Degradation Of Pollutants In Water Research Articles

Advancing Nanopulsed Plasma Bubbles for the Degradation of Organic Pollutants in Water: From Lab to Pilot Scale

The transition from lab-scale studies to pilot-scale applications is a critical step in advancing water remediation technologies. While laboratory experiments provide valuable insights into the underlying mechanisms and method effectiveness, pilot-scale studies are essential for evaluating their practical feasibility and scalability. This progression addresses challenges related to operational conditions, effectiveness and energy requirements in real-world scenarios. In this study, the potential of nanopulsed plasma bubbles, when scaled up from a lab environment, was explored by investigating critical experimental parameters, such as plasma gas, pulse voltage, and pulse repetition rate, while also analyzing plasma-treated water composition. To validate the broad effectiveness of this method, various classes of highly toxic organic pollutants were examined in terms of pollutant degradation efficiency and energy requirements. The pilot-scale plasma bubble reactor generated a high concentration of short-lived reactive species with minimal production of long-lived species. Additionally, successful degradation of all pollutants was achieved in both lab- and pilot-scale setups, with even lower electrical energy-per-order (EEO) values at the pilot scale, 2–3 orders of magnitude lower compared to other advanced oxidation processes. This study aimed to bridge the gap between lab-scale plasma bubbles and upscaled systems, supporting the rapid, effective, and energy-efficient destruction of organic pollutants in water.

Enhanced photocatalytic degradation activity of titanium dioxide by adsorbing aromatic amines through N-bonding

Narrowing the wide band gap of TiO2 (~3.2eV) to enhance its visible light efficiency is crucial for advancing photocatalytic degradation of organic pollutants in industrial wastewater. In this study, we achieved band gap reduction and slowed recombination rates by adsorbing some aromatic amines, like aniline and its electron-donating derivatives, onto TiO2. The predominantly present N-bonded amine species reduced the band gap and decelerated charge carriers’ recombination, enhancing photocatalytic degradation under visible light. In contrast, the amine with electron-withdrawing group is adsorbed as only H-bonded species, which showed no improvement in photocatalytic activity, performing similarly to pristine TiO2. This surface modification strategy offers potential for creating visible light-driven photocatalysts for effective degradation of organic pollutants in water.

Pulsed Light Technology: Is it Sustainable?

Abstract Pulsed light is a non-thermal method that was initially researched for microbial inactivation using high-power, broad-spectrum light pulses, with the UV-C light portion being the most lethal. This method was introduced to the Western hemisphere with the Hiramoto US patent in 1984 and was developed by PurePulse Technologies. It obtained the FDA approval for food use in 1996 and has been under continuous study and testing by academic institutions since 1998. It is linked to sustainable development goals 2, 3, 6, and 12, but its relation to goal 13 is particularly important, although hindered by lack of data. While numerous applications beyond microbial inactivation have been developed, only two are currently used industrially, namely, the decontamination of food contact surfaces for packaging and the enhancement of vitamin D concentration in edible fungi. Other potential applications include enzyme inactivation, phytochemical synthesis, water pollutant degradation, protein allergen inactivation, mycotoxin inactivation, modification of functional properties of proteins, and starch modification. The main advantage of pulsed light is its rapid effects although it is limited to surfaces and transparent liquids. Further refinement of dosimetry should facilitate the easier scaling up of laboratory results to more industrial applications. Information © The Author 2024

Synthesis of ferrate by electrolysis of iron at extreme pH for remediation of aquatic environments from dye and antibiotic wastes

Abstract The presence of dyestuffs and antibiotics in aquatic environments creates toxic contaminants and microbial resistance, which are harmful to human health and require special handling methods. The Advanced Oxidation Process method with ferrate (Fe(VI)) oxidising material has the potential for effective degradation of water pollutants, is environmentally friendly, and is easy to prepare. Therefore, in this study, ferrate synthesis from the electrolysis of iron at extreme pH for the remediation of the aquatic environment from waste dyes and antibiotics has been successfully carried out. Electrolysis was performed in a 14 M NaOH electrolyte using iron and zinc plates as anode and cathode electrodes, respectively. The effects of synthesis parameters such as time, NaOH concentration, and ferrate stability were observed. In addition, ferrate was applied to degrade the dyes methylene blue and the antibiotic ciprofloxacin. The degradation mechanism and application parameters such as pH, dosage, and time were also observed. The success of the synthesis was confirmed by the presence of FeO(OH) groups and the Na2FeO4 peaks characterised using FTIR, XRF, and XRD. Ferrate application for dyes obtained the best results on methylene blue degradation of 98% at pH 8 and a contact time of 70 minutes. The optimum ciprofloxacin degradation of 86.7% was obtained at pH 7 and 120 minutes. Dye degradation occurs through the breakdown of the C-S=C and azo (N=N) bonds. In contrast, in antibiotics, it occurs through the reaction of HFeO4 −/H2FeO4 with the active site of the piperazine ring. This shows that ferrate can potentially produce water remediation from dye and antibiotic waste for a better environment.

Construction of AgI/NH2-MIL-125(Ti) heterojunction: Efficient degradation of organic pollutants in water by visible light response

Photocatalytic technology is an effective means to convert clean solar energy into green chemical energy, which has broad application prospects. Metal-organic framework (MOFs) composites have been widely used to remove pollutants from water. In this paper, the photocatalytic effect of NH2-MIL-125(Ti)[NM125(Ti)] photocatalyst with different AgI content on pollutants in water under visible light irradiation were studied. The successful preparation of AgI/NH2-MIL-125(Ti) photocatalyst was proved by the characterization of the physical and chemical structure of the composite material. When the dosage of AgI is 0.5 mmol, the removal rate of TC by AgI/NH2-MIL-125(Ti) is the highest (82 %). In addition, the photoelectrochemical test also proved that AMNT-0.5 mmol photocatalyst has higher electron-hole separation efficiency. After five cycle tests, the composite photocatalyst of ANMT-0.5 mmol still has good stability. The enhancement of the performance of ANMT-0.5 mmol photocatalyst can be attributed to: (i) the introduction of AgI increases the absorption of visible light in the composite; (ii) The close relationship between AgI and NM125(Ti) accelerates the separation of electron-hole pairs, thus improving the photocatalytic performance.

Ti3+ self-doped TiO2 nanoparticles immobilized on self-pillared pentasil zeolite nanosheets: An efficient visible-light-driven degradation photocatalyst

Ti3+ defective TiO2 nanoparticles (TiO2-NPs) were synthesized through slow hydrolyzation of tetrabutyl titanate and low-temperature annealing, followed by loading on self-pillared pentasil (SPP) zeolite nanosheets to construct a TiO2/zeolite hybrid composite by solid-state dispersion. The obtained TiO2-NPs/SPP composite exhibited a distinct red-shift in the UV–vis absorption spectrum and a significantly reduced band gap due to the introduced Ti3+ defects and the consequent oxygen vacancies (VO), leading to an enhanced visible-light responsivity. The diverse porosity and house-of-cards nanosheet morphology of the SPP support not only promoted the efficient loading and stable immobilization of TiO2-NPs nanoparicles through micropore migration and surface adhesion but also endowed the adsorbability to the TiO2-NPs/SPP composite. The adsorptive photodegradation of methylene blue (MB) was used to evaluated the photocatalytic performance of TiO2-NPs/SPP, and a 95.6 % degradation rate of MB was observed after 3 h illumination with visible-light. The adsorptive effect strongly promoted the accessibility of MB molecules to the active TiO2 species, leading to a remarkable enhancement in degradation efficiency. Moreover, a superior recyclability embodied in the retention of 96.4 % photocatalytic activity after three regeneration cycles indicated the TiO2-NPs/SPP composite to be practical for water pollutant degradation.

Novel N-ZnO/p-BN adsorption-photocatalytic composites with interfacial bonding for efficient synergistic degradation of pollutants in water

Exploring green methods for removing organic pollutants from water bodies has attracted significant attention. In this research, N-ZnO/p-BN adsorption-photocatalytic composites were prepared by a simple solvothermal method, and various analytical characterizations confirmed the formation of B-O-Zn bonds at the heterojunction interface that facilitated the separation of photogenerated carriers and revealed a type-II mechanism of charge transfer in the heterostructure. The photodegradation efficiency for oxytetracycline (OTC) by composites with different N-ZnO loadings was investigated under simulated sunlight, and the degradation efficiency of the optimal sample (50 wt% N-ZnO/p-BN) for 50 mg/L OTC reached 92.2 % at 120 min. Efficient pollutant enrichment, broadened light absorption range, high dispersion of the photocatalysts, and effective charge migration are all important factors for improving photocatalytic activity. Furthermore, the photocatalytic process was further investigated, experiments showed that the N-ZnO/p-BN composites were universally applicable under a variety of conditions and possessed the characteristics of low dosage and high degradable concentration. Finally, a rational photocatalytic mechanism was proposed for the degradation system and the degradation pathways of the main degradation model OTC were analyzed and deduced. Therefore, this study provides new ideas for designing high-performance adsorption-photocatalytic composites.

Review on polyaniline-based nanocomposite heterogeneous catalysts for catalytic reduction of hazardous water pollutants.

Water contamination by highly toxic substances has generated serious ecological disturbances and health problems for humans. Hence, decontamination of toxic pollutants using advanced, inexpensive, and eco-friendly approaches is the current demand. Heterogeneous catalyst-based catalytic reduction processes have offered the opportunity to transform hazardous water pollutants into non-hazardous products via sustainable, eco-friendly, and efficient routes and might be a competitive substitute for existing traditional water purification techniques. However, the key challenges linked with pure heterogeneous catalysts include agglomeration and poor dispersion, stability, recovery, and reusability, which result in poor activity and efficiency. Thus, it is essential to produce multipurpose polymer-based composite catalysts using conducting polymers, which are exceptionally good supportive and matrix materials. The blending of metal-based nanomaterials with polyaniline conducting polymers produces highly stable and efficient heterogeneous nanocomposite catalysts with amazing catalytic activity against a wide range of water pollutants. The heterogeneous catalytic reductive degradation of immensely toxic pollutant water has gained substantial curiosity because of its excellent physicochemical and surface characteristics, porous structure, recoverability, and recyclability. Therefore, this review presents the latest efforts to generate various polyaniline-based nanocomposite catalysts using a polyaniline matrix and various nanofiller materials and their potential applications in heterogeneous catalytic reduction degradation of water pollutants.

Photoelectrochemical Oxidation of Glycerol over g-C3N4 Nanosheets Coupled with Metal-Assisted Hybrid Carbon Quantum Dots

Carbon quantum dots (CDs) are the most promising candidates of the carbon family with a size of less than 10nm. They owned superior properties such as high solubility in aqueous medium, low toxicity, biocompatibility, stable photoluminescence, spectral convertor, and act as electron reservoirs. These properties make CDs suitable for photo-electrochemical catalytic applications. Low quantum yield and activity in the visible light spectrum of CDs may restrict their applicability. To address this issue, doping and surface passivation of CDs is the only approach to improve their physicochemical characteristics, visible light absorption, and quantum yield by altering their size and structure. Metals are electron-efficient entities and act as electron donors. As a result, when metal ions are doped into CDs, the charge density and charge transition between the core of the CDs and the metal ions increases. This results in a greater improvement in the physicochemical properties of CDs as compared to non-metal doping[1]. Metal-assisted CDs i.e. hybrid CDs tend to modulate energy band positions, change the electronic structure, increase quantum yield, and generate new emissive traps in CDs. The photoluminescence property of CDs can be enhanced due to the surface plasmonic resonance (SPR) effects of metal nanoparticles (NPs). Hybrid CDs also show better catalytic performance as compared to the pristine CDs. It helps to enhance the active sites on the CDs surface to facilitate catalytic performance.By keeping these properties, the hybrid CDs were effectively utilized in the field of dye decolorization, degradation of water pollutants, storage materials, and as a sensor[2][3]. The photo-assisted electrochemical glycerol valorization is one of the prominent methods for producing value-added chemicals such as glycolic acid. However, it is a challenge to achieve high yield and selectivity of products. This research investigated the fabrication of heterojunction of g-C3N4 (CN) with CDs and Bi-assisted CDs (BiCD) as a sustainable photoactive material. The heterojunction was obtained by incorporating CDs and BiCD (5wt.% each) onto CN nanosheets by in-situ thermal polymerization treatment and named CDCN and BiCDCN. The prepared composite was analyzed by structural (XRD), functional (XPS) microscopic (FESEM, FETEM) spectroscopic (UV-Vis, PL, TRPL, EDS), and photoelectrochemical characterization techniques.The band gap of CN was obtained as 2.78 eV which was reduced to 2.69 eV for CDCN and 2.62eV for BiCDCN, increasing the absorbance in the visible light zone. The existence of CDs and BiCDs was confirmed by, FETEM investigation (Fig.1a). The XPS analysis of the composite revealed the presence of Bi 4f chemical state of bismuth metal. The calculated TRPL lifetime was 0.28ns for BiCDCN and 2.51 ns for CDCN which was lower than that of CN (9.31 ns) suggesting the rapid electron transfer ability of BiCDCN. In the presence of light and glycerol, the composite BiCDCN had the maximum photocurrent density of 12 mA/cm2, followed by CDCN (1.6 mA/cm2) and CN (1.3 mA/cm2) at 1.2 V. The photoelectrochemical oxidation of glycerol was performed at 0.8V for 3h. The detected products were glycolic acid, glyceric, glyoxylic acid, and oxalic acid. The addition of CD to CN increased the glycerol conversion and yield of glycolic acid & glyoxylic acid significantly. The composite exhibited 43% selectivity towards glycolic acid and 34% for glyoxylic acid. The glycerol conversion and yield of these two products were further enhanced by Bi doping. BiCDCN had a total glycerol conversion of 21%, followed by CDCN at 5.7% and CN at 3.8%. The BiCDCN had the highest yield of glycolic acid at 8.9 % and that for CDCN was 2.4 % and 1.2 % for CN (Fig.1b). The glyoxylic acid yield was 7.2%, 2.2%, and 0.8% for BiCDCN, CDCN, and CN, respectively. Figure 1

Investigation of the mechanism and stability of highly efficient photocatalytic degradation of Methylene blue using Ni doped CdS photocatalyst

Methylene blue (MB) is commonly utilized in chemical indicators, dyes, biological colors, and pharmaceuticals. Its aqueous solution is poisonous and carcinogenic, posing a significant threat to the ecological environment. The wurtzite-phase NixCd1−xS was synthesized using the hydrothermal technique in this study. Ni doped CdS enhanced its photocatalytic efficiency and resistance to photocorrosion, enabling its application in the photocatalytic destruction of MB. The incorporation of Ni did not change the crystal structure and microstructure of CdS, but increased the visible light absorption range and decreased the band gap width slightly, which promoted the migration of photogenerated electrons and reduced their recombination with holes, resulting in higher photogenerated carrier separation efficiency of NixCd1−xS. The photocatalytic decolorization rate of Ni0.06Cd0.94S for 100 mL of 10 mg/L MB at 240 min is 91.3 %, and the reaction rate constant is 0.01102 min−1, which is 4.42 times that of wurtzite-phase CdS. The photocatalytic mechanism of NixCd1−xS and its composite was analyzed using trap experiments in conjunction with the band structure of the sample. Additionally, the stability of NixCd1−xS was evaluated. The results indicated that the stability was superior to that of CdS. The findings demonstrate that Ni0.06Cd0.94S exhibits good catalytic activity and stability, making it a viable catalyst for the photocatalytic degradation of organic pollutants in water.

High valent manganese-oxo species activation of peroxymonosulfate by different phases manganese oxides nanoplates for catalytic water decontamination

Advanced oxidation processes involving high-valent metal-oxo species have garnered increasing attention for their effective pollutant degradation in water. However, less is known about the mechanism of the species in the manganese oxides (MnOx) system. Therefore, it is crucial to design MnOx catalysts to systematically clarify the high-valent metal-oxo species reaction mechanism. In this study, MnOx nanoplates including Mn3O4, Mn5O8, and Mn2O3 were synthesized via a facile thermal treatment of a Mn(OH)2 precursor to activate peroxymonosulfate (PMS) for mechanism studies. The Mn3O4 catalyst exhibited superior catalytic performance and reusability owing to its unique spinel structure and rapid electron transfer properties. The first-order rate constant for Mn3O4 is 0.64 min−1, which is 3.7 and 1.5 times higher than those of Mn5O8 and Mn2O3, respectively. Scavenging experiments, electron paramagnetic resonance, and electrochemical analysis revealed that free radicals played a negligible role, while the formation of high-valent Mn-oxo species was promoted, facilitated by the Mn3O4-PMS* complex. These high-valent Mn-oxo species were highly reactive towards various pollutants. Moreover, the degradation intermediates of bisphenol A (BPA) in the Mn3O4/PMS system were identified, further elucidating the interactions between high-valent Mn-oxo species and BPA. Additionally, the Mn3O4 catalyst exhibited excellent catalytic performance under practical conditions and maintained superior stability over six cycles. This work provides crucial insights into the role of transition metal oxides in activating PMS for the catalytic degradation of emerging pollutants.

Nitrogen-doped bismuth ferrite nanozymes: Tailored electronic structure for organic pollutant degradation

The insufficient catalytic activity and non-recyclability of nanozymes are major obstacles for nanozyme-mediated water purification. Since electronic transfer is the basic essence of catalysis-mediated redox reactions, this research reveals that meticulous tuning of the electronic structure of magnetic bismuth ferrite (BiFeO3) through nitrogen doping, allows for excellent performance in organic pollutants degradation in water (including dyestuff and antibiotics), along with magnet separation-mediated recyclability. Mechanically speaking, nitrogen-doping rational optimize their peroxidase-like activity by increasing the electron density of the Fe-N active center, meanwhile, the tailored bandgap significantly enhances the full-spectrum absorption, especially in the near-infrared region (NIR). Consequently, a light-enhanced N-doped BiFeO3 nanozyme has been engineered to generate excessive reactive oxygen species (14.63-fold in total) for pollutants degradation with recyclable capacity, 94.27 % for Methylene Blue and over 60 % for multiple antibiotics. This study underscores the efficacy of fine-tuning the electronic structure in enhancing the catalytic performance of nanozymes for organic pollutants removing.

Visible-Light Photocatalytic Degradation Efficiency of Tetracycline and Rhodamine B Using a Double Z-Scheme Heterojunction Catalyst of UiO-66-NH2/BiOCl/Bi2S3.

BiOCl is a promising photocatalyst, but due to its weak visible light absorption capacity and low photogenerated electron-hole pair separation rate, its practical application is limited to a certain extent. In this study, a novel double Z-scheme heterojunction UiO-66-NH2/BiOCl/Bi2S3 catalyst was constructed to broaden the visible light response range and promote high photogenerated hole-electron separation of BiOCl. Its photocatalytic performance is evaluated by dissociating tetracycline (TC) and rhodamine B (RhB) in visible light. The optimal proportion of UiO-66-NH2/BiOCl/Bi2S3 hybrids exhibits the best degradation efficiency of visible light illumination (∼93% in 120 min for TC and ∼98% in 60 min for RhB). The synergistic effect of a large visible light response range and the Z-scheme charge transfer mechanism ensure the excellent visible photocatalytic activity of UiO-66-NH2/BiOCl/Bi2S3. It is proven that h+ and •O2- are the main active substances in the photocatalysis process by active substance capture experiments and electron spin resonance tests. The intermediates and degradation processes are analyzed by high-performance liquid chromatography-mass spectrometry. This study proves that the new UiO-66-NH2/BiOCl/Bi2S3 photocatalyst has great application potential in the field of water pollution degradation and will provide a new idea for the optimization of BiOCl.

Thioxanthone Functionalized NanoTiO2 Composites as Photocatalyst for Degradation of Organic Dyes.

Titanium dioxide (TiO2) photocatalytic technology has the advantages of high catalytic activity, high chemical stability, nontoxicity, and low cost. Therefore, it finds widespread applications in the degradation of organic pollutants in water, antibacterial, environmental purification, and other fields. In this study, we have obtained a photocatalyst by modifying nanoTiO2 with the photosensitizer thioxanthone. The light-harvesting units of thioxanthone and nanoTiO2 can work synergistically to capture light energy. As a heterogeneous photocatalytic material, it can efficiently degrade organic dyes such as Rhodamine B, methyl blue and methyl orange. Specifically, the degradation rate of 0.1 mmol/L Rhodamine B can reach 97% after 35 min of irradiation, and methyl blue and methyl orange can also reach 98 and 56%, respectively.

Hollow Nanospheres of Conjugated Microporous Polymers for the Degradation of Organic Pollutants in Water

Hollow Nanospheres of Conjugated Microporous Polymers for the Degradation of Organic Pollutants in Water

Collaborative adsorption and photocatalytic degradation of high concentration pharmaceutical pollutants in water using a novel dendritic fibrous nano-silica modified with chitosan and UiO-66

This study presents a novel hybrid mesoporous material for degrading drug pollutants in water. The hybrid materials, derived from UiO-66 metal-organic framework and chitosan, coated on nano-silica, showed excellent drug adsorption through hydrogen-bonding interactions and efficient photodegradation of antibiotics. The hybrid material's enhanced conductivity and reduced band gap significantly improved pollution reduction by minimising electron-hole recombination. This allows for more efficient charge transport and better light absorption, boosting the material's ability to break down pollutants. Structural and morphological analyses were conducted using various techniques, including scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Optimising the adsorption-photodegradation process involved investigating pH, catalyst dose, and radiation time. Non-linear optimisation revealed an efficiency exceeding 85 % for 400 mg/L tetracycline and doxycycline, the model antibiotics. The optimal parameters for maximal elimination were determined as pH = 4.3, hybrid mesosphere dose = 4.0 mg/mL, and radiation time = 10 min. Kinetic studies favored pseudo-second-order diffusion models over pseudo-first-order models. The hybrid mesosphere showed sustained efficiency after three cycles and performed well in real aqueous samples, removing over 80 % of each antibiotic. This study demonstrates the potential of the hybrid mesoporous material for removing pharmaceutical pollutants in water systems.

Rationally designed β-FeOOH/N,P-MXene Schottky-junction for efficient removal of pollutants from wastewater

Effective separation of photogenerated electrons and holes, as well as providing ample reactive sites, is crucial for enhancing the activity of photocatalytic degradation of pollutants in water. In this study, we have expanded MXene through a simple water swelling method and successfully doped N and P elements into MXene via a hydrothermal process. This modification not only exfoliates the layered structure of MXene, enlarging its specific surface area and providing abundant reactive sites but also endows MXene with enhanced metallic properties. As a result, an N,P-MXene/FeOOH Schottky junction photocatalyst is constructed. Our photocatalytic experiments revealed that the FO-NPM200/H2O2 system performs well under extreme pH conditions and exhibits excellent photocatalytic stability across a wide pH range (1–13), suggesting its outstanding potential for practical applications in complex environments. Under conditions of pH = 7 without the presence of inorganic salt ions, the degradation rate of tetracycline reached 98.1 %, and the photocatalytic reduction rate of the common heavy metal salt Cr(VI) was as high as 99.4 %. We have also unveiled the band structure of FO-NPM200 using UPS and UV–vis DRS. This research paves a new way for the design and construction of Schottky junction photocatalysts.

Efficient sonocatalytic degradation of pyrene using a novel and magnetically recoverable graphitic carbon nitride – cobalt ferrite – graphene oxide (g-C3N4/CoFe2O4@GO) nanocomposite with an enhanced Z-scheme electron transfer pathway

The use of ultrasound in the presence of semiconductor materials is considered a novel technique for the degradation of hazardous organic pollutants in water. In this study, graphitic carbon nitride (g), graphene oxide (GO), and Cobalt ferrite, CoFe2O4 (CF) nanoparticles were synthesized via soft-template-assisted synthesis, Hummer's, and hydrothermal methods, respectively. Subsequently, the hybrid magnetic g-C3N4/CoFe2O4/GO (g-CF1@GO, g-CF2@GO, g-CF3@GO, and g-CF4@GO) nanocomposites were prepared via a simple hydrothermal route at 180 °C. The crystallite structure, functional groups, morphology, and energy band gaps were characterized by XRD diffraction, FT-IR, TEM, and UV–vis DRS. The heterostructure nanocomposites were formed, as evidenced by the TEM data, with an average crystallite size of 13.4 nm and band gap energies of 2.19–1.80 eV, suggesting their suitability for sono/photo degradation processes. Pyrene, a tetracyclic polycyclic aromatic hydrocarbon (PAH) was chosen as a model pollutant to evaluate the performance of the prepared nanocomposites toward sonocatalytic degradation. The nanocomposites exhibited higher degradation performances than individual materials. The sonocatalytic degradation of pyrene revealed that the g-CF4@GO nanocomposite exhibited the highest sonocatalytic activity and achieved 86.7 and 92.3 % degradation efficiency for 10 and 5 mg/L of pyrene under ultrasonic irradiation (40 mg/L, 50 W and 20 kHz) in 120 min. In addition, the sonocatalytic degradation of pyrene is performed in the absence of any oxidant and follows a pseudo-first-order kinetics. Trapping experiments were carried out to investigate the sonocatalytic degradation mechanism, and the results showed that ●O2− was the major reactive species. The easily recoverable magnetic nanocomposite via a simple magnet was tested for its recyclability and reusability, and it was observed that it could degrade up to 78 % of pyrene in four cycles.

Unlocking enhanced photocatalytic power: Donor-acceptor synergy in non-metallic g-C3N4 hollow nanospheres

Selecting safe, non-toxic, and non-metallic semiconductor materials that facilitate the degradation of pollutants in water stands out as an optimal approach to combat environmental pollution. Herein, graphitic carbon nitride (g–C3N4)–based hollow nanospheres nonmetallic photocatalyst modified with covalent organic framework materials named TpMA, based on 1, 3, 5-trimethylchloroglucuronide (Tp) and melamine (MA), was successfully synthesized (abbreviated as CNTP). The ordered electron donor-acceptor structure inherent in TpMA contributed to enhancing the transport efficiency of photogenerated carriers in CNTP. The CNTP photocatalysts exhibited excellent performance in degrading rhodamine B and tetracycline in visible light, with optimal degradation rates reached more than 90% in 60 and 80 min, respectively, which were 5.3 and 3.0 times higher than those of pure CNNS. The increased photocatalytic efficiency observed in CNTP composites could be traced back to the covalently connection between the two molecules, forming a π-conjugated system that facilitated the separative efficiency of photogenerated electron-hole pairs and intensified the utilization of visible light. This study provided a new means to design and fabricate highly efficient and environmentally friendly non-metallic photocatalytic materials.

Persulphate assisted photoelectrochemical degradation of organic pollutants in water on a silver nanoparticle modified Cu2O photoanode

This work presents the photoelectrochemical production of sulphate radicals using fluorine-doped tine oxide – silver nanoparticles – copper(I) oxide (FTO-AgNPs-Cu2O) photoanode in the presence of peroxydisulphate salt for the enhanced degradation of selected organic pollutants in water. Firstly, Cu2O was prepared via a facile and template-free one-pot method, then AgNPs were photo-reduced on the surface of the Cu2O, and the resultant product was immobilised on an FTO conductive substrate to form FTO-AgNPs-Cu2O photoanode. When the electrode was applied for the abatement of tetracycline in the presence of 3 mM peroxydisulphate salt and 1.5 V external potential, the degree of tetracycline degradation and mineralisation after 90 min was 82 % and 78 % respectively. Furthermore, the same system was able to achieve degradation of 81 % sulfamethoxazole degradation within 90 min and 100 % orange II dye degradation within 30 min. The photoanode was efficient in the treatment of real wastewater containing tetracycline. Scavenger studies reveal that holes, hydroxyl, and sulphate radicals significantly participated in the degradation process. The electrode is stable and therefore applicable for the abatement of other organic pollutants in a persulphate-assisted photoelectrochemical degradation system.