marinus). Although the lampricides have been applied since the late 1950s, their photochemical behavior in natural environments is still not well understood. This study examines the indirect photodegradation of these two compounds and the resulting yields of organic and inorganic photoproducts in water samples collected from five tributaries of Lake Michigan. The tributaries were selected to span the length of Lake Michigan and its natural carbonate geologic gradient. In the presence of dissolved organic matter (DOM), the niclosamide photodegradation rate triples, while the rate of TFM photodegradation is unchanged. Additionally, the yield of lampricide organic products is influenced by DOM because many of the organic photoproducts themselves are prone to DOM-mediated indirect photodegradation. The indirect photodegradation of niclosamide is primarily mediated by reaction with singlet oxygen, which accounts for more than 50% of the increased photodegradation rate. Additionally, hydroxyl radicals and carbonate radicals (CO3-˙) influence niclosamide indirect photolysis, and their contribution is dependent on the specific river water chemistry. For example, CO3-˙ contribution to niclosamide photodegradation, while small, is greater in southern tributaries where there is higher carbonate alkalinity.

A field analysis of lampricide photodegradation in Great Lakes tributaries.

The lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2',5-dichloro-4'-nitrosalicylanilide (niclosamide) are added to Great Lakes tributaries to target the sea lamprey, an invasive parasitic fish. This study examines the photochemical behavior of the lampricides in Carpenter Creek, Sullivan Creek, and the Manistique River. The observed loss of TFM in Carpenter and Sullivan Creeks (i.e., 34 and 19%) was similar to the loss of bromide in parallel time of passage studies (i.e., 30 and 29%), demonstrating that TFM photodegradation was minimal in both tributaries during the lampricide application. Furthermore, the absence of inorganic and organic photoproducts in the Manistique River demonstrates that TFM and niclosamide photodegradation was minimal in this large tributary, despite its long residence time (i.e., 3.3 days). Kinetic modeling was used to identify environmental variables primarily responsible for the limited photodegradation of TFM in the field compared to estimates from laboratory data. This analysis demonstrates that the lack of TFM photodegradation was attributable to the short residence times in Carpenter and Sullivan Creeks, while depth, time of year, time of day, and cloud cover influenced photochemical fate in the Manistique River. The modeling approach was extended to assess how many of the 140 United States tributaries treated with lampricides in 2015 and 2016 were amenable to TFM photolysis. While >50% removal of TFM due to photolysis could occur in 13 long and shallow tributaries, in most systems lampricides will reach the Great Lakes untransformed.

Anchoring of silver nanoparticles on graphitic carbon nitride sheets for the synergistic catalytic reduction of 4-nitrophenol.

In this paper, a facile process was developed for anchoring of silver nanoparticles on graphitic carbon nitride sheets (Ag/g-C3N4) with high catalytic activity for reduction of 4-nitrophenol. The morphology and structure of the as-prepared Ag/g-C3N4 composite were investigated by FESEM, TEM, XRD and XPS. The reaction mechanism and the reduction kinetics of 4-nitrophenol under different light irradiation were systematically studied. The results showed that the obtained Ag/g-C3N4 composite exhibited a much higher electro/photo catalytic activity and stability for reduction of 4-nitrophenol. Significantly, due to the synergistic effect and interaction between highly dispersed Ag nanoparticles (Ag NPs, ∼7.2 nm) and lamellar g-C3N4, not only transfer of interfacial charge, but also the separation of photoinduced electrons occurred when the reaction was proceeded under light. In addition, the composite exhibited high stability and reusability during the cycling experiments. The results showed that the Ag/g-C3N4 composite is an effective and stable electro/photo catalyst for reduction of 4-nitrophenol.

Energy characterisation of ultrasonic systems for industrial processes.

Obtaining accurate power characteristics of ultrasonic treatment systems is an important step towards their industrial scalability. Calorimetric measurements are most commonly used for quantifying the dissipated ultrasonic power. However, accuracy of these measurements is affected by various heat losses, especially when working at high power densities. In this work, electrical power measurements were conducted at all locations in the piezoelectric ultrasonic system equipped with ½â€³ and ¾â€³ probes. A set of heat transfer calculations were developed to estimate the convection heat losses from the reaction solution. Chemical dosimeters represented by the oxidation of potassium iodide, Fricke solution and 4-nitrophenol were used to chemically correlate the effect of various electrical amplitudes and treatment regimes. This allowed estimation of sonochemical-efficiency (SE) and energy conversion (XUS) of the ultrasonic system. Results of this study showed overall conversion efficiencies of 60-70%. This correlated well with the chemical dosimeter yield curves of both organic and inorganic aqueous solutions. All dosimeters showed bubble shielding and coalescence effects at higher ultrasonic power levels, less pronounced for the ½â€³ probe case. SE and XUS values in the range of 10(-10) mol/J and 10(-3) J/J respectively confirmed that conversion of ultrasonic power to chemical yield declined with amplitude.

Sol-hydrothermal synthesis of inorganic-framework molecularly imprinted TiO2/SiO2 nanocomposite and its preferential photocatalytic degradation towards target contaminant.

Inorganic-framework molecularly imprinted TiO2/SiO2 nanocomposite (MIP-TiO2/SiO2) was successfully prepared by sol-hydrothermal method using 4-nitrophenol as template. The morphology, structure, optical property, zeta-potential and photocurrent of MIP-TiO2/SiO2 were characterized. The adsorption performance and photocatalytic selectivity were also studied. MIP-TiO2/SiO2 shows higher adsorption capacity and selectivity than the non-imprinted TiO2/SiO2 (NIP-TiO2/SiO2). Kinetics results show that the adsorption equilibrium of 4-nitrophenol on MIP-TiO2/SiO2 is established within 20 min, and the adsorption process obeys the pseudo-second-order model. Moreover, MIP-TiO2/SiO2 can completely degrade 4-nitrophenol within 30 min, while NIP-TiO2/SiO2 takes 110 min. It was found that the MIP-TiO2/SiO2 photocatalyst shows molecular recognition ability, leading to selective adsorption and molecular recognitive photocatalytic degradation of 4-nitrophenol. Furthermore, because of its inorganic framework, MIP-TiO2/SiO2 shows excellent reusability.

TiO2 nanoparticles: low-temperature hydrothermal synthesis in ionic liquids/water and the photocatalytic degradation for o-nitrophenol.

The well-crystallized anatase TiO2-IL nanoparticles were synthesized by one-step routes under low-temperature using room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate as an additional solvent with water. The photocatalytic properties of TiO2 nanoparticles were evaluated by photocatalytic degradation experiments of o-nitrophenol. The TiO2 nanoparticles show a higher photocatalytic activity than the TiO2 with pure water and commercial TiO2 (P25), which may be related to the high crystallinity. The TiO2-IL nanoparticles still hold a high photocatalytic activity after the catalyst was recycled nine times. Chemical oxygen demand removal was achieved under optimum experimental conditions.

Selective photo-reduction of p-nitrophenol to p-aminophenol by Au deposited CdS nanostructures of different shapes having large surface area.

The preparation and photocatalytic reductive ability of a new spongy flower or cotton bud like amorphous CdS microstructures (size = 200-300 nm) having intermediate crystal phase between cubic and hexagonal structure and possesses much larger surface area ca. 119 m2 g(-1) is demonstrated here. Structural analysis has been done by TEM, XRD, BET surface area, UV-Vis absorption, luminescence analysis, and photocatalytic study. The photoreactivity of as-prepared CdS for p-nitrophenol reduction to p-aminophenol conversion under visible light (150 W halogen lamp) irradiation has been found to be greatly enhanced from 62% to 94% (yield) and 81% to 100% (selectivity) after 1 wt% Au deposition. The obtained p-aminophenol yield is always better than 32% for CdS nanosphere (size 10-12 nm) and 40% for CdS nanorod (length/width in nm = 126/6). Surface passivation with a thin layer of SiO2 coating over this flower like spongy CdS appreciably increased the BET surface area to 158 m2 g(-1) and displayed stable photocatalytic activity for p-nitrophenol reduction up to 30 h of light exposure as compared to bare CdS of low activity because of its easy photodissolution. A good co-relation between the BET surface area and surface photoactivity of as-prepared CdS with the conventional cubic and hexagonal CdS nanoparticles of different dimensions is established here.

Spectroscopic investigations on the simulated solar light induced photodegradation of 4-nitrophenol by using three novel copper(II) porphyrin-TiO2 photocatalysts.

Three porphyrins containing different functional groups (-OH, C-O2C2H5, -COOH), 5-(4-hydroxy) phenyl-10,15,20-triphenyl porphyrin (1a), 5-(4-ethylacetatatomethoxy) phenyl-10,15,20-triphenyl porphyrin (1b), 5-(4-carboxylatomethoxy) phenyl-10,15,20-triphenyl porphyrin (1c), were synthesized and characterized spectroscopically. The CuPp(2a, 2b, 2c)-TiO2 photocatalysts were then prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis-DRS), Fourier-transform infrared spectroscopy (FT-IR). The photocatalytic activities of the photocatalysts were investigated by carrying out the photodegradation of 4-nitrophenol in aqueous solution under simulated solar irradiation. It was found that the CuPp(2a, 2b, 2c)-TiO2 enhanced the photocatalytic efficiency of bare TiO2 in photodegrading the 4-NP due to the interaction between CuPp(2a, 2b, 2c) and TiO2, resulted in the enhancement of the photogenerated electron-hole separation. The reasons of this enhanced photocatalytic activity were also discussed. Based on the present study, it could be considered as a promising photocatalyst for the further industrial application.

In situ assembly of well-dispersed Au nanoparticles on TiO2/ZnO nanofibers: a three-way synergistic heterostructure with enhanced photocatalytic activity.

The TiO(2)/ZnO nanofibers embedded by Au nanoparticles (TiO(2)/ZnO/Au NFs) were fabricated by combining the electrospinning technique (for TiO(2)/ZnO nanofibers) and an in situ reduction approach (for Au nanoparticles). X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electronmicroscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy and photoluminescence spectroscopy, were used to characterize the as-synthesized nanofibers. The results showed that small Au nanoparticles (Au NPs) were well dispersed on the TiO(2)/ZnO nanofibers (TiO(2)/ZnO NFs). And, the TiO(2)/ZnO/Au nanofibers showed high charge separation efficiency under ultraviolet excitation, as evidenced by photoluminescence spectra. The photocatalytic studies revealed that the TiO(2)/ZnO/Au NFs exhibited enhanced photocatalytic efficiency of photodegradation of Methyl orange (MO) and 4-nitrophenol (4-NP) compared with the pure TiO(2) nanofibers, ZnO nanofibers and TiO(2)/ZnO NFs under ultraviolet excitation, which might be attributed to the high separation efficiency of photogenerated electron-hole pairs based on the photosynergistic effect among the three components of TiO(2), ZnO and Au. And, the TiO(2)/ZnO/Au NFs could be easily separated and recycled due to their one-dimensional nanostructural property.

High efficiency degradation of 4-nitrophenol by microwave-enhanced catalytic method.

Application of the microwave-enhanced catalytic degradation (MECD) method on the abatement of 4-nitrophenol (4-NP) using nickel oxide was studied. A mix-valenced nickel oxide was prepared from nickel nitrate aqueous solution through a precipitation with sodium hydroxide and an oxidation by sodium hypochlorite with/without microwave-assisted heating. They were characterized by X-ray (XRD), infrared spectroscopy (IR), temperature programmed reduction (TPR), and transmission electron micrographs (TEM). Their catalytic activities towards the degradation of 4-NP were investigated through continuous bubbling of air during the liquid phase and evaluated quantitatively with high pressure liquid chromatography (HPLC). Also, the effect of the kinds of catalyst, temperature, pH, initial concentration, and dosage of catalyst on the efficiency of 4-NP degradation was investigated. The results showed that the 4-NP was completely degraded using the high efficiency MECD method within 15 min under [H(+)] = 1.0M, T = 40 °C, and C = 200 ppm over nickel oxide.

Gamma radiation-induced degradation of p-nitrophenol (PNP) in the presence of hydrogen peroxide (H2O2) in aqueous solution.

The synergistic effect of gamma radiation with hydrogen peroxide (H(2)O(2)) for p-nitrophenol (PNP) decomposition in aqueous solution was evaluated. The PNP solution with initial concentration of 50mg/L was irradiated in the presence of extra H(2)O(2) at initial concentration of 0, 20, 40, and 80 mg/L. The experimental results showed that the decomposition of PNP conformed to the pseudo-first-order reaction kinetics under the applied conditions. When initial H(2)O(2) concentration was in the range of 0-80 mg/L, higher concentration of H(2)O(2) was more effective for the decomposition, mineralization and nitrogen release of PNP. However, the removal of total organic carbon (TOC) and total nitrogen (TN) was not as effective as that of PNP. Ammonia and nitrate were detected as the main inorganic nitrogen products of PNP decomposition without extra H(2)O(2), whereas nitrate was considered as a final inorganic nitrogen product with extra H(2)O(2) in the initial concentration range of 0-80 mg/L. Major decomposition products, including organic acids were identified by LC/MS and IC. Possible pathways for PNP decomposition by gamma radiation in aqueous solution were proposed.

Degradation of p-nitrophenol using acoustic cavitation and Fenton chemistry.

Due to increasing human requirements, newer chemical species are being observed in the effluent streams with higher loadings such that efficacy of conventional treatment techniques is decreased and a combination of advanced oxidation processes is implemented for enhanced treatment ability and better energy efficiency. In the present work, the efficacy of combination of sonochemistry and Fenton chemistry has been investigated for wastewater treatment considering p-nitrophenol as model pollutant at pilot scale operation. Degradation of p-nitrophenol has been investigated under various operating conditions based on the use of ultrasound, Fenton process, ultrasound and H(2)O(2), ultrasound and Fe, ultrasound and FeSO(4), ultrasound and conventional Fenton process and ultrasound and advanced Fenton process. Two different initial concentrations of 0.5 and 1% of p-nitrophenol have been used for the experiments. In conventional Fenton and advanced Fenton process, two loadings of FeSO(4) and Fe powder 0.5 and 1g/l and three ratios of FeSO(4):H(2)O(2) and Fe:H(2)O(2) (1:5, 1:7.5 and 1:10) were investigated respectively. In all the systems investigated, maximum extent of degradation (66.4%) was observed for 0.5% p-nitrophenol concentration (w/v) using a combination of ultrasound and advanced Fenton process. The novelty of the work is in terms of investigating the efficacies of combined advanced oxidation processes based on the use of cavitation and Fenton chemistry at pilot scale operation and tries to establish the missing design related information for large scale operation of wastewater treatment.

Enhanced degradation of 4-nitrophenol by microwave assisted Fe/EDTA process.

A microwave assisted zero-valent iron oxidation process was studied in order to investigate the synergetic effects of MW irradiation on Fe/EDTA system (Fe/EDTA/MW) treated 4-nitrophenol (4-NP) from aqueous solution. The results indicated that the thermal effect of microwave improved the removal effect of 4-NP and TOC through raising the temperature of the system, as well as the non-thermal effect generated by the interaction between the microwave and the Fe resulting in an increase in the hydrophobic character of Fe surface. During the degradation of 4-NP in Fe/EDTA/MW system, the optimum value for MW power, Fe, EDTA dosage was 400 W, 2 g and 0.4 mM, respectively. The possible pathway for degrading the 4-NP was proposed based on GC/MS and HPLC analysis of the degradation intermediates. The concentration change course of the main bio-refractory by-products, the aminophenol formed in the degradation of 4-NP suggested a more efficient degradation and mineralization in Fe/EDTA/MW system. Finally, BOD(5)/COD(Cr) of the solution increased from 0.237 to 0.635 after reaction for 18 min, indicating that the biodegradability of wastewater was greatly improved by Fe/EDTA/MW system and would benefit to further treatment by biochemical methods.

Visible light photoelectrocatalysis with salicylic acid-modified TiO2 nanotube array electrode for p-nitrophenol degradation.

This research focused on immersion method synthesis of visible light active salicylic acid (SA)-modified TiO2 nanotube array electrode and its photoelectrocatalytic (PEC) activity. The SA-modified TiO2 nanotube array electrode was synthesized by immersing in SA solution with an anodized TiO2 nanotube array electrode. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), UV-vis diffuse reflectance spectrum (DRS), and Surface photovoltage (SPV) were used to characterize this electrode. It was found that SA-modified TiO2 nanotube array electrode absorbed well into visible region and exhibited enhanced visible light PEC activity on the degradation of p-nitrophenol (PNP). The degradation efficiencies increased from 63 to 100% under UV light, and 79-100% under visible light (lambda>400 nm), compared with TiO2 nanotube array electrode. The enhanced PEC activity of SA-modified TiO2 nanotube array electrode was attributed to the amount of surface hydroxyl groups introduced by SA-modification and the extension of absorption wavelength range.

Evaluation of a TiO2 photocatalysis treatment on nitrophenols and nitramines contaminated plant wastewaters by solid-phase extraction coupled with ESI HPLC-MS.

Nitration reactions of aromatic compounds are commonly involved in different industrial processes for pharmaceutical, pesticide or military uses. For many years, most of the manufacturing sites used lagooning systems to treat their process effluents. In view of a photocatalytic degradation assay, the wastewater of a lagoon was investigated by using HPLC coupled with mass spectrometry. The wastewater was highly concentrated in RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) and two herbicides Dinoterb (2-tert-butyl-4,6-dinitrophenol) and Dinoseb (2-sec-butyl-4,6-dinitrophenol). First of all, an analytical method using solid-phase extraction (SPE) combined with HPLC ESI MS/MS was put in work for identification and titration of RDX, HMX and the two dinitrophenols in a complex natural matrix. Then, the UV/TiO2 treatment was investigated for pollutants removal. Dinitrophenolic compounds were significantly degraded after a 8-h-exposition of the wastewater/TiO2 suspension, whereas RDX and HMX were poorly affected.

Photo-catalyzed degradation of p-nitrophenol employing TiO2 and UV radiations.

Heterogeneous photocatalysis on metal oxide semiconductor particles is an advanced oxidation technology (AOT), which has been effective means of removing organic pollutants from water streams as it utilizes ultraviolet light with semiconductors acting as photocatalyst and leads to complete mineralization of pollutants to environmentally harmless compounds. In the present investigation, the photo-catalyzed degradation studies of p-Nitrophenol (PNP) were carried out in laboratory scale immersion well UV photo-reactor using semiconductor photo-catalyst TiO2 in suspension. For this purpose, low pressure 12 W mercury lamp was used and the effect of (i) time of irradiation, (ii) dose of TiO2, (iii) initial concentration of PNP and (iv) the addition of H2O2 to the system was studied to arrive at optimum process parameters for the complete degradation and decolorization of PNP. Simple UV irradiation could not achieve significant degradation of PNP. But UV+aeration+TiO2+ H2O2 combination achieved almost complete degradation of PNP. The spectrophotometric analysis showed that the rate of degradation of PNP was very fast in initial two hours and the maximum degradation was achieved in 5 hours. The degradation was found to increase in the order UV < UV + aeration < UV + aeration + TiO2 < UV + aeration + TiO2+ H2O2, and the degradation was found to be almost 100% for UV + aeration + TiO2 + H2O2, 91% for UV + aeration + TiO2, 43% for UV + aeration and only 26% for UV irradiation.

Microwave assisted catalytic oxidation of p-nitrophenol in aqueous solution using carbon-supported copper catalyst.

Carbon-supported copper (Cu/GAC) catalyst was prepared by conventional impregnation method and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The sizes of Cu particles dispersing on the surface of GAC were 0.3-1.5 microm, which could be penetrated by microwave so that Cu/GAC catalyst could absorb microwave energy effectively. The catalysis of Cu/GAC in microwave assisted catalytic oxidation of p-nitrophenol (PNP) in aqueous solution was investigated through a fixed bed reactor under ambient pressure and continuous flow mode. PNP removal reached 91.8% under optimized conditions, corresponding to 88% of TOC removal. It showed a higher PNP degradation and total organic carbon (TOC) removal for Cu/GAC catalyst than GAC alone, and Cu/GAC catalyst kept on a high catalysis and a good stability for a long time run, which indicated that GAC structure and catalytic capacity were improved by the load of Cu.

Occurrence of 2,4-dichlorophenol and of 2,4-dichloro-6-nitrophenol in the Rhone River Delta (Southern France).

The compounds 2,4-dichlorophenol (2,4-DCP) and 2,4-dichloro-6-nitrophenol (6-nitro-2,4-DCP) have been detected at microg L(-1) levels (10(-9)-10(-8) M) during the summer season 2005 in the water of the Rhône river delta. Compound 2,4-DCP would mainly derive from the transformation of the herbicide dichlorprop, heavily used in flooded rice farming (1400 kg in the delta region in 2005), in addition to being an impurity of the commercial herbicide. Field data show a fast concentration decrease of 2,4-DCP in the period June 21st to July 5th, accompanied by a corresponding increase of 6-nitro-2,4-DCP. This could imply a possible nitration process of 2,4-DCP into 6-nitro-2,4-DCP, with quite elevated yield (33%). Nitration of 2,4-DCP can be induced by photoproduced *NO2, the reaction kinetics (calculated in the presence of Fe(III) + nitrite under irradiation as model system) being d[6-nitro-2,4-DCP]/dt = 650 [2,4-DCP] [*NO2]. Interestingly, the yield of the process (38%) is similar to that suggested by field data. An indirect assessment of [*NO2] in surface water in different sites of the Rhône delta indicated that 2,4-DCP could be transformed into 6-nitro-2,4-DCP in a couple of weeks or less in the shallow water (10 cm depth) of the rice fields, a time scale that is compatible with field data. Photonitration of 2,4-DCP is thus a possible process to account for the occurrence of 6-nitro-2,4-DCP in the Rhône delta.

Solar-based detoxification of phenol and p-nitrophenol by sequential TiO2 photocatalysis and photosynthetically aerated biological treatment.

Simulated solar UV/TiO(2) photocatalysis was efficient to detoxify a mixture of 100 mgphenoll(-1) and 50 mgp-nitrophenol (PNP) l(-1) and allow the subsequent biodegradation of the remaining pollutants and their photocatalytic products under photosynthetic aeration with Chlorella vulgaris. Photocatalytic degradation of phenol and PNP was well described by pseudo-first order kinetics (r(2)>0.98) with removal rate constants of 1.9x10(-4) and 2.8x10(-4)min(-1), respectively, when the pollutants were provided together and 5.7x10(-4) and 9.7x10(-4)min(-1), respectively, when they were provided individually. Photocatalytic pre-treatment of the mixture during 60 h removed 50+/-1% and 62+/-2% of the phenol and PNP initially present but only 11+/-3% of the initial COD. Hydroquinone, nitrate and catechol were identified as PNP photocatalytic products and catechol and hydroquinone as phenol photocatalytic products. Subsequent biological treatment of the pre-treated samples removed the remaining contaminants and their photocatalytic products as well as 81-83% of the initial COD, allowing complete detoxification of the mixture to C. vulgaris. Similar detoxification efficiencies were recorded after biological treatment of the irradiated mixture with activated sludge microflora or with an acclimated consortia composed of a phenol-degrading Alcaligenes sp. and a PNP-degrading Arthrobacter sp., although the acclimated strains biodegraded the remaining pollutants faster. Biological treatment of the non-irradiated mixture was inefficient due to C. vulgaris inhibition.