Degradation Of Diethyl Phthalate Research Articles

Degradation of diethyl phthalate by photolysis of hydrogen peroxide electrogenerated using a Printex L6 carbon modified with Benzophenone cathode in an improved tangential flow cell

In this work, a gas diffusion electrode (GDE) made of Printex L6 carbon modified with 2.0% w/w of benzophenone-3,3′,4,4′-tetracarboxylic dianhydride (PL6C/BTDA 2%) was employed as cathode in a new 3D printed electrochemical cell with tangential flow. With this configuration, the performance of the technology was evaluated for hydrogen peroxide (H2O2) electrogeneration and remediation of aqueous wastes contaminated with diethyl phthalate (DEP) using different H2O2-based advanced oxidation processes (AOPs). The electrogeneration study was carried out varying the current density applied to the system, and it was found that 50 mA cm-2 was the best performing value, resulting in remarkable Faradaic efficiencies of nearly 100%. This led to the production of higher amounts of H2O2 (442.5 mg L-1) in 90 minutes at an acceptable energy consumption (8.5 kWh kg-1) compared to values reported in the literature. Based on these findings, H2O2-based AOPs were employed to investigate the removal of DEP in cathodic compartment, including mediated electrochemical degradation with electrogenerated H2O2 (e-H2O2) and the integration of this technology with ultraviolet-C (UVC) photolysis (e-H2O2/UVC). The integrated e-H2O2/UVC obtained the best performance compared to single photolysis and e-H2O2, leading to the total elimination of DEP (90 μmol L-1) within only 30 min of treatment, reaching the highest kinetic rate constant (0.3 min-1). Fifteen by-products, generated through oxidation processes studied, were successfully identified by LC-MS/MS, enabling the proposal of the degradation mechanism of DEP.

Preparation of CeO2 Supported on Graphite Catalyst and Its Catalytic Performance for Diethyl Phthalate Degradation during Ozonation

Catalysts for the efficient catalytic decomposition of ozone to generate reactive free radicals to oxidize pollutants are needed. The graphite-supported CeO2 catalyst was optimally prepared, and its activity in ozonation was evaluated using the degradation of diethyl phthalate (DEP) as an index. The stability of CeO2/graphite catalyst and the influence of operating conditions on its catalytic activity were investigated, and the mechanism of CeO2/graphite catalytic ozonation was analyzed. CeO2/graphite had the highest catalytic activity at a Ce load of 3.5% and a pyrolysis temperature of 400 °C with the DEP degradation efficiency of 75.0% and the total organic carbon (TOC) removal efficiency of 48.3%. No dissolution of active components was found during the repeated use of CeO2/graphite catalyst. The ozone dosage, catalyst dosage, initial pH, and reaction temperature have positive effects on the DEP degradation by CeO2/graphite catalytic ozonation. The presence of tert-butanol significantly inhibits the degradation of DEP at an initial pH of 3.0, 5.8, or 9.0, and the experimental results of the •OH probe compound pCBA indicate that the CeO2/graphite catalyst can efficiently convert ozone into •OH in solution. The DEP degradation in the CeO2/graphite catalytic ozonation mainly depends on the •OH in the bulk solution formed by ozone decomposition.

Degradation of Dimethyl Phthalate and Diethyl Phthalate by Bacteria Isolated from Jazan, Saudi Arabia

P hthalate esters (PAEs) are commonly utilized in commercial, industrial, and medical applications. Various concentrations of PAEs have been detected in seawater samples and treated wastewater obtained from wastewater treatment plants in Saudi Arabia. Since these compounds pose adverse effects to human health, it is vital to develop efficient strategies to eliminate phthalate contamination from environments. In the present study, an enrichment technique was used to isolate phthalate-degrading bacteria from seawater and from activated sludge collected at Jazan Wastewater Treatment Plant, Saudi Arabia. Bacteria with the capability of degrading dimethyl phthalate (DMP) or diethyl phthalate (DEP) were isolated using minimum salt medium supplemented with these compounds as the sole carbon and energy source. High-performance liquid chromatography (HPLC) was utilized to evaluate the residual concentration of DMP and DEP. Using the 16S rRNA gene sequencing technique, the isolates with maximum DMP biodegradation activity were identified as Achromobacter sp. M1 and Pseudomonas sp. M2, while the isolates with maximum DEP biodegradation activity were identified as Pseudomonas sp. E2 and Pseudomonas sp. E3. The optimum bacterial growth was achieved at 30°C, pH 7.0, and 2% NaCl, except for Pseudomonas sp. E3, which demonstrated its maximum growth in the absence of NaCl. The highest biodegradation rate for all the bacterial strains (> 99.0%) was achieved at 30°C, pH 7.0, and up to 2% NaCl within 4 days. Concurrently, Pseudomonas sp. M2 and Pseudomonas sp. E2 exhibited remarkable degradation rates (97.5% and 56.7%, respectively) at 4% NaCl whereas Pseudomonas sp. E3 showed its highest DEP degradation (82.4%) after 4 days in the absence of NaCl. This study offers potential candidates, including Achromobacter sp. M1, Pseudomonas sp. M2, Pseudomonas sp. E2, and Pseudomonas sp. E3, for the proficient biodegradation of DMP and DEP.

Photocatalytic activation of peroxymonosulfate (PMS) by CNN@NH2-MIL-101(Fe) Z-scheme heterojunction for phthalates degradation under visible light irradiation

Phthalates (PAEs) are known to pose a serious threat to the environment and human health duo to their endocrine disrupting effects, thus a great deal of effort has been made to develop destruction technologies for PAEs treatment in the water environment, such as peroxymonosulfate (PMS)-based advanced oxidation technology. Here we prepared an environmentally friendly visible light catalyzer, a heterojunction of carbonitride nanosheets (CNN) doped with NH2-iron metal organic frameworks (NH2-MIL-101(Fe)), for the activation of PMS to efficaciously remove two representative PAEs—diisobutyl phthalate (DIBP) and diethyl phthalate (DEP)—from the aquatic environment. The CNN@NH2-MIL-101(Fe) photocatalyst possesses an excellent visible light harvesting performance with a narrow band gap (1.66 eV), low recombination ratio of photoinduced carriers, and long charge lifetime. The pore volume and surface area of the composite material was increased compared with any single component. The optimum CNN@NH2-MIL-101(Fe) catalyst manifested the high performance to activate PMS to degrade DIBP and DEP under visible irradiation with maximum removal of 94.5 ± 2.2 % and 83.4 ± 0.9 %, respectively. Four main active species (•OH, O2−•, SO4−•, and h+) were involved in PAEs photodegradation, with h+ and SO4−• playing a key role in the degradation of DIBP, and h+ in the degradation of DEP. The degradation mechanism of DIBP and DEP mainly involved the ester bond cleavage and oxidationby active species. Additionally, the CNN@NH2-MIL-101(Fe) heterojunction exhibited high and stable catalytic performance to activate PMS for PAEs destruction under pH 3 – 9. Therefore, this study provides a new strategy for designing and selecting environment-friendly treatment approach for the effective eradication of PAEs via a PMS-based advanced oxidation process.

An integrated Metagenomic-Pangenomic strategy revealed native microbes and magnetic biochar cooperation in plasticizer degradation

There has been growing concern over the release of plasticizers from plastic products, and the high levels of plasticizers in the environment have led to a threat to ecological security. Although some plasticizers may naturally degrade, their slow removal and prolonged life cycle remain challenges. To address this, this study explored a unique hybrid strategy using native field microorganisms and magnetic biochar (MBC) to support the upstream degradation of plasticizers. Diethyl phthalate (DP) was used as the test subject. The study found that MBC treatment led to high level of total organic carbon (TOC) and various organic products, demonstrating the degradation of DP. Analysis of the hybrid metagenomic model showed that several species of Pseudomonas can degrade downstream phenylmethanal and Pseudomonas nitroreducens has the ability to cooperate well with MBC due to its iron receptor and transporter. Additionally, a Pigmentiphaga species was found to have the ability to fully mineralize DP. Analysis of the Pigmentiphaga pangenome revealed that genes related to DP biodegradation were shared by members of this genus. Although some members of Pseudomonas is known to be pathogenic, the species identified in the study may not be harmful as they lack virulence factors. The study provides evidence regarding the cooperation between native biodegraders and MBC in mineralizing plasticizers, offering a new solution for removing phthalate plasticizers from soil and surface water.

Insights into multi-pathway peroxymonosulfate activation by copper-doped Ca/Mn perovskite oxides for diethyl phthalate degradation

Peroxymonosulfate (PMS) activation based on metallic catalysts with versatile mineral structures and superior catalytic properties has attracted much attention. In this study, we built a CaMnO3(CMO) with copper dopped to promote PMS activation by Mn(III)/Mn(IV) and Cu(I)/Cu(II) redox cycles with the synergistic effect of bimetal for efficient degradation of diethyl phthalate (DEP). Under optimal conditions, 95.7% of DEP (10 mg L−1) degradation was realized in 60 min, and the mineralization reached 75%, while only 26.9% of DEP was removed with little TOC removal by CaMnO3. Unexpectedly, not only •OH, O2•− and SO4•−, but also nonradical pathway singlet oxygen (1O2) was found to be involved in the CMO-Cu/PMS system. The redox cycles of Mn(III)/Mn(IV) and Cu(I)/Cu(II) effectively promoted PMS activation to reactive oxygen species (ROS), which were responsible for DEP degradation. Furthermore, density functional theory (DFT) calculations and liquid chromatograph-mass spectrometer (LCMS) were combined to explore the degradation pathway. This work provides a new insight for developing heterogeneous perovskites for PMS activation to construct more efficient method for water treatment.

Degradation of diethyl phthalate using a visible photocatalytic membrane reactor

Degradation of diethyl phthalate using a visible photocatalytic membrane reactor

Degradation of Diethyl Phthalate by HO• and SO4• – in the Aqueous Phase: Mechanisms, Kinetics, and Toxicity

The chemical degradation processes of diethyl phthalate (DEP) induced by HO• and SO4• – in aqueous solution were studied in a theoretical way. Not only radical addition and H-abstraction reactions but also single-electron transfer processes of DEP were considered. The thermodynamic and kinetic results indicate that the more favorable pathways are the H abstraction occurring in aliphatic side chains for all HO•/SO4• –-initiated degradation reactions of DEP. Subsequent reaction mechanisms of crucial primary intermediates were taken into account. At 298 K, the total rate constants for DEP degradation reactions induced by HO• and SO4• – are 2.34 × 109 and 1.24 × 108 M–1 s–1, respectively. They are in accordance with the experimental data. In comparison to SO4• –, HO• has higher reactivity toward DEP in the research temperature range of 273–303 K. Considering the impact on the water eco-environment and human health, DEP and its 10 products have no bioaccumulation potential, but most products are developmentally toxic, except for (Z)-ethyl-2,5-dioxopent-3-enoate. Moreover, (Z)-ethyl-2,5-dioxopent-3-enoate is acutely toxic to fish; phthalic acid is mutagenicity positive; and we should pay more attention to them in the future.

Biodegradation of diethyl phthalate and phthalic acid by a new indigenous Pseudomonas putida.

Diethyl phthalate (DEP) is one of the extensively used plasticizers which has been considered a priority hazardous pollutant due to its carcinogenic, endocrine disrupter, and multi-toxic effects on humans. The identification of DEP in different parts of the ecosphere has increased the global community's attention to the elimination of this pollutant in a bio-eco-friendly way. In this research, a novel aerobic bacterial strain nominates as ShA (GenBank accession number: MN298858) capable of consuming DEP as carbon and energy sources, was isolated from the upper phase (0-10 cm) of Anzali international wetland sediments by enrichment culture method. Morphological characteristics and 16S rRNA gene sequence analysis demonstrated that strain ShA belonged to Pseudomonas putida. The substrate utilization test demonstrated that strain ShA was able to grow in mineral salt medium containing dimethyl phthalate (DMP) and phthalic acid (PA) isomers including terephthalic and isophthalic acid. Degradation assay showed strain ShA completely degraded 200 mg/L DEP within 22 h (pH 7.0, 30 °C). Surprisingly, PA as the main intermediate of DEP biodegradation was identified by GC-FID. Moreover, the rapid degradation of 2000 mg/L PA to CO2 and H2O was viewed in 22 h by strain ShA. The possible route of DEP degradation was DEP directly to PA and then PA consumption for growth. This study obtained results that provide a great contribution to applying strain ShA in the biodegradation of low molecular weight of PAEs and PA isomers in natural ecosystems. This is the first report of a P. putida strain able to degrade DEP and PA.

Mechanistic insight into sulfite-enhanced diethyl phthalate degradation by hydrogen atom under UV light

As one of the attractive photochemical technologies, sulfite combined with UV light has been demonstrated to be efficient for recalcitrant organic pollutant degradation, but the underlying mechanism of these processes under aerobic conditions has not been fully explored. In this study, we found that diethyl phthalate (DEP) could be efficiently degraded by sulfite/UV under aerobic conditions. Quenching studies combined with electron paramagnetic resonance spectrometry indicated that oxidative radicals (SO3•−, SO4•− and •OH), hydrated electron (eaqs-) and hydrogen atom (H•) were generated in sulfite/UV system under aerobic conditions. H• was found to be the dominant reactive species for DEP degradation while other oxidative radicals had a limited role. It was interesting to found that ethanol and tert-butyl alcohol could promote DEP degradation. This was mainly ascribed to that ethanol and tert-butyl alcohol could quench the reaction of oxidative radicals with sulfite and the generated H•/eaqs-, which favored DEP degradation. DEP degradation was largely dependent on solution pH and alkaline conditions favored DEP degradation. Anions (CO32– and Cl-) and low concentration of organic acid (citrate and oxalate) had neglect effects on DEP degradation, while humic acid greatly inhibited the degradation of DEP. Our results indicated that H• generated during sulfite/UV process might also played an important role in pollutant degradation and the presence of oxidative radical quenchers (e.g. alcohols) favored the reductive degradation of pollutant in the process.

Electrolytic core–shell Co@C for diethyl phthalate degradation

• A high-value utilization strategy of CO 2 converted carbon materials was provided. • CO 2 was used as a feedstock to prepare Co@C catalyst. • Co@C was synthesized by the molten salt electrochemical conversion. • Co@C catalyst showed a high turnover frequency value of 2.28 min −1 . • DFT calculations identified the activation mechanism of PMS by Co@C. Greenhouse gases carbon dioxide (CO 2 ) can be converted into high value-added carbon materials by molten salt electrolysis. Herein, we employ CO 2 as the inorganic carbon source to prepare a core–shell catalyst (Co@C) by molten salt electrolysis for the activation of peroxymonosulfate (PMS) to degrade diethyl phthalate (DEP). The electrolytic Co@C catalyst presents a high catalytic performance for the degradation of DEP with a high turnover frequency (TOF) value (2.28 min −1 ), a relatively low catalyst dosage (Cat = 50 mg L –1 ), low oxidant concentration (PMS = 0.46 mM), a wide range of pH applicability (pH = 3–9), and low activation energy ( E a = 38.88 kJ mol −1 ). In addition, the Co leaching rate is low (<1 mg L –1 ) in the pH range of 5–11 and the total organic carbon (TOC) removal was reached 78.9% under the catalyst dosage was 50 mg L –1 . The DEP degradation pathways mainly involved ethyl formate elimination, ethoxy abstraction, carboxyl abstraction, decarboxylation, hydroxy abstraction, esterification and ring cleavage of DEP. Further, theoretical calculations confirm that Co nanoparticles (Co NPs) encapsulated with graphitized carbon shell derived from CO 2 reduce the work function (WF) of catalysts, enhance the length of bond O–O ( I O-O ) of PMS molecule, and facilitate the charge transfer from the catalysts to PMS molecule. This work provides a new insight into the utilization of CO 2 served as inorganic carbon sources and the design of heterogeneous catalysts.

Mechanism of significant enhancement of VO2-Fenton-like reactions by oxalic acid for diethyl phthalate degradation

• OA favors DEP degradation in VO 2 activation of H 2 O 2 . • The mechanism of OA promoting pollutant degradation was studied. • DEP could be degraded over a wide pH range in VO 2 /H 2 O 2 /OA system. It has been reported that the addition of reducing agents such as ascorbic acid and hydroxylamine to Fenton or Fenton-like systems can accelerate the circulation of Fe(III)/Fe(II), thereby accelerating the degradation of pollutants. However, few studies investigated the effect of reducing agents on pollutant degradation by heterogeneous Fenton-like reactions using other transition metals (e.g. vanadium (V) oxides) as activator. In this study, we investigated the effect of oxalic acid (OA), an inexpensive and environmentally-friendly reducing agent, on diethyl phthalate (DEP) degradation by VO 2 -Fenton-like reactions. The results showed that 92% of DEP was degraded in VO 2 /H 2 O 2 /OA system while only 3% and 37% of DEP was degraded with H 2 O 2 and VO 2 /H 2 O 2 respectively, demonstrating that the addition of OA can significantly promote the degradation of DEP in VO 2 /H 2 O 2 system. Electron paramagnetic resonance analysis showed that OH was the dominant reactive species, which increased rapidly with the increase of OA concentration in the range of 0–2 mM. Increasing the VO 2 dosage (0.1–1.0 g L −1 ) and OA concentration (0.05–2.0 mM) could increase the degradation rate of DEP while the increase of OA concentration was more effective in promoting DEP degradation. Moreover, in the presence of OA, DEP could be efficiently degraded over a wide pH range (pH 3–11), and OA was also found capable of promoting DEP degradation in H 2 O 2 /V(IV) and H 2 O 2 /V 2 O 5 systems. This study provides a novel strategy to enhance Fenton-like reactions for pollutant degradation and environmental remediation.

Mass balance and kinetics of biodegradation of endocrine disrupting phthalates by Cellulosimicrobium funkei in a continuous stirred tank reactor system

This study investigated the potential ofCellulosimicrobium funkeifor degrading dimethyl phthalate (DMP) and diethyl phthalate (DEP). Effect of different initial concentrations of phthalates on their biodegradation and growth ofC. funkeiwas examined using shake flasks and a continuous stirred tank reactor (CSTR). Complete degradation of both DMP and DEP was achieved in CSTR, even up to 3000 and 2000 mg/L initial concentrations, respectively. Simultaneous degradation of the phthalates in mixture, i.e. more than 80% and 55% biodegradation efficiency were achieved at 1000 and 2000 mg/L initial concentrations of DMP and DEP, respectively, using the CSTR. Mass balance analysis of the degradation results suggested proficient degradation of DMP and DEP with biomass yield values of 0.64 and 0.712, respectively. The high values of inhibition constant Kiestimated using the Tessier and Edward substrate inhibition models indicated very good tolerance ofC. funkeitoward biodegradation of DMP and DEP.

Application of Fungus Enzymes in Spent Mushroom Composts from Edible Mushroom Cultivation for Phthalate Removal.

Spent mushroom composts (SMCs) are waste products of mushroom cultivation. The handling of large amounts of SMCs has become an important environmental issue. Phthalates are plasticizers which are widely distributed in the environment and urban wastewater, and cannot be effectively removed by conventional wastewater treatment methods. In this study, SMCs are tested for their ability to remove phthalates, including benzyl butyl phthalate (BBP), di-n-butyl phthalate (DBP), and diethyl phthalate (DEP). Batch experiments reveal that BBP, DBP, and DEP can be degraded by the SMC enzyme extracts of four edible mushrooms: Pleurotus eryngii, Pleurotus djamor, Pleurotus ostreatus, and Auricularia polytricha. Potential fungus enzymes associated with BBP, DBP, and DEP degradation in SMCs (i.e., esterases, oxygenases, and oxidases/dehydrogenases) are uncovered by metaproteomic analysis using mass spectrometry. Bioreactor experiments indicate that the direct application of SMCs can remove BBP, DBP, and DEP from wastewater, through adsorption and biodegradation. The results of this study extend the application of white-rot fungi without laccases (e.g., Auricularia sp.) for the removal of organic pollutants which are not degraded by laccases. The application of SMCs for phthalate removal can be developed into a mycoremediation-based green and sustainable technology.

Isotope fractionation of diethyl phthalate during oxidation degradation by persulfate activated with zero-valent iron

This study reports the 13C and 2H isotope fractionation associated with the oxidation of diethyl phthalate (DEP) by persulfate (PS) activated with zero-valent iron (ZVI) using three concentration levels (0.2, 0.5 and 1.0 g L−1) at different pH values, 3, 7 and 11, respectively. The results showed that the degradation of DEP followed a pseudo first-order kinetics. The fastest degradation was found at neutral conditions (pH 7). Similar carbon and hydrogen isotope fractionation (εC and εH) was observed during the oxidation of DEP by ZVI activated PS at pH 3, 7 and 11. At ZVI concentration of 0.5 g L−1, the correlation of 13C and 2H fractionation (Λ) were obtained to be 12.7 ± 3.5, 11.1 ± 4.2 and 12.0 ± 2.9 at pH 3, 7 and 11, respectively. The concentration of ZVI has no effect on the correlation of 13C and 2H fractionation (Λ). In addition, radical quenching approach and electron paramagnetic resonance (EPR) were combined to explore the dominant radical species in the ZVI activated PS reaction, and hydroxyl radical (•OH) was found to be the predominant radical at all pH studied. The results of CSIA show the addition of •OH to the aromatic ring of DEP is the main reaction mechanism, which is consistent with the results of radical quenching experiment and EPR study. Carbon and hydrogen apparent kinetic isotope effects (AKIEs) obtained from •OH reactions with DEP supported the hypothesis of CH bond cleavage. Thus, carbon and hydrogen isotope enrichment factors clearly distinguish the different reaction mechanisms and hence, are a promising approach to improve understanding of radical species reaction pathways for chemical oxidation of DEP.

Oxidation of phthalate acid esters using hydrogen peroxide and polyoxometalate/graphene hybrids

Phthalate acid esters (PAEs) have been adsorbed and oxidatively degraded into small molecules including lactic acid (LA), formic acid (FA), H2O and CO2 using polyoxometalates (POMs)/graphene hybrids. We demonstrated that super-lower concentrations of PAEs could be oxidized, which was due to their unique structure. POM molecules have been embedded onto graphene to form H5PMo10V2O40@surfactant(n)/Graphene(L wt%) (abbreviated as HPMoV@Surf(n)/GO(L wt%)) using surfactants with the carbon chain length n = 2, 4, 6 and 8 for the loading of HPMoV. The coexistence of the graphene and surfactant layer (on HPMoV@Surf(n)/GO(20 wt%)) adsorbed PAE molecules and transported them rapidly to HPMoV active sites. And n values determined the electron transfer ability between graphene and POMs that promoted PAEs oxidation. The loading of POMs on the surface of graphene permitted HPMoV@Surf(n)/GO(L wt%) act as interfacial catalyst which degraded various PAEs (i.e., diethyl phthalate (DEP), diallyl phthalate (DAP) and di (2-ethylhexyl) phthalate (DEHP)) while removed more than 70% of TOC and COD. The degradation of DEP achieved 93.0% with HPMoV@Surf(n)/GO(20 wt%) and H2O2, which followed first-order kinetics and the reaction activation energy (Ea) of 23.1 kJ/mol. Further, HPMoV@Surf(n)/GO(20 wt%) showed potential for the removal of PAEs in Wastewater Treatment Plant (WWTP), and the degradation efficiency for PAE (DEP) in secondary effluent achieved 55.0%. In addition, the loading method for POMs on graphene eliminated the leaching of POMs from graphene, and the degradation efficiency could still reach 88.1% after ten recycles.

Bacterial consortium for efficient degradation of di-ethyl phthalate in soil microcosm

Bacterial consortium for efficient degradation of di-ethyl phthalate in soil microcosm

Influence of anatase-brookite composition on photocatalytic degradation of diethyl phthalate

Considering the present situation of exploitation of TiO2 as a photocatalyst, optimization of its polymorphs (anatase, brookite, and rutile) becomes critical. In the present study, TiO2 nanoparticles have been synthesized using the sol-gel technique to understand the effect of heat treatment-induced anatase-brookite composition on photocatalytic diethyl phthalate removal. The influence of heat treatment on structural characteristics of TiO2 is investigated by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). Bot, XRD and Raman results indicated the coexistence of brookite and anatase. At the same time, UV–visible diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL) revealed the optical modifications caused by the presence of brookite in the anatase network to alter the photo absorption and photoemission characteristics. The photocatalytic degradation of diethyl phthalate was observed as 95 % under UV–visible illumination (for 225 min) in the presence of the sample, calcined at 200 °C.

Synthesis of a magnetically separable LDH-based S-scheme nano-heterojunction for the activation of peroxymonosulfate towards the efficient visible-light photodegradation of diethyl phthalate

Herein, a stable and S-scheme Fe3O4@CuCr-LDH nanocomposite was synthesized and used for the photocatalytic degradation of diethyl phthalate (DEP) through the activation of peroxymonosulfate (PMS). In comparison with pure Fe3O4, and LDH, the Fe3O4@CuCr-LDH nanocomposite demonstrated significantly enhanced photocatalytic activity due to its S-scheme charge-carrier migration mechanism. The prepared composite was also magnetically recoverable from the treated water which is favorable to avoid the production of secondary pollution. The integration of the composite and visible light showed the presence of a synergy factor of 14 for the degradation of diethyl phthalate. However, the photocatalytic performance of Fe3O4@CuCr-LDH was dependent on the different physicochemical parameters; wherein, the higher degradation efficiency was achieved using the solution pH of 8, the catalyst, DEP, and PMS concentrations of 1 g L−1, 20 mg L−1, and 8 mM, respectively. The high photocatalytic activity of the catalyst was maintained after 5 consecutive reaction runs and the stability of the material was proved by the XPS. Moreover, the ICP-AES analysis proved that the leaching of Fe, Cr, and Cu is lower than the standard concentration in the drinking water. Finally, the mineralization ability and the decreased toxicity of the treated solution of DEP were assessed.

Efficient destruction of emerging contaminants in water by UV/S(IV) process with natural reoxygenation: Effect of pH on reactive species

UV/sulfite systems with oxygen have recently been considered as advanced oxidation processes in view of the participation of oxysulfur radicals. However, the contribution of •OH and the efficiency of destructing emerging contaminants (ECs) in water remain largely unclear. Here, the UV/S(IV) process was applied with natural reoxygenation to degrade two typical ECs, diethyl phthalate (DEP) and bisphenol A (BPA) showing different properties. Solution pH played the key role in determining the reactive species, and both DEP and BPA were more favorably degraded at more alkaline conditions with higher utilization efficiency of SO32−. Specifically, the H•, O2•−, •OH and SO3•− were identified at acidic condition, but the amount of •OH accumulated significantly with the elevation of pH. Competitive quenching experiments showed that eaq− and •OH dominated the degradation of DEP and BPA at alkaline condition, respectively. Besides, DEP showed higher quantum efficiency for the indirect photolysis and mineralization degree than that of BPA at pH 9.2 mainly due to the direct use of the primary photoproduct. The possible transformation mechanisms of S(IV) and mineralization routes of both pollutants were proposed. This study may provide new insights into the mechanisms involved in UV/S(IV) process and a promising alternative for efficient removal of ECs in water.