Persistent Organic Pollutants In Water Research Articles

Research progress of persistent organic pollutants in water: classification, sources, potential risks, and treatment approaches

Abstract The occurrence of persistent organic pollutants (POPs) in almost every sphere of life and their notorious effects have been a global concern for quite a few decades, regardless of the fact that notable conventions have banned the standard POPs. Control measures and numerous technologies are being researched, but still exhibits challenges to completely curb these chemicals’ destructive effects. The negative impacts of the POPs in terms of environmental and human health are a growing concern. In recent years, studies have proven that the list of POPs keeps increasing, and their concentrations levels are widely varied region wise. The current review presents sources and classification of POPs. Furthermore, the deleterious consequences due to POPs on environment and human health have been illustrated. A few potential methodologies that can be implemented to control the hazardous effects of POPs have been discussed.

Enhanced activation of PMS by a novel MnFe2O4@N-PC-GM composite for rapid 1-naphthol degradation: Formation and mechanism of singlet oxygen

A novel magnetic catalyst, MnFe2O4 functionalized N-doped porous carbon/geopolymer (MnFe2O4 @N-PC-GM) composite, was synthesized using pine cones and geopolymer as precursors for efficient and sustainable removal of 1-naphthol. Experimental results indicated that MnFe2O4 particles were distributed in in the structure of N-PC-GM carrier, greatly increasing the number of active sites. The removal ratio of 1-naphthol was up to 86.06% in MnFe2O4 @N-PC-GM/PMS system, and the degradation process followed pseudo-second-order kinetics (R2 = 0.996). Quenching experiments and EPR analysis validated that 1-naphthol was degraded in MnFe2O4 @N-PC-GM/PMS system mainly through a non-radical oxidation pathway dominated by 1O2. X-ray photoelectron spectroscopy (XPS) and degradation experiments in different gas atmosphere demonstrated that the sources of 1O2 were closely related to the existence of oxygen vacancies (OVs), the conversion of dissolved oxygen as well as the introduction of active sites (N, Mn and Fe). Furthermore, the good degradation rate of 1-naphthol in real water confirmed the feasibility of MnFe2O4 @N-PC-GM/PMS system in practical application. This work provided a new strategy for the treatment of persistent organic pollutants in water.

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.

Photocatalytic Degradation of Perfluorooctanoic Acid on Pb-doped TiO2 Coated with Reduced Graphene Oxide.

Poor reactivity of extraordinarily strong per- and polyfluoroalkyl substances (PFAS) with TiO2 makes it necessary to advance photocatalytic materials. In this present work, lead (Pb)-doped TiO2 coated with reduced graphene oxide (TiO2 -Pb/rGO) was prepared using hydrothermal method and then its photocatalytic activity with various PFAS in water, especially perfluorooctanoic acid (PFOA), was investigated. PFAS decomposition kinetics by TiO2 -Pb/rGO was compared to neat TiO2 , Pb-doped TiO2 (TiO2 -Pb) and rGO-coated TiO2 (TiO2 /rGO). TiO2 -Pb/rGO (0.33 g/L) under UV showed superior removal of PFOA (10 mg/L) at 98% after 24 hr, following TiO2 -Pb/UV at 80%, TiO2 /rGO/UV at 70%, TiO2 /UV at <10%, and UV at <10%. Doping of TiO2 with Pb and introduction of rGO to TiO2 greatly changed the physicochemical properties of TiO2 and the subsequent charge transfer mechanism. Radical scavenger experiments indicated that holes, superoxide radical anion, and singlet oxygen were responsible for the observed PFOA decomposition. Decomposition of PFOA by TiO2 -Pb/rGO under UV led to formation of short-chain perfluorocarboxylic acids (PFCAs) as reaction intermediates through step-by-step removal of CF2 units. Polyfluoroalkyl substance (6:2 fluorotelomer sulfonate (6:2FTS)) and long-chain PFCAs such as PFOA were significantly removed and defluorinated by TiO2 -Pb/rGO while it was ineffective towards perfluorosulfonic acids and short-chain PFCAs. Removal kinetics decreased in order of 6:2FTS > PFOA >> PFOS > PFHpA ≈ PFHxS ≈ PFBA ≈ PFBS. Pb doping to TiO2 /rGO showed better performance than Fe doping. Overall, this study implied that proper designing of TiO2 photocatalytic materials enables to expedite decomposition of persistent organic pollutants in water, in particular highly challenging fluorinated chemicals.

Effects of Film Thickness of ALD-Deposited Al2O3, ZrO2 and HfO2 Nano-Layers on the Corrosion Resistance of Ti(N,O)-Coated Stainless Steel.

The goal of this stydy was to explore the potential of the enhanced corrosion resistance of Ti(N,O) cathodic arc evaporation-coated 304L stainless steel using oxide nano-layers deposited by atomic layer deposition (ALD). In this study, we deposited Al2O3, ZrO2, and HfO2 nanolayers of two different thicknesses by ALD onto Ti(N,O)-coated 304L stainless steel surfaces. XRD, EDS, SEM, surface profilometry, and voltammetry investigations of the anticorrosion properties of the coated samples are reported. The amorphous oxide nanolayers homogeneously deposited on the sample surfaces exhibited lower roughness after corrosion attack compared to the Ti(N,O)-coated stainless steel. The best corrosion resistance was obtained for the thickest oxide layers. All samples coated with thicker oxide nanolayers augmented the corrosion resistance of the Ti(N,O)-coated stainless steel in a saline, acidic, and oxidising environment (0.9% NaCl + 6% H2O2, pH = 4), which is of interest for building corrosion-resistant housings for advanced oxidation systems such as cavitation and plasma-related electrochemical dielectric barrier discharge for breaking down persistent organic pollutants in water.

Metal–organic framework-based materials: emerging high-efficiency catalysts for the heterogeneous photocatalytic degradation of pollutants in water

Water pollution has become one of the most important global environmental pollution problems, wherein various toxic and persistent organic pollutants in water pose a major threat to the environment.

Perovskite manganese oxides with tunable metal–oxygen covalency for efficient bisphenol A degradation

The metal–oxygen covalency of manganese oxides is the main factor affecting the degradation efficiency of persistent organic pollutants in water.

Hierarchical-pore UiO-66-NH2 xerogel with turned mesopore size for highly efficient organic pollutants removal

Persistent organic pollutants in water are not only a potential threat to human health, but also cause damage to the ecological environment. Hence, the removal of large organic pollutants from wastewater is of great importance for environmental protection. Herein, hierarchical-pore UiO-66-NH2 xerogels (H-UiO-66-NH2 xerogels) with different mesopore size, H-UiO-66-NH2-11.6nm and H-UiO-66-NH2-3.7nm, were successfully synthesized by combining sol-gel-based method and acid modulator, featuring the characteristics of simple operation, rapid and scalable process, low cost, and the high space-time yield (STY). N2 adsorption-desorption isotherms reveal that the obtained H-UiO-66-NH2 xerogels possess high surface area, hierarchical-pore structures, large pore volume, and turntable mesopore size. Batch adsorption experiments demonstrate that H-UiO-66-NH2-11.6nm has excellent adsorption performance for reactive red 195 (RR 195) dye removal. The maximum adsorption capacity of H-UiO-66-NH2-11.6nm is 884.96mgg-1, which is 4.7 times of the microporous UiO-66-NH2 (185.15mgg-1). Moreover, the removal efficiency of H-UiO-66-NH2-11.6nm for RR 195 can exceed 99%. The adsorption mechanism reveals that the excellent RR 195 capture stems from the large mesoporous structure and abundant adsorption sites provided by the Zr cluster and -NH2 groups in H-UiO-66-NH2-11.6nm. Besides, H-UiO-66-NH2-11.6nm also exhibits a much larger adsorption capacity for some other organic pollutants, such as tetracycline, reactive black 5, and amoxicillin, demonstrating that the H-UiO-66-NH2 xerogel has great potential for organic pollutant removal.

Functional Silane-Based Nanohybrid Materials for the Development of Hydrophobic and Water-Based Stain Resistant Cotton Fabrics Coatings.

The textile-finishing industry, is one of the main sources of persistent organic pollutants in water; in this regard, it is necessary to develop and employ new sustainable approaches for fabric finishing and treatment. This research study shows the development of an efficient and eco-friendly procedure to form highly hydrophobic surfaces on cotton fabrics using different modified silica sols. In particular, the formation of highly hydrophobic surfaces on cotton fabrics was studied by using a two-step treatment procedure, i.e., first applying a hybrid silica sol obtained by hydrolysis and subsequent condensation of (3-Glycidyloxypropyl)trimethoxy silane with different alkyl(trialkoxy)silane under acid conditions, and then applying hydrolyzed hexadecyltrimethoxysilane on the treated fabrics to further improve the fabrics’ hydrophobicity. The treated cotton fabrics showed excellent water repellency with a water contact angle above 150° under optimum treatment conditions. The cooperative action of rough surface structure due to the silica sol nanoparticles and the low surface energy caused by long-chain alkyl(trialkoxy)silane in the nanocomposite coating, combined with the expected roughness on microscale due to the fabrics and fiber structure, provided the treated cotton fabrics with excellent, almost super, hydrophobicity and water-based stain resistance in an eco-sustainable way.

Crystalline Violet Wastewater Treatment by Low-Temperature Plasma Combined with Industrial Solid Waste Red Mud

Low-temperature plasma (LTP) technology has been successfully used to treat persistent organic pollutants in water. Efforts have been devoted to combine catalysts and LTP to improve the degradation efficiency of pollutants and energy utilization efficiency. Herein, industrial solid waste red mud as a novel catalyst was added to an LTP system to treat crystalline violet (CV) wastewater. The energy yield at 50% CV decomposition and TOC after a 30 min reaction by the plasma treatment, red mud adsorption, and red mud/plasma treatment were compared. The effects of the main operating parameters, such as red mud dosing amount, initial pH, discharge voltage, and initial concentration of CV, on the removal efficiency of CV were investigated. The best degradation of CV was achieved with a red mud dosage of 2 g, a neutral environment, and a discharge voltage of 22 kV. When the red mud was recycled three times, the removal efficiency decreased a little in the red mud/plasma system. Hydroxyl radical plays an important role in the treatment of CV. The red mud was characterized by BET, SEM, XRD, and FT-IR, and the structure of the red mud was not greatly affected after being used in the red mud/plasma system.

Visible-Light-Active Black TiO2 Nanoparticles with Efficient Photocatalytic Performance for Degradation of Pharmaceuticals.

Special attention has recently been paid to surface-defective titanium dioxide and black TiO2 with advanced optical, electrical, and photocatalytic properties. Synthesis of these materials for photodegradation and mineralization of persistent organic pollutants in water, especially under visible radiation, presents interest from scientific and application points of view. Chemical reduction by heating a TiO2 and NaBH4 mixture at 350 °C successfully introduced Ti3+ defects and oxygen vacancies at the surface of TiO2, with an increase in the photocatalytic degradation of amoxicillin—an antibiotic that is present in wastewater due to its intense use in human and animal medicine. Three TiO2 samples were prepared at different annealing temperatures to control the ratio between anatase and rutile and were subjected to chemical reduction. Electron paramagnetic resonance investigations showed that the formation of surface Ti3+ defects in a high concentration occurred mainly in the anatase sample annealed at 400 °C, contributing to the bandgap reduction from 3.32 eV to 2.92 eV. The reduced band gap enhances visible light absorption and the efficiency of photocatalysis. The nanoparticles of ~90 m2/g specific surface area and 12 nm average size exhibit ~100% efficiency in the degradation of amoxicillin under simulated solar irradiation compared with pristine TiO2. Mineralization of amoxicillin and by-products was over 75% after 48 h irradiation for the anatase sample, where the Ti3+ defects were present in a higher concentration at the catalyst’s surface.

Reaction mechanisms and toxicity evolution of Sulfamethoxazole degradation by CoFe-N doped C as Electro-Fenton cathode

As a typical sulfonamide antibiotic, sulfamethoxazole (SMX) will cause serious harm to human health and ecological environment. In this study, CoFe-N doped C was prepared as cathode catalyst of electro-Fenton for degrading SMX, and 91% of SMX could be removed within 5 h under optimum conditions (pH = 1, U = -0.7 V). In order to understand degradation mechanisms, Density Functional Theory (DFT) was combined with Liquid Chromatography-Mass Spectrometry (LC-MS), four pathways were proposed, and benzene ring fracture was the most important step. Concomitantly, the toxicity of degradation intermediates was predicted by ECOSAR software and the toxicity of most intermediates was lower than that of SMX. Therefore, this study has a certain reference value for removing the pollution of persistent organic pollutants in water.

Graphitic biochar with in situ confined magnetic iron oxides via synchronous pyrolysis of lignin as an effective H2O2 activator for fast degradation of organic pollutants.

Magnetic iron oxide confined in carbon capsules/biochar composite (FeOx@g-BC) was created using in-situ synchronous pyrolysis of alkali lignin as a low-cost carbon source. Characterization results indicated the FeOx was confined in carbon nanotubes and carbon capsules, inhibiting growing of nanoparticles and deactivation. The composite catalyst demonstrated significant activity in activating H2O2 for the degradation of persistent organic pollutants in water over a wide pH range. Particularly, tetracycline (TC) could be completely degraded within 25min, even at a high pH of 6.8, which performed much better than previously reported Fenton-like catalysts. Moreover, the excellent magnetism of FeOx@g-BC aided in its recovery and reuse. The stability of FeOx@g-BC recycling was also measured by continuous cycles of reactions. According to ESR analysis and free radical quenching studies, OH and 1O2 were discovered as the dominant active species governing the degradation of TC, and two pathways of TC degradation were proposed. This study developed a novel heterogeneous catalyst for catalytic degradation of persistent organic contaminants in water by the value-added usage of lignin.

Dual-regulation effects of intramolecular doping and surface modification on carbon nitride towards efficient degradation of bisphenol A

A new photo-enzyme composite catalyst is prepared based on a dual-modification strategy that is the intramolecular doping of p-benzoquinone and following surface decoration of horseradish peroxidase (HRP) for g-C3N4. The fabricated CNBQ/HRP photo-enzyme composite catalyst can effectively break down bisphenol A (BPA) in water, which exhibits a maximal 7.78 times rate constant and 4.18 times mineralization efficiency relative to original g-C3N4. The investigation results reveal that the dual-regulation effect of the formed intramolecular donor-accepter structure and the photo-enzyme synergistic catalysis can be induced in CNBQ/HRP photo-enzyme composite catalyst, which promotes the high-efficiency separation of charge carriers and the production of •OH so as to dramatically enhance the catalytic degradation BPA performance. This work enriches and develops the modification method of g-C3N4-based catalytic system for treating persistent organic pollutants in water.

Development of superabsorbent hydrogel based on Gum Arabic for enhanced removal of anxiolytic drug from water

The growing consumption of anxiolytic drugs like diazepam (DZP) has aggravated the problem of persistent organic pollutants in water. Due to its characteristics, the removal of DZP from water and wastewater is a challenging task. As an effort to deals with this issue, in this study, we report the development of a hydrogel based on Gum Arabic (GA) grafted with poly(acrylic acid) (GA-g-PAAc) to be used in the adsorptive removal of DZP from water. The hydrogel formation was confirmed by Fourier-transform infrared (FTIR) spectroscopy and thermal analysis (TGA/DTG) analyses. Images obtained by scanning electron microscopy (SEM) revealed that GA-g-PAAc hydrogel exhibits a porous morphology while swelling experiments suggest a superabsorbent characteristic (degree of swelling> 600%). From batch experiments, it was found that the removal of DZP reached remarkable percentages (>80%) before 300 min in moderate experimental conditions (pH 7, 25 °C, 150 mg of adsorbent). The adsorption of DZP on GA-g-PAAc followed the pseudo-first order kinetics, and the mechanism was described by the linear Langmuir isotherm. The maximum adsorption capacity (qmax) was calculated to be 15.16 mg g−1 (at 25 °C), which is comparable or superior to other adsorbent materials used in DZP removal. Reuse experiments showed that GA-g-PAAc keeps appreciable adsorption ability even after five reuse cycles. The results reported here suggest this superabsorbent hydrogel could be a promising adsorbent material to treat water contaminated by anxiolytic drugs, like DZP.

Recent-enhancements in visible-light photocatalytic degradation of organochlorines pesticides: A review

Organochlorine pesticides (OCPs) belong to class of chlorinated hydrocarbon derivative. They come under the category of most hazardous pesticides and therefore have been banned in many countries. These compounds are highly toxic, bio-accumulative and highly persistent in nature and therefore removal of such pesticide is need of the hour. There have been conventional techniques based on the physical, chemical, and biological processes to decontaminate the contaminated water depending on the virtues of toxic contaminants present in wastewater. These conventional techniques have been utilized on a large scale by the industries. However, these techniques do not manage to remove the contaminants to a large extent and have different drawbacks. Therefore, to overcome such shortcomings, a highly efficient green technique is required to disintegrate the toxic contaminants either completely or convert them into non-hazardous substances.Photocatalysis is a green technique and has attracted attention in the degradation of persistent organic pollutants in water and convert them into non-hazardous compounds. This review outlines all major types of OCPs, their metabolites, the different techniques for their removal global concern towards pesticide effect and areas which requires additional research, have been discussed here.

Occurrence and distribution of persistent organic pollutants in water of Chinese lakes and reservoirs

Occurrence and distribution of persistent organic pollutants in water of Chinese lakes and reservoirs

Application of thymine-based copolymers in the quantification of organic pollutants in water by sensitized fluorescence

Bio-inspired copolymers based on thymine can interact with certain organic molecules and therefore they can be used as organized media or as optical sensors for analytical determinations. Particularly, the thymine-based copolymers have a high affinity for benzo(a)pyrene (BaP) and pyrene (Pyr), two main persistent organic pollutants in water. In the present work, such interaction is applied for the development of a simple analytical method based on fluorescence enhancement of BaP and Pyr. Since BaP and Pyr fluorescence spectra are strongly overlapped, a multivariate analysis of the data is proposed. The selectivity of the method was achieved through a parallel factors analysis (PARAFAC) of excitation-emission fluorescence matrices. The method performance was tested by simultaneous determination of BaP and Pyr in water samples, without pre-concentration steps or full chromatographic resolution. Studies of recovery for both analytes added to tap and surface waters were done, obtaining results in the order of 87–115%. The analysis was performed in the presence of additional species whose signals overlap with those of the analytes. In all cases, the calculated analytical figures of merit were compared with those obtained by the reference chromatographic method. In addition, a comparison of our method with the reference one is made based on the calculation of their respective eco-scales. The quality of the achieved results indicates that a second-order advantage was reached, while our method represents a greener alternative than the reference chromatographic methodology.

ANALISIS DE LA BIORREMOCIÓN DE HIDROCARBUROS AROMÁTICOS POLICÍCLICOS EN AGUA POR SPME-GC/MS

The persistent organic pollutants in water, such as, polycyclic aromatic hydrocarbons (PAHs) represent a potential risk for the environment and human health. The USEPA classified the PAHs pyrene, phenanthrene and naphthalene within the 16 PAH of the priority pollutants for their toxicity, distribution and occurrence in the environment. The aim of this study was to evaluate a microbial consortium from an ore waste as an alternative to remove these three PAHs in water. The consortium was stabilized using the PAHs as the only carbon source. The bioremoval of the PAHs was analyzed using the environmentally friendly technique called solid phase microextraction coupled with gas chromatography and mass spectrometry (SPME-GC/MS). The PAHs percent recoveries were reported in a range of 85 - 97 %. The percentage removal for naphthalene, pyrene and phenanthrene was 99 %, 98 % and 94 %, respectively at a concentration of 100 mg/L after 14 days of incubation. The pH values reported (pH = 5.2 - 5.6) may indicate the PAHs degradation in water. It is concluded that the microbial consortium studied has potential for removal of PAHs from water.

Determination of Persistent Organic Pollutants in Water and Sediment Samples from Kızılırmak River

Yasaklanmalarının üzerinden onlarca yıl geçmesine rağmen kalıcılıkları nedeniyle hala doğada bulunabilen Kalıcı organik kirleticiler (KOK)’den organik klorlu pestisit (OCP), polibromlu difenileter (PBDE) ve poliklorlu bifenil (PCB)’ler sedimentte birikerek çevre ve iklim koşullarına bağlı olarak suya geri salınmaktadırlar. Kızılırmak Nehri ise İç Anadolu Bölgesi’nden doğarak Karadeniz’e dökülen on ilin sınırları içinden geçen Türkiye’nin en uzun nehridir. Kızılırmak Nehri’nin Kırıkkale sınırları içindeki bölümü üzerinde organize sanayi bölgesi, petrokimya ve silah tesisleri bulunmakta, şehrin kanalizasyon deşarjı da nehre yapılmaktadır. Bu nedenle suda bulunan ve sedimentte birikmiş olan KOK’ların miktarı nehrin suyunun kullanıldığı bölgeler için önem taşımaktadır. Bu çalışmada Haziran 2018 ile Mayıs 2019 tarihleri arasındaki 1 yıl boyunca toplanan 60 sediment ve 60 su örneğinde 9 OCP (α, β, γ-hekzaklorosiklohekzan, hekzaklorobenzen, heptaklor, 4,4’-diklorodifenil dikloroetan- 4,4’-DDE, 4,4’-diklorodifenil dikloroetilen- 4,4’-DDD, 2,4’-diklorodifenil trikloroetan- 2,4’-DDT, 4,4’-diklorodifenil trikloroetan- 4,4’-DDT), 7 PCB (28, 52, 101, 118, 138, 153, 180) ve 6 PBDE (17, 47, 66, 100, 153, 183) olmak üzere toplam 22 KOK’un miktarına bakılarak varsa mevsimsel değişikliklerin ortaya konulması amaçlanmıştır. Yapılan analizler sonucunda en sık tespit edilen KOK’un 4,4’-DDE, kalıntı konsantrasyonunun en yüksek olduğu ayın ise Ağustos olduğu belirlenmiştir.