Heterogeneous Fenton-like Process Research Articles

Tetracycline degradation through selective activation of molecular oxygen by a fluidic sequential photoelectro-Fenton system

The heterogeneous Fenton-like process is regarded as a promising strategy for reactive oxygen species (ROS) production by driving a two-electron oxygen reduction reaction toward H2O2 and stepping activating the as-generated H2O2 to ROS. Therefore, a fluidic sequential photoelectro-Fenton (PEF) system was developed for the selective activation of molecular oxygen to generate ROS. The system comprises a hydrogen peroxide (H2O2) electrolyzer and a photocatalytic membrane reactor (PCMR). The H2O2 electrolyzer employed a PEI-O/CNT air self-diffusion electrode to achieve high selectivity for H2O2 production without aeration. In the subsequent stage, within the PCMR, two-dimensional Fe/C3N4 with a nanoconfinement structure selectively converted H2O2 into ROS. The exceptional tetracycline (TC) degradation efficiency (96.0 %) was attributable to the synergistic effects of radical and non-radical pathways. The fluidic sequential PEF system achieved efficient and energy-saving H2O2 production (0.134 kWh/g of H2O2) and TC degradation (1.7 kWh/kg of TC). In addition, the PEF system not only has a good effect on removing tetracycline in real water but also can effectively remove a variety of antibiotic pollutants, which has a good prospect for practical application. This research contributed new insights into the development of the fluidic sequential PEF process.

Boosting the Ni(II)-EDTA decomplexation and Ni(II) immobilization in a heterogeneous Fenton-like system with L-cysteine functionalized zero-valent iron

The remarkable stability and detrimental environmental impacts of nickel(II)-ethylenediaminetetraacetic acid (Ni(II)-EDTA) complexes originated from electroplating effluents have sparked a growing curiosity about their efficient remediation. In this study, L-cysteine functionalized zero-valent iron (C-ZVIbm) was synthesized via a ball-milling method and employed as a heterogeneous Fenton-like catalyst to decomplex Ni(II)-EDTA and immobilize Ni(II) from wastewater. The results demonstrated that the pseudo-second-order kinetic rate constant (2.096 L·mol−1·min−1) for EDTA degradation in the C-ZVIbm/H2O2 system was 123.3 times that in the ZVIbm/H2O2 system (0.017 L·mol−1·min−1). The incorporation of L-cysteine onto the surface of ZVI significantly enhanced the H2O2 activation, reactive oxygen species (OH, O2−, and 1O2) generation, and the sequential Ni(II)-EDTA decomplexation and EDTA degradation. The results of capture experiments revealed that 1O2 played a crucial role in the degradation of EDTA in the C-ZVIbm/H2O2 system. The optimization of the experimental variables indicated that the degradation of EDTA and the reduction/adsorption of Ni(II) were antagonistic in the C-ZVIbm/H2O2 system, resulting in an efficient reduction/immobilization of Ni(II) and an inhibition of EDTA degradation at a higher dosage of C-ZVIbm. Our findings provide new insights into the promising heterogeneous Fenton-like process that enables the decomplexation of Ni(II)-EDTA, the degradation of EDTA, and the synchronous immobilization of Ni(II).

Structural, magnetic, and electronic structure of the nanostructured (CoMn)50Ni50 powders used in dye discoloration via a heterogeneous Fenton-like process

Structural, magnetic, and electronic structure of the nanostructured (CoMn)50Ni50 powders used in dye discoloration via a heterogeneous Fenton-like process

Spatial Confinement of Co Nanoparticles in N-Doped Carbon Nanorods for Wastewater Purification via CaSO3 Activation.

Spatial confinement of organic pollutants and reactive oxygen species (e.g., SO4•- and •OH) with ultrashort lifetime inside the scale of chemical theoretical diffusion could provide a greatly promising strategy to overcome the limitation of mass transfer in the heterogeneous Fenton-like oxidation process. Herein, we first reported spatial confinement of cobalt nanoparticles in N-doped carbon nanorods (Co-NCNRs), by encapsulating Co nanoparticles into N-doped carbon nanorods, in activating CaSO3 for antibiotic degradation. Compared to Na2SO3 and NaHSO3, CaSO3 could slowly and persistently discharge SO32- due to its low solubility, thus avoiding the depletion of the generated SO3•- and •OH under the high concentration of sulfite ions. Fully physical characterizations confirmed that the 3D hydrogel was mostly transformed into the nanorod structure of Co-NCNRs at 550 °C. Co atoms were successfully nanoconfined into N-doped carbon nanorods, which contributes to mass transfer and prevents the agglomeration of Co nanoparticles, thus enhancing its catalytic activity and stability in activating CaSO3 for water decontamination. The catalytic performance, kinetic research, influences of inorganic anions, pH, and degradation mechanism of chlortetracycline degradation catalyzed by the Co-NCNRs/CaSO3 system have been studied in detail. This work not only proposed a facile method for synthesis of nanoconfined catalyst but also provided an excellent Co-NCNRs/CaSO3 system for wastewater treatment.

Diethylenetriaminepentaacetic acid (DTPA)-reinforced fenton-like process for efficient abatement of sulfamethazine at circumneutral pH in simulated groundwater

The present study proposed a promising heterogeneous Fenton-like process that a chelating agent (diethylenetriaminepentaacetic acid, DTPA) was introduced into the nZVI/H2O2 system to improve its oxidation capacity for abatement of sulfamethazine (SMT) at circumneutral pH in the simulated groundwater. The nZVI/DTPA/H2O2 system possessed a high oxidation performance for the elimination of SMT under the selected experimental conditions within 45 min of reaction. OH was considered as the predominant radical special accountable for SMT degradation. The roles of DTPA in the reaction system mainly include complexing with Fe2+ to prevent the passivation of nZVI, and forming the Fe2+-DTPA complex to rapidly decompose H2O2 to produce OH and other free radicals. The degradation patterns of SMT in the nZVI/DTPA/H2O2 system were inferred on account of density functional theory (DFT) calculation and the detection of intermediates via LC-MS analysis. Besides, nZVI/DTPA/H2O2 process could effectively reduce biological toxicity of SMT by prediction based on QSAR analysis. The coexisting ions such as Cl−, SO42−, and humic acid (HA) had negligible influences for the oxidative abatement of SMT, while HCO3− had a concentration-dependent inhibitory effect. The oxidation capacity of nZVI/DTPA/H2O2 process in actual water matrix and different pollutants were also discussed.

Regulating localized state electron and ordered electron transfer in Cu2Se using Indium element for efficient heterogeneous Fenton-like process

Local electron density at the reaction center atoms is closely related to the H2O2 activation performance of a heterogeneous Fenton-like catalyst. However, the random electron transfer often restricts the oriented electron delivery to the active center. In this study, we proposed that only efficient electrons and their ordered transfer were desirable to boost Cu(II)/Cu(I) cycle for H2O2 activation based on regulation of local electron density and electron transfer efficiency of Cu atoms in Cu2Se. Experimental results and density function theory (DFT) calculation proved that Indium atom can drive electrons to accumulate on Cu active center and provide an efficient electron transfer pathway in CuInSe2 (from Se → Cu to In → Se → Cu). Hence, compared with Cu2Se, more reductive electrons can participate in the H2O2 activation process for CuInSe2, which resulted in much more efficient ofloxacin (OFX) degradation with a TOC removal rate up to 71.5 %. The electron exchange capacity of CuInSe2 was further regulated by changing the atomic ratios of Cu and In elements including CuInSe2, Cu1.5In0.5Se2 and Cu1.75In0.25Se2. CuInSe2 had the lowest electron exchange capacity and exhibited the highest reaction activity with a radical transformation efficiency from H2O2 of 9.83 × 10-4, in contrast, the value for Cu1.75In0.25Se2 was 2.78 × 10-4. We provided a new insight for improving the heterogeneous Fenton catalytic performance.

Iron-doped catalyst synthesis in heterogeneous Fenton like process for dye degradation and removal: optimization using response surface methodology

Iron-doped hydrochar can effectively remove the methyl orange dye (MO). In this study, iron-doped hydrochar (5% Fe@BC) was successfully synthesized through a two-step hydrothermal carbonization (HTC) process, using FeSO4.7H2O and sawdust. It was subsequently employed for MO removal. The characterization of the synthesized Fenton-like catalyst (5% Fe@BC) was conducted, using scanning electron microscopy, Fourier-transform infrared and X-ray diffraction techniques to confirm the presence of iron species. The effects of different operating parameters such as catalyst mass, H2O2 concentration, solution pH, organic pollutant concentration, and reaction temperature have been examined. The Box-Behnken design combined with three factors: catalyst mass X1, temperature X2, organic pollutant concentration X3. The response surface methodology coupled with Box-Behnken Design was used to optimize the key variables and response. With this approach, an exhaustive assessment of the variables influencing the optimization process was performed. A significant quadratic model was generated through analysis of variance with a P-value of 0.0001 and an R2 of 0.99. This confirms a strong relationship between the variables and the response, as well as a high level of model predictability. The optimum conditions were achieved with a catalyst mass of 0.5 g/L, a temperature of 35.5 °C, and an MO concentration of 50 mg/L. The result indicates that 93% of the discoloration efficiency was achieved within 60 min under the optimal conditions. Iron doping in the (5% Fe@BC) plays a crucial role in the degradation and removal of MO. Therefore, the 5% Fe@BC prepared from sawdust and iron salts (FeSO4·7H2O) through a two-step HTC process is an inexpensive and effective catalyst for removing organic pollutant from aqueous solutions, using heterogeneous Fenton-like process.

Efficient degradation of methylene blue by FeS2/MoS2 in heterogeneous Fenton-like process

Iron-based materials as Fenton catalysts exist the problems of low activation efficiency of hydrogen peroxide (H2O2) and narrow applicable pH range. Herein, we synthesized materials with different ratios of molybdenum to iron, named as MoS2/FeS2, and used them for the degradation of methylene blue (MB). Notably, the MB degradation rate of FeS2/MoS2/H2O2 system reached 99.9 % within 30 min under neutral conditions, and its degradation rate constant was 34.3 and 21.8 times than that of MoS2 alone and physical mixture of FeS2 + MoS2, respectively. The MB degradation rate was 81.4–99.9 % at solution pH of 3–11, suggesting that FeS2/MoS2 is applicable to the Fenton-like process at wide pH. The morphology and composition of materials were analyzed by X-ray diffraction (XRD), Barrett-Emmett-Teller (BET), Transmission electron microscopy (TEM) and Scanning electron microscope (SEM). The X-ray photoelectron spectroscopy (XPS) and experimental results showed that Mo and S accelerated Fe2+/Fe3+ cycling was the main reason for the enhancement of catalyst activity. The main reactive oxygen species (ROS) was singlet oxygen (1O2) in the system. After 4 applications of FeS2/MoS2, the MB degradation rate still reached more than 90 % within 30 min, which indicates the excellent stability of material. In summary, FeS2/MoS2 has promising prospects for the degradation of wastewater.

Inert magnesium-doped Co3O4 spinel assembling catalytic membrane for instantaneous peroxymonosulfate activation and contaminants elimination

The practical application of heterogeneous Fenton-like processes in wastewater treatment is limited by inadequate catalyst recovery and limited mass transfer in traditional batch mode. Consequently, a catalytic membrane composed of inert magnesium (Mg)-doped Co3O4 spinel (MCO) was crafted to activate peroxymonosulfate (PMS) for the elimination of organic contaminants. The incorporation of the less electronegative Mg induced electronic polarization on the MCO surface, resulting in the generation of sufficient electron-rich Co centers, thereby amplifying its electron-donating properties in PMS activation and enhancing the inherent catalytic activity of the spinel. Regarding the catalytic membrane, the stacked porous structure of the MCO layer achieved reactive sites exposure, mass transfer enhancement, and reactive species availability. Remarkably, the MCO@polyethersulfone (PES) membrane/PMS system instantaneously activated PMS, displaying an elimination kinetic constant of 0.039 ms−1 for tetracycline. The MCO@PES membrane exhibited exceptional catalytic performance and stability in long-term operational studies. Mechanistic investigations elucidated that the highly accessible SO4−, OH, and 1O2 within the catalytic membrane facilitated the immediate elimination of contaminants. This study serves as a valuable reference for the application of transition metal spinel-based catalytic membranes in wastewater treatment.

Triple reaction centers Vo-Ce-CuO nanosheets with single Ce atom for the Fenton-like degradation of niflumic acid

Vo (oxygen vacancy)-Ce-CuO nanosheet catalysts were studied for degrading niflumic acid (NFA) by the heterogeneous Fenton-like process (HFLP). NFA removal percentage of optimal Vo-Ce0.05-CuO reached 92% after 60 min of Fenton-like reactions and dropped only 0.28% after five times of recycles. Synergetic effects of triple reaction centers with electron-rich Vo centers, single Ce atom centers, and electron-deficient Cu centers have been demonstrated for generating hydroxyl radicals (OH) by H2O2 decomposition. The electrons from the organic pollutants adsorbed at the electron-deficient Cu centers could be transferred to Vo and Ce via the internal bridge bond to balance the electron transfer. H2O2 could directly obtain electrons from electron-rich Vo and single Ce atom centers to produce OH with a high H2O2 utilization efficiency instead of reducing metal ions by consuming H2O2. For the first time, we demonstrate that triple reaction centers with single Ce atom could improve the conversion percentage of H2O2 to OH with 71.1%. OH, HO2/O2− and 1O2 were the primary oxidants in the HFLP, in which OH played the dominant role.

Catalytic degradation of crystal violet and methyl orange in heterogeneous Fenton-like processes

Metals-loaded (Fe3+, Cu2+ and Zn2+) activated carbons (M@AC) with different loading ratios (0.1%, 0.5%, 1%, 5% and 10%) were prepared and employed for catalytic degradation of dye model compounds (crystal violet (CV) and methyl orange (MO)) in wastewater by heterogeneous Fenton-like technique. Compared with Cu@AC and Zn@AC, 0.5% Fe3+ loaded AC (0.5Fe@AC) had better catalytic activity for dyes degradation. The effects of dyes initial concentration, catalyst dosage, pH and hydrogen peroxide (H2O2) volume on the catalytic degradation process were investigated. Cyclic performance, stability of 0.5Fe@AC and iron leaching were explored. Degradation kinetics were well fitted to the pseudo-second-order model (Langmuir-Hinshelwood). Almost complete decolorization (99.7%) of 400 mg L−1 CV was achieved after 30 min reaction under the conditions of CV volume (30 mL), catalyst dosage (0.05 g), H2O2 volume (1 mL) and pH (7.7). Decolorization of MO reached 98.2% under the same conditions. The abilities of pyrolysis char (PC) of dyeing sludge (DS) and metal loaded carbon to remove dye pollutants were compared. The intermediate products were analyzed and the possible degradation pathway was proposed. This study provided an insight into catalytic degradation of triphenylmethane- and aromatic azo-based substances, and utilization of sludge char.

A sustainable solution for diclofenac degradation from water by heterojunction bimetallic nanocatalyst

BackgroundDiclofenac (DCF), a recalcitrant pharmaceutical compound, poses severe environmental concerns due to several health hazards. The Fenton, photo-Fenton, and photo-Fenton-like processes are popular advanced oxidation processes for eliminating toxins from water bodies. Due to its high reactivity and surface properties, nanotechnology has opened newer technological advances in the Fenton-like advanced treatment processes. MethodA facile and one-pot synthesis produces the nanocomposite materials. The natural phytochemicals, in situ, produce the nanoparticles of Fe(NPs) and Ag(NPs), and bentonite is supported with these nanoparticles to create an innovative heterojunction nanocatalyst BN@(Fe(NPs)+(AgNPs)). Additionally, the batch investigations utilize these materials in the photo-Fenton-like degradation of diclofenac in aqueous mediums. Significant findingsThe heterojunction nanocatalyst showed synergistic effects in the remediation of DCF. The nanocatalyst is highly efficient in degrading the DCF (2.0 mg L−1) and removes 83 and 70% of DCF within 2 h under UV-A and LED light irradiations, respectively. Interestingly, the degradation process mineralizes DCF to 74% under UV-A irradiation. Moreover, degrading DCF in a heterogeneous light-assisted Fenton-like process was favorably influenced by increased Fe(II) concentration in the bulk solution. The BN@(Fe(NPs)+Ag(NPs)) nanocatalyst possessed reasonably high stability and reusability for practical applications. Further, the nanocatalyst showed relatively high selectivity in the degradation of DCF using two different natural water samples.

Heterogeneous Fenton-like Photocatalytic Process towards the Eradication of Tetracycline under UV Irradiation: Mechanism Elucidation and Environmental Risk Analysis

The problem of the deep elimination of antibiotics in environmental bodies is exceptionally warranted. In this work, a ternary nanocomposite of FeNi3/SiO2/CuS (FSC) was fabricated and then integrated with UV light irradiation and hydrogen peroxide as the heterogeneous Fenton-like photocatalytic system for the decomposition of tetracycline (TC) from aqueous media. During this process, various influencing parameters such as pH, catalyst dosage, initial content of TC, hydrogen peroxide (H2O2) dose, and operating time were explored. At optimized circumstances, i.e., 5 of pH, 10 mg/L of TC concentration, 150 mg/L of H2O2 dosage, and 200 min of degradation time, the elimination proportion of TC was 96%. The results of capture agent tests clarified that hydroxyl radical (HO•) played the predominant role in the photocatalytic decontamination of TC. Moreover, with the elevated contact time and content of H2O2, the efficiency of TC decontamination increased significantly. Additionally, the findings of the stability and reusability experiments of the fabricated nanocomposite showed that the percentage of TC removal decreased by only about 5% after six cycles. Furthermore, the photocatalytic mechanism of the decontamination of TC over the FSC photocatalyst was elucidated. Eventually, the non-carcinogenic risk analysis in the surface water sample was carried out using multiple photocatalytic processes for the first time. These outcomes obtained in this study validate that coupling the photocatalytic system and the H2O2 oxidation agent facilitates the elimination of a great variety of pharmaceutical contaminants from aqueous media.

Tuning the intrinsic catalytic sites of magnetite to concurrently enhance the reduction of H2O2 and O2: Mechanism analysis and application potential evaluation

Heterogeneous Fenton-like process based on H2O2 activation has been widely tested for water purification, but its application still faces some challenges such as the use of high doses of chemicals (including catalysts and H2O2). Herein, a facile co-precipitation method was utilized for small-scale production (∼50 g) of oxygen vacancies (OVs)-containing Fe3O4 (Vo-Fe3O4) for H2O2 activation. Experimental and theoretical results collaboratively verified that H2O2 adsorbed on the Fe site of Fe3O4 tended to lose electrons and generate O2•-. While the localized electron from OVs of Vo-Fe3O4 could assist in donating electrons to H2O2 adsorbed on OVs sites, this allowed more H2O2 to be activated to •OH, which was 3.5 folds higher than Fe3O4/H2O2 system. Moreover, the OVs sites promoted dissolved oxygen activation and decreased the quenching of O2•- by Fe(III), thus promoting the generation of 1O2. Consequently, the fabricated Vo-Fe3O4 achieved much higher oxytetracycline (OTC) degradation rate (91.6%) than Fe3O4 (35.4%) at a low catalyst (50 mg/L) and H2O2 dosage (2 mmol/L). Importantly, further integration of Vo-Fe3O4 into fixed-bed Fenton-like reactor could effectively eliminate OTC (>80%) and chemical oxygen demand (COD) (21.3%∼50%) within the running period. This study provides promising strategies for enhancing the H2O2 utilization of Fe mineral.

Competitive study of homogeneous and heterogeneous Fenton-like flow-through propoxur oxidation in ROC solution.

Reverse osmosis is used as a tertiary treatment for wastewater reclamation. However, sustainable management of the concentrate (ROC) is challenging, due to the need for treatment and/or disposal. The objective of this research was to investigate the efficiency of homogeneous and heterogeneous Fenton-like oxidation processes in removing propoxur (PR), a micro-pollutant compound, from synthetic ROC solution in a submerged ceramic membrane reactor operated in a continuous mode. A freshly prepared amorphous heterogeneous catalyst was synthesized and characterized, revealing a layered porous structure of 5-16 nm nanoparticles that formed aggregates (33-49 μm) known as ferrihydrite (Fh). The membrane exhibited a rejection of >99.6% for Fh. The homogeneous catalysis (Fe3+) exhibited better catalytic activity than the Fh in terms of PR removal efficiencies. However, by increasing the H2O2 and Fh concentrations at a constant molar ratio, the PR oxidation efficiencies were equal to those catalyzed by the Fe3+. The ionic composition of the ROC solution had an inhibitory effect on the PR oxidation, whereas increased residence time improved it up to 87% at a residence time of 88 min. Overall, the study highlights the potential of heterogeneous Fenton-like processes catalyzed by Fh in a continuous mode of operation.

Fabrication of Cu0-composited CuFe2O4 magnetic nanoparticles on diatomite support for efficient degradation of tetracycline hydrochloride by a Fenton-like system

Paramagnetic Cu/CuFe2O4/DE composites were fabricated by a one-step solvothermal method to design a heterogeneous Fenton-like catalyst to degrade tetracycline hydrochloride (TC). The Cu/CuFe2O4/DE were characterized by SEM, TEM, XRD, BET, and XPS methods. The catalytic activity of CuFe2O4 was improved using diatomite and Cu0. Diatomite (DE) enhanced the dispersity of Cu/CuFe2O4, minimized metal ions leaching, and improved stability. The Cu0 is used for the regeneration of Fe3+. The synergy between Cu+/Cu2+ and Fe2+/Fe3+ redox pairs promotes hydroxyl radical production upon H2O2 decomposition. The synthesized materials were characterized by SEM, TEM, XRD, BET, and XPS, and their catalytic activities were discussed and analyzed. 95.5 % TC was degraded within 90 min (initial conditions, pH = 5.0 and [TC] 50 mg/L), and showing excellent anti-interference ability to the presence of SO42-, Cl-, NO3-, CO32- and humic acid (HA).The presence of active species, viz., •OH and •O2- radicals generated in the Cu/CuFe2O4/DE/H2O2 system were detected by ESR quenching measurements. The •OH and •O2- mediated TC degraded pathways were proposed using the intermediates identified by LC-MS data. The novel heterogeneous Fenton-like process developed using Cu/CuFe2O4/DE/H2O2 is robust for TC degradation as exemplified in its stability and reusability measurements.

Preparation and Characterization of a Coordination Polymer Based on Iron (III)-Cyamelurate as a Superior Catalyst for Heterogeneous Fenton-Like Processes.

We report on a new iron (iii)-cyamelurate-based coordination polymer. The new material based on a heptazine derivative was prepared in aqueous medium and characterized by a variety of techniques including TGA, FTIR, XRD, HRTEM, and STEM. Due to the high structural stability of the complex in aqueous media, its heterogeneous Fenton-like catalytic activity was evaluated using a model molecule. The results obtained showed a high catalytic activity in both in basic and acid media. The pseudo-first-order rate constants normalized by iron(III) concentrations was approximately 1000 times higher than the result obtained for traditional heterogeneous catalysts based on iron(III) oxyhydroxides. The best observed catalytic activities were attributed to the increase in the binding sites of Fe3+ ions, in parallel with the increased exposure of the catalytic sites, leading to a higher atomic efficiency of the reaction.

Molybdenum disulfide co-catalysis boosting nanoscale zero-valent iron based Fenton-like process: Performance and mechanism

The conventional Fenton process has the drawbacks of low efficiency of Fe3+/Fe2+ conversion, low utilization of H2O2, and narrow range of pH. In this paper, molybdenum sulfide (MoS2) was used as a co-catalyst to boost the nanoscale zero-valent iron (nZVI) based heterogeneous Fenton-like process for the degradation of Rhodamine B (RhB). The catalytic performance, influences of parameters, degradation mechanism, and toxicity of intermediates were explored. Compared with the conventional like-Fenton process, the existence of MoS2 accelerated the decomposition of H2O2 and the RhB degradation rate constant of MoS2/nZVI/H2O2 reached more than six times that of nZVI/H2O2. In addition, the effective pH range of MoS2/nZVI/H2O2 was broadened to 9.0 with 84.9% of RhB being removed within 15 min. The co-catalytic system of MoS2 and nZVI was stable and had high reusability according to the results of four consecutive runs. Quenching tests and electron paramagnetic resonance (EPR) demonstrated that hydroxyl radical (·OH), superoxide anions (·O2−), and singlet oxygen (1O2) were all involved in MoS2/nZVI/H2O2. Compared with nZVI/H2O2 system, MoS2 not only increased the corrosion of nZVI but also accelerated the conversion of Fe3+/Fe2+. ECOSAR analysis suggested that the overall acute and chronic toxicity of the degradation products decreased after treatment. Hence, this MoS2 co-catalytic nZVI based Fenton-like process can be used as a promising alternative for the treatment of organic wastewater.

Feasibility of a Heterogeneous Nanoscale Zero-Valent Iron Fenton-like Process for the Removal of Glyphosate from Water

Glyphosate is a widely used herbicide, and it is an important environmental pollutant that can have adverse effects on human health. Therefore, remediation and reclamation of contaminated streams and aqueous environments polluted by glyphosate is currently a worldwide priority. Here, we show that the heterogeneous nZVI-Fenton process (nZVI + H2O2; nZVI: nanoscale zero-valent iron) can achieve the effective removal of glyphosate under different operational conditions. Removal of glyphosate can also take place in the presence of excess nZVI, without H2O2, but the high amount of nZVI needed to remove glyphosate from water matrices on its own would make the process very costly. Glyphosate removal via nZVI--Fenton was investigated in the pH range of 3-6, with different H2O2 concentrations and nZVI loadings. We observed significant removal of glyphosate at pH values of 3 and 4; however, due to a loss in efficiency of Fenton systems with increasing pH values, glyphosate removal was no longer effective at pH values of 5 or 6. Glyphosate removal also occurred at pH values of 3 and 4 in tap water, despite the occurrence of several potentially interfering inorganic ions. Relatively low reagent costs, a limited increase in water conductivity (mostly due to pH adjustments before and after treatment), and low iron leaching make nZVI-Fenton treatment at pH 4 a promising technique for eliminating glyphosate from environmental aqueous matrices.

Three-Dimensionally Printed Zero-Valent Copper with Hierarchically Porous Structures as an Efficient Fenton-like Catalyst for Enhanced Degradation of Tetracycline

Three-dimensionally printed materials show great performance and reliable stability in the removal of refractory organic pollutants in Fenton-like reactions. In this work, hierarchically porous zero-valent copper (3DHP-ZVC) was designed and fabricated via 3D printing and applied as a catalyst for the degradation of tetracycline (TC) through heterogeneous Fenton-like processes. It was found that the 3DHP-ZVC/H2O2 system could decompose over 93.2% of TC within 60 min, which is much superior to the homogeneous Cu2+/H2O2 system under similar conditions. The leaching concentration of Cu2+ ions in the 3DHP-ZVC/H2O2 system is 2.14 times lower than that in the Cu powder/H2O2 system in a neutral environment, which could be ascribed to the unique hierarchically porous structure of 3DHP-ZVC. Furthermore, 3DHP-ZVC exhibited compelling stability in 20 consecutive cycles. The effects of co-existing inorganic anions, adaptability, and pH resistance on the degradation of TC were also investigated. A series of experiments and characterizations revealed that Cu0 and superoxide radicals as reducing agents could facilitate the cycling of Cu(II)/Cu(I), thus enhancing the generation of hydroxyl radicals to degrade TC. This study provides new insights into employing promising 3D printing technology to develop high-reactivity, stable, and recycling-friendly components for wastewater treatment.