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•g-C3N4/Fe3O4/Ag photocatalyst was successfully synthesized.•A complete removal efficiency of diazinon was accomplished.•Hydroxyl radicals (OH˚) highly facilitated the photocatalytic ...removal of diazinon.
Herein, a well-known pesticide named diazinon was successfully removed from aqueous solutions by the UV photocatalytic process in which g-C3N4/Fe3O4/Ag was applied as a nanocomposite. Initially, g-C3N4/Fe3O4/Ag nanocomposite was synthesized by a hydrothermal method and XRD, FT-IR, SEM, EDX and PL analyses were employed to identify the nanocomposite structure. The best conditions for the complete removal of diazinon (DZN) (i.e., 100 %) were obtained after 60 min under the following conditions: pH = 7, catalyst dosage of 0.5 g/L and DZN concentration of 5 mg/L. The removal reaction followed the first order kinetic model (k, 0.067; R2, 0.9982). Furthermore, the effects of several scavengers such as ammonium oxalate (AO), tert-butanol (TB) and benzoquinone (BQ) on the performance of the removal reaction were investigated revealing that the hydroxyl ions played an active role in the reaction. Finally, the photocatalytic process using the nanocomposite g-C3N4/Fe3O4/Ag proved to be promising for the removal of DZN pesticide from aqueous media.
In this study photo-catalytic degradation of chlorobenzene from aqueous solutions using CQD decorated Fe-doped TiO2 immobilized in Glass Fibers (GF) was investigated. Characteristics of the ...synthesized photo-catalyst were determined by EF-SEM, EDX, BET, XRD, FTIR, and DRS analysis. Additionally, DRS analysis demonstrated adding CQD to the TiO2–Fe reduced its band gap energy from 2.96 eV to 2.91eV, while that was 3.10 eV for undoped TiO2. Among that three photo-catalysts, GF/CQD(4.5 wt%) decorated Fe–TiO2 composite had performance nearly 100.0%, when pH was 5 and low concentration of chlorobenzene. In addition, GF/CQD(4.5 wt%) decorated Fe–TiO2 composite show it could be well applied for five times and with a little reduction on the performance. Also, no detectable Fe found to be released from the composite. Minimum inhibitory concentration (MIC) for E. coli bacteria was 12.2 mg L−1 of chlorobenzene residual. Our findings show the catalyst was successful for chlorobenzene removal in the wastewater effluent. In conclusion, present hybrid composite could successfully and safely remove chlorobenzene from synthetic aqueous solution.
•Improving the light adsorption at visible range.•Reducing band gap energy.•Well done supporting the composite onto the GF.
The present study aimed to model and optimize the dimethyl phthalate (DMP) degradation from aqueous solution using UV
C
/ Na
2
S
2
O
8
/Fe
2+
system based on the response surface methodology (RSM). A ...high removal efficiency (97%) and TOC reduction (64.2%) were obtained under optimum conditions i.e. contact time = 90 min, SPS concentration = 0.601 mM/L, Fe
2+
= 0.075 mM/L, pH = 11 and DMP concentration = 5 mg/L. Quenching experiments confirmed that sulfate radicals were predominant radical species for DMP degradation. The effect of CO
3
−
on DMP degradation was more complicated than other aquatic background anions. The possible pathway for DMP decomposition was proposed according to HPLC and GC–MS analysis. The average oxidation state (AOS) and carbon oxidation state (COS) values as biodegradability indicators demonstrated that the UV
C
/SPS/Fe
2+
system can improve the bioavailability of DMP over the time. Finally, the performance of UV
C
/SPS/Fe
2+
system for DMP treatment in different aquatic solutions: tap water, surface runoff, treated and raw wastewater were found to be 95.7, 88.5, 80.5, and 56.4%, respectively.
Graphical abstract
In this research, a new sample treatment technique termed solvent-assisted dispersive solid phase extraction (SA-DSPE) was developed. The new method was based on the dispersion of the sorbent into ...the sample to maximize the contact surface. In this approach, the dispersion of the sorbent at a very low milligram level was achieved by injecting a mixture solution of the sorbent and disperser solvent into the aqueous sample. Thereby, a cloudy solution formed. The cloudy solution resulted from the dispersion of the fine particles of the sorbent in the bulk aqueous sample. After extraction, the cloudy solution was centrifuged and the enriched analytes in the sediment phase dissolved in ethanol and determined by flame atomic absorption spectrophotometer. Under the optimized conditions, the detection limit for lead and cadmium ions was 1.2 μg L(-1) and 0.2 μg L(-1), respectively. Furthermore, the preconcentration factor was 299.3 and 137.1 for cadmium and lead ions, respectively. SA-DSPE was successfully applied for trace determination of lead and cadmium in fruit (Citrus limetta, Kiwi and pomegranate) and water samples. Finally, the introduced sample preparation method can be used as a simple, rapid, reliable, selective and sensitive method for flame atomic absorption spectrophotometric determination of trace levels of lead and cadmium ions in fruit and water samples.
Abstract
Antibiotics are resistant compounds with low biological degradation that generally cannot be removed by conventional wastewater treatment processes. The use of yolk-shell nanostructures in ...spinning disc photocatalytic reactor (SDPR) enhances the removal efficiency due to their high surface-to-volume ratio and increased interaction between catalyst particles and reactants. The purpose of this study is to investigate the SDPR equipped to Fe
3
O
4
@void@CuO/ZnO yolk-shell thin film nanostructure (FCZ YS) in the presence of visible light illumination in the photocatalytic degradation of amoxicillin (AMX) from aqueous solutions. Stober, co-precipitation, and self-transformation methods were used for the synthesis of FCZ YS thin film nanostructure and the physical and chemical characteristics of the catalyst were analyzed by XRD, VSM,, EDX, FESEM, TEM, AFM, BET, contact angle (CA), and DRS. Then, the effect of different parameters including pH (3–11), initial concentration of AMX (10–50 mg/L), flow rate (10–25 mL/s) and rotational speed (100–400 rpm) at different times in the photocatalytic degradation of AMX were studied. The obtained results indicated that the highest degradation efficiency of 97.6% and constant reaction rate of AMX were obtained under LED visible light illumination and optimal conditions of pH = 5, initial AMX concentration of 30 mg/L, solution flow rate of 15 mL/s, rotational speed of 300 rpm and illumination time of 80 min. The durability and reusability of the nanostructure were tested, that after 5 runs had a suitable degradation rate. Considering the appropriate efficiency of amoxicillin degradation by FCZ YS nanostructure, the use of Fe
3
O
4
@void@CuO/ZnO thin film in SDPR is suggested in water and wastewater treatment processes.
•Polyaniline (PAN) and polypyrrole (PPY) can be suitable coatings for SPME fibers.•PAN–PPY nano composite was electrochemically deposited on inner surface of stainless steel tube.•On-line in-tube ...SPME followed by HPLC was developed for extraction of parabens.•Several important factors affecting extraction efficiency were investigated and optimized.•The method was applied for analysis of the parabens in water, milk, and juice samples.
In this work, a novel and efficient on-line in-tube solid phase microextraction method followed by high performance liquid chromatography was developed for preconcentration and determination of trace amounts of parabens. A nanostructured polyaniline–polypyrrole composite was electrochemically deposited on the inner surface of a stainless steel tube and used as the extraction phase. Several important factors that influence the extraction efficiency, including type of solid-phase coating, extraction and desorption times, flow rates of the sample solution and eluent, pH, and ionic strength of the sample solution were investigated and optimized. Under the optimal conditions, the limits of detection were in the range of 0.02–0.04μgL−1. This method showed good linearity for parabens in the range of 0.07–50μgL−1, with coefficients of determination better than 0.998. The intra- and inter-assay precisions (RSD%, n=3) were in the range of 5.9–7.0% and 4.4–5.7% at three concentration levels of 2, 10, and 20μgL−1, respectively. The extraction recovery values for the spiked samples were in the acceptable range of 80.3–90.2%. The validated method was successfully applied for analysis of methyl-, ethyl-, and propyl parabens in some water, milk, and juice samples.
Herein, the efficient degradation of a highly consumed antibiotic known as metronidazole (MNZ) in aqueous solutions using Co/g-C
3
N
4
/Fe
3
O
4
nanocomposite under visible light irradiation was ...accomplished. Initially, the photocatalyst (Co/g-C
3
N
4
/Fe
3
O
4
) was synthesized by a simple hydrothermal method and then characterized by several analytical techniques, namely EDS, SEM, XRD, UV–vis DRS, and FTIR. The efficiency of the synthesized photocatalyst with regard to the degradation of the studied antibiotic (MNZ) under visible light irradiation was fully evaluated. The influential operational parameters affecting the efficiency of the degradation process such as pH (2–10), nanocomposite dosage (0.2–1 g/L), MNZ concentration (5–20 mg/L), and irradiation time (0–80 min) were optimized. The results revealed that the maximum degradation efficiency for MNZ was obtained under the following conditions: irradiation time of 60 min, pH = 8, MNZ concentration of 5 mg/L, and photocatalyst dosage of 0.7 g/L. In addition, the degradation of MNZ followed the pseudo-first-order kinetic model. The best rate constant (
k
) value was determined to be 0.0102 min
−1
with the correlation coefficient (
R
2
) of 0.992. According to the results of the quenching tests, it was found out that hydroxyl radicals (OH°) were the main species responsible for the MNZ degradation. Furthermore, the applied photocatalyst (Co/g-C
3
N
4
/Fe
3
O
4
) exhibited a high level of recovery and stability after five cycles of reuse. Co/g-C
3
N
4
/Fe
3
O
4
/Vis system exhibited an excellent performance in the treatment of wastewater and real water samples. Finally, it was concluded that the synthesized nanocomposite could be potentially used as a promising and suitable photocatalyst in the degradation of other antibiotics.
Conventional wastewater treatment processes are often unable to remove antibiotics with resistant compounds and low biological degradation. The need for advanced and sustainable technologies to ...remove antibiotics from water sources seems essential. In this regard, the effectiveness of a spinning disc photocatalytic reactor (SDPR) equipped with a visible light-activated Fe
O
@SiO
-NH
@CuO/ZnO core-shell (FSNCZ CS) thin film photocatalyst was investigated for the decomposition of amoxicillin (AMX), a representative antibiotic. Various characterization techniques, such as TEM, FESEM, EDX, AFM, XRD, and UV-Vis-DRS, were employed to study the surface morphology, optoelectronic properties, and nanostructure of the FSNCZ CS. Key operating parameters such as irradiation time, pH, initial AMX concentration, rotational speed, and solution flow rate were fine-tuned for optimization. The results indicated that the highest AMX decomposition (98.7%) was attained under optimal conditions of 60 min of irradiation time, a rotational speed of 350 rpm, a solution flow rate of 0.9 L/min, pH of 5, and an initial AMX concentration of 20 mg/L. Moreover, during the 60 min irradiation time, more than 69.95% of chemical oxygen demand and 61.2% of total organic carbon were removed. After the photocatalytic decomposition of AMX, there is a substantial increase in the average oxidation state and carbon oxidation state in SDPR from 1.33 to 1.94 and 3.2, respectively. Active species tests confirmed that ·OH and ·O
played a dominant role in AMX decomposition. The developed SDPR, which incorporates a reusable and robust FSNCZ CS photocatalyst, demonstrates promising potential for the decomposition of organic compounds.
Abstract
Environmental destruction, water crisis, and clean energy are among the very important challenges worldwide based on sustainable development goals. Photocatalytic fuel cell, a potential ...candidate for converting chemical energy into electrical energy through a pollution-free method, holds promise in addressing these challenges. In this regard, we investigated the response of a photoanode covered with UiO66-NH
2
-TiO
2
/NiF on a porous nickel foam as an attractive electrochemical response to remove antibiotics from aqueous solution and simultaneously produce electricity using a one-step hydrothermal synthesis. Nickel foam with its fine structure provides a suitable space for the interaction of light, catalyst, and efficient mass transfer of reactive molecules. It appears that it can be used as a competitive electrode in fuel cells. In order to investigate the properties of the photocatalyst, structural analyses including XRD, FESEM, FTIR, and UV–vis DRS were utilized. Additionally, polarization and electrochemical tests such as chronoamperometry and EIS were measured to further examine the electrochemical features of the PFC photoanode system. The obtained results under optimal conditions (SMZ concentration = 20 ppm, pH = 6, irradiation time = 120 min) were as follows: removal efficiency of 91.7%, P
max
= 16.98 μW/cm
2
, J
sc
= 96.75 μA/cm
2
, V
oc
= 644 mV. The light-induced current flow in UiO66-NH
2
-TiO
2
/NiF exhibited prominent and reproducible photocurrent responses, indicating efficient and stable charge separation in TiO
2
/NiF composite materials, which is a promising strategy for pollutant removal and simultaneous electricity generation.
Here, a combined pretreatment oxidation process (O3/H2O2) was investigated to enhance the biodegradability of raw landfill leachate (RLL) and biomethane potential (BMP) in anaerobic reactors. The ...central composite design (CCD) and response surface methodology (RSM) were employed to optimize the operational parameters influencing on RLL bioavailability in O3/H2O2 process: pH, Oxygen Flow rate, Reaction Time, and H2O2 concentration. The findings revealed that the O3/H2O2 increased biodegradability index (BOD5/COD) of RLL from 0.41 to 0.68 under optimized condition (pH=8, Oxygen flow= 0.25 L.min−1, Reaction Time= 25 min, H2O2 concentration= 2.5 g.L−1). Furthermore, the effects of O3/H2O2 process on BMP of RLL were surveyed under mesophilic anaerobic reactors (Temperature: 37 ± 1 °C) in viewpoints of operational performance and methane yield in a batch mode for incubation period of 24 days. The results showed that O3/H2O2 process simultaneously improve the BMP by 2.99 times higher in a shorter lag-phase period (5 days) compared with control. The pretreatment O3/H2O2 and mesophilic anaerobic digestion process revealed a feasible and efficient method for enhance BMP of RLL.
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•Oxidation pretreatment process (O3/H2O2) was employed to enhance RLL bioavailability.•O3/H2O2 revealed efficient technology to lower lag-phase of RLL anaerobic digestion.•Methane yield of 0.158 LH4/gsCOD removed achieved from O3/H2O2-assisted anaerobic reactor.
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