Degradation Of Pollutants In Water Research Articles

Zinc-doped C4N3/BiOBr S-scheme heterostructured hollow spheres for efficient photocatalytic degradation of tetracycline.

Photocatalytic degradation of organic pollutants in water is of great significance to the sustainable development of the environment, but encounters limited efficiency when a single compound is used. Thus, there have been enormous efforts to find novel photocatalytic heterostructured composites with high performance. In this work, a novel S-scheme heterostructure is constructed with BiOBr and Zn2+ doped C4N3 (Zn-C4N3) by a solvothermal method for efficient photodegradation of tetracycline (TC), a residual antibiotic difficult to be removed from the aquatic environment. Thanks to Zn2+-doping induced improvement in chemical affinity between Zn-C4N3 and BiOBr, well-formed Zn-C4N3/BiOBr heterostructured hollow spheres are formed. This structure can efficiently suppress fast recombination of photogenerated electron-hole pairs to enhance the photocatalytic activity of BiOBr dramatically. At a room temperature of 25 °C and neutral pH 7, the catalyst can degrade a significant portion of TC pollutants within 30 min under visible light. Also, the Zn-C4N3/BiOBr heterostructure displays good stability after recycling experiments. Free radical capture experiments and ESR tests show that ˙O2- is the main active substance for photocatalytic degradation of TC. This study provides new insights for constructing heterostructures with an intimate interface between the two phases for photocatalytic applications.

Synergistically enhanced photoelectrocatalytic degradation of ciprofloxacin via oxygen vacancies and internal electric field on a NiSe2/WO3 photoanode

This study presents the in situ deposition of nickel selenide (NiSe2) on tungsten trioxide (WO3) nanorods to enhance the photoelectrocatalytic degradation of organic pollutants in water.

Multifunctional polymer-based nanocomposites for synergistic adsorption and photocatalytic degradation of mixed pollutants in water.

Water pollution is a growing concern for mankind due to its harmful effects on humans, animals and plants. Usually, several pollutants are present in wastewater. For example, dyes and antibiotics are found in wastewater because of their widespread use in factories and hospitals. However, one single technique, e.g. either adsorption or photocatalysis, cannot easily remove more than one kind of pollutant, especially by using one single material in water. For this reason, here multifunctional iron(ii,iii) oxide/poly(N-isopropylacrylamide-co-methacrylic acid)/silver-titanium dioxide (Fe3O4/P(NIPAM-co-MAA)/Ag-TiO2) nanocomposites were used to remove a mixture of pollutants from water. Specifically, three types of experiments were performed to evaluate the adsorption capacity and photodegradation activity of the nanocomposites towards the dye basic fuchsin (BF) and the antibiotic ciprofloxacin (CIP), which were added sequentially to the nanocomposites dispersion or were concurrently present as a mixture. The results demonstrated that the nanocomposites could adsorb BF, and subsequently photodegrade CIP under visible-light irradiation, if BF was the first added pollutant. As well, the nanocomposites could first degrade CIP under visible-light irradiation, and then adsorb BF if they were initially put in contact with CIP. Finally, the ability of adsorbing BF and photodegrading CIP was confirmed in the co-presence of the two pollutants.

Solid-waste-recycled CuO/C3N4 S-scheme heterojunctions for efficient photocatalytic antibiotic degradation.

With the increasing severity of antibiotic pollution, the development of effective green photocatalysts for the degradation of organic pollutants in water has attracted extensive attention. Herein, we have prepared CuO/C3N4 S-scheme heterogeneous photocatalysts via recycling Cu resources from Cu-containing electroplating sludges. By mediating the acid leaching process, copper in electroplating sludges was dissolved selectively, while other metal species were retained in the residues. The CuO/C3N4 S-scheme heterojunction not only effectively suppressed the recombination of photogenerated charge carriers of C3N4, but also preserved the strong reducing electrons of C3N4 and the strong oxidizing holes of CuO, retaining the outstanding redox ability of CuO/C3N4. Therefore, CuO/C3N4 photocatalysts exhibited good catalytic performance in the degradation of tetracycline (over 95% in 2 h). In addition, CuO/C3N4 S-scheme heterojunctions achieved a high mineralization rate (45% in 2 hours), thus reducing secondary pollution during the degradation. This work provides a reliable direction for designing novel S-scheme heterojunction photocatalytic materials by using metal sources in solid waste.

Hydrodynamic Cavitation Enhanced SR-Aops Degradation of Organic Pollutants in Water: A Review

Hydrodynamic Cavitation Enhanced SR-Aops Degradation of Organic Pollutants in Water: A Review

Nitrogen-rich cobalt metal–organic framework as a heterogeneous catalyst for the degradation of organic dye pollutants in water via peroxymonosulfate activation

A Co3-btca heterogeneous catalyst can activate PMS to efficiently degradate organic dyes rhodamine B and methyl violet in water.

Preparation and photocatalytic activity of CoFe2O4 nanoparticle modified rod-like Mn0.3Cd0.7S photocatalysts with S-scheme heterojunction

With the continuous progress of photocatalytic technology in environmental pollution control, the recovery of photocatalysts has gradually become a hot topic of concern. To solve this problem, a magnetically recoverable rod-shaped CoFe2O4/Mn0.3Cd0.7S with S-scheme heterojunction photocatalyst was successfully constructed. The phase composition, morphology, light absorption, and surface chemical environment of the samples were measured. The photocatalytic degradation rate of tetracycline by CoFe2O4/Mn0.3Cd0.7S is higher than that either of CoFe2O4 and Mn0.3Cd0.7S. The degradation efficiency of 1%CoFe2O4/Mn0.3Cd0.7S showed the best performance of 82.1% within 60 min. The rate constant for first-order kinetics of 1%CoFe2O4/Mn0.3Cd0.7S was about 1.72 times that of pure Mn0.3Cd0.7S. It was found that the enhanced photoactivity of the CoFe2O4/Mn0.3Cd0.7S heterojunction photocatalyst was due to the wider absorption range of visible light and the improved inhibition of electron and hole recombination. It is also found that the CoFe2O4/Mn0.3Cd0.7S heterojunction photocatalyst has excellent magnetic recovery ability under the external magnetic field. The photostability of as-prepared CoFe2O4/Mn0.3Cd0.7S heterojunction photocatalyst was studied, and a reasonable S-scheme electron-hole transfer mechanism was proposed according to the band structure. These advances provide a new way to improve the photoactivity of magnetic recyclable photocatalysts, and the synthetic magnetic recyclable rod CoFe2O4/Mn0.3Cd0.7S has a potential application prospect in the degradation of water pollutants.

High efficiency manganese cobalt spinel structure catalytic ozonation ceramic membrane for in situ BPA degradation and membrane fouling elimination

In recent years, micropollutants contamination in aquatic environments has received increasing attention. Bisphenol A (BPA), an endocrine-disrupting compound, has emerged as a substantial threat to water safety owing to its widespread presence in various aquatic environments. To address this issue, this study focused on the development of ceramic membranes incorporating manganese-cobalt oxides (MCOs) to catalyze the ozone-based degradation of BPA. The catalytic layer was prepared by hydrothermal in-situ growth method, which enhanced BPA degradation during water treatment and improved the ceramic membrane’s resistance to contamination. Moreover this study investigated the synergistic effect of catalytic ozone oxidation in mitigating ceramic membrane pollution and degrading micropollutants. The catalytic mechanism and the contamination modeling were examined systematically to determine the mechanism of micropollutant contamination on ceramic membranes. The experimental results showed that the modified ceramic membrane exhibited a higher BPA removal efficiency (90.6%) and flux recovery (99.5%) than the unmodified membrane (64.2% and 79%, respectively). Furthermore, the MCOs-modified ceramic membrane (CCM) effectively enhanced the generation of hydroxyl radicals during ozonolysis. This enhancement resulted in better degradation of organic pollutants in water, thus improving the quality of the treated water. The combination of ceramic membrane catalytic separation with ozone oxidation technology offers a potential solution for the degradation of emerging pollutants and the mitigation of ceramic membrane pollution.

Streamlined fabrication of AuPtRh trimetallic nanoparticles supported on Ti3C2MXene for enhanced photocatalytic activity in cephalosporins degradation

The escalating prevalence of cephalosporin antibiotics in wastewater poses a serious threat to public health and environmental balance. Thus, it is crucial to develop effective methods for removing cephalosporin antibiotics from water sources. Herein, we propose the use of AuPtRh trimetallic nanoparticles supported on Ti3C2MXene as a photocatalyst for the degradation of cephalosporin antibiotics. Initially, AuPtRh nanoparticles were uniformly grown onto Ti3C2MXene sheets using one-step reduction technique. The prepared AuPtRh/Ti3C2MXene exhibited a complete degradation of cefixime and ceftriaxone sodium, while an impressive degradation efficiency of 91.58 % for cephalexin was achieved after 60 min of exposure to visible light, surpassing the performance of its individual AuPtRh nanoparticles and Ti3C2MXene. The enhanced photoactivity of AuPtRh/Ti3C2MXene was resulted from improved light absorption capacity and efficient generation, separation, and transfer of charge carriers driven by the formation of heterojunction between AuPtRh and Ti3C2MXene. Electron paramagnetic resonance and radicals trapping experiments results revealed that •O2– and h+ are the principal reactive species governing the degradation of cephalosporins. The photocatalyst exhibited excellent stability and could be reused four times without significant loss in efficiency. Our study highlights the potential of MXene composites for environmental remediation, offering insights into designing sustainable AuPtRh/Ti3C2MXene photocatalyst for water pollutant degradation.

Rapid photocatalytic degradation of organic pollutants by Al3+ doped CuO powders under low power visible light and natural sunlight

The photocatalytic degradation of organic pollutants is a promising approach to deal with dye industry wastes released into water bodies. However rapid, inexpensive, and low power visible light photocatalytic degradation of water pollutants is challenging. This study tries to address these constraints by using inexpensive doped CuO Powders under low-power visible household LED light. Also, direct illumination of sunlight to achieve better photocatalytic degradation, reducing device and operational costs. Further, photocatalytic degradation is enhanced by doping of Al3+ in CuO. Under several optimized conditions, rapid and almost complete degradation of three different dyes, Methylene Blue (MB), Rhodamine B (RhB), and Methyl Orange (MO) were achieved within 6 min of light irradiation under household LED and within 30 min of direct irradiation of sunlight. Even after five times of repeated use of the catalyst, no significant decrease in the photocatalytic activity was observed indicating its stability and sustainability.

Efficient removal of tetracycline hydrochloride by high entropy oxides in visible photo-Fenton catalytic process

ABSTRACT A novel type of oxide material, high entropy oxide (Mn0.2Fe0.2Co0.2Ni0.2Cu0.2)3O4 (MFO) composites with spinel structure were successfully synthesized by a simple solution combustion in this paper, and it was first applied to the degradation of antibiotic organic pollutants in water by photo-Fenton. SEM and BET characterization showed that the composite was porous and had a large specific surface area. XPS results showed that Fe, Mn, Cu, Co and Ni all participated in the redox reaction of the catalytic process. The redox pairs of Mn2+/Mn3+, Cu+/Cu2+, Co2+/Co3+, Ni2+/Ni3+ can accelerate the Fe2+/Fe3+ redox cycling in MFO to activate H2O2 and produce more reactive oxygen species. The catalytic performance of MFO composite was investigated using tetracycline hydrochloride (TC-HCl) as a model pollutant. The results displayed that the degradation rate of TC-HCl by MFO was 92.9% when the initial pH was 4, the dose of H2O2 was 50 mM, and the irradiation time was 60 min. The high entropy oxide MFO composites could build up an internal electric field, which restrains electron–hole recombination, improves the transfer of photogenerated charge carriers and maximize photocatalytic property. In addition, the free radical capture experiment determined that the main active species of the degradation reaction were e−, •O2 − and •OH. The synergistic effect of the five components in the high entropy oxide strengthens lattice distortion and defects, increases oxygen vacancies, and thus has enhanced catalytic effect for TC-HCl degradation. This work shows that high entropy oxides have excellent catalytic performance for tetracycline organic pollutants, and it is speculated that high entropy oxides have good application prospects in the field of advanced oxidation technology for the degradation of organic pollutants.

Synergistic photogeneration of reactive oxygen species by Fe species self-deposited on resorcinol-formaldehyde towards the degradation of phenols under visible light

In this study, a heterogeneous photo-Fenton catalyst of Fe species/resorcinol-formaldehyde (Fe/RF) was synthesized in the degradation process of phenols under visible light in a homogeneous photo-Fenton system. The in situ generated H2O2 by bare RF in the medium and the follow-added Fe2+ can construct homogeneous photo-Fenton system, and Fe/RF heterogeneous photo-Fenton catalyst was formed after the reaction through Fe species self-deposition. Due to the addition of Fe2+, more hydroxyl radical (·OH) generated in the homogeneous Fenton system, which lead to the higher degradation efficiency of phenols that achieved 90.5 % with 150 min. Fe/RF was subsequently formed and more C=O functional group in the structure appeared, which was beneficial to the production of H2O2. The above-mentioned results can be proved by the involved calculation and experimental results. Fe species, including Fe2+ and Fe3+, were beneficial to the conversion of reactive oxygen species (ROSs), and further improved the degradation efficiency of Phenols. Since the existence of photo-generated electrons, Fe2+ concentration in the solution can maintain a stable level. Interestingly, the degradation efficiency of Phenols was higher when Fe3+ was used instead of Fe2+ as the additive, which may be caused by the promotive effect of Fe3+ on singlet oxygen (1O2) generation. In addition, the degradation efficiency of Phenols under alkaline conditions was higher than that under acid conditions, which broke the limit of traditional Fenton process that works mostly in acidic medium. This study shows promising results in terms of synergistic photocatalytic/photo-Fenton processes for the degradation of organic pollutants in water.

A comprehensive insight on plasma-catalytic degradation of organic pollutants in water: Comparison between ZnO and TiO2

A novel system combining underwater plasma bubbles and high voltage nanopulses was combined for the first time with ZnO and TiO2 for the degradation of organic pollutants in water. The effect of catalyst loading, discharge power and plasma gas on pollutant degradation was investigated whereas the plasma-catalytic mechanism was explored through the quantification of plasma species, COD/TOC measurements and scavenging experiments in the presence and absence of catalysts. The increased efficiency in the presence of either ZnO or TiO2, especially under plasma gases (air and oxygen) able to produce UV radiation in the range of wavelengths absorbed by both catalysts, lies on the increased concentration of the critical reactive species (e.g. ·O2−, ·ΟΗ, H2O2). Compared to plasma alone process, H2O2 was significantly enhanced in the presence of TiO2 and decreased in the presence of ZnO, whereas ·OH concentration was higher in the plasma-ZnO but lower in the plasma-TiO2 system which supports the overall superior performance of ZnO compared to TiO2. The synergy of plasma-ZnO process compared to that of plasma-TiO2 was ∼2.4 and ∼1.5 times higher for Orange II (OII) and Methylene Blue (MB), respectively, exhibiting a very low electrical energy per order (1.4 kWh m−3 for OII and 0.31 kWh m−3 or MB). The present effort contributes on providing fundamental insights and further expand of plasma-catalysis for water treatment.

TiO2/Arabic Gum for Degradation of Pollutants in Water

Emerging contaminants and pollution are environmental problems threatening public health. Antibiotic ciprofloxacin and methylene blue dye are pollutants frequently detected in water systems worldwide. Photocatalysis is a process for water treatment. TiO2-based catalysts synthesized with natural gums show improved photocatalytic properties. Here, the sol–gel method synthesized TiO2/Arabic gum for photocatalytic performance. The innovation of this work was synthesized at 400 °C and investigated their photocatalytic proprieties using methylene blue and ciprofloxacin as model pollutants. XRD showed that the photocatalyst was in the anatase phase. The result showed that TiO2 with a band gap of 3.29 eV was achieved at a calcination temperature of 400 °C. Corresponding FTIR results suggest only the existence of functional groups related to TiO2. The SEM and BET method characterization indicated that TiO2/Arabic gum were spherical-shaped nanoparticles arranged in clusters with a mesoporous structure, contributing to photocatalytic performance. In addition, photocatalytic studies showed that the methylene blue dye and ciprofloxacin antibiotic degradation rates reached 99% and 94% under UV light, respectively. The hole (h+) and OH ⦁ radicals are essential in photodegradation. The synthesized material showed excellent photostability and maintained almost the same degradation percentage in the three consecutive cycles tested on the different pollutants. The TiO2/Arabic gum is an excellent candidate for future use in treating contaminants in aqueous media using photocatalysis. Therefore, TiO2/Arabic gum nanoparticles are a promising material for wastewater treatment.

Experimental and theoretical confirmation of CeFeCu trimetal oxide/Bi2O3 S-scheme heterojunction for boosted photocatalytic degradation of sulfamethoxazole and toxicity evaluation

Photocatalytic degradation of pharmaceutical pollutants in water or wastewater is becoming a hot topic for environmental clean-up. Herein, a novel CeFeCu trimetal oxide (CFC TMO)/Bi2O3 (CFCB) photocatalysts were prepared through precursor mixing, ultrasonication, and calcination methods and used for photocatalytic degradation of sulfamethoxazole (SMZ). The pseudo-first order kinetic rate of CFCB-2 catalyst on degradation of SMZ reached 0.0577 min−1 which is 4.93 and 10.02 times higher than of α-Bi2O3 and CFC TMO under visible light illumination. This was proved by the strong interaction between the pristine materials as confirmed by XPS and density functional theory (DFT) calculations. DFT calculations indicated that having more orbital distribution could make it easier to capture more electrons and produce more radicals through electron transfer. Meanwhile SMZ by-products showed no sign of cytotoxicity towards human embryonic kidney cell line (HEK 293) and human intestinal epithelial cell line (CACO-2). The findings of the scavenger experiments and ESR measurements proved that •OH and •O2− radicals played superior role in decomposition of SMZ. Furthermore, the S-scheme charge carrier transfer and degradation pathway of SMZ are proposed and analysed. This study paves ways into promising strategy for the construction of α-Bi2O3 based novel S-scheme heterojunction for environmental decontamination and can be extended to other applications such as Fenton-like reactions and persulfate activation.

Effects of SnO2 coupling on the structure and photocatalytic performance of TiO2/sepiolite composites

The use of titanium dioxide in the degradation of water pollutants encounters several challenges, including particle agglomeration leading to a reduction in its specific surface area and a high rate of photogenerated electron-hole recombination, resulting in a lower quantum efficiency. Therefore, in this work, we first employed sepiolite to load titanium dioxide, mitigating particle agglomeration. Building upon this, tin dioxide was coupled with it to enhance the photogenerated charge separation. The SnO2/TiO2/sepiolite photocatalytic composites were synthesized using the sol–gel method at 450 ℃. The resulting composites underwent thorough characterization encompassing phase composition, morphology, chemical valence states, specific surface area, optical properties, and photocatalytic activity. The outcomes demonstrate an augmentation in the specific surface area of TiO2/Sep composites following the sepiolite (Sep) loading. Among these, the TiO2/Sep composite (with a Sep: TiO2 mass ratio of 10 %) exhibited the most favorable photocatalytic performance, displaying a first-order reaction rate constant of 0.010 min−1, surpassing that of pure TiO2 by a factor of 2.0. The introduction of SnO2 expedited the migration of photogenerated charge across interfaces, curbing the recombination of photogenerated pairs, thus enhancing quantum efficiency. In light of the presence of sepiolite, the addition of SnO2 further amplified the photocatalytic performance. Optimal results were achieved when the molar ratio of SnO2:TiO2 was set at 1:4, leading to the highest photocatalytic efficiency observed in the SnO2/TiO2/Sep composite. This composite exhibited a first-order reaction rate constant of 0.027 min−1, marking a notable 2.7-fold increase compared to the TiO2/Sep counterpart. The investigation of band potentials, charge transfer pathways, and the photocatalytic mechanism within SnO2/TiO2/Sep composite materials was conducted through a comprehensive analysis involving electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) valence band spectroscopy, electron paramagnetic resonance spectra (EPR) and active radical experiments.

Mechanistic insights into removal of bisphenol A from activate peroxymonosulfate by Fe-C coupled biochar with the assistance of electric-field activation

Iron-carbon micro electrolysis activated persulfate (Fe-C/PS) treatment of wastewater is characterized by high oxidation efficiency and no secondary pollution, Limitations such as short reaction lifetime and hardening of Fe-C usually make it insufficient to achieve the desired treatment effect.The research is a new type of electric field in the auxiliary, promote biochar activation peroxymonosulfate (PMS) by micro electrolysis produce active free radicals to degradation of organic pollutants in water. namely IC-BC/PMS-EC，Using biochar as electron shuttle, electric field was introduced in the process of iron-carbon microelectrolysis activation of PMS promoted the electron transfer in the solution， The results showed that the reaction system could achieve 100% removal effect in 20 min. Fe2+/Fe3+ released by Fe-C was below the ambient concentration, which constituted a stable cycle in the electrocatalytic system and efficiently activated PMS. The work found that applied electric field and Fe-C micro-electrolysis activation both improved the efficiency of persulfate advanced oxidation progress. The activated system superimposition strengthened on coupled action and enhanced the performance for the degradation of organic pollutants in water. In summary, IC-BC/PMS-EC system is an economical, efficient and promising new system in the process of activating PMS to degrade pollutants.

MOF based nanocomposites for photocatalytic degradation of pollutants in water: A critical review

Metal-organic framework (MOF) based nanocomposites have a wide range of applications; however, research output indicates that MOF based nanocomposites have attracted great attention in the area of water treatment, particularly photodegradation of water pollutants. This comes as a result of high water pollution, water scarcity, poor drinking water quality and the emerging of tenacious micropollutants found in water bodies. Majority of water pollutants can be treated via photocatalytic processes and MOF is a remarkable modifying and support material for photocatalytic nanomaterials. MOF have tremendous physicochemical properties which provide opportunities for unique fabrication and modification of photocatalytic nanocomposites with enhanced efficiency, recovery, recyclability and reusability in water treatment. In this review, MOF-based nanocomposites, fabrication techniques, classifications, mechanisms as well as challenges and future prospects for the photocatalytic degradation of pollutants in water are investigated and discussed.

The synergistic degradation of pollutants in water by photocatalysis and PMS activation.

In recent years, the synergistic degradation of water pollutants through advanced oxidation technology has emerged as a prominent research area due to its integration of various advanced oxidation technologies. The combined utilization of peroxymonosulfate (PMS) activation technology and photocatalysis demonstrates mild and nontoxic characteristics, enabling the degradation of water pollutants across a wide pH range. Moreover, this approach reduces the efficiency of electron hole recombination, broadens the catalyst's light response range, facilitates electron transfer of PMS, and ultimately improves its photocatalytic performance. The paper reviews the current research status of photocatalytic technology and PMS activation technology, respectively, while highlighting the advancements achieved through the integration of photocatalytic synergetic PMS activation technology for water pollutant degradation. Furthermore, this review delves into the mechanisms involving both free radicals and nonradicals in the reaction process and presents a promising prospect for future development in water treatment technology. PRACTITIONER POINTS: Degradation of water pollutants by photocatalysis and PMS synergistic action has emerged. Synergism can enhance the generation of free radicals. This technology can provide theoretical support for actual wastewater treatment.

Enhanced Photocatalytic Degradation of Tetracycline-Class Pollutants in Water Using a Dendritic Mesoporous Silica Nanocomposite Modified with UiO-66

Enhanced Photocatalytic Degradation of Tetracycline-Class Pollutants in Water Using a Dendritic Mesoporous Silica Nanocomposite Modified with UiO-66