Removal Of Dimethyl Phthalate Research Articles

Repurposing waste-iron electrocoagulated algal biomass as effective heterogenous (bio)electro-fenton catalyst for phthalate removal from wastewater

The presence of refractory micropollutants in natural waters poses significant environmental and health risks. Preferably, advanced oxidation techniques like electro-Fenton (EF) and bio-electro-Fenton (BEF) are used to mitigate micropollutants; nevertheless, their field-scale implementation is limited by prohibitive catalyst cost. As an alternative, waste-iron electrocoagulated algal biomass (A-BC/Fe) was explored as a heterogeneous Fenton catalyst to eliminate dimethyl phthalate (DMP) from wastewater. The Fenton-conducive morphological, chemical, and electrochemical properties of the A-BC/Fe catalyst were revealed by detailed characterisation. In EF treatment, 10 mg/L of DMP was completely degraded within 15 min at pH of 7.0, 50 mM Na2SO4, and cathode potential of − 1.4 V vs. Ag/AgCl. Moreover, the EF system achieved 87.80 ± 2.10% and 96.14 ± 1.10% of DMP removal from secondary and tertiary treated municipal sewage, respectively. The A-BC/Fe catalyst-driven EF process disintegrated DMP into benign non-toxic by-products and showed stable performance over eight batch cycles with only a 1.71% decline in DMP removal efficiency. Further, the A-BC/Fe-catalysed BEF system eliminated 94.81 ± 1.90% of DMP in 4 h while achieving a maximum power density of 124.03 ± 5.64 mW/m2. This investigation underscores the potential of repurposing electrocoagulated algal biomass as a sustainable heterogenous catalyst for micropollutant remediation.

Improvement of heterogeneous electro-Fenton oxidation of dimethyl phthalate by embedding Fe/Co bimetallic active sites into waste wine lees biochar

Phthalates (PAEs) are frequently detected in the water environment and pose a severe threat to the ecosystem and human health. Electro-Fenton technology is regarded as an effective approach to degrade PAEs; however, the preparation of inexpensive and efficient cathode materials has restricted its further application. In this study, Fe/Co bimetallic sites were incorporated into solid waste wine lees to synthesize highly active heterogeneous catalyst, and dimethyl phthalate (DMP) was chosen as the target pollutant to investigate the activity of the catalyst. Both the degradation of DMP and the removal of total organic carbon (TOC), the performance of Fe/Co co-modified biochar (FeCo@NOPC) is superior to that of Fe (Co) alone (Fe@NOPC/Co@NOPC) and modified biochar (NOPC). Under neutral conditions. Within 5 h, the DMP removal rate reached 89 % and TOC was reduced by approximately 40 %. The mechanism study reveals that the degradation of DMP is mainly attributed to the OH generated by the cathode, and the anodic oxidation and cathode adsorption only play minor roles. Finally, the degradation path of DMP was analyzed by LC-MS technique. This study offers a novel way to utilize solid waste and reduce the cost of heterogeneous electro-Fenton system.

Novel fabrication of the recyclable Bi7O9I3/chitosan and BiOI/chitosan heterostructure with improved photocatalytic activity for degradation of dimethyl phthalate under visible light.

Among the bismuth oxyhalides, bismuth oxide has the shortest band gap and high absorption power in the visible light region. Dimethyl phthalate (DMP) has been identified as endocrine-disrupting plasticizer and emerging pollutant, which was selected as the target pollutant to evaluate the efficacy of the studied catalytic process. In this work, Bi7O9I3/chitosan and BiOI/chitosan were efficaciously synthesized by the hydrothermal process method. Characterizing prepared photocatalysts was done by employing transmission electron microscopy, X-ray diffraction, scanning electron microscopy energy-dispersive spectroscopy, and diffuse reflectance spectroscopy. For this study, the test design was performed using the Box-Behnken Design (BBD) method in which the variables of pH, Bi7O9I3/chitosan dose, and dimethyl phthalate concentration were examined for the catalytic removal of dimethyl phthalate in the presence of visible light. Our detected results disclosed that the order of efficiency in DMP removal was as follows: Bi7O9I3/chitosan > BiOI/chitosan > Bi7O9I3 > BiOI. Also, the maximum pseudo-first-order kinetic coefficient for Bi7O9I3/chitosan was 0.021 (min)-1. When the synthesized catalysts were exposed to visible light irradiation, the predominant active species were O2- and h+ for degradation of DMP. The study on the reuse of Bi7O9I3/chitosan showed that this catalyst could be reused 5 times without significant reduction in efficiency, which indicates the cost-effectiveness and environmental friendliness of using this catalyst.

Enhancement of the degradation efficiency of dimethyl phthalate by microwave-induced wet oxidation with lower energy consumption

Dimethyl phthalate, a common ingredient in the manufacture of plastics, is a typical persistent substance in the organic wastewater environment owing to its lipophilic and refractory properties. To achieve higher degradation of dimethyl phthalate, this study uses an experimentally constructed high-pressure resistant microwave-catalyzed experimental system, which can establish a coupling between the microwave and pressure fields in the wet oxidation process. Three types of catalysts are investigated for catalytic degradation, along with the effects of variables, such as reaction temperature, system pressure, and catalyst concentration, on the removal of dimethyl phthalate. Increasing the reaction temperature effectively increases the reaction rate constant. In addition, the COD content reduces from 4161.8 to 1710.5 mg/L within 5 min. Further, the energy flow and economy indices of the entire process are comprehensively analyzed. Finally, the analysis of the degradation intermediate and other characterization techniques reveals that the pollutant is degraded by ·OH.

An oxidoreductase enzyme, fungal laccase immobilized on zeolitic imidazolate frameworks for the biocatalytic degradation of an endocrine-disrupting chemical, dimethyl phthalate

This study investigated a facile one-pot synthesis procedure of zeolitic imidazolate frameworks (ZIF) and laccase immobilization for use in the biodegradation of an endocrine-disrupting chemical (EDC), dimethyl phthalate (DMP). The as-synthesized Lac-ZIF’s characterization results revealed preserved crystallinity of the ZIF particles and lightly enzyme-coated decahedral particles. The immobilized laccase demonstrated enhanced temperature and storage stabilities for up to 65 ℃ and 20 d, respectively, for the DMP removal. While a reduced maximum velocity (Vmax) after the laccase immobilization (0.651–0.238 mg L−1 h−1) was observed, the Lac-ZIF presented a higher DMP removal efficiency (90.1%) compared to the free laccase (53.2%) within 4 h of contact time. Additionally, after 5 cycles of reuse, the Lac-ZIF retained a remarkable 95.2% efficiency and improved effectiveness in DMP decontamination from river water samples than the free laccase. Furthermore, the resulting DMP degradation metabolites were studied and revealed the production of relatively less toxic compounds after probable complete microbial mineralization. The study, therefore, demonstrates that Lac-ZIF has an admirable performance in the effective removal of phthalates from wastewater, making it a promising candidate for environmental remediation.

Synergistic removal of sulfamethoxazole and dimethyl phthalate by five constructed wetland substrates

Frequent detection and joint toxicity of sulfonamides (SAs) and phthalate acid esters (PAEs) in water environment have caused serious health and safety problems that can be reduced by vertical flow constructed wetland (VFCW). However, it remains unclear what kind of substrate used in VFCW can synergistically remove SAs and PAEs. In this study, it was determined if biochar, zeolite, vermiculite, peat and sand synergistically removed sulfamethoxazole (SMX) and dimethyl phthalate (DMP) as representatives of SAs and PAEs by using batch and column experiments. The batch experiments showed that pseudo-second-order and intraparticle diffusion kinetics and Freundlich isotherm could better describe the synergistic adsorption of SMX and DMP on each substrate. SMX promoted hydrophobic interaction between DMP and each substrate so that low concentration DMP almost was adsorbed completely at neutral pH. Both neutral and alkaline pH conditions were favorable for synergistic adsorption of SMX and DMP on each substrate. The column experiments showed that removal of SMX or DMP in VFCW by substrate adsorption alone was limited with run time increasing, but SMX and DMP were effectively removed with run time increasing when loaded with simulated wastewater, SMX and DMP. The VFCW not only removed 94.7% SMX and 91.8% DMP after running 50 d, but also improved total nitrogen removal. In conclusion, these results strongly suggest that biochar, zeolite, vermiculite, peat and sand filled in VFCW can synergistically remove SMX and DMP.

Exploring simultaneous elimination of dimethyl phthalate and nitrogen by a novel constructed wetlands coupled with dielectric barrier discharge plasma

Dimethyl phthalate (DMP) contamination, as an emerging pollutant, has posed acute health risks to humans due to its potential disruption in reproductive function and endocrine system disorders. In this study, the dielectric barrier discharge (DBD) plasma and constructed wetlands (CWs) were coupled to explore the simultaneous enhancement of DMP and nitrogen removal. The results showed that the coupling DBD plasm and CWs obtained an efficient elimination of DMP (87.7–97.3%), and nitrogen removal was also improved simultaneously with higher removal of ammonia nitrogen (97.7–98.6%) and total nitrogen (TN, 22.6–40.6%). TN removal efficiency was promoted gradually by increasing the concentration of influent DMP due to the DMP decomposition into small molecules by DBD plasma, which could provide carbon source to promote denitrification for subsequent CWs. The DMP degradation processes in the coupling system were reflected by three-dimensional excitation emission matrix fluorescence spectrum and gas chromatograph-mass spectrometer, which indicated that DMP solution was activated in the DBD plasma and more organic by-products were produced. Additionally, monomethyl phthalate and phthalic acid were main degradation intermediate products of DMP. It indicated that coupling DBD plasma and CWs broke the carbon–oxygen single bond of DMP and converted it into less toxic compounds with less-refractory substances. This study provides assistant information on the application of the coupling DBD plasma and CWs technology for treating wastewater containing toxic and non-biodegradable contaminants.

Integrated Electro-Ozonation and Fixed-Bed Column for the Simultaneous Removal of Emerging Contaminants and Heavy Metals from Aqueous Solutions

In the current study, an integrated physiochemical method was utilized to remove tonalide (TND) and dimethyl phthalate (DMP) (as emerging contaminants, ECs), and nickel (Ni) and lead (Pb) (as heavy metals), from synthetic wastewater. In the first step of the study, pH, current (mA/cm2), and voltage (V) were set to 7.0, 30, and 9, respectively; then the removal of TND, DMP, Ni, and Pb with an electro-ozonation reactor was optimized using response surface methodology (RSM). At the optimum reaction time (58.1 min), ozone dosage (9.4 mg L−1), initial concentration of ECs (0.98 mg L−1), and initial concentration of heavy metals (28.9 mg L−1), the percentages of TND, DMP, Ni, and Pb removal were 77.0%, 84.5%, 59.2%, and 58.2%, respectively. For the electro-ozonation reactor, the ozone consumption (OC) ranged from 1.1 kg to 3.9 kg (kg O3/kg Ecs), and the specific energy consumption (SEC) was 6.95 (kWh kg−1). After treatment with the optimum electro-ozonation parameters, the synthetic wastewater was transferred to a fixed-bed column, which was filled with a new composite adsorbent (named BBCEC), as the second step of the study. BBCEC improved the efficacy of the removal of TND, DMP, Ni, and Pb to more than 92%.

Bisulfite-assisted surface Fenton-like degradation of dimethyl phthalate by ferrihydrite-H2O2 system

As a common plasticizer, phthalic acid esters (PAEs) have been widely employed to improve the flexibility and workability of polymetric materials, thus leading to their widespread distribution in soils and wastewater. Moreover, PAEs raised great public concerns due to their endocrine-disrupting effects, which could damage reproductive system and body development at low exposure dose. In the present study, a ferrihydrite-H2O2-bisulfite ternary system was developed to achieve efficient degradation of dimethyl phthalate (DMP). Our results showed that 86.6 % of total DMP could be removed within 240 min by the ferrihydrite-H2O2-bisulfite ternary system, in which the respective optimum concentration of ferrihydrite, H2O2 and bisulfite was set as 1.0 g/L, 5.0 mM and 2.0 mM. For comparison, negligible DMP removal was observed in the binary systems of ferrihydrite-H2O2, ferrihydrite-bisulfite and H2O2-bisulfite. Hydroxyl radical (•OH) was identified as the dominant reactive species for DMP degradation based on the results of electron paramagnetic resonance (EPR) analysis and free radicals quenching experiments. By complexing with iron species, bisulfite could accelerate the reduction of Fe(III) to Fe(II), thus increasing the generation of •OH by ∼4 times in the heterogeneous ferrihydrite-H2O2 system. Furthermore, ferrihydrite exhibited excellent recyclability without any modification as indicated by the negligible decrease in the catalytic degradation efficiency of DMP. Thus, in addition to efficient degradation of PAEs in wastewater, our study would shed light on the in-situ soil remediation technology on the basis of bisulfite-assisted heterogeneous Fenton-like reactions.

Synergistic effect of ferrous ion-activated hydrogen peroxide and persulfate on the degradation of phthalates in aquatic environments by non-target analysis

Oxidative degradation of most recalcitrant organics in the wastewater by exciting the oxidative potential and high efficacy of economic and environmental compatible oxidants is currently an extensively studied field of research. In this study, an efficient phthalate esters (PAEs) degradation method utilizing dual oxidants persulfate (PS) and hydrogen peroxide in the presence of ferrous ions was developed with high removal efficiency, small oxidant dosage and wide pH range. Compared with the degradation efficiency of single systems including Fe2+/ H2O2 (40 %), PS (24 %) and Fe2+/PS (49 %) for dimethyl phthalate (DMP) degradation, the combining PS and H2O2 activated by Fe2+ is more effective, with the removal efficiency of 95 %. The synergistic effect of PS and H2O2 in the Fe2+-containing system on PAEs degradation was reflected by the degradation products determined by non-target analysis of various oxidation processes. The results showed that the degradation of DMP in two single oxidant systems was dominated by aromatic compounds via dealkylation, hydroxyl addition and decarboxylation, while DMP in the PS/H2O2/FeSO4 system was mainly deeply oxidized to aliphatic molecules through further dearomatization, which was vulnerable for the mineralization of DMP to CO2 and H2O. In addition, the EPR technique combined with DMPO captured SO4•− and •OH signals in the presence of the same Fe2+ and oxidant dosage, revealing that a higher intensity of ·OH and SO4•− generated in the combined oxidative process resulted in a high removal of DMP. This work lays the groundwork for recalcitrant organics removal to apply synergistic activation mode in the AOPs system.

Enhanced Ozone Oxidation by a Novel Fe/Mn@γ−Al2O3 Nanocatalyst: The Role of Hydroxyl Radical and Singlet Oxygen

Catalytic ozonation is a potential alternative to address the dye wastewater effluent, and developing an effective catalyst for catalyzing ozone is desired. In this study, a novel Fe/Mn@γ−Al2O3 nanomaterial was prepared and successfully utilized for catalytic ozonation toward dye wastewater effluent components (dimethyl phthalate and 1−naphthol). The synthesized Fe/Mn@γ−Al2O3 exhibited superior activity in catalytic ozonation of dimethyl phthalate and 1−naphthol in contrast to Fe@γ−Al2O3 and Mn@γ−Al2O3. Quench and probe tests indicated that HO° contributed to almost all removal of dimethyl phthalate, whereas O3, HO°, and singlet oxygen participated in the degradation of 1−naphthol in the Fe/Mn@γ−Al2O3/O3 system. The results of XPS, FT−IR, and EPR suggested that HO° and singlet oxygen were generated from the valence variations of Fe(II/III)and Mn(III/IV). Moreover, the Fe/Mn@γ−Al2O3/O3 system could also have excellent efficacy in actual water samples, including dye wastewater effluent. This study presents an efficient ozone catalyst to purify dye wastewater effluent and deepens the comprehension of the role and formation of reactive species involved in the catalytic ozonation system.

Degradation of Dimethyl phthalate through Fe(II)/ Peroxymonosulfate heightened by fulvic acid: efficiency and possible mechanism

Ferrous iron (Fe(II)) reacts with peroxymonosulfate (PMS) to form active oxidants that can degrade refractory organic pollutants. However, the conversion rate of Fe(III) to Fe(II) is slow, which limits its actual application. In the study, the effect of fulvic acid (FA) on the degradation of dimethyl phthalate (DMP) by Fe(II)/PMS was investigated. Moreover, the degradation process of DMP was predicted by the preliminary identification of active free radicals and intermediates. As expected, FA gave rise to a higher concentration of Fe(II) than that in Fe(II)/PMS to enhance the removal of DMP in Fe(II)/PMS system. The precipitate, involved in FA and iron, was an important composite to promote the degradation of DMP in the system. Also, the response surface methodology (RSM) was applied to model and optimize the degradation conditions of DMP. The highest removal efficiency (85.70%) was obtained at pH = 3.86, [PMS] = 0.96 mM, [FA] = 11.44 mg/L and [DMP] = 5 μM. The results of free radical quenching experiments and EPR showed that ·OH and SO4 •- were the main active radicals in this system. The degradation intermediates of DMP were monomethyl phthalate (MMP), phthalic acid, and benzoic acid. Discoveries of this study had raised current understanding of the application of FA keeping the cycles of Fe(II)/Fe(III) for peroxymonosulfate activation, which could afford valuable information for the degradation of organic pollutants by FA/Fe(II)/PMS.

Enhancement of the electro-Fenton degradation of organic contaminant by accelerating Fe3+/Fe2+ cycle using hydroxylamine

The Electro-Fenton process can generate reactive oxygen species capable of oxidizing refractory organic contaminants. However, low regeneration efficiency of Fe2+ restricts its application. Herein, hydroxylamine (HA) was added into the Electro-Fenton (HA/Electro-Fenton) process to accelerate the transformation of Fe3+ to Fe2+. Using dimethyl phthalate (DMP) as target contaminant, the HA/Electro-Fenton system alleviated the two-stage reaction process and accelerated the removal of DMP in the pH range of 2.0–6.0. With improving DMP concentration from 5 mg L-1 to 50 mg L-1, their degradation rate increased in the HA/Electro-Fenton system, while decreased in the Electro-Fenton system. The addition of HA had negligible effect on electro-generation of H2O2, but facilitate the redox cycle of Fe3+/Fe2+ and the generation of hydroxyl radicals, thus improving the degradation of DMP. The final transformation products of HA were N2, N2O, and NO3−. The presence of PO43− improved DMP degradation, while Cl− and organic matters inhibited DMP removal in varying degrees. This study provided useful reference to solve the low efficiency of Fe3+/Fe2+ cycle and expand the pH application range in the Electro-Fenton process.

Lanthanum/titanium dioxide immobilized onto industrial waste with enhanced photocatalytic activity, and the degradation of dimethyl phthalate

Titanium dioxide (TiO2) is an effective photocatalyst for organic removal. However, its efficacy is hampered by the recombination of photogenerated electrons and holes. This paper presented an eco-friendly, synthetic lanthanum (La)/TiO2 supported on lithium silicon powder (L) to significantly improve photocatalysis. The results showed that 74.4% dimethyl phthalate (DMP) removal was achieved in the ultraviolet (UV)-La-TiO2/L (LTL1) system, which was considerably higher than UV-TiO2/L (TL) (60.1%) and UV-L (18.3%). The enhanced LTL1 photocatalysis was based on the synergic effect between TiO2 and La with L matrix. The photocatalysis efficiency was further improved by hydrogen peroxide (H2O2), while the DMP removal rate reached 100% in the UV-LTL1-H2O2 system. The DMP activation mechanisms and degradation pathways in the UV-LTL1-H2O2 system were carefully examined, revealing that increased hydroxyl free radical (OH•) and superoxide ion radicals (O2−•) were pivotal to the higher degradation rate. Overall, the findings suggested that LTL1 showed considerable application promise for the low-cost and eco-friendly organic removal from water.

Enhanced photocatalytic degradation of dimethyl phthalate by magnetic dual Z-scheme iron oxide/mpg-C3N4/BiOBr/polythiophene heterostructure photocatalyst under visible light

A new magnetic dual Z-scheme heterostructure photocatalyst, consisting of mesoporous graphitic carbon nitride (mpg-C3N4), BiOBr, polythiophene (PTh), and magnetic iron oxide, was developed, and its structural, optical, and electrochemical properties were analyzed. The photocatalyst was employed for the degradation of dimethyl phthalate (DMP) in water under visible light to evaluate its photocatalytic activity. The results revealed that the photocatalytic activity of the new heterostructure photocatalyst was superior to that of its single-component counterparts. The reaction kinetics of photocatalytic DMP degradation followed pseudo first-order kinetics and the reaction rate constant was 3.7- and 4.5-fold higher than those of pristine g-C3N4 and BiOBr, respectively. The enhanced photocatalytic performance was chiefly attributed to the dual Z-scheme heterostructure generated between mpg-C3N4, PTh, and BiOBr, which effectively hindered the recombination of photogenerated electron and hole pairs in mpg-C3N4 and BiOBr, improving the photogenerated carrier transfer efficiency. Radical trapping test results indicated that the active species, h+, ·O2–, and ·OH, coexisted during the photocatalytic reaction process, and that h+ played a major role in the destruction of DMP molecules. DMP was degraded into intermediate small-molecule products, such as acids and alcohols, which were ultimately mineralized to CO2 and H2O. The magnetic property of the new heterostructure photocatalyst enabled its straightforward separation from water using magnetic separation technology for further reuse. This study provides a new material and method for the effective removal of DMP from aqueous solution.

Photocatalytic removal of dimethyl phthalate using heterogeneous photofenton process with zero iron nanoparticles

ABSTRACT Phthalates are classified as priority pollutants due to their mutagenic, carcinogenic and endocrine disruptive effects. This study aimed at investigating the efficiency of heterogeneous photo Fenton process with zero iron nanoparticles (HPF/nZVI) in the removal of dimethyl phthalate (DMP) from aqueous media. For this purpose, we tried to use a UV-Vis Spectrophotometer device as a simple and available method instead of the chromatographic techniques for measuring DMP concentrations in aqueous samples. Hence, the DMP concentration in several samples was measured by the both HPLC device and UV-Vis spectrophotometer. The results showed that the process efficiency increased from 56% to 96% with the increase in H2O2 dosage from 0.01 to 0.1 mM/L, respectively. By increasing the initial concentration of the DMP from 2 to 50 mg/L, the process efficiency was reduced from 99% to 74% after 120 min. According to the results, under optimal conditions, the HPF/nZVI process efficiency for the removal of DMP and COD was 94% and 77%, respectively, after 60 min of reaction time. In addition, the results indicated that the combined photocatalytic process of HPF/nZVI due to the synergistic effects of UV, H2O2 and nZVI in the production of hydroxyl radicals was more effective than the single mode in the removal of DMPs. Therefore, the proposed method can be used effectively to remove such pollutants and offered higher performance compared to the conventional methods.

In-situ synthesis of {111}TiO2/Ti photoelectrode to boost efficient removal of dimethyl phthalate based on a bi-functional interface

• A strategy for efficiently specific removal of DMP pollutant is proposed. • {111}TiO 2 /Ti photoelectrode is in-situ constructed by vapor-phase hydrothermal method. • Highly-exposed {111} facet provides both high reaction activity and Lewis acid sites. • The {111}TiO 2 /Ti presents the highest removal enhancement to target DMP. • {111}TiO 2 /Ti presents excellent anti-interference ability and stability in practical use. We report a novel strategy for preferentially removing dimethyl phthalate (DMP) over rutile {111}TiO 2 /Ti photoelectrode. One-dimensional ordered TiO 2 nanorod arrays with highly-exposed {111} facet on top were in situ grown on Ti mesh via vapor-phase hydrothermal method. {111}TiO 2 /Ti provided a bi-functional interface with a combination of high reaction activity and Lewis acid sites. The photoelectrocatalytic degradation results revealed that {111}TiO 2 /Ti exhibited the highest removal enhancement towards DMP compared with non-target bisphenol A (BPA) and atrazine (ATZ) in both single pollutant and co-existed systems. The factor F enhancement was defined to quantitatively analyze the removal enhancement, which were as high as 12.81 and 11.06 towards DMP in the above two systems, respectively. In addition, {111}TiO 2 /Ti also presented an outstanding anti-interference ability when DMP was presented with 10-fold concentration of non-target pollutants. The specific PEC removal of DMP on {111}TiO 2 /Ti photoelectrode was investigated in detail. In situ ATR-FTIR spectroscopy results indicated that the {111} facet displayed stronger Lewis acidity in comparison with TiO 2 /Ti, promoting characteristic adsorption towards target DMP molecule (Lewis base site). DFT results further explored the favorable adsorption configuration of DMP on {111} facet. The time-resolved photoluminescence decay spectra (TRPL) and electron paramagnetic resonance (EPR) spectra confirmed the highly-exposed {111} facet possessed a significant photo-generated holes accumulation. The quenching experiments indicated that •OH was the major active specie in the PEC degradation of DMP. The possible degradation pathways of DMP were proposed by deeply analyzing intermediates. {111}TiO 2 /Ti exhibited excellent stability in recycling experiments, which would have wide applications in practical treatment.

Accelerated Fe2+ Regeneration in an Effective Electro-Fenton Process by Boosting Internal Electron Transfer to a Nitrogen-Conjugated Fe(III) Complex.

The regeneration rate of Fe2+ from Fe3+ dictates the performance of the electro-Fenton (EF) process, represented by the amount of produced hydroxyl radicals (·OH). Current strategies for the acceleration of Fe2+ regeneration normally require additional chemical reagents, to vary the redox potential of Fe2+/Fe3+. Here, we report an attempt at using the intrinsic property of the electrode to our advantage, i.e., nitrogen-doped carbon aerogel (NDCA), as a reducing agent for the regeneration of Fe2+ without using foreign reagents. Moreover, the pyrrolic N in NDCA provides unpaired electrons through the carbon framework to reduce Fe3+, while the graphitic and pyridinic N coordinate with Fe3+ to form a C-O-Fe-N2 bond, facilitating electron transfer from both the external circuit and pyrrolic N to Fe3+. Our Fe2+/NDCA-EF system exhibits a 5.8 ± 0.3 times higher performance, in terms of the amount of generated ·OH, than a traditional Fenton system using the same Fe2+ concentration. In the subsequent reaction, the Fe2+/NDCA-EF system demonstrates 100.0% removal of dimethyl phthalate, 3-chlorophenol, bisphenol A, and sulfamethoxazole with a low specific energy consumption of 0.17-0.36 kW·h·g-1. Furthermore, 90.1 ± 0.6% removal of dissolved organic carbon and 83.3 ± 0.9% removal of NH3-N are achieved in the treatment of domestic sewage. The purpose of this work is to present a novel strategy for the regeneration of Fe2+ in the EF process and also to elucidate the role of different N species of the carbonaceous electrode in contributing to the redox cycle of Fe2+/Fe3+.

Electro-Fenton approach in oxidative degradation of dimethyl phthalate - The treatment of aqueous leachate from landfills

Herein, the dimethyl phthalate (DMP) contamination, as an emerging pollutant, has been cost-effectively removed from landfill leachate through an advanced oxidation process, that is the electro-Fenton (EF) process. For this purpose, a quadratic polynomial model was developed via response surface methodology (RSM). Furthermore, the analysis of variance (ANOVA) was performed for evaluating the significance of the proposed assumptions. The actual removal rate of 99.1% was obtained with optimal values of 4 mg L−1 of initial DMP concentration, 50 mM Na2SO4, 600 μL L−1 H2O2, 8-minute electrolytic time, solution pH 3 and 6 mA cm−2 current density for the process variables and was consistent with the expected 99.6% removal rate. Satisfactory correlation coefficients were obtained, and a non-significant value of 0.0618 for model mismatch confirmed that the proposed model is extremely important and can successfully predict the effectiveness of DMP removal. The kinetics of the process and the effect of the presence of some radical scavengers were studied to understand the exact mechanism of DMP degradation. Therefore, it was observed that the reaction of hydroxyl radicals with DMPs followed the first-order kinetics model. Moreover, it was established that the optimal ratio of H2O2/Fe2+ mole was 1.6 and the electricity consumption was 0.157 kWh m−3. The elaborated treatment model used to remove DMP from landfill leachate showed that DMP contamination was effectively removed with a 95.6% removal efficiency in the investigating process.

Water stable SiO2-coated Fe-MOF-74 for aqueous dimethyl phthalate degradation in PS activated medium

The poor water stability of metal-organic frameworks (MOFs) significantly hindered their catalytic application in advanced oxidation system. A protective outer layer was an effective strategy to solve this problem. However, the commonly used coating techniques are too complicated or too difficult to accurately control, thus, the applicability was relatively low. In this study, a water stable MOF core-SiO2 shell nanomaterial (Fe-MOF-74@SiO2) was synthesized by a facile hydrothermal method, and applied to activate persulfate (PS) for dimethyl phthalate (DMP) degradation. The catalyst water stability and DMP degradation in the system were investigated, suggesting that the SiO2-coated catalyst was more stable and exhibited higher DMP degradation efficiency over the pure MOF. It was found that pH had negligible effects on Fe-MOF-74@SiO2 + PS system, while, higher temperature facilitated the degradation of DMP. The activation mechanism was studied by quenching experiments combined with electron paramagnetic resonance, indicating that SO4⋅− played a major role in the activation of PS with Fe-MOF-74@SiO2 for DMP removal, while ⋅OH also involved in the catalytic process. Finally, possible DMP degradation pathways were proposed. These findings indicated that the core-shell structured Fe-MOF-74@SiO2 showed promise for DMP degradation by PS advanced oxidation system.