Removal Of Persistent Organic Pollutants Research Articles

Urchin-like Ni-Fe-Mo sulfide: An effective electrochemical calcium sulfite activator for tetracycline degradation

Sulfite is deemed as a promising precursor to produce highly reactive species for contaminants remediation. Herein, the urchin-like Ni-Fe-Mo sulfide (NiFeMoSx) was anchored in-situ on nickel foam as a cathode to activate CaSO3 for efficient degradation of tetracycline (TC) under natural condition. The degradation efficiency reached 92.7% within 60 min, which was about 1.81 times higher than that of the electro-Fenton process based on NiFeMoSx. The beneficial performance came from the synergistic activation of CaSO3 by simultaneous rapid redox cycles of Fe(II)/Fe(III) and Ni(II)/Ni(III) on the NiFeMoSx cathode. Specifically, the primary intermediates Fe(II)-HSO3- and Ni(II)-SO32- triggered a series of radical chain reactions, accompanied the reduction of Ni(III)/Fe(III) by electrochemistry and electron donor of Mo(IV) and S2- on the surface of the catalyst. The regeneration of the Fe(II)/Ni(II) was quickly realized and subsequently triggered the chain reactions, which would accelerate the formation rate of reactive species, such as SO4∙−, ·OH, O2∙− and 1O2, of which 1O2 and O2•- played important roles on degradation TC. This work provides a promising application for the efficient removal of persistent organic pollutants by metal sulfide activated sulfite.

Attuning doped ZnO-based composites for an effective light-driven mineralization of pharmaceuticals via PMS activation

Water treatment technologies need to go beyond the current control of organic contaminants and ensure access to potable water. However, existing methods are still costly and often inadequate. In this context, novel catalysts that improve the mineralization degree of a wider range of pharmaceuticals through more benign and less consuming methodologies are highly sought after. ZnO, especially when doped, is a well-known semiconductor that also excels in the photocatalytic removal of persistent organic pollutants. In this study, we investigated the effect of doping ZnO nanoparticles with either copper, gallium or indium on the structure, morphology, photophysical properties and photocatalytic mineralization of pharmaceuticals. Their architecture was further improved through the fabrication of composites, pairing the best performing doped ZnO with either BaFe12O19 or nickel nanoparticles. Their suitability was tested on a complex 60-ppm multi-pollutant solution (tetracycline, levofloxacin and lansoprazole). The activation strategy combined photocatalysis with peroxymonosulfate (PMS) as an environmentally friendly source of highly oxidative sulfate radicals. The alliance of doped ZnO and BaFe12O19 was particularly successful, resulting in magnetic microcroquette-shaped composites with excellent inter-component synergy. In fact, indium outperformed the other proposed metal dopants, exceeding 97% mineralization after 1 h and achieving complete elimination after 3 h. All composites excelled in terms of reusability, with no catalytic loss after 10 consecutive cycles and minimal leakage of metal ions, highlighting their applicability in water remediation.

Constructing of Fe-Cu bimetallic MOFs derived electro-Fenton cathode for efficient norfloxacin removal

Heterogeneous electro-Fenton (H-EF) is a promising technology for the removal of persistent organic pollutants. It is urgently necessary to exploit effective cathode. In this study, the development of a stable FeCu-N doped C is modified in carbon felt (FC12-NC@CF) as a cathode for norfloxacin removal in heterogeneous electro-Fenton. FC12-NC, with a typical rod-like morphology derived from Fe/Cu bimetal MOF, is synthesized via carbonization in N2. The synergistic effect of Fe-Cu accelerated electron transfers and remarkably enhanced the oxygen reduction reaction (ORR) toward the two-electron process (n = 2.13). At a wide pH range (pH 3–9), norfloxacin (NOR) is removed efficiently within 90 min, while the modified cathode has excellent stability and catalytic capacity after six recycle runs. A possible mechanism of NOR removal was suggested for this H-EF process, confirming that hydroxyl radicals were the main active species. Based on the experimental results, the intermediates of NOR and the possible degradation pathways were proposed. According to the Toxicity Estimation Software Tool (T.E.S.T.), the toxicity of NOR was predicted to be partly minimized after the H-EF reaction. The prepared cathode was cost-effective, demonstrating a good application prospect in wastewater treatment.

Visible light-responsive Ce-doped ZnO ceramic nanostructures as effective photocatalysts for removal of persistent organic pollutants from contaminated waters

Cerium-doped zinc oxide (ZnO) ceramic nanostructures were conceived and prepared by means of electrospinning-calcination method. Morphological analysis based on scanning electron microscopy (SEM) disclosed a transition from spherical to rod-shaped features in ZnO ceramic nanostructures upon cerium (Ce) doping amount. Powder X-ray diffraction (XRD) indicated that the unit cell parameters remained unchanged for doped ZnO, while a new diffraction peak at 2θ = 28.57° occurred above 0.5% Ce, corresponding to cubic CeO2. The results are further supported by X-ray Photoelectron Spectroscopy (XPS) investigations, which clearly confirmed the occurrence of Ce4+ ions upon the increase of Ce incorporation during the synthesis. Photocatalytic screening assays for methylene blue (MB) degradation using a visible light source, demonstrated superior performance for the doped material with 0.1% Ce content, yielding the highest pseudo-first-order rate constant (k = 4.795 × 10−2 min−1). Additionally, the best catalyst ZnO:Ce (0.1%), showed rate constants of 1.018 × 10−2 min−1 and 3.675 × 10−2 min−1 for photodegradation of metronidazole (MNZ) and ciprofloxacin (CIP), respectively, under the established optimal conditions. The catalyst stability was confirmed through multiple reuse cycles. The present study points out the effective Ce-doped ZnO nanostructures for versatile photocatalytic applications.

Developing Prussian blue/wood-derived biochar catalyst for persistent organic pollutant degradation: Preparation, characterization, and mechanism

Biomass-derived biochar shows broad promise for persistent organic pollutants (POPs) degradation and thus establishes a more sustainable homestead. However, effective catalytic performance is still challenging. Herein, an efficient catalyst (Prussian blue decorated wood-derived biochar, PBB) was constructed by introducing Prussian blue (PB) into wood-based biochar to activate peroxymonosulfate (PMS) for removing POPs. After anchoring of PB, the degradation performance of biochar was enhanced (degradation efficiency of methylene blue (MB, 20 mg/L) increased from 52% of biochar to 95% of PBB within 60 min). The PBB presents effective MB degradation performance with a wide pH value (3.0 < pH < 11.0) or co-existing diverse anions (Cl−, NO3−, H2PO4−, and HCO3−). Electron paramagnetic resonance (EPR) analysis as well as electrochemical tests confirmed that the non-radical pathway (1O2) is the key to biochar activation of PMS, but by restricting PB into the biochar, the radical pathway (SO4•- and •OH), the non-radical pathway (1O2), and direct electron transfer can work together to activate PMS. In addition, the degradation efficiency could remain about 80% after five-time cyclic tests. This work elucidates the role of PB nanoparticles in enhancing biochar catalysts, which can inspire the development of a carbon-neutralized, cost-effective, and effective strategy for POPs removal.

Recent Trends and Advancement in the Removal of Persistent Organic Pollutants from Wastewater by Hybrid Electrocoagulation Chemical Degradation Processes

Recent Trends and Advancement in the Removal of Persistent Organic Pollutants from Wastewater by Hybrid Electrocoagulation Chemical Degradation Processes

Enhanced removal of perfluoroalkyl substances using MMO-TiO2 visible light photocatalyst

Exploration of easily produced visible light photocatalysts is still necessary. Thus, this study investigated the catalytic performance of a mixed metal oxide-titanium dioxide (MMO-TiO2) to remove perfluorooctanoic acid (PFOA), a typical and harmful perfluoroalkyl substance, under visible light conditions. Analysis of degradation efficiencies revealed that MMO-TiO2 exhibited a remarkable removal efficiency of 95.99 ± 1.49 %, surpassing other catalysts, including TiO2, ZnAl, MMO, and ZnAl-TiO2. MMO-TiO2, derived from ZnAl-TiO2 calcination, displayed a 5.66-fold higher apparent degradation rate constant (1.07 × 10−2 min−1) compared to ZnAl-TiO2 (1.89 × 10−3 min−1). These materials were characterized via X-ray powder diffractometry, Fourier transform infrared-attenuated total reflectance, N2 adsorption-desorption analysis, and field emission-scanning electron microscopy. Results revealed that O2•- radicals play a pivotal role as the predominant species that mediate PFOA removal. Comparative experiments using probe compounds confirmed increased O2•- production during MMO-TiO2 photoreaction under visible light. In addition, this study explored the effect of operational parameters, such as catalyst dose, initial PFOA concentration, solution pH, and water matrices on the photocatalytic removal process. These findings provide insight into the removal of PFOA using MMO-TiO2, highlighting the potential of this visible light catalyst for the eco-friendly removal of persistent organic pollutants in aquatic systems.

Application Potential of Layered Double Hydroxides for The Treatment of Persistent Organic Pollutants

Layered double hydroxides (LDHs) is a widely used emerging material. With its adjustable composition, other ions or materials can be incorporated on the surface or in the layer to synthesize modified materials with stronger ability to capture target pollutants. Persistent organic pollutants (POPs) exist in air, water and soil for a long time, which not only affect the ecosystem and ecological balance, but also endanger human health. Therefore, it is of great significance to study the application potential of LDHs in the treatment of POPs. The removal mechanism of persistent organic pollutants by LDHs includes adsorption and activated persulfate oxidation. The factors affecting the removal of POPs by LDHs include the characteristics of LDHs itself (including the inherent characteristics of composition, structure, morphology, etc.), coexisting substrates, temperature, etc.

Recent advances in water falling film reactor designs for the removal of organic pollutants by advanced oxidation processes: A review

Chemical wastewater from industrial and urban activities is a major environmental concern. Advanced oxidation processes (AOPs) have emerged as efficient techniques for the removal of persistent organic pollutants from wastewater. AOPs generate highly reactive hydroxyl radicals (•OH) that effectively degrade and mineralize a wide range of organic contaminants in aqueous solutions. Research is ongoing to find simple and efficient reactor designs for AOPs. Water falling film (WFF) reactor designs have been effectively utilized for the removal of various organic pollutants from wastewater. This review provides an overview of the development and application of WFF reactor designs for organic pollutants degradation by various AOPs. This work summarizes recent studies on treating organic pollutants, highlights current challenges in applying WFF reactors for water treatment using AOPs, and proposes future research directions. The review aims to guide researchers and stimulate further investigations into practical applications of WFF reactors in wastewater treatment.

IDENTIFICATION SOURCES OF EMISSION PERSISTENT ORGANIC POLLUTANTS IN UKRAINE AND WAYS TO REDUCE EMISSIONS FROM THE MOST PROBLEMATIC SOURCES

Persistent organic pollutants (POPs) belong to a group of toxicants, which, due to their extremely dangerous impact on human health, is regulated by a special international agreement — the Stockholm Convention on POPs. Each Party to the Convention must develop and consistently update the National Implementation Plan for the requirements of this Convention. Ukraine developed a National Implementation Plan in 2007. Today, the plan needs to be revised and supplemented, taking into account the changes that have occurred in the structure of sources and volumes of POP emissions. During the time that has passed since the development of the first edition of the National Plan, new approaches have appeared to prevent the emission of POPs. The article contains the results of an expert analysis of changes in the volume and structure of POP emission sources in the world and in Ukraine. Calculations of POPs emissions, made according to the UNEP methodology, showed that the largest sources of POPs emissions in Ukraine are: sintering production and electric arc smelting of steel in ferrous metallurgy; production of thermal and electrical energy from biomass in the energy industry; incineration of solid household and hazardous waste. For the most problematic sources of POP emissions, the most promising methods and practices for preventing the formation and removal of POPs from the products of technological process have been determined. Bibl. 25, Fig. 4, Tab. 3.

Z-scheme MnO2/Mn3O4 heterojunctions with efficient peroxymonosulfate activation for organic pollutant removal

The exploration of efficient heterogeneous catalysts for persistent organic pollutant removal is extremely attractive. In the present work, MnO2/Mn3O4 photo-Fenton catalysts were designed by a facile hydrothermal route to activate peroxymonosulfate (PMS) under visible light irradiation for organic pollutant degradation. The optimized MnO2/Mn3O4 heterojunction shows excellent Rhodamine B (RhB) removal efficiency, whose apparent kinetic constant is 11.9 and 5.36 times as high as the MnO2 and Mn3O4. Meanwhile, there is a neglectable attenuation in catalytic performance after 5 recycling runs. Based on the active species trapping experiments, the non-radical process contributes more than the radical process during RhB degradation. Moreover, factors including the dosage of PMS, initial RhB concentration, initial pH, the presence of various anions, different organic pollutants, and water sources are investigated. Systematical characterizations reveal that the enlarged specific surface areas and the efficient charge separation aroused from the Z-scheme mechanism are attributed to the enhanced photo-Fenton performance. The present work contributes to the construction of the Mn-based photo-Fenton catalyst with efficient PMS activation capacity for environmental remediation.

Design of Bi4O5Br2/g‐C3N4 heterojunction for efficient photocatalytic removal of persistent organic pollutants from water

AbstractDyes and antibiotics as typical persistent organic pollutants (POPs) are widely present in the environment, but can hardly be removed completely by traditional water treatment methods. Here, we designed Bi4O5Br2/g‐C3N4 composite nanosheets for efficient photocatalytic removal of POPs in water. The Bi4O5Br2/g‐C3N4 composite with a heterojunction structure exhibited high adsorption and photocatalytic activity for removal of tetracycline (TC) and ciprofloxacin (CIP) with excellent cyclic stability, owing to its large specific surface area as well as enhanced charge separation and visible light utilization. Our characterization revealed that h+ and ·OH are responsible for the photocatalytic degradation of TC and CIP. This work provides insights into the design of photocatalytic materials with synergy of adsorption and photocatalytic degradation, and offers a heterojunction construction strategy for addressing the increasingly severe environmental issues.

Some Aspects of the Synthesis, Characterization and Modification of Poly(ether)sulfone Polymeric Membrane for Removal of Persistent Organic Pollutants in Wastewater Samples

Some Aspects of the Synthesis, Characterization and Modification of Poly(ether)sulfone Polymeric Membrane for Removal of Persistent Organic Pollutants in Wastewater Samples

Catalytic membrane with multiscale iron-based catalysts anchored on 2D/2D hybrid g-C3N4/layered clay for pollutant removal

The catalytic membrane, which combines the physical barrier and peroxymonosulfate (PMS)/visible light (Vis)-induced catalytic oxidation functionalities while minimizing biofouling, exhibits great promise as a material for the removal of persistent organic pollutants from wastewater. In this study, three catalytic membranes composed of 2D/2D hybrid g-C3N4/kaolinite with nitrogen vacancies and modified with different iron species (γ-FeOOH nanosheets, Fe2O3 quantum dots, and Fe single atoms) were prepared via vacuum filtration. Evaluation of the catalytic performance demonstrated that γ-FeOOH nanosheets-modified sample exhibited a relatively higher water flux (258.13 L m-2 h-1). In contrast, Fe single atom-modified sample achieved improved bisphenol A removal efficiency (97.39%) under the PMS/Vis synergetic system. Interestingly, the Fe2O3 quantum dots-modified sample exhibited the highest rate constant based on the retention time. Furthermore, the Fe single atom-modified sample showed consistent removal of bisphenol A, reaching nearly 100% during continuous-flow operation for 180 min, while maintaining a flux of approximately 200 L m-2 h-1. Quenching experiments suggested that •O2−, 1O2, and h+ were the most important oxidizing species involved in the reaction of the three membranes. Statistical analysis indicated that variations in the average pore size of the membranes were key factors influencing the catalytic activity. Overall, this study offers an in-depth insight into the systematic and quantitative assessment of 2D/2D hybrid g-C3N4/layered clay-based catalytic membranes for wastewater treatment.

The fate of three typical persistent organic pollutants in bioretention columns as revealed by stable carbon isotopes

There is a lack of simple and effective methods to quantify the fate processes of persistent organic pollutants (POPs) in bioretention systems. In this study, the fate and elimination processes of three typical 13C-labeled POPs in regularly added bioretention columns were quantified using stable carbon isotope analysis techniques. The results showed that the modified media bioretention column removed more than 90% of Pyrene, PCB169 and p,p'-DDT. Media adsorption was the dominant removal mechanism for the reduction of the three exogenous organic compounds (59.1–71.8% of the input) although plant uptake (5.9–18.0%) was also important. Mineralization was effective in degrading pyrene (13.1%) but had a very limited effect on p,p'-DDT and PCB169 removal (<2.0%), the reason for which may be related to the aerobic conditions of the filter column. Volatilization was relatively weak and negligible (<1.5%). The presence of heavy metals inhibited the removal of POPs to some extent: media adsorption, mineralization and plant uptake were reduced by 4.3–6.4%, 1.8–8.3% and 1.5–3.6% respectively. This study suggests that bioretention systems are an effective measure for the sustainable removal of POPs from stormwater and that heavy metals can inhibit the overall performance of the system. Stable carbon isotope analysis techniques can help to investigate the migration and transformation of POPs in bioretention systems.

Genomic Diversity and Phenotypic Variation in Fungal Decomposers Involved in Bioremediation of Persistent Organic Pollutants.

Fungi work as decomposers to break down organic carbon, deposit recalcitrant carbon, and transform other elements such as nitrogen. The decomposition of biomass is a key function of wood-decaying basidiomycetes and ascomycetes, which have the potential for the bioremediation of hazardous chemicals present in the environment. Due to their adaptation to different environments, fungal strains have a diverse set of phenotypic traits. This study evaluated 320 basidiomycetes isolates across 74 species for their rate and efficiency of degrading organic dye. We found that dye-decolorization capacity varies among and within species. Among the top rapid dye-decolorizing fungi isolates, we further performed genome-wide gene family analysis and investigated the genomic mechanism for their most capable dye-degradation capacity. Class II peroxidase and DyP-type peroxidase were enriched in the fast-decomposer genomes. Gene families including lignin decomposition genes, reduction-oxidation genes, hydrophobin, and secreted peptidases were expanded in the fast-decomposer species. This work provides new insights into persistent organic pollutant removal by fungal isolates at both phenotypic and genotypic levels.

Coral-like B-doped g-C3N4 with enhanced molecular dipole to boost photocatalysis-self-Fenton removal of persistent organic pollutants

Fenton process is a popular advanced oxidation process for water purification. However, it requires an external addition of H2O2, thus raising safety threats and economic costs and encountering the problems of slow cycling of Fe2+/Fe3+ and low mineralization efficiency. Herein, we developed a novel photocatalysis-self-Fenton system based on coral-like B-doped g-C3N4 (Coral-B-CN) photocatalyst for 4-chlorophenol (4-CP) removal where H2O2 can be in situ generated by photocatalysis over Coral-B-CN, the cycling of Fe2+/Fe3+ was accelerated by photoelectrons, and the photoholes promoted 4-CP mineralization. Coral-B-CN was innovatively synthesized by hydrogen bond self-assembly followed by calcination. B heteroatom doping produced enhanced molecular dipole, while the morphological engineering exposed more active sites and optimized band structure. The effective combination of the two enhances charge separation and mass transfer between the phases, resulting in efficient in-situ H2O2 production, faster Fe2+/Fe3+ valence cycling and enhanced hole oxidation. Accordingly, nearly all 4-CP can be degraded during 50 min under the combined action of more ·OH and holes with stronger oxidation capacity. The mineralization rate of this system reached 70.3%, which is 2.6 and 4.9 times higher than that of Fenton process and photocatalysis, respectively. Besides, this system maintained excellent stability and can be applied in a broad range of pHs. The study would provide important insights into developing improved Fenton process with high performance for the removal of persistent organic pollutants.

Effects of persistent organic pollutants on environment, health and mountains: a review

Persistent organic pollutants (POPs) are chemicals that persist in the environment, bioaccumulate through the food chain and can exhibit toxicity with threatening effects to the environment, humans and animals. Due to their volatility and semi-volatility, they are found in air and they have the potential to be transported to high-altitude mountain locations as well as to high-latitude areas. The objectives of this study are; firstly, to look into the environmental and health impacts of POPs; secondly, to look into studies that covered the transport of POPs through atmospheric air, water and other POP sources such as sediments and soils; and, thirdly, to look into possible solutions that have been put forward regarding POP removal from the environment. The methodology that was used to look for references was through the Google, PubMed, Google Scholar and ResearchGate. The initial search retrieved 63 peer-reviewed articles and abstracts. The studies revealed that, POPs remain in the environment, causing health effects through their toxicity. Humans and animals take in POPs through the food chain because of the lipophilic nature of these compounds. Solutions that have been put forward by the studies are stopping the use of POPs, substituting POPs with non-toxic chemical compounds and having a wide range of non-chemical alternatives.

Fabrication of CoFe2O4/Mn3O4 decorated ultrathin graphitic carbon nitride nanosheets membrane for persistent organic pollutants removal: Synergistic performance and mechanisms

Integration of sulfate radicals-based advanced oxidation processes (SR-AOPs) with separation membranes has enthralled considerable attentions because it can remove persistent toxic micropollutants in a low-energy and cost-effective manner. However, fabrication of such an integrated membrane simultaneously with excellent self-cleaning property, catalytic capability and long-term durability remains a challenge. Herein, for the first time, CoFe2O4 (CFO) and Mn3O4 (MO) nanoparticles were anchored on ultrathin graphitic carbon nitride (UCN) nanosheets via a solvothermal method to prepare heterogeneous Fenton-like catalysts (MO/CFOUCN). Systematic characterizations demonstrated the successful preparation of powder catalysts with favorable degradation ability. Notably, the optimal composite catalyst possessed satisfactory degradation (94.5 %) and kinetic rate (0.1367 min−1) for norfloxacin (NOR) within 30 min. Thereafter, an integrated MO/CFO/UCN@P membrane was fabricated by vacuum-assisted filtration of the catalyst on a supporting membrane surface. It was interestingly found that, benefiting from the synergistic effect of in-situ oxidation and membrane filtration, activating peroxymonosulfate (PMS) endowed the membrane with high removal rates (over 91.8 % for tetracycline, bisphenol A, humic acid (HA)) and high permeation flux (332.7 L·m−2·h−1) driven solely by gravity. Significantly, the membrane achieved a flux recovery rate of 91.9 % with the assistance of PMS after filtering HA solution. Furthermore, quenching experiments and electron paramagnetic resonance (EPR) tests confirmed that both radical and nonradical pathways contributed to the mineralization of NOR. Based on the detection of intermediates in the degradation process, potential NOR degradation pathways were proposed. Overall, this study provided new ideas about integrating Fenton-like catalysts with membrane technology for removal of persistent organic pollutants.

Recent advances in application of metal-organic frameworks (MOFs) as adsorbent and catalyst in removal of persistent organic pollutants (POPs).

The presence of persistent organic pollutants (POPs) in the aquatic environment is causing widespread concern due to their bioaccumulation, toxicity, and possible environmental risk. These contaminants are produced daily in large quantities and released into water bodies. Traditional wastewater treatment plants are ineffective at degrading these pollutants. As a result, the development of long-term and effective POP removal techniques is critical. In water, adsorption removal and photocatalytic degradation of POPs have been identified as energy and cost-efficient solutions. Both technologies have received a lot of attention for their efforts to treat the world's wastewater. Photocatalytic removal of POPs is a promising, effective, and long-lasting method, while adsorption removal of persistent POPs represents a simple, practical method, particularly in decentralized systems and isolated areas. It is critical to develop new adsorbents/photocatalysts with the desired structure, tunable chemistry, and maximum adsorption sites for highly efficient removal of POPs. As a class of recently created multifunctional porous materials, Metal-organic frameworks (MOFs) offer tremendous prospects in adsorptive removal and photocatalytic degradation of POPs for water remediation. This review defines POPs and discusses current research on adsorptive and photocatalytic POP removal using emerging MOFs for each type of POPs.