Effect of Pseudomonas sp. HF-1 inoculum on construction of a bioaugmented system for tobacco wastewater treatment: analysis from quorum sensing

To better construct a bioaugmented system for tobacco wastewater treatment, activated sludge was inoculated with different concentrations of the nicotine-degrading bacterium Pseudomonas sp. HF-1. The results showed that inoculum concentrations of 0.55?±?0.01 and 1.10?±?0.03 mg/g (dry weight of strain HF-1/dry weight of activated sludge) were best to ensure strain HF-1 survival and successful bioaugmentation. The release pattern of autoinducer (AI) for quorum sensing in the bioaugmented system was also investigated. During the period of HF-1 inoculation, compared with failed bioaugmented systems, AI-2 was significantly increased in the successful systems, suggesting that AI-2-mediated bacterial communication played an important role in the colonization of HF-1. When inoculation of strain HF-1 was stopped, the amount of AI-2 decreased and leveled out in all systems. Notably, there was a greater than threefold increase of short-chain AHLs in failed bioaugmented systems, but no increase in successful ones, implying that the fluctuation of short-chain AHLs could be an indicator of the failure of bioaugmentation. Thus, AI-2-mediated quorum sensing could be implemented to facilitate HF-1 colonization.     

Effective utilization of dichloromethane by a newly isolated strain Methylobacterium rhodesianum H13

An effective dichloromethane (DCM) utilizer Methylobacterium rhodesianum H13 was isolated from activated sludge. A response surface methodology was conducted, and the optimal conditions were found to be 4.5 g/L Na₂HPO₄·12H₂O, 0.5 g/L (NH₄)₂SO₄, an initial pH of 7.55, and a temperature of 33.7 °C. The specific growth rate of 0.25 h^?1 on 10 mM DCM was achieved, demonstrating that M. rhodesianum H13 was superior to the other microorganisms in previous investigations of DCM utilization. DCM mineralization paralleled the production of cells, CO₂, and water-soluble metabolites, as well as the release of Cl^?, whereas the carbon distribution and Cl^? yield varied with DCM concentrations. The facts that complete degradation only occurred with DCM concentrations below 15 mM and repetitive degradation of 5 mM DCM could proceed for only three cycles were ascribed to pH decrease (from 7.55 to 3.02) though a buffer system was employed.     

Application of the Fenton’s process in a bubble column reactor for hydroquinone degradation

The aim of this study was to assess the degradation and mineralization of hydroquinone (HQ) by the Fenton’s process in a bubble column reactor (BCR). The effect of the main operating variables, namely, air flow rate, effluent volume, hydrogen peroxide (H₂O₂) concentration, catalyst (Fe²⁺) dose, initial pH, and temperature, were assessed. For all air flow rates tested, no concentration gradients along the column were noticed, evidencing that a good mixing was reached in the BCR. For the best conditions tested ([H₂O₂] = 500 mg/L, [Fe²⁺] = 45 mg/L, T = 24 °C, Q _air = 2.5 mL/min, pH = 3.0, and V = 5 L), complete HQ degradation was reached, with ~ 39% of total organic carbon (TOC) removal, and an efficiency of the oxidant use—η _H2O2—of 0.39 (ratio between TOC removed per H₂O₂ consumed normalized by the theoretical stoichiometric value); moreover, a non-toxic effluent was generated. Under these conditions, the intermediates and final oxidation compounds identified and quantified were a few carboxylic acids, namely, maleic, pyruvic, and oxalic. As a strategy to improve the TOC removal, a gradual dosage of the optimal H₂O₂ concentration was implemented, being obtained ~ 55% of mineralization (with complete HQ degradation). Finally, the matrix effect was evaluated, for which a real wastewater was spiked with 100 mg/L of HQ; no reduction in terms of HQ degradation and mineralization was observed compared to the solution in distilled water.     

Degradation of the potential rodent contraceptive quinestrol and elimination of its estrogenic activity in soil and water

Quinestrol has shown potential for use in the fertility control of the plateau pika population of the Qinghai–Tibet Plateau. However, the environmental safety and fate of this compound are still obscure. Our study investigated degradation of quinestrol in a local soil and aquatic system for the first time. The results indicate that the degradation of quinestrol follows first-order kinetics in both soil and water, with a dissipation half-life of approximately 16.0 days in local soil. Microbial activity heavily influenced the degradation of quinestrol, with 41.2 % removal in non-sterile soil comparing to 4.8 % removal in sterile soil after incubation of 10 days. The half-lives in neutral water (pH 7.4) were 0.75 h when exposed to UV light (λ?=?365 nm) whereas they became 2.63 h when exposed to visible light (λ?>?400 nm). Acidic conditions facilitated quinestrol degradation in water with shorter half-lives of 1.04 and 1.47 h in pH 4.0 and pH 5.0 solutions, respectively. Moreover, both the soil and water treatment systems efficiently eliminated the estrogenic activity of quinestrol. Results presented herein clarify the complete degradation of quinestrol in a relatively short time. The ecological and environmental safety of this compound needs further investigation.     

Heterogeneous Fenton degradation of bisphenol A catalyzed by efficient adsorptive Fe3O4/GO nanocomposites

A new method for the degradation of bisphenol A (BPA) in aqueous solution was developed. The oxidative degradation characteristics of BPA in a heterogeneous Fenton reaction catalyzed by Fe₃O₄/graphite oxide (GO) were studied. Transmission electron microscopic images showed that the Fe₃O₄ nanoparticles were evenly distributed and were ～6 nm in diameter. Experimental results suggested that BPA conversion was affected by several factors, such as the loading amount of Fe₃O₄/GO, pH, and initial H₂O₂ concentration. In the system with 1.0 g L^?1 of Fe₃O₄/GO and 20 mmol L^?1 of H₂O₂, almost 90 % of BPA (20 mg L^?1) was degraded within 6 h at pH 6.0. Based on the degradation products identified by GC–MS, the degradation pathways of BPA were proposed. In addition, the reused catalyst Fe₃O₄/GO still retained its catalytic activity after three cycles, indicating that Fe₃O₄/GO had good stability and reusability. These results demonstrated that the heterogeneous Fenton reaction catalyzed by Fe₃O₄/GO is a promising advanced oxidation technology for the treatment of wastewater containing BPA.     

Microbial degradation characteristics and kinetics of novel pyrimidynyloxybenzoic herbicide ZJ0273 by a newly isolated Bacillus sp. CY

ZJ0273 (propyl 4-(2-(4,6-demethoxy pyrimidin-2-yloxy)benzylamino)benzoate) is a novel herbicide developed in China for oilseed crop. Sixteen bacteria capable of utilizing ZJ0273 as the sole carbon source were isolated from soils. One of the isolates was designated as Bacillus sp. CY based on its physiological and biochemical characteristics and phylogenetic analysis of 16S rDNA sequences. The present study aimed to investigate the ZJ0273 degradation characteristics and kinetics by Bacillus sp. CY which has the ability to utilize ZJ0273 as the sole source of carbon and energy under aerobic conditions. The optimum biodegradation temperature, pH, and ZJ0273 initial concentration were 20–40 °C, 5.0–9.0, and 50–400 mg/l, respectively. Strain CY degraded 65 % of ZJ0273 (initial concentration of 50 mg/l) during 30 days of incubation in basal mineral medium at pH 8.0 and 35 °C. DT50 (half-life value), k (degradation rate constant of ZJ0273), and R ² are 19.20 days, 0.0361 day^?1, and 0.9464, respectively.     

Solar CPC pilot plant photocatalytic degradation of bisphenol A in waters and wastewaters using suspended and supported-TiO2. Influence of photogenerated species

Photocatalytic degradation of bisphenol A (BPA) in waters and wastewaters in the presence of titanium dioxide (TiO₂) was performed under different conditions. Suspensions of the TiO₂ were used to compare the degradation efficiency of BPA (20 mg L^?1) in batch and compound parabolic collector (CPC) reactors. A TiO₂ catalyst supported on glass spheres was prepared (sol–gel method) and used in a CPC solar pilot plant for the photodegradation of BPA (100 μg L^?1). The influence of OH·, O₂ ^·?, and h ⁺ on the BPA degradation were evaluated. The radicals OH· and O₂ ^·? were proved to be the main species involved on BPA photodegradation. Total organic carbon (TOC) and carboxylic acids were determined to evaluate the BPA mineralization during the photodegradation process. Some toxicological effects of BPA and its photoproducts on Eisenia andrei earthworms were evaluated. The results show that the optimal concentration of suspended TiO₂ to degrade BPA in batch or CPC reactors was 0.1 g L^?1. According to biological tests, the BPA LC₅₀ in 24 h for E. andrei was of 1.7?×?10^?2 mg cm^?2. The photocatalytic degradation of BPA mediated by TiO₂ supported on glass spheres suffered strong influence of the water matrix. On real municipal wastewater treatment plant (MWWTP) secondary effluent, 30 % of BPA remains in solution; nevertheless, the method has the enormous advantage since it eliminates the need of catalyst removal step, reducing the cost of treatment.     

Electro-Fenton degradation of the antibiotic sulfanilamide with Pt/carbon-felt and BDD/carbon-felt cells. Kinetics,reaction intermediates,and toxicity assessment

The degradation of 230 mL of a 0.6-mM sulfanilamide solution in 0.05 M Na₂SO₄ of pH 3.0 has been studied by electro-Fenton process. The electrolytic cell contained either a Pt or boron-doped diamond (BDD) anode and a carbon-felt cathode. Under these conditions, organics are oxidized by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton’s reaction between initially added (and then electrochemically regenerated) Fe²⁺ and cathodically generated H₂O₂. From the decay of sulfanilamide concentration determined by reversed-phase liquid chromatography, an optimum Fe²⁺ concentration of 0.20 mM in both cells was found. The drug disappeared more rapidly using BDD than Pt, and, in both cases, it was more quickly removed with raising applied current. Almost total mineralization was achieved using the BDD/carbon-felt cell, whereas the alternative use of Pt anode led to a slightly lower mineralization degree. In both cells, the degradation rate was accelerated at higher current but with the concomitant fall of mineralization current efficiency due to the greater increase in rate of the parasitic reactions of hydroxyl radicals. Reversed-phase liquid chromatography allowed the identification of catechol, resorcinol, hydroquinone, p-benzoquinone, and 1,2,4-trihydroxybenzene as aromatic intermediates, whereas ion exclusion chromatography revealed the formation of malic, maleic, fumaric, acetic, oxalic, formic, and oxamic acids. NH₄ ⁺, NO₃ ^?, and SO₄ ^2? ions were released during the electro-Fenton process. A plausible reaction sequence for sulfanilamide mineralization involving all detected intermediates has been proposed. The toxicity of the solution was assessed from the Vibrio fischeri bacteria luminescence inhibition. Although it acquired its maximum value at short electrolysis time, the solution was completely detoxified at the end of the electro-Fenton treatment, regardless of the anode used.     

Medium optimization for the production of anti-cyanobacterial substances by Streptomyces sp. HJC-D1 using response surface methodology

Bioremediation using isolated anti-cyanobacterial microorganism has been widely applied in harmful algal blooms (HABs) control. In order to improve the secretion of activated anti-cyanobacterial substances, and lower the cost, a sequential optimization of the culture medium based on statistical design was employed for enhancing the anti-cyanobacterial substances production and chlorophyll a (Chl a) removal by Streptomyces sp. HJC-D1 in the paper. Sucrose and KNO₃ were selected as the most suitable carbon and nitrogen sources based on the one-at-a-time strategy method, and sucrose, KNO₃ and initial pH were found as major factors that affected the anti-cyanobacterial ability of the isolated stain via the Plackett–Burman design. Based on the response surface and canonical analysis, the optimum condition of culture medium was obtained at 22.73 g l^-1 of sucrose, 0.96 g l^-1 of KNO₃, and initial pH 8.82, and the Chl a removal efficiency by strain HJC-D1 increased from 63?±?2 % to 78?±?2 % on the optimum conditions.     

The effects and the toxicity increases caused by bicarbonate,chloride, and other water components during the UV/TiO<Subscript>2</Subscript> degradation of oxazaphosphorine drugs

The influences of HCO₃ ^?, Cl^?, and other components on the UV/TiO₂ degradation of the antineoplastic agents ifosfamide (IFO) and cyclophosphamide (CP) were studied in this work. The results indicated that the presence of HCO₃ ^?, Cl^?, NO₃ ^?, and SO₄ ^2? in water bodies resulted in lower degradation efficiencies. The half-lives of IFO and CP were 1.2 and 1.1 min and increased 2.3–7.3 and 3.2–6.3 times, respectively, in the presence of the four anions (initial compound concentration = 100 μg/L, TiO₂ loading =100 mg/L, anion concentration = 1000 mg/L, and pH = 8). Although the presence of HCO₃ ^? in the UV/TiO₂/HCO₃ ^? system resulted in a lower degradation rate and less byproduct formation for IFO and CP, two newly identified byproducts, P11 (M.W. = 197) and P12 (M.W. = 101), were formed and detected, suggesting that additional pathways occurred during the reaction of ?CO₃ ^? in the system. The results also showed that ?CO₃ ^? likely induces a preferred ketonization pathway. Besides the inorganic anions HCO₃ ^?, Cl^?, NO₃ ^?, and SO₄ ^2?, the existence of dissolved organic matter in the water has a significant effect and inhibits CP degradation. Toxicity tests showed that higher toxicity occurred in the presence of HCO₃ ^? or Cl^? during UV/TiO₂ treatment and within 6 h of reaction time, implying that the effects of these two anions should not be ignored when photocatalytic treatment is applied to treat real wastewater.     

Electrochemical Monitoring of Methylparathion Degradation in an Acid Aqueous Medium in Presence of Cu(II)

Abstract

A study was undertaken to determine the effect of Cu(II) in degradation of methylparathion (o,o-dimethyl o, 4-nitrophenyl phosphoriotioate) in acid medium. Initial electrochemical characterization of Cu(II) and methylparathion was done in an aqueous medium at a pH range of 2–7. Cu(II) was studied in the presence of different anions and it was observed that its electroactivity depends on pH and is independent of the anion used. Methylparathion had two reduction signals at pH ≤ 6 and only one at pH > 6. The pesticide's transformation kinetic was then studied in the presence of Cu(II) in acid buffered aqueous medium at pH values of 2, 4, and 7. Paranitrophenol appeared as the only electroactive product at all three pH values. The reaction was first order and had k values of 5.2 × 10^?3 s^?1 at pH 2, 5.5 × 10^?3 s^?1 at pH 4 and 9.0 × 10^?3 s^?1 at pH 7. It is concluded that the principal degradation pathway of methylparathion in acid medium is a Cu(II) catalyzed hydrolysis reaction.     

Electrooxidation of industrial wastewater containing 1,4-dioxane in the presence of different salts

The treatment of 1,4-dioxane solution by electrochemical oxidation on boron-doped diamond was studied using a central composite design and the response surface methodology to investigate the use of SO₄ ^2? and HCO₃ ^? as supporting electrolytes considering the applied electric current, initial chemical oxygen demand (COD) value, and treatment time. Two industrial effluents containing bicarbonate alkalinity, one just carrying 1,4-dioxane (S1), and another one including 1,4-dioxane and 2-methyl-1,3-dioxolane (S2), were treated under optimized conditions and subsequently subjected to biodegradability assays with a Pseudomonas putida culture. Electrooxidation was compared with ozone oxidation (O₃) and its combination with hydrogen peroxide (O₃/H₂O₂). Regarding the experimental design, the optimal compromise for maximum COD removal at minimum energy consumption was shown at the maximum tested concentrations of SO₄ ^2? and HCO₃ ^? (41.6 and 32.8 mEq L^?1, respectively) and the maximum selected initial COD (750 mg L^?1), applying a current density of 11.9 mA cm^?2 for 3.8 h. Up to 98 % of the COD was removed in the electrooxidation treatment of S1 effluent using 114 kWh per kg of removed COD and about 91 % of the COD from S2 wastewater applying 49 kWh per kg of removed COD. The optimal biodegradability enhancement was achieved after 1 h of electrooxidation treatment. In comparison with O₃ and O₃/H₂O₂ alternatives, electrochemical oxidation achieved the fastest degradation rate per oxidant consumption unit, and it also resulted to be the most economical treatment in terms of energy consumption and price per unit of removed COD.     

Fenton-like degradation of nalidixic acid with Fe3+/H2O2

The Fenton-like degradation of nalidixic acid was studied in this work. The effects of Fe³⁺ concentration and initial H₂O₂ concentration were investigated. Increasing the initial H₂O₂ concentration enhances the degradation and mineralization efficiency for nalidixic acid, while Fe³⁺ shows an optimal concentration of 0.25 mM. A complete removal of nalidixic acid and a TOC removal of 28 % were achieved in 60 min under a reaction condition of [Fe³⁺]?=?0.25 mM, [H₂O₂]?=?10 mM, T?=?35 °C, and pH?=?3. LC–MS analysis technique was used to analyze the possible degradation intermediates. The degradation pathways of nalidixic acid were proposed according to the identified intermediates and the electron density distribution of nalidixic acid. The Fenton-like degradation reaction of nalidixic acid mainly begins with the electrophilic attack of hydroxyl radical towards the C₃ position which results in the ring-opening reaction; meanwhile, hydroxyl radical attacking to the branched alkyl groups of nalidixic acid leads to the oxidation at the branched alkyl groups.     

Bioremediation assessment of diesel–biodiesel-contaminated soil using an alternative bioaugmentation strategy

This study investigated the effectiveness of successive bioaugmentation, conventional bioaugmentation, and biostimulation of biodegradation of B10 in soil. In addition, the structure of the soil microbial community was assessed by polymerase chain reaction-denaturing gradient gel electrophoresis. The consortium was inoculated on the initial and the 11th day of incubation for successive bioaugmentation and only on the initial day for bioaugmentation and conventional bioaugmentation. The experiment was conducted for 32 days. The microbial consortium was identified based on sequencing of 16S rRNA gene and consisted as Pseudomonas aeruginosa, Achromobacter xylosoxidans, and Ochrobactrum intermedium. Nutrient introduction (biostimulation) promoted a positive effect on microbial populations. The results indicate that the edaphic community structure and dynamics were different according to the treatments employed. CO₂ evolution demonstrated no significant difference in soil microbial activity between biostimulation and bioaugmentation treatments. The total petroleum hydrocarbon (TPH) analysis indicated a biodegradation level of 35.7 and 32.2 % for the biostimulation and successive bioaugmentation treatments, respectively. Successive bioaugmentation displayed positive effects on biodegradation, with a substantial reduction in TPH levels.     

Biodegradation of toluene vapor in coir based upflow packed bed reactor by <Emphasis Type="Italic">Trichoderma asperellum</Emphasis> isolate

In the present study, a new biofiltration system involving a selective microbial strain isolated from aerated municipal sewage water attached with coir as packing material was developed for toluene degradation. The selected fungal isolate was identified as Trichoderma asperellum by 16S ribosomal RNA (16S rRNA) sequencing method, and pylogenetic tree was constructed using BLASTn search. Effect of various factors on growth and toluene degradation by newly isolated T. asperellum was studied in batch studies, and the optimum conditions were found to be pH 7.0, temperature 30 °C, and initial toluene concentration 1.5 (v/v)%. Continuous removal of gaseous toluene was monitored in upflow packed bed reactor (UFPBR) using T. asperellum. Effect of various parameters like column height, flow rate, and the inlet toluene concentration were studied to evaluate the performance of the biofilter. The maximum elimination capacity (257 g m^?3 h^?1) was obtained with the packing height of 100 cm with the empty bed residence time of 5 min. Under these optimum conditions, the T. asperellum showed better toluene removal efficiency. Kinetic models have been developed for toluene degradation by T. asperellum using macrokinetic approach of the plug flow model incorporated with Monod model.     

Biodegradation of C.I. Acid Red 1 by indigenous bacteria <Emphasis Type="Italic">Stenotrophomonas</Emphasis> sp. BHUSSp X2 isolated from dye contaminated soil

A significant proportion of xenobiotic recalcitrant azo dyes are being released in environment during carpet dyeing. The bacterial strain Stenotrophomonas sp. BHUSSp X2 was isolated from dye contaminated soil of carpet industry, Bhadohi, India. The isolated bacterial strain was identified morphologically, biochemically, and on the basis of 16S rRNA gene sequence. The isolate decolorized 97 % of C.I. Acid Red 1 (Acid RED G) at the concentration of 200 mg/l within 6 h under optimum static conditions (temperature ?35 °C, pH 8, and initial cell concentration 7?×?10⁷ cell/ml). Drastic reduction in dye degradation rate was observed beyond initial dye concentration from 500 mg/l (90 %), and it reaches to 25 % at 1000 mg/l under same set of conditions. The analysis related to decolorization and degradation was done using UV-Vis spectrophotometer, HPLC, and FTIR, whereas the GC-MS technique was utilized for the identification of degradation products. Phytotoxicity analysis revealed that degradation products are less toxic as compared to the original dye.     

Photocatalytic degradation of acetaminophen in modified TiO2 under visible irradiation

This study investigated the photocatalytic degradation of acetaminophen (ACT) in synthetic titanium dioxide (TiO₂) solution under a visible light (λ >440 nm). The TiO₂ photocatalyst used in this study was synthesized via sol–gel method and doped with potassium aluminum sulfate (KAl(SO₄)₂) and sodium aluminate (NaAlO₂). The influence of some parameters on the degradation of acetaminophen was examined, such as initial pH, photocatalyst dosage, and initial ACT concentration. The optimal operational conditions were also determined. Results showed that synthetic TiO₂ catalysts presented mainly as anatase phase and no rutile phase was observed. The results of photocatalytic degradation showed that LED alone degraded negligible amount of ACT but with the presence of TiO₂/KAl(SO₄)₂, 95 % removal of 0.10-mM acetaminophen in 540-min irradiation time was achieved. The synthetic TiO₂/KAl(SO₄)₂ presented better photocatalytic degradation of acetaminophen than commercially available Degussa P-25. The weak crystallinity of synthesized TiO₂/NaAlO₂ photocatalyst showed low photocatalytic degradation than TiO₂/KAl(SO₄)₂. The optimal operational conditions were obtained in pH 6.9 with a dose of 1.0 g/L TiO₂/KAl(SO₄)₂ at 30 °C. Kinetic study illustrated that photocatalytic degradation of acetaminophen fits well in the pseudo-first order model. Competitive reactions from intermediates affected the degradation rate of ACT, and were more obvious as the initial ACT concentration increased.     

Pathways of reductive degradation of crystal violet in wastewater using free-strain Burkholderia vietnamiensis C09V

A new strain isolated from activated sludge and identified as Burkholderia vietnamiensis C09V was used to biodegrade crystal violet (CV) from aqueous solution. To understand the degradation pathways of CV, batch experiments showed that the degradation using B. vietnamiensis C09V significantly depended on conditions such as pH, initial dye concentration and media components, carbon and nitrogen sources. Acceleration in the biodegradation of CV was observed in presence of metal ions such as Cd and Mn. More than 98.86C of CV (30 mg l^?1) was degraded within 42 h at pH 5 and 30 °C. The biodegradation kinetics of CV corresponded to the pseudo first-order rate model with a rate constant of 0.046 h^?1. UV–visible and Fourier transform infrared spectroscopy (FTIR) were used to identify degradation metabolites. Which further confirmed by LC-MS analysis, indicating that CV was biodegraded to N,N-dimethylaminophenol and Michler’s ketone prior to these intermediates being further degraded. Finally, the ability of B. vietnamiensis C09V to remove CV in wastewater was demonstrated.     

Biosorption and degradation of decabromodiphenyl ether by <Emphasis Type="Italic">Brevibacillus brevis</Emphasis> and the influence of decabromodiphenyl ether on cellular metabolic responses

There is global concern about the effects of decabromodiphenyl ether (BDE209) on environmental and public health. The molecular properties, biosorption, degradation, accumulation, and cellular metabolic effects of BDE209 were investigated in this study to identify the mechanisms involved in the aerobic biodegradation of BDE209. BDE209 is initially absorbed by wall teichoic acid and N-acetylglucosamine side chains in peptidoglycan, and then, BDE209 is transported and debrominated through three pathways, giving tri-, hepta-, octa-, and nona-bromodiphenyl ethers. The C–C bond energies decrease as the number of bromine atoms on the diphenyl decreases. Polybrominated diphenyl ethers (PBDEs) inhibit protein expression or accelerate protein degradation and increase membrane permeability and the release of Cl^?, Na⁺, NH₄ ⁺, arabinose, proteins, acetic acid, and oxalic acid. However, PBDEs increase the amounts of K⁺, Mg²⁺, PO₄ ^3?, SO₄ ^2?, and NO₃ ^? assimilated. The biosorption, degradation, accumulation, and removal efficiencies when Brevibacillus brevis (1 g L^?1) was exposed to BDE209 (0.5 mg L^?1) for 7 days were 7.4, 69.5, 16.3, and 94.6 %, respectively.     

Fe(III)–EDDS complex in Fenton and photo-Fenton processes: from the radical formation to the degradation of a target compound

The present work compares the efficiency of homogenous Fenton and photo-Fenton processes in the presence of Fe(III)–EDDS complex under different experimental conditions. 4-tert-Butylphenol (4-t-BP), which is one of the endocrine disrupting chemicals, was used as a model pollutant to investigate the Fenton and photo-Fenton application. The efficiency of homogenous photo-Fenton process was significantly much higher than homogenous Fenton process, which is due to the rapid formation of Fe²⁺ under UV irradiation of the iron complex and the photochemical formation of HO^? from the photolysis of the complex Fe(III)–EDDS. Through the degradation of 4-t-BP, the effect of Fe(III)–EDDS concentration, H₂O₂ concentration, pH, and oxygen was investigated in both processes. Such trend was also correlated with pH calculating the polychromatic Fe²⁺ quantum yield formation at pH 4.0, 6.0, and 8.6. The results showed that at high Fe(III)–EDDS and H₂O₂ concentrations, a negative effect was found. By the way, the Fenton process was found to be enhanced at basic pH. These results can be very useful for the use and optimization of such iron complex in water treatment process as function of different physico-chemical conditions.