This study aiming to determine the optimal conditions to degrade an organophosphate pesticide diazinon (DZN) at low levels concentrations (μg.mL−1) and to identify the by-products generated. The ...degradation processes utilized were the Fenton and photo-Fenton. The iron concentration Fe2+, the hydrogen peroxide concentrations H2O2, and the solution pH are the investigated parameters. The Doehlert three-parameter experimental design was applied to model and optimize both degradation processes. The mathematical models suggested were assessed and validated by application of analysis of variances ANOVA. In the case of Fenton process, the greatest yield of degradation (79%) was obtained at Fe2+ = 35 mg.L−1 (0.63 mmol.L−1), H2O2 = 423 mg.L−1 (12.44 mmol.L−1), and pH = 5.0. In photo-Fenton process, the maximum yield of degradation (96%) was obtained under the conditions of Fe2+ = 29 mg.L−1 (0.52 mmol.L−1), H2O2 = 258 mg.L−1 (7.59 mmol.L−1) and pH = 4.6. QuEChERS (quick, easy, cheap, effective, rugged, and safe), as extraction technique, and GC-MS/MS (gas chromatography coupled with triple quadrupole mass spectrometry) were used to identify the by-products degradation of DZN. The identified compounds are diazoxon, triethyl phosphate, triethyl thiophosphate, 2-isopropyl-5-ethyl-6-methylpyrimidine-4-ol, 2-isopropyl-6-methylpyrimidine-4-ol (IMP) and hydroxydiazinon. Three possible pathways for diazinon degradation have been suggested and the hydroxylation, oxidation and hydrolysis are likely probable degradation mechanisms.
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•Fenton and photo-Fenton degradation of diazinon in trace levels were developed.•Total elimination was achieved in photo-Fenton degradation within 5 min.•New methodology to detect ultra-trace by-products resulting from photo-degradation.•Several possible pathways for elimination of diazinon have been proposed.
Photodegradation of an industrial Azo dye C.I Basic Red 46, was examined in a semi-pilot scale prototype solar photoreactor under solar radiation. In our study, photodegradation of the dye was ...optimized using Response Surface Methodology (RSM) based on Box-Wilson approach. The Artificial Neural Network (ANN) was used to establish suitable modeling and optimal conditions for the Solar UV/Immobilized-TiO
2
process in order to evaluate the individual effects of three factors that independently affect the effectiveness of the photodegradation process: (1) initial concentration of the dye, (2) pH, and (3) flow rate. The RSM was in good agreement with the prediction model (R
2
Dec
= 0.95); meanwhile, the ANN approach revealed that the predicated model fit perfectly with the experimental data to yield the highest value of R
2
= 0.999. The effects of these three factors could be estimated from a second-order polynomial equation, and the optimal parameters of photodegradation consisted of three main parameters: (1) initial concentration of colorant 10.65 mg.L
−1
, (2) pH 10.82, and (3) rate of fluid flow of 852 L h
−1
. The decolorization removal efficiency under these optimal conditions was 99%.
The photodegradation of an industrial azo dye C.I Basic Red 46 was examined in a fixed-bed photoreactor using UV-lamps simulated to the solar irradiation. In our photodecolorization study, the ...UV/TiO2 process was optimized using the Box-Behnken approach to evaluate the synergistic effects of three independent parameters (initial concentration of the dye, flow rate, and UV intensity) on mineralization effectiveness. The response surface methodology was in good promise with the prediction model (coefficients of determination of decolorization and mineralization were R2Dec = 0.997 and R2TOC = 0.994, respectively). The effects of the factors could be estimated from a second–order polynomial equation and student’s t-test. The optimal parameters of decolorization and mineralization were as follows: initial concentration of colorant 25 mg L−1, rate of fluid flow 0.3 L min−1, and ultraviolet light intensity 38.1 W m−2. The decolorization and mineralization removal efficiency under these optimal conditions were 100% and 57.63% respectively. These results indicate that optimization using response surface methodology, based on the Box-Behnken approach, is an excellent tool for determining the optimal conditions, and the process can be easily extrapolated for a specific treatment of real waste water containing the azo dye C.I Basic Red 46. Also, the intermediates that were produced during photodegradation process of Basic Red 46 were determined by GC/MS.
Chlorpyrifos (CPF) is a widely used organophosphate insecticide, though its excessive use causes environmental contamination, raising concerns about its adverse effects on human health. In this ...regard, Urtica dioica stands out as a promising candidate for counteracting chemical ‘contaminant’ toxicity thanks to its therapeutic properties. Therefore, our study aimed to investigate the potential of an Urtica dioica ethanolic extract (UDE) to mitigate chlorpyrifos-induced toxicity. Eight compounds in the Urtica dioica ethanolic extract have been identified, most of which present significant potential as antioxidant, anti-inflammatory, and neuroprotective agents. Chlorpyrifos exposure altered hatching rates, increased the incidence of teratogenic effects, and upregulated the expression of brain-derived neurotrophic factor (Bdnf) in zebrafish larvae telencephalon. On the other hand, UDE demonstrated a preventive effect against CPF-induced teratogenicity, which is expressed by a lower morphological deformity rate. Moreover, the UDE showed a rather protective effect, maintaining the physiological condition of the telencephalon. Additionally, CPF altered the locomotor behavior of larvae, which was characterized by irregular swimming and increased activity. This defective behavioral pattern was slightly attenuated by the UDE. Our findings suggest that the UDE possesses significant protective properties against CPF-induced toxicity, probably conferred by its natural antioxidant and anti-inflammatory contents. Still, further research is needed to elucidate the recruited mechanisms and implicated pathways on UDE’s protective effects.
Recently, environmental scientists have been focused their attention on the occurrence of emerging contaminants in water, such as disinfection by products (DBPs), including chlorophenols. These ...pollutants can be a public health problem due to their carcinogenic properties. In this work, ultra-high pressure liquid chromatography (UHPLC) coupled to a photodiode array detector (PDA) was used for the development of an analytical method capable of simultaneous identification and quantification of two chlorophenols namely, 2-chlorophenol and 2,4-dichlorophenol in water samples. In addition, a solid phase extraction (SPE) procedure for the extraction of these compounds was optimized. The chlorophenols were separated by an Acquity BEH C18 (100×2.1mm, 1.7μm) column with a mobile phase of acetonitrile/ultrapure water/formic acid (55/45/0.1, v/v/v). The flow rate of the mobile phase was 0.4mLmin−1. The optimized SPE–UHPLC/PDA technique was evaluated in terms of robustness, considering the enrichment factor for all of the studied chlorophenols. Linear calibration was obtained with correlation coefficients r2⩾0.998. Intra-day and inter-day precision was less than 5% and accuracy ranged from 99.95% to 103.32%, respectively. The obtained extraction recoveries were higher than 98%. The pre-concentration factor was 2.500 for the both analytes. Under optimized conditions, the detection limits of the overall SPE–UHPLC/PDA method were in the ngL−1 level. The excellent performance of the developed method, as well as the short analysis time makes it a promising analytical tool for the screening of chlorophenols in environmental water samples.
Background. Refinement of crude vegetable oil generates a large amount of wastewater and is a source of water pollution due to the presence of surfactants and phenols. Phenols are toxic aromatic ...compounds that can be lethal to fauna and flora, entraining the deceleration or blocking of the self-purification of biological treatments. In addition, surfactants can limit biological processes by inhibiting microorganisms that degrade organic matter. Objectives. The aim of the present study was to evaluate the treatment of refinery rejects loaded with phenols and detergents by coagulation flocculation using cactus pads (genus Opuntia) as a bio-flocculant and 30% iron(III) chloride (FeCl3) for surfactant and phenol removal. In addition, operating costs were evaluated for these pollution mitigation methods. Methods. The effectiveness of cactus pads as a bio-flocculant and 30% FeCl3 for surfactant and phenol removal were studied using a jar test. The study was conducted on vegetable oil refinery wastewater from a refinery company in Casablanca, Morocco. Results. The pollution load in wastewater varied widely from day to day. We evaluated the effect of cactus juice and 30% FeCl3 on high and low pollution loads. Opuntia pads showed a favorable potential for the treatment of low pollution load wastewater, with 78% and 90% of surfactant and phenol removed, respectively. However, the removal of high pollution load was less effective (42% and 41% removal of surfactant and phenol, respectively). The turbidity of low and high pollution load was reduced by 98.85% and 86%, respectively. The results demonstrate that 30% FeCl3 can effectively treat both low and high pollution loads (90% and 89% phenol removal, respectively, and 90% and 70% surfactant removal, respectively (optimal concentration 1.48 g/l). The turbidity was reduced by over 96% for both high and low pollutants. Conclusions. The results of the present study indicate that cactus as a natural flocculant and reject rich in FeCl3 could be effectively used for the low-cost effective treatment of crude vegetable oil refinery rejects. Competing Interests. The authors declare no competing financial interests
•The formation of complex compounds of Fe(III)-chlorophyll is shown by MLCT phenomenon.•The existence of ion Fe(III) in chlorophyll can improve the performance of chlorophyll.•The complex compound of ...Fe(III)-chlorophyll is paramagnetic.•The complex compound of Fe(III)-chlorophyll is an ionic compound.•The complex compound of Fe(III)-chlorophyll has efficiency values of 1.35%.
The energy crisis is a major problem facing the world today and will need a renewable energy source that is environmentally friendly; one of these is the dye sensitized solar cell (DSSC). DSSC is photochemical electric cell that can convert solar energy into electrical energy. This research aims to study the characteristics of chlorophyll compounds with the addition of metal ions Fe(III) and to determine the effect of Fe(III) on the performance of chlorophyll as a photosensitizer in the DSSC. The formation of complex compounds of Fe(III)-chlorophyll is shown by the phenomenon of metal ligand charge transfer (MLCT) at a wavelength of 263.00nm and absorption transition d-d at 745.00nm. Fourier transform infrared characterization of the binding of Fe-O complex compounds appears at 486.06cm−1. The complex compound of Fe(III)-chlorophyll has a magnetic moment value of 9.62 Bohr Magneton (BM). The existence of ion Fe(III) in chlorophyll can improve the performance of chlorophyll as a dye sensitizer with a maximum current of 4.00mA/cm2, maximum voltage of 0.18volts and efficiency values of 1.35%.
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