Tourmaline synergized with persulfate for degradation of sulfadiazine: Influencing parameters and reaction mechanism

Multiple interface coupling on natural tourmaline enables high-efficiency removal of antibiotic: Superior property and mechanism

Reasonably designing highly active, environmentally friendly, and cost-effective catalysts for efficient elimination of pollutants from water is desirable but challenging. Herein, an efficient heterogeneous photo-Fenton catalyst tourmaline (TM)/tungsten oxide (WO3-x) (named TW10) containing tungsten/boron/iron (W/B/Fe) synergistic active centers and 90% of cheap natural tourmaline (TM) mineral rich in Fe and B elements. The TW10 catalyst can quickly activate peroxymonosulfate (PMS) to generate massive active free radicals, which may induce the rapid and efficient degradation of tetracycline (TC). The TW10/PMS/Visible light system can effectively degrade up to 98.7% of tetracycline (TC) in actual waters (i.e. seawater, Yellow River, and Yangtze River water), and the catalytic degradation rates reach 1.65, 5.569, and 2.38 times higher than those of TM, WO3-x, and commercial P25 (Degussa, Germany), respectively. In addition, the catalyst can be recycled and reused multiple times. Electron spin resonance spectroscopy (EPR), X-ray photoelectron spectroscopy (XPS), and liquid chromatograph-mass spectrometer (LC-MS) analyses confirm that the synergistic catalytic effect of W/B/Fe sites on the TW10 catalyst accelerates the electron transfer between Fe(II) and Fe(III), as well as between W(V) and W(VI), and thus promotes the rapid degradation of TC. The catalytic reaction mechanism and degradation pathway of TC were explored. This work provides a feasible route for the design and development of new eco-friendly and efficient catalyst.

Self-polarized schorl optimizing TiO2 for photocatalytic persulfate activation and organic pollutants degradation

Photocatalytic activation of persulfate has exhibited tremendous potential in water purification because of its green and environmentally friendly process. However, this process often exhibits low activation efficiencies and difficult recovery of the photocatalyst. Herein, schorl-supported nano-TiO2 composite photocatalysts (S/TiO2) were prepared by a mechanical grinding method for efficient activation of potassium monopersulfate (PMS). The anatase TiO2 nanoparticles with particle size of approximately 30 nm was uniformly loaded on the surface of schorl via forming Si-O-Ti bonds. The S/TiO2 assisted with PMS (S/TiO2-PMS) exhibited remarkable degradation performance and stability. In this system (S/TiO2-PMS), the C/C0 value of phenol solution (10 ppm) were decreased to 0.070 and 0 after 30 min and 90 min of irradiation, where the degradation extent were 93.0% and 100% respectively. The rate of phenol degradation with S/TiO2-PMS was 12.6 times that seen with TiO2-PMS. The oxidation active species were holes and SO4•- in S/TiO2-PMS system subjected to simulated sunlight. It was demonstrated that the polarization electric field of the schorl enhanced the separation efficiency of the photoinduced electrons and holes for improving the performance of the S/TiO2-PMS. On the other hand, the transformations of Fe3+ and Fe2+ on the schorl surface further promotes the activation of PMS. This work provides a new choice for designing TiO2-based photocatalytic persulfate activation system targeting the field of advanced oxidation water treatment.

Harnessing the power of natural minerals: A comprehensive review of their application as heterogeneous catalysts in advanced oxidation processes for organic pollutant degradation

The release of untreated wastewater into water bodies has become a significant environmental concern, resulting in the accumulation of refractory organic pollutants that pose risks to human health and ecosystems. Wastewater treatment methods, including biological, physical, and chemical techniques, have limitations in achieving complete removal of the refractory pollutants. Chemical methods, particularly advanced oxidation processes (AOPs), have gained special attention for their strong oxidation capacity and minimal secondary pollution. Among the various catalysts used in AOPs, natural minerals offer distinct advantages, such as low cost, abundant resources, and environmental friendliness. Currently, the utilization of natural minerals as catalysts in AOPs lacks thorough investigation and review. This work addresses the need for a comprehensive review of natural minerals as catalysts in AOPs. The structural characteristics and catalytic performance of different natural minerals are discussed, emphasizing their specific roles in AOPs. Furthermore, the review analyzes the influence of process factors, including catalyst dosage, oxidant addition, pH value, and temperature, on the catalytic performance of natural minerals. Strategies for enhancing the catalytic efficiency of AOPs mediated by natural minerals are explored, mainly including physical fields, reductant addition, and cocatalyst utilization. The review also examines the practical application prospects and main challenges associated with the use of natural minerals as heterogeneous catalysts in AOPs. This work contributes to the development of sustainable and efficient approaches for organic pollutant degradation in wastewater.

Sulfadiazine degradation by combination of hydrodynamic cavitation and Fenton-persulfate: parametric optimization and deduction of chemical mechanism

This paper reports the degradation of the sulfadiazine (SDZ) drug with a hybrid advanced oxidation process (AOP) of heterogeneous α-Fe₂O₃/persulfate coupled with hydrodynamic cavitation. The major objectives of the study are parametric optimization of the process and elucidation of the chemical mechanism of degradation. The optimum conditions for maximum SDZ degradation of 93.07 ± 1.67% were as follows: initial SDZ concentration = 20 ppm, pH = 4, α-Fe₂O₃ = 181.82 mg/L, Na₂S₂O₈ = 348.49 mg/L, H₂O₂ = 0.95 mL/L, inlet pressure = 0.81 MPa (8 atm), orifice plate configuration: hole dia. = 2 mm and number of holes = 4. Density functional theory (DFT) calculations revealed that the atoms of SDZ with a high Fukui index (f ⁰) were potentially active sites for the attack of ^•OH and [Formula: see text] radicals. Fukui index calculation revealed that atom 11 N has a higher value of f ⁰ (0.1026) for oxidation at the α-amine group of the sulfadiazine molecule. Degradation intermediates detected through LC-MS/MS analysis corroborated the results of DFT simulations. Using these results, a chemical pathway has been proposed for SDZ degradation.

A comprehensive review on persulfate activation treatment of wastewater

With increasingly serious environmental pollution and the production of various wastewater, water pollutants have posed a serious threat to human health and the ecological environment. The advanced oxidation process (AOP), represented by the persulfate (PS) oxidation process, has attracted increasing attention because of its economic, practical, safety and stability characteristics, opening up new ideas in the fields of wastewater treatment and environmental protection. However, PS does not easily react with organic pollutants and usually needs to be activated to produce oxidizing active substances such as sulfate radicals (SO₄^-) and hydroxyl radicals (OH) to degrade them. This paper summarizes the research progress of PS activation methods in the field of wastewater treatment, such as physical activation (e.g., thermal, ultrasonic, hydrodynamic cavitation, electromagnetic radiation activation and discharge plasma), chemical activation (e.g., alkaline, electrochemistry and catalyst) and the combination of the different methods, putting forward the advantages, disadvantages and influencing factors of various activation methods, discussing the possible activation mechanisms, and pointing out future development directions.

Sulfide-modified zero-valent iron activated periodate for sulfadiazine removal: Performance and dominant routine of reactive species production

In this work, sulfide-modified zero-valent iron (S-Fe⁰) was used to activate periodate (IO₄^-, PI) for sulfadiazine (SDZ) removal. 60 μM SDZ could be completely removed within only 1 min by S-Fe⁰/PI process. Compared with other oxidants including H₂O₂, peroxymonosulfate (PMS), peroxydisulfate (PDS), S-Fe⁰ activated PI exhibited better performance for SDZ removal but with lower Fe leaching. Compared with Fe⁰/PI process, S-Fe⁰/PI process could reduce more than 80% Fe⁰ and PI dosage. Inorganic ions and nature organic matters had negligible effect on SDZ removal in S-Fe⁰/PI system inducing its good SDZ removal efficiency in natural fresh water. 80.2% SDZ still could be removed within 2 min after 7th run. S-Fe⁰/PI process also exhibited 2.5 - 20.1 folds enhancement for various pollutants removal compared with Fe⁰/PI process. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical tests, and density functional theory (DFT) calculation were conducted to confirm the presence of sulfurs could enhance the reactivity of S-Fe⁰ thus increased the efficiency of PI activation for antibiotics removal. Electron paramagnetic resonance spectroscopy (EPR) tests, radical quenching experiments, quantitative detection and DFT calculation were performed to illustrate the role of multiple reactive species in SDZ removal and the dominant pathway of multiple reactive species production. IO₃^·, ^·OH, O₂^-·, ¹O₂, Fe^IV, and SO₄^·- all participated in SDZ removal. ^·OH played the major role in SDZ removal and the dominant routine of ^·OH production was IO₄^- → O₂^-· → H₂O₂ → ^·OH. Meanwhile, S-Fe⁰/PI process could efficiently mineralize SDZ and reduce the toxicity. Comparison with other PI activation approaches and SDZ treatment techniques further demonstrated S-Fe⁰ was an efficient catalyst for PI activation and present study process was a promising approach for antibiotics removal.

Comparison of Four Tourmalines for PS Activation to Degrade Sulfamethazine: Efficiency, Kinetics and Mechanisms

Four types of tourmalines (TMs, S1, S2, S3 and S4) for activating persulfate (PS) to degrade sulfamethazine (SMT) were compared to find the most efficient catalyst. The four TMs were mesoporous materials with abundant functional groups, but were different in terms of size, composition, specific surface area, contact angle, and zero potential point. The removal of SMT in S1, S2, S3 and S4 systems with PS at the optimum reaction conditions ([SMT]₀ = 5 mg/L, [PS]₀ = 4 mM, [TM]₀ = 5 g/L, pH₀ = 5, and T = 25 °C) were 99.0%, 25.5%, 26.0%, and 51.0%, respectively, which might be related to the metal content of TM. Although the degradation of SMT in the S1/PS/SMT system was not dominated by SO₄^•− and •OH, the radicals contributed to the SMT removal in the S2, S3, and S4 systems. ¹O₂ and holes both contributed to the degradation of SMT in the four systems. The metal at the X position might be related to the generation of ¹O₂ and holes, while Fe of TM was mainly related to the generation of free radicals, such as SO₄^•−. Electrochemical impedance spectroscopy tests confirmed that the separation of electrons and holes on the TM surface could be promoted by adding PS and SMT. S1 presented a higher electron-transfer rate than the other three TMs. The PS activation by TM with a high metal content at the X position provided an efficient and low-consumption treatment for antibiotic refractory wastewater.

Lattice B-doping evolved ferromagnetic perovskite-like catalyst for enhancing persulfate-based degradation of norfloxacin

Series of B-doped perovskite-like materials CeCu_0.5Co_0.5O₃ (B-C³O) were fabricated with unique ferromagnetic property due to partial substitution of non-magnetic 2p-impurities boron in the lattice. Then, B-C³O was used for activating peroxymonosulfate (PMS) for the degradation of norfloxacin (NOR), one kind of emerging pollutants with the concentration level up to mg/L in wastewaters. The results indicated that 5.0% B-C³O exhibited stable catalytic ability at pH 3.0-9.0 and high degradation efficiency in co-existing inorganic Cl^-, SO₄^2-, NO₃^-, H₂PO₄^- and organic humic acid. Non-radical ¹O₂, radicals •OH and SO₄^•-, as well as ClO^- were detected with synergy effect for NOR degradation. By quantifying free radicals, •OH with 0.52 µM and SO₄^•- with 10.91 µM were obtained at 180 min, verifying the leading role of SO₄^•-. The degradation process involved the defluorination and decarboxylation, as well as opening of quinolone and piperazinyl rings. Adopting alfalfa as the model plant, the toxicity effect before and after NOR degradation was finally evaluated with seed germination rate and chlorophyll content as the physiological indicators. In summary, non-metal B-doping not only provides a creative strategy for the development of ferromagnetic perovskite-like materials, but also affords excellent catalysts for aiding the advanced oxidation technology for removal of emerging pollutants in wastewaters.

Occurrence and distribution of antibiotics in groundwater, surface water, and sediment in Xiong'an New Area, China, and their relationship with antibiotic resistance genes

The emergence and pollution of antibiotics in surface water in various regions have drawn widespread concern because of the harm to aquatic ecosystems and human health. In this study, we aim to first investigate contamination and ecological risks of 39 antibiotics in Xiong'an New Area (XANA), China, and then illuminate relative abundances of antibiotic resistance genes (ARGs) and their correlations with antibiotics. The sum of antibiotic concentrations in the water circulation system, including surface water, groundwater, and sediment was 12.71-260.56 ng/L, ND-196.12 ng/L, and 38.03-406.31 ng/g, respectively. In surface water and sediment, cephalosporins and quinolones were the primary antibiotics, accounting for 45% and 16% of the total antibiotic concentrations in surface water and for 62% and 32% of the total antibiotic concentrations in sediment; this suggests a significant interaction between the two media. The antibiotic concentration was the highest in shallow groundwater at depths of <50 m (mean concentration of 79.22 ± 56.46 ng/L), indicating that surface water was a possible source of antibiotic contamination in groundwater. AMX presented the highest risk in both surface and groundwater and should be controlled as a priority. Moreover, the selection pressure of antibiotics on ARGs was discovered in the sediment in XANA, because the enrichment of sulA was significantly correlated with spiramycin and lincomycin and the enrichment of bla_OXA-1 was significantly correlated with roxithromycin, ciprofloxacin, ofloxacin, and sulfapyridine. Thus, our investigation revealed potential antibiotic contamination in multiple environmental media in XANA, which should be addressed to prevent more serious pollution.

A review: Application of tourmaline in environmental fields

Heavy metals and organic pollutants could pose long-term threats to the ecosystem and human health, so it is urgent for us to find a friendly and efficient material to remove pollutants in environment. Since tourmaline is widely distributed in natural environment and has many excellent physical and chemical properties including radiating far infrared energy, permanently releasing negative ions, producing an electrostatic field, releasing rare microelements, and stimulating the growth and metabolism of microorganisms and plants, tourmaline had been conducted to alleviate environmental pollution. This review summarizes the application of tourmaline in aqueous solutions and soil polluted by heavy metals and organic pollutants, the factors that affect the removal of pollutants by tourmaline and the removal mechanisms. In addition, to ensure the safe use of tourmaline, this review also elaborates the environment risks of tourmaline through its toxicity indexes to soil and plant.