Degradation Of Tc Research Articles

A BiOIO3/BiOBr n-n heterojunction was constructed to enhance the photocatalytic degradation of TC

Nowadays, heterojunction materials are of great interest in photocatalytic degradation studies of organic pollutants owing to their high separation efficiency from photogenerated carriers. In this study, BiOIO3/BiOBr n-n type heterojunctions were successfully synthesized and used for photocatalytic degradation of TC. Under visible light, the degradation rate of the 10%BiOIO3/BiOBr heterojunction reached 74.91% after 80 min irradiation, which was 26.79% and 22.67% higher than that of pure BiOBr and BiOIO3, respectively. The formation of BiOIO3/BiOBr n-n type heterojunction enhanced the light absorption ability, and the internal electric field formed between them accelerated the electron-hole pairs separation and transfer, thus enhancing the photocatalytic activity, which was confirmed by UV–Vis DRS, electrochemical and PL spectrum tests. Meanwhile, as confirmed by SEM and TEM, the BiOIO3/BiOBr heterojunction adheres face to face, and the large and tight contact area provides more channels for electron migration. Moreover, the active species that take part in the photocatalytic reaction were identified as ∙O2− and h+ by radical trapping experiments. According to the HPLC-MS test, the possible photocatalytic degradation pathways of TC were investigated. Finally, the charge transfer mechanism of BiOIO3/BiOBr n-n heterojunction is proposed. This study may offer a design pathway for constructing visible light responsive bismuth-based heterojunction materials and may also provide some ideas for solving the growing problem of antibiotic contamination.

Insights into the well-dispersed nano-Fe3O4 catalyst supported by N-doped biochar prepared from steel pickling waste liquor for activating peroxydisulfate to degrade tetracycline

The harmless and high-value added utilization of steel pickling waste liquor (SPWL) is a major challenge in the metallurgical advancement. Herein, well-dispersed nano-Fe3O4 (NF) composite with N-doped biochar as a spatial support (NF/0.5N3BC) is synthesized from SPWL and corncob, which has a large specific surface area (159.12 m2/g) and mesoporous structure. Besides, it exhibits excellent degradation efficiency (91.56%) and rate constant (0.042 min−1) of tetracycline (TC, 50 mg/L) by activating peroxydisulfate (PDS). Both free radicals and non-free radicals contribute to the TC degradation, among which the Fe species, defective edges, C = O, graphitic-N, and pyridinic-N are identified as the possible active sites. Particularly, N3BC cooperates with NF to form an internal electronic field to accelerate the Fe(III)/Fe(II) redox cycle and direct electron transfer process. Further, the possible degradation pathways are proposed based on DFT and HPLC-MS analysis, and the toxicity prediction results verify that NF/0.5N3BC + PDS system has an excellent TC degradation/detoxification ability. This study provided a novel strategy for high-value added utilization of SPWL and economically feasible treatment of TC-contaminated wastewater, so as to realizing the goal of “treating waste with waste”.

Singlet oxygen-dominated non-radical oxidation in biochar/peroxymonosulfate system for efficient degradation of tetracycline hydrochloride: Surface site and catalytic mechanism

BackgroundBiochar has attracted much attention in peroxymonosulfate (PMS) activation for the elimination of organic pollutants in water. However, the factor to determine the catalytic efficiency of biochar and the evolution of reactive oxygen species (ROS) remain equivocal and elusive. Method & resultIn this study, Camellia oleifera shell-derived biochar (COSB) was prepared by one-step pyrolysis. The pyrolysis temperature could tune the catalytic performance of COSB. Owing to more C=O groups and defects, the COSB-1000 prepared at 1000 °C showed the optimal activity in PMS activation. In the presence of 0.4 g∙L−1 of COSB-1000 and 1.0 g∙L−1 PMS, 91.57% of tetracycline hydrochloride (TC, 20 mg·L−1) was degraded within 105 min. In addition, the COSB-1000/PMS system demonstrated good anti-interference ability and a wide pH applicability from 3.0 to 11.0. Quenching experiment and electron spin resonance (EPR) spectroscopy suggested that the non-radical oxidation process dominated by the generated 1O2, which was converted from O2•−, play the vital role in TC degradation by the COSB-1000/PMS system. Furthermore, four possible degradation pathways of TC in the COSB-1000/PMS system are proposed by the mass spectroscopy, and the growth-inhibition of Escherichia coli showed that the degradation intermediates were low toxicity. Significant findingsThe results here shed light on the generation of 1O2 by biochar and deepen the insight for the environmentally-friendly catalysts derived from biomass in activating PMS for wastewater treatment.

Modification of WO3 photoanode with NiFe-LDHs nanosheets array for efficient Photoelectrocatalytic removal of tetracycline

A novel WO3@NiFe-LDHs photoanode was successfully synthesized by electrochemical depositing NiFe-LDHs nanosheets array on the surface of nanoplate WO3 photoanode, in which NiFe-LDHs nanosheets formed a hetero-junction with WO3 and offered mass transfer sites to improve the bulk and interfacial charge separation of WO3@NiFe-LDHs photoanodes. In addition, TC was captured by NiFe-LDHs nanosheets, which not only facilitated the direct charge transfer for TC degradation, but also induced TC to be photo-sensitizer to enhance the light absorbance of WO3@NiFe-LDHs photoanode. Moreover, NiFe-LDHs nanosheets acted as surface catalytic sites for accelerating the water activation to generate highly oxidizing •OH. Therefore, the optional WO3@NiFe-LDHs2.5 photoanode displayed the highest PEC removal of TC with a degradation percentage of 92.3% and total organic carbon removal of 70.4% at 0.6 V (vs Ag/AgCl) bias, and showed higher photocurrent density compared with pristine WO3 photoanode. Furthermore, WO3@NiFe-LDHs photoanode showed favorable stability in the PEC degradation process, and TC was finally mineralized into CO2, H2O and some small molecular products. This work provides a deep insight on the modification of interfacial reaction to enhance the PEC degradation performance, which offered a potential route for designing PEC system with the concept of treating pollution with pollution.

Interfacial modulation of ZnIn2S4 with high active Zr-S4 sites for boosting photocatalytic activation of oxygen and degradation of emerging contaminant

Interfacial modulation of catalysts for constructing active sites can greatly promote its catalytic activity, while the mechanism on reactive species production at different interfaces still needs to be revealed. In this study, Zr-S4 active sites were usefully constructed on ZnIn2S4 nanosheets, which effectively modulated the reaction interface and band structure, thus boosting the photocatalytic activity. The optimized material (Zr1.2-ZIS) showed a ∼3-fold kinetic rate constant for photocatalytic degradation of tetracycline compared with the pristine ZnIn2S4. Moreover, TC underwent a different degradation pathway over the modified catalyst due to regulation of reactive species after photo-activation. The Zr-S4 centers were energetically favorable for activating O2 into •O2- and •OH, as a more reactive d-band electron was obtained and the adsorption of •O2- as well as its further conversion into •OH was promoted. Theoretical calculations on Fukui index and toxicity also confirmed the dramatical toxicity reduction during TC degradation by Zr1.2-ZIS.

Synergistic coupling of piezoelectric and plasmonic effects regulates the Schottky barrier in Ag nanoparticles/ultrathin g-C3N4 nanosheets heterostructure to enhance the photocatalytic activity

Although plasmonic metal can provide energetic hot electrons by localized surface plasmon resonance (LSPR) effect in plasmonic metal/semiconductor systems during photocatalysis, the high Schottky barrier limits the electron migration at the interface, which is a scientific problem to be solved urgently. Herein, we employed the cooperative piezoelectric field in the plasmonic metal/semiconductor composite system to provide the strain, which can generate a polarized charge that attracts free electrons at the interface, thus moving the band edge down and facilitating the interfacial transfer of the electrons. As a demonstration case of this idea, Ag nanoparticles/ultrathin g-C3N4 nanosheets (Ag/UTCN) were constructed for realizing the synergistic plasmonic and piezoelectric effect, exhibiting the significantly enhanced photocatalytic activity, and the optimal photocatalytic TC degradation rate reached 93.7% and H2 production rate reached 2615 μmol h−1 g−1, respectively. Results of photochemical analysis illustrated that the semiconductor (in the case of UTCN nanosheets) with piezoelectric properties is employed to couple the plasmonic metal (in the case of Ag nanoparticles), which can enable more hot electron injection into the conduction band of the semiconductor to achieve effective carrier separation. This strategy provides a feasible solution for enhancing the efficiency of the photocatalytic system through the synergy of multiple fields.

Nitrogen-doped porous carbon derived from graphite of solid waste for activating peroxymonosulfate to degradation tetracycline

Nitrogen-doped porous carbon material based on graphite of solid waste and urea was prepared by mixing and pyrolysis method, the performance and mechanism of the prepared materials as catalysts to activate peroxymonosulfate (PMS) for ctetracycline (TC) degradation were investigated. Results indicated that addition of urea and sodium bicarbonate (NaHCO3) effectively enhanced the degradation of TC. When the mass ratio of graphite/urea/NaHCO3 and pyrolysis temperature was 1: 2: 2 and 800 °C, respectively, the obtained catalyst had optimal performance for activating PMS to TC degradation. The degradation efficiency of TC reached 99.8% within 30 min under the conditions of 0.10 g/L catalyst, 0.20 g/L PMS and 20 mg/L TC solution. Results suggested that the catalyst had well catalytic repeatability, versatility and adaptability under different conditions. The radical quenching test, electrochemistry experiment and electron paramagnetic resonance (EPR) measurements suggested that superoxide radical (O2•-) and singlet oxygen (1O2) plays dominant roles in TC degradation. XPS indicated that pyridine N, graphite N and functional groups of CO and –COOH were the potential active sites for PMS activation. This provides new insights for the recycling of solid waste and preparation of high-performance carbon based catalysts for wastewater treatment via Fenton-like process.

Multifunctional polyoxotungstocobaltate anchored fern-leaf like BiVO4 microstructures for enhanced photocatalytic and supercapacitive performance

In this study, a simple sonochemical approach for molecular anchoring of CoW12O40 [12-tungstocobaltate (II)] on fern-leaf like BiVO4 microstructures was employed. The various compositions were prepared by varying contents (0.5%, 1%, 1.5%, 2% and 5%) of CoW12O40 (hereafter denoted as CoWO). The as-synthesized samples were characterized and confirmed by various physicochemical tools. Furthermore, the performance of resulting composites was tested toward visible light driven photocatalytic treatment of organic pollutants and supercapacitor. Among them, 1CoWO/BVO composites showed optimal performance as compared to other composites and bare fern-leaf like BiVO4. To be specific, the photocatalytic performance of 1CoWO/BVO showed 97% and 78% degradation of methylene blue dye (MB) and tetracycline drug (TC), respectively. Additionally, the reusability of optimal 1CoWO/BVO photocatalyst was confirmed by performing its five consecutive runs towards degradation of MB and TC. Moreover, 1CoWO/BVO electrode yielded the specific capacitance of 245 F g−1 at 2 mV/s scan rate, supporting its applicability as an efficient supercapacitor electrode. The synergistic effect of CoWO and BiVO4 dominated their bare counterparts towards photocatalytic as well as electrochemical performance. Thus, this work rationally opens up the avenues to employ POMs based novel hybrid materials for future environmental and energy storage application.

Removal mechanism of tetracycline-Cr(Ⅵ) combined pollutants by different S-doped sludge biochars: Role of environmentally persistent free radicals

In this work, by using sodium thiosulfate as the S source, S-doped biochars were prepared to remove tetracycline/hexavalent chromium (TC-Cr (Ⅵ)) combined pollutants in aqueous solutions. The concentration of environmentally persistent free radicals (EPFRs) was used to directly determine the degradation of TC and the reduction of Cr (Ⅵ). The concentration of EPFRs in S-doped hydrothermal + pyrocarbon (S-HPBC) (3.64 × 1019 spins/g) was greater than that of S-doped hydrochar (S-HBC) (5.64 × 1018 spins/g) and S-doped pyrocarbon (S-PBC) (6.53 × 1018 spins/g). The increase in EPFRs concentration after S doping was positively correlated with the number of defect structures. In the TC-Cr (Ⅵ) system, the reduction efficiency of Cr (Ⅵ) decreased due to competition for electrons, while the TC degradation efficiency remained high. This was likely because Cr (Ⅵ) reduction promoted the degradation of TC. In addition, de-complexation was the primary factor for the removal of TC-Cr (Ⅵ), and some ROS were consumed during this process. The thiophene groups (-C-S-C-) that formed after S-doping of biochar were the main functional groups involved in the catalytic degradation of TC. In the radical pathway, SO4•- and •OH provided the greatest contribution to the degradation of TC, while 1O2 contributed the most to TC degradation via a non-radical pathway. The regeneration experiment confirmed that S-doped biochar could be reused and maintained a high pollutant removal efficiency. S-HPBC is a promising modified biochar material for removing mixed pollutants.

Robust degradation of tetracycline antibiotic through recyclable Fe3S4/Ti3C2MXene composites

Fe3S4/Ti3C2MXene shows over 90% TC degradation via Fenton activity, driven by the generation of reactive oxygen species. It exhibits remarkable reusability and stability over multiple cycles, promising sustainable TC removal from wastewater.

Ultrafast degradation of SMX and TC by CoSiO x activated peroxymonosulfate: efficiency and mechanism.

To address the concern about residual antibiotics in effluent of sewage treatment plants, cobalt silicate (CoSiO x ) was prepared by hydrothermal method and employed as an activator of peroxymonosulfate (PMS) for the rapid degradation of antibiotics. Taking sulfamethoxazole (SMX) and tetracycline (TC) as representatives of antibiotics, the effects of operation parameters (CoSiO x and PMS dosage) and water quality parameters (temperature, solution pH, bicarbonate, chloride, and natural organic matter) on degradation of target pollutants by a CoSiO x activated PMS process (CoSiO x /PMS) were investigated. The mechanism involved in the interaction of CoSiO x and PMS was also elucidated. The results indicated that CoSiO x /PMS can degrade SMX and TC at fast pseudo-first-order rate constants (0.47 and 0.56 min-1 respectively) under optimal conditions. Increasing the dosage of PMS and CoSiO x appropriately was beneficial to the degradation of antibiotics. Chloride, bicarbonate, and HA showed negative effects on the degradation process due to their free radical-scavenging ability and were ranked as chloride < bicarbonate < HA. Abundant [triple bond, length as m-dash]Co-OHs and oxygen vacancies on the surface of CoSiO x contributed to its excellent activation capability towards PMS. The radical scavenging experiments indicated that target pollutant degradation mainly resulted from the attack of sulfate radicals (43.0% contribution) and hydroxyl radicals (52.9% contribution). The practicality of CoSiO x /PMS was verified by continuous flow test. This study provides a cheap, highly efficient, and feasible advanced depollution method based on CoSiO x .

EVALUATION OF ANTIMICROBIAL SENSITIVITY TO TETRACYCLINE EXPOSED TO NON-THERMAL PLASMA

Tetracyclines comprise a large group of broad-spectrum antibiotics used in human and veterinary medicine. Its mechanism of action, via oral ingestion, is to inhibit bacterial protein synthesis, but a large amount (70%) is eliminated without being metabolized, which presents a risk for the arising of antibiotic-resistant species. In this study, the degradation of Tetracycline TC by non-thermal plasma NTP and the antimicrobial sensitivity of the treated solution are investigated. The degradation was followed by chromatographic analysis while the efficiency of NTP in inhibiting the action of TC on bacteria was evaluated by antimicrobial sensitivity test by disk diffusion method. The results showed a high rate of TC degradation, over 90%, in 10 min of NTP treatment for a 60 mL (107 mg L-1) sample and very slow increase up to 94% in 30 min. The antimicrobial sensitivity test of TC after degradation by NTP showed no antibiotic activity. Therefore, our findings are encouraging, since the removal efficiency is below the minimum threshold require, to prevent with high probability, outgrowth of antibiotic-resistant bacteria. In addition, the results confirm that the NTP treated solution is safe to the environment.

Improved visible light triggered photocatalytic activities of BiOCl photocatalysts via a synergistic effect of doping and heterojunction engineering.

To manipulate the photocatalytic activities of BiOCl photocatalysts, doping and heterojunction engineering are simultaneously adopted. Herein, the photocatalysts Sm3+-doped BiOCl and BiOCl:Sm3+@yg-C3N4 were designed, in which their phase structure, morphology, optical properties and photocatalytic activities were systematically discussed. Excited at 408 nm, red emissions are seen from Sm3+-doped BiOCl microplates and their intensities were impacted by doping content, reaching the maximum value when the Sm3+ content was 1 mol% and the involved concentration mechanism was dominated by quadrupole-quadrupole interaction. Through analyzing the degradation of TC, the visible light triggered photocatalytic behaviors of the resultant compounds were studied. Compared with BiOCl microplates, an improved TC removal ability was seen in Sm3+-doped BiOCl microplates and the products with a Sm3+ content of 0.5 mol% show the best performance. Moreover, through constructing the heterojunction with g-C3N4, the TC removal capacity was further enhanced and the BiOCl:Sm3+@60%g-C3N4 exhibits the optimal photocatalytic activity, which was also much better than that of the commercial SnO2 and TiO2. Accordingly, the ˙O2-, h+ and ˙OH active species were proven to contribute to the involved visible light driven photocatalytic mechanism. Furthermore, the separation and recombination of photogenerated carries via the Z-scheme transfer process in the designed heterojunction composites, led to splendid photocatalytic properties. Additionally, it was verified that the TC solution treated with synthesized compounds was nontoxic toward plant growth. Our findings may propose an available route to regulate the photocatalytic performance of the visible light driven photocatalysts.

Self-assembled A-D-A type indacenodithiophene-based small conjugated molecule/TiO2 for enhancing the photocatalytic activity.

Herein, A-D-A type indacenodithiophene-based small conjugated molecule IDT-COOH and IDT-COOH/TiO2 photocatalysts with stable non-covalent bonding have been successfully synthesized via in situ electrostatic assembly. The self-assembled three-dimensional π-conjugation structure IDT-COOH with high crystallinity not only broadens the visible absorption to produce more photogenerated carriers but also provides directional charge-transfer channels to accelerate the charge mobility. Thus, 7 log inactivation of S. aureus in 2 h and 92.5% decomposition of TC in 4 h under visible light exposure are achieved for optimized 30% IDT-COOH/TiO2. The dynamic constants (k) of S. aureus disinfection and TC degradation for 30% IDT-COOH/TiO2 are 3.69 and 2.45 times compared to those of self-assembled IDT-COOH, respectively. The notable inactivation performance is among the best reported for conjugated semiconductor/TiO2 photocatalysts for photocatalytic sterilization. ˙O2-, e- and ˙OH are the primary reactive species in the photocatalytic process. The strong interfacial interaction between TiO2 and IDT-COOH is in favour of rapid charge transfer, which leads to enhanced photocatalytic performance. This work offers a feasible method to fabricate TiO2-based photocatalytic agents with a wide visible light response and improved exciton dissociation.

Broad-spectrum photocatalytic tetracycline degradation performance of an in-situ plasmonic Bi nanoparticle doped 0D/2D Z scheme heterostructure

Fabrication of broad-spectrum (UV–vis-NIR) active photocatalysts for effectively harnessing the abundant NIR light in the solar spectrum is the biggest challenge. Herein, the facile one-pot solid-state synthesis of an in-situ plasmonic bismuth-doped 0D/2D Z scheme heterostructure (BS) by loading Bi2O3 quantum dots (B) on 2D SnO2 nanosheets (S) is reported. The successful heterostructure fabrication was confirmed using various characterization techniques. The composites demonstrated excellent broad-spectrum photocatalytic degradation efficacy toward TC. When irradiated with an 18 W LED, the 2BS composite exhibited a 35.1 and 2.03-fold increased TC degradation rate co-efficient compared to S and B, respectively. Further, the 2BS composite showed a 5.5 times higher degradation rate constant than B after NIR light irradiation. Moreover, the composite displayed commendable stability after a four-cycle recycling experiment. At last, a plausible charge transfer mechanism under LED and NIR light illumination has been proposed following the results of the radical trapping experiment.

Activation of peroxymonosulfate by S-scheme Bi2S3/doped gCN heterostructure photocatalyst for highly efficient visible light driven tetracycline degradation: Insights into reaction mechanisms

A solid state microwave (MW) assisted hydrothermal method was used to prepare S-scheme heterojunction composite Bi2S3@doped gCN (BS@CN). TC was degraded upto 99.9 % under 20 min visible light, with synergistic action of 0.2 g/L catalyst having 10 wt% Bi2S3 (BS(10)@CN) and 1.5 g/L PMS, for initial TC concentration of 50 mg/L, exhibiting first order rate constant (kapp): 0.215 min−1. The modulation of band-structure due to the generation of heterojunction, coupled with different surface-bound redox cycles, i.e.,Co2 +/Co3 +surf.,Ce3 +/Ce4 +surf. andBi3 +/Bi4 +surf., helped the charge migration, separation of excited e-/h+ and production of reactive species, like,SO4∙-,∙OH,O2∙-,O21, etc., that played important roles towards TC degradation. Band-structure determination, XPS analysis and other characterizations revealed the formation of S-scheme configuration and corresponding surface-bound metastable complexes towards self-regeneration and excellent catalytic activity of the composite, even in the contaminated real-life surface water sources. Extensive intermediate analysis was carried out to develop a detailed TC degradation pathway. The BS@CN photocatalyst can be recycled multiple times, without significant loss of photocatalytic activity (∼88 % TC degradation after 5 cycles). This study demonstrated the design and fabrication of metal oxide doped gCN/metal chalcogenide-based heterojunction photocatalysts that have potential applications towards the removal of refractory contaminants in aqueous medium.

Synergistic Effect of Amorphous Ti(IV)-Hole and Ni(II)-Electron Cocatalysts for Enhanced Photocatalytic Performance of Bi2WO6

Bi2WO6 has become a common photocatalyst due to its advantages of simple synthesis and high activity. However, the defects of pure Bi2WO6 such as low light reception hinder its application in photocatalysis. In this study, based on the modification of Bi2WO6 with Ti(IV) as a cavity co-catalyst, new Ni- and Ti-doped nanosheets of Bi2WO6 (Ni/Ti-Bi2WO6) were prepared by a one-step wet thermal impregnation method and used for the photocatalytic degradation of tetracycline. The experimental results showed that the photocatalytic activity of Ni/Ti-Bi2WO6 modified by the two-component catalyst was significantly better than those of pure Bi2WO6 and Ti-Bi2WO6 modified with Ti(IV) only. The photocatalytic effect of Ni/Ti-Bi2WO6 with different Ni/Ti molar ratios was investigated by the degradation of TC. The results showed that 0.4Ni/Ti-Bi2WO6 possessed the best photocatalytic performance, with a degradation rate of 92.9% at 140 min TC. The results of cycling experiments showed that the catalyst exhibited high stability after five cycles. The scavenger experiment demonstrated that the h+ and O2− were the main reactive species. The enhanced photocatalytic activity of Bi2WO6 could be attributed to the synergistic effect between the Ti(IV) as a hole cocatalyst and Ni(II) as an electron cocatalyst, which effectively promoted the separation of photogenerated carriers.

Highly efficient pollutants removal over Mo/Mo2C/CoAl-LDH heterostructure: photo-chemical co-driven peroxymonosulfate activation and singlet oxygen-dominated oxidative decomposition

Novel Mo/Mo2C/CoAl-LDH (CoAl layered double hydroxide) photocatalysts were fabricated through a hydrothermal route and applied for efficient PMS activation and typical pollutants (tetracycline/TC, ciprofloxacin/CIP, methylene blue/MB, congo red/CR and rhodamine B/RhB) degradation. Specifically, tetracycline removal efficiency of 99 % (TC, 20 mg/L) with a TOC mineralization efficiency of 65 % was achieved by the Mo/Mo2C/CoAl-LDH/PMS/Vis system within 4 min-reaction, and the obtained reaction rate constant was 5.5 and 41.5 times greater than that of CoAl-LDH/PMS/Vis and Mo/Mo2C/PMS/Vis system, respectively. The exceptional performance over this joint system was mainly attributed to the synergism of the MoCo dual active components and the involved photocatalysis. The quenching/ESR investigations clearly demonstrated that all of the generated species contributed to TC degradation, and among them the singlet oxygen showed the greatest impact. The toxicity assessment suggested that most of degraded intermediates become more eco-friendly to the environment. Moreover, the involved reaction mechanism and degradation pathways of TC were proposed and discussed in detail. This work provides a promising strategy for PMS activation and environmental purification through an integrated photo-chemical catalysis.

Facile defect construction of TiO2 nanotube for excellent photocatalytic degradation of tetracycline under visible light

Developing facile fabricating cheap photocatalyst with high activity is a promising strategy for the degradation of tetracycline. Herein, we report that the well-designed photocatalysts with optimal activity and stability prepared via facile Ar atmosphere calcination with H-titanate nanotubes as precursors. The excellent visible light behavior is attribute to suitable oxygen vacancies (Ti3+ sites) acted as charge carrier traps so as to accelerate the separation of the photogenerated electrons and holes and favorable for the photocatalytic reaction. Significantly, the photocatalyst exhibited repeatedly activity without degradation in the cyclic stability experiment attributed to the highly stable of oxygen vacancies (Ti3+ sites) in water or air under visible light illumination. The excellent photocatalytic efficiency for TC degradation exhibited both h+ and ⋅O2– were significant active species under visible light irradiation. These findings promote a facile method to construct efficient photocatalyst for TC degradation with defect-mediated strategy.

Biomass juncus derived carbon modified with Fe3O4 nanoparticles toward activating peroxymonosulfate for efficient degradation of tetracycline

In this work, Fe3O4 nanoparticles anchored biomass juncus derived carbon (Fe3O4@JDC) was developed as a highly efficient heterogeneous peroxymonosulfate (PMS) activator to degrade organic pollutants. As-prepared catalyst was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometer techniques. High loading and good dispersion of Fe3O4 nanoparticles on JDC lead to excellent degradation performance for tetracycline (90.2 %, 60 min) and other pollutants (above 80 %), and the reaction rate constant (k) is 3.73 times (0.0384 min−1) than that of pure JDC (0.0103 min−1) in the presence of PMS. Additionally, chemical oxygen demand (COD) removal rate of Fe3O4@JDC/PMS system (64.7 %, 60 min) is best than other systems (JDC system, JDC/PMS system, etc.). The quenching tests and electron paramagnetic resonance (EPR) data further demonstrate that TC degradation is an integrative contribution of both non-radical (1O2) and free radical (O2−, SO4−, and OH) pathways. Furthermore, Fe3O4@JDC also exhibits superior reusability (81.1 % degradation efficiency after five cycles) and magnetic separation ability.