Efficient Removal Of Antibiotics Research Articles

Electric field driven tourmaline/hematite dual mineral photocatalysis for efficient antibiotic removal

Hematite (Fe2O3) has garnered attention due to its stability, economic viability, and non-toxic nature. However, the rapid recombination of charge carriers hampers its practical application. On the other hand, tourmaline's inherent surface electric field facilitates the rapid separation of photogenerated electrons and holes. In this study, two directly mined natural minerals, tourmaline and hematite (TFO), were successfully combined. Characterization and experiments indicate that the pronounced enhancement of photocatalytic activity in Fe2O3 is attributed to the electric field effect on the surface of tourmaline. TFO successfully removes 93% of tetracycline (TC, 50 ppm) within 60 min. The reaction rate constant for TFO composite material (0.0410 min−1) is 8.5 times that of tourmaline (0.0048 min−1) and 14.1 times that of hematite (0.0029 min−1). Simultaneously, it markedly improves light absorption and charge carrier separation capabilities. Through simulations of various natural environmental factors, TFO demonstrates excellent practicality. Analyzing and detecting active species revealed the involvement of four types of active species, with ·OH radicals making the most significant contribution. The photocatalytic mechanism was proposed. Furthermore, the degradation pathway of tetracycline and the toxicity of its metabolites were investigated. This work provides additional inspirations and insights for photocatalytic materials performance enhancement and natural resources green governance environment.

Efficient adsorption of antibiotics in aqueous solution through ZnCl2-activated biochar derived from Spartina alterniflora

In recent years, Spartina alterniflora as an invasive species has seriously threatened the native coastal ecosystem of China. There is a lack of effective management and utilization methods towards Spartina alterniflora at present. To realize the ecological remediation and resource utilization of Spartina alterniflora, the functional biochar (BC) materials were successfully prepared using Spartina alterniflora as the substrates via the high temperature calcination method, which were utilized for efficient removal of antibiotics. The biochar was further activated by ZnCl2 (ZnBC) and optimized under different calcination temperatures and ZnCl2 dosages to improve the adsorption ability. Among these biochar materials, the ZnCl2-activated biochar obtained under the mass ratio of Spartina alterniflora to ZnCl2 of 1:5 and calcination temperature of 600 °C (ZnBC-600) exhibited the strongest adsorption performance towards sulfadiazine (SDZ) and ciprofloxacin (CIP), which can be attributed to the larger specific surface area, richer pore structure and more abundant surface oxygen-containing functional groups. Additionally, the adsorption kinetics and isotherms demonstrated that the adsorption of both SDZ and CIP onto ZnBC-600 (1:5) followed the pseudo-second-order kinetic model and Freundlich model. At the same time, the performances of Spartina alterniflora biochar derived from different biomass were compared under the condition of activation with ZnCl2, presenting the superior performance of ZnCl2 activated Spartina alterniflora biochar. Moreover, the adsorption mechanism of ZnBC-600 (1:5) was proposed, illustrating the crucial roles of effects of electrostatic attraction, pore filling, oxygen-containing groups complexation, π-π stacking and hydrogen bonding in the adsorption of antibiotics. Above all, this study not only provides a feasible strategy for the preparation of functional biochar derived from Spartina alterniflora for removing organic pollutants, but also opens up a new pathway for resource utilization of Spartina alterniflora.

Metal-organic framework gel derived magnetic hierarchical porous Fe-N-C catalyst as peroxymonosulfate activator for efficient degradation of amoxicillin via singlet oxygen-dominated nonradical pathway

The rational design of transition metal and nitrogen co-doped carbon-based catalysts for the efficient removal of antibiotics through non-radical pathway of peroxymonosulfate (PMS) activation has attracted widespread attention. Herein, a magnetic hierarchical porous Fe-N-C catalyst (FeBDC-NH2-800) was successfully constructed by pyrolyzing the hierarchical porous precursor metal–organic framework gel (FeBDC-NH2) consisting of nitrogen-containing ligands. Benefiting from the defective heterojunction structure, the catalyst exhibited effective and efficient degradation towards amoxicillin (AMX) by activating PMS to produce 1O2. The degradation of AMX was up to 97.4 % within 30 min, which was 2.48 and 2.16 times more than that of FeBDC-NH2/PMS and nanosized Fe3O4/PMS respectively. The high degradation performance could be maintained toward low pollutant concentration conditions and cycle experiments, manifesting its possibility for practical application. Combining the data of quenching experiments, electron spin resonance spectra, electrochemical experiments, X-ray photoelectron spectra and density functional theory calculation, the mechanism was revealed that radical pathway contributed little during degradation while singlet oxygen played a significant role. The cleavage of lattice oxygen and defective heterogeneous structure of FeBDC-NH2-800 contributed together to promote PMS for 1O2 production.

Carbon quantum dots/BiVO4 S-scheme piezo-photocatalysts improved carrier separation for efficient antibiotic removal

Reasonable design of an efficient S-scheme photocatalyst remains an ongoing challenge due to the limitation of interfacial charge separation efficiency. Herein, CQDs/BiVO4 S-scheme heterojunction with Bi–O–C bond was synthesized by introducing carbon quantum dots (CQDs) growth on BiVO4 piezo-photocatalyst and absorbed visible light up to 750 nm. Under light + ultrasonic conditions, the reaction rate constant (k) of BVO/C-0.10 reached 0.0517 min−1 on tetracycline (TC) degradation, which was 2.24 and 4.04 times higher than those of BiVO4 and CQDs, respectively. The enhanced performance was attributed to the improved efficiency of the photogenerated carrier separation, originating from the combination of piezoelectric effect and S-scheme heterojunction with Bi–O–C bond. The Bi–O–C bond at the CQDs (3–8 nm) and BiVO4 interfaces connected the two semiconductor materials and provided an atomic-level interface channel for carrier migration. The piezoelectric properties of the composites were investigated by piezo−response force microscopy (PFM). Based on Mott−Schottky curves, X-ray photoelectron spectroscopy (XPS), and scavenging experiments, the possible piezo-photocatalytic mechanism was proposed in combination with the band structures and characteristics of CQDs and BiVO4. This work furnishes unique insights into developing efficient S-scheme piezo-photocatalysts for purifying wastewater.

Modeling of Mass Transfer and Reaction Kinetics in ZnO Nanoparticle Micro-Reactor Systems for AMX and DOX Degradation

This study aims to model the coupled phenomena of photocatalytic reaction and mass transfer in the degradation of Amoxicillin (AMX) and Doxycycline (DOX) using Zinc oxide (ZnO) nanoparticles within microreactor systems. The objective is to gain a comprehensive understanding of the dynamic interaction between the photocatalytic degradation kinetics and the mass transfer processes to optimize the conditions for efficient antibiotic removal from contaminated water. This involves characterizing the reaction kinetics via the Langmuir-Hinshelwood model, estimating the mass transfer coefficients, and analyzing the effects of axial dispersion to ensure the accurate determination of intrinsic kinetic constants and minimize mass transfer limitations. This study used a syringe pump to ensure a consistent flow of antibiotic solution into the microreactor. The results indicate that AMX reaches adsorption equilibrium more rapidly than DOX, corresponding to its faster photocatalytic degradation kinetics and higher final conversion rate (89% for AMX, 86% for DOX). The mass transfer coefficient (kd) was estimated using the Sherwood number, derived from three different models, with the constant Sherwood model best fitting the R1 microreactor data. An analysis of the Damköhler number (DaII) indicates that high flow rates minimize mass transfer limitations in the R1 microreactor, allowing the determination of near-intrinsic kinetic constants. On the contrary, at low flow rates, kinetic constants are apparent as a result of mass-transfer limitations. The study concludes that higher flow rates (≥ 10 mL/h) in the R1 microreactor are preferable to approach intrinsic kinetics and reduce mass transfer limitations during photocatalytic degradation of antibiotics. These findings underscore the potential of ZnO-based oxidation processes in treating antibiotic-contaminated water with optimized conditions, providing a pathway for efficient and sustainable wastewater treatment.

Magnetically separable Cd/CdS-ZnFe2O4/α-Fe2O3 Z-scheme heterostructure for boosting the photo-Fenton removal of antibiotic

The photocatalytic degradation of antibiotic pollution under visible light is significant for environmental protection. However, developing photocatalysts that exhibit strong responsiveness to visible light, along with high efficiency and stability, poses a substantial challenge. In this study, we have successfully constructed Cd/CdS-ZnFe2O4/α-Fe2O3 heterostructured photocatalysts. ZnFe2O4/α-Fe2O3 nanoparticles would grow on the surface of Cd/CdS, which forms the Z-Scheme heterostructure. The samples were characterized by structure, morphology, elemental and electrochemical analysis. The results show that the Cd/CdS-ZnFe2O4/α-Fe2O3 catalyst has reached 91.72% tetracycline degradation performance in the photo-Fenton reaction. Through the experimental results and the energy band position, the internal Z-scheme heterojunction reaction mechanism of improving photo-Fenton degradation performance was proposed. This research would contribute to advancing the rational design and synthesis of heterojunction photocatalysts for efficient antibiotic removal under visible light.

Disclosing the intrinsic nature of efficient removal of antibiotics in N/S dual-doped porous carbon-based materials: The manipulation of internal electric field

N/S co-doping has emerged as a prevailing strategy for carbon-based adsorbents to facilitate the antibiotic removal efficiency. Nevertheless, the underlying interplay among N, S, and their adjacent vacancy defects remains overlooked. Herein, we present a novel in situ strategy for fabricating pyridinic-N dominated and S dual-doped porous carbon adsorbent with rich vacancy defects (VNSC). The experimental results revealed that N (acting as the electron donor) and S (acting as the electron acceptor) form an internal electric field (IEF), with a stronger IEF generated between pyridinic-N and S, while their adjacent vacancy defects activate carbon π electrons, thus enhancing the charge transfer of the IEF. Density functional theory (DFT) calculations further demonstrated that the rich charge transfer in the IEF facilitated the π-π electron donor-acceptor (EDA) interaction between VNSC and tetracycline (TC) as well as norfloxacin (NOR), and thus is the key to adsorption performance of VNSC. Consequently, VNSC exhibited high adsorption capacities toward TC (573.1 mg g−1) and NOR (517.0 mg g−1), and its potential for environmental applications was demonstrated by interference, environmentally relevant concentrations, fixed-bed column, and regeneration tests. This work discloses the natures of adsorption capacity for N/S dual-doped carbon-based materials for antibiotics.

Puissant synergistic effect between g-C3N4 and MIL-100(Fe) for highly stable enhanced activation of H2O2 to degrade antibiotic tetracycline hydrochloride

The release of antibiotics in the environment has raised concerns about ecological damage and human health. As a promising technology, Fenton-like processes have been extensively studied to degrade pollutants in water and achieve rapid and efficient removal. Composites of metal-organic frameworks (MOFs) and graphitic carbon nitride (g-C3N4) have shown excellent performance in Fenton-like processes as a potent combination. However, there is a lack of similar studies to confirm their outstanding catalytic performance and stability in catalyzing the H2O2 process. Therefore, to complete the research in this field and to explore the efficient removal of antibiotics, composites of g-C3N4 and MIL-100(Fe) (CNMIL-x) were fabricated by post-synthesis for highly efficient H2O2 activation to remove tetracycline hydrochloride (TC-HCl). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) show that the characteristic morphology and peaks of g-C3N4 and MIL-100(Fe) varied according to the mass ratio between them. According to X-ray photoelectron spectroscopy (XPS), Fe is primarily in the Fe(Ⅲ) state. Besides, CNMIL-1.5 shows a SBET value of 598.46 m2·g−1, a Vpore of 0.42 cm3·g−1, and a pore size of 7.31 nm, which are significantly enhanced compared with g-C3N4. During TC-HCl degradation, the degradation rate of CNMIL-1.5 (0.02772 min−1) is 9.1 and 1.8 times faster compared to that of g-C3N4 and MIL-100(Fe), respectively. Furthermore, the excellent stability of CNMIL-1.5 are demonstrated by the quintuple cyclic experiments and characterization. A possible degradation mechanism dominated by •OH as well as a relative pathway of TC-HCl removal are proposed.

Facile preparation of NiFe2O4/biochar composite adsorbent for efficient adsorption removal of antibiotics in water

The removal of antibiotics by adsorption was considered to be a cheap and efficient treatment method. Herein, magnetic NiFe2O4/biochar (NFO/BC) composites were prepared by hydrothermal growth of nickel ferrite nanoparticles on sawdust derived biochar. It was found that NFO/BC composites had developed pore structure, rich oxygen-containing functional groups, and strong magnetism. The maximum adsorption capacity of the prepared magnetic composite for tetracycline (TC) was 420.41 mg g−1. The results of adsorption thermodynamics and adsorption kinetics showed that the adsorption process is a spontaneous process, which conforms to Langmuir model and pseudo second-order kinetic model. The influence experiment of pH and ionic strength confirmed that electrostatic interaction and hydrogen bonding are the key factors affecting the adsorption process. Additionally, pore filling and π-π interaction also existed in the adsorption process of tetracycline. This recyclable magnetic composite provides a feasible research idea for the efficient removal of antibiotics from water.Graphical

Activation of persulfate by biochar-supported sulfidized nanoscale zero-valent iron for degradation of ciprofloxacin in aqueous solution: process optimization and degradation pathway.

The pollution of antibiotics, specifically ciprofloxacin (CIP), has emerged as a significant issue in the aquatic environment. Advanced oxidation processes (AOPs) are capable of achieving stable and efficient removal of antibiotics from wastewater. In this work, biochar-supported sulfidized nanoscale zero-valent iron (S-nZVI/BC) was adopted to activate persulfate (PS) for the degradation of CIP. The impacts of different influencing factors such as S/Fe molar ratios, BC/S-nZVI mass ratios, PS concentration, S-nZVI/BC dosage, CIP concentration, initial pH, coexisting anions, and humic acid on CIP degradation efficiency were explored by batch experiments. The results demonstrated that the highest degradation ability of S-nZVI/BC was achieved when the S/Fe molar ratio was 0.07 and the BC/S-nZVI mass ratio was 1:1. Under the experimental conditions with 0.6 g/L S-nZVI/BC, 2 mmol/L PS, and 10 mg/L CIP, the degradation rate reached 97.45% after 90 min. The S-nZVI/BC + PS system showed significant degradation in the pH range from 3 to 9. The coexisting anions affected the CIP degradation efficiency in the following order: CO32- > NO3- > SO42- > Cl-. The radical quenching experiments and electron paramagnetic resonance (EPR) revealed that oxidative species, including SO4•-, HO•, •O2-, and 1O2, all contribute to the degradation of CIP, in which •O2- plays a particularly prominent role. Furthermore, the probable degradation pathway of CIP was explored according to the 12 degradation intermediates identified by LC-MS. This study provides a new idea for the activation method of PS and presents a new approach for the treatment of aqueous antibiotics with highly catalytic active nanomaterials.

Efficient Degradation of Ciprofloxacin in Water over Copper-Loaded Biochar Using an Enhanced Non-Radical Pathway.

The development of an efficient catalyst with excellent performance using agricultural biomass waste as raw materials is highly desirable for practical water pollution control. Herein, nano-sized, metal-decorated biochar was successfully synthesized with in situ chemical deposition at room temperature. The optimized BC-Cu (1:4) composite exhibited excellent peroxymonosulfate (PMS) activation performance due to the enhanced non-radical pathway. The as-prepared BC-Cu (1:4) composite displays a superior 99.99% removal rate for ciprofloxacin degradation (initial concentration 20 mg·L-1) within 40 min. In addition, BC-Cu (1:4) has superior acid-base adaptability (3.98~11.95) and anti-anion interference ability. The trapping experiments and identification of reactive oxidative radicals confirmed the crucial role of enhanced singlet oxygen for ciprofloxacin degradation via a BC-Cu (1:4)/PMS system. This work provides a new idea for developing highly active, low-cost, non-radical catalysts for efficient antibiotic removal.

Synergy of rapid adsorption and photo-Fenton-like degradation in CoFe-MOF/TiO2/PVDF composite membrane for efficient removal of antibiotics from water

The reasonable construction of composite membranes with dual functions of rapid adsorption and photo-Fenton-like oxidation degradation holds great significance in the field of wastewater purification. Herein, a poly(vinylidene fluoride)-based composite membrane (denoted as CFT/PVDF) was meticulously prepared through a nonsolvent induced phase separation (NIPS) process with the introduction of cobalt-iron metal–organic framework (CoFe-MOF) and TiO2 (Degussa P25). The composite membrane exhibited an excellent adsorption ability for removing a variety of organic pollutants from water. With the integration of adsorptive filtration and in situ photo-Fenton-like degradation, the removal efficiency of tetracycline hydrochloride reached up to 92.9% through the CFT/PVDF membrane in one filtration process, and the remarkable performance could be maintained after ten consecutive cycles. Moreover, a group of CFT/PVDF membranes was connected in series to realize the fast and continuous wastewater treatment. The photo-Fenton-like oxidation mechanism and possible degradation pathways were proposed on the basis of active-species detections and degradation intermediates analysis. The toxicological analysis indicated that tetracycline was in situ degraded into less toxic intermediates and even nontoxic substances by the CFT/PVDF composite membrane. This work provides some valuable guidance on the construction of self-cleaning membranes for sustainable wastewater remediation and potential applications.

Efficient removal of antibiotics from water by highly crosslinked metal-alginate particles: Preparation, isotherms, kinetics, and microbiological assay

Traces of antibiotics reaching aquatic environment lead to the emergence of antimicrobial resistance (AMR). The efficient removal of antibiotics (ATBs) traces from wastewater is essential to tackle the AMR. In this study, a novel solid-state crosslinking method of alginate (ALG) was developed and applied to specifically remove ATBs from water. A wide range of crosslinkers (Ca2+, Zn2+, Cu2+, Ni2+, Fe3+ and Al3+) was used and the crosslinking nature, density, and distribution were evidenced by FTIR, ICP-MS, and SEM-EDS. Compared with ionotropic gelation, the novel solid-state crosslinking method proved superior in term of ease of production, high crosslinking degree, and ATBs removal capacity. Fe-ALG and Zn-ALG showed high removal capacity of ciprofloxacin (356.5 mg/g and 928.6 mg/g) and doxycycline (90 mg/g and 690 mg/g), however, they were less effective toward amoxicillin (11.5 mg/g and 6 mg/g). Removal isotherms and kinetics followed type I and pseudo-second order suggesting a chemisorption removal mechanism. Fe-ALG was successfully regenerated with no loss in ATB removal capacity. The microbiological assay showed significant reductions of antibacterial activities after ATBs removal from water. Overall, metal-ALG systems obtained by solid-state crosslinking are promising for ATBs removal from wastewater giving the ease of production, high efficiency, regenerability, and scalability potential.

Catalytic microenvironment regulation by introducing biochar into MIL-101Fe derivative for enhanced persulfate activation: Efficient antibiotic removal and RSM optimization

Persulfate-based advanced oxidization process was widely investigated in antibiotic removal. MOFs-derived carbon was potential in activating persulfate, while the inevitable sintering and agglomeration effect of catalysts during carbonization resulted in reduced performance. Low-cost biochar was a desired carrier in designing functional composites. Herein, MIL-101Fe-derived carbon/biochar composites (MCB-900) were prepared via carbonizing MIL-101Fe/corn stalk composites. Biochar supporting achieved the dispersion of MIL-101Fe derivative avoiding the agglomeration effect, but also regulated the catalytic microenvironment with more accessible active sites, high porosity, and structural defects. Accordingly, MCB-900 exhibited more efficient norfloxacin (NOF) removal (96.44 %) than biochar (32.90 %) or MIL-101Fe-derived carbon (79.49 %) via exciting PDS by the transformation of Fe species and carbonyl groups. It was found that NOF degradation was ascribed to radical and non-radical oxidization (SO4•-, O2•-, and 1O2), involving two possible degradation pathways according to LC-MS. MCB-900/PDS system exhibited high anti-interference capability for pH (2–10) and anions (Cl-, HCO3–, H2PO4-), and was suitable for actual water matrixes and various organic pollutants removal. Further, with optimization by RSM, low dosages of PDS and MCB-900 could also reach high NOF removal (>95 %). Combining emerging MOFs with traditional biochar, this work provided an effective means and reference to design high-efficiency catalysts for antibiotic removal in water treatment.

Precursor-oriented design of nano-alumina for efficient removal of antibiotics

Rapid and efficient removal of environmental antibiotics is vital to curb bacterial resistance. Through rational precursors-oriented design, we attain the best Al2O3 absorbent by 500 °C calcination of ammonium aluminium carbonate hydroxide (AACH) precursor from NH4HCO3 route (AACH-NH4HCO3-500) for fast and efficient removal of tetracycline (TC) and other antibiotics from environmental waters including high-salinity wastewater. AACH-NH4HCO3-500 (0.25 g·L−1) can remove (69.92 ± 1.78)% of aqueous TC (0.025 g·L−1) within 5 min and (97.62 ± 2.75)% within 2 h, and the adsorption capacity is 444.4 mg·g−1, which is the highest qmax of TC for the 2 h-adsorptions among numerous adsorbents. AACH-NH4HCO3-500 has fine tolerance to the coexisting substances, and can be easily regenerated and reused, and has no harm even discarded. The relations among the synthetic methods, the structural features, and the adsorption functions of Al2O3 are disclosed through a systematic comparison of the commercial Al2O3 and different Al2O3 nanomaterials attained from three precursors produced by five different routes. The reasons behind the exceptional adsorption performance are discussed throughout. Our findings would facilitate the development of excellent adsorbents for removal of other pollutants.

Novel conjugated microporous polymers for efficient tetracycline adsorption: insights from theoretical investigations

This paper presents a detailed theoretical understanding of the noncovalent interactions between antibiotics tetracycline and conjugated microporous polymer (CMP), which is important to understand the recent experimental finding of efficient removal of antibiotics by CMP materials. We show that the co-work of π-π and H-π interactions determines the final equilibrium structures, when a tetracycline molecule spontaneously adsorbs to the surface or within the pores of the CMP network at physisorption distances. The binding energies for tetracycline/CMP systems are calculated to be −0.31 ∼ −1.15 eV, demonstrating the reliability of the adsorption. The electronic structures of CMP nanostructures remain basically undamaged upon the tetracycline adsorption. The replacement of benzothiadiazole unit with S and N heteroatoms to the phenyl moiety in the linker effectively enhanced the molecular polarity of CMP molecule and increases the interaction area between tetracycline and CMP network, consequently enhancing the average binding energies notably. Our calculations provide useful theoretical guidance for design of novel carbon-based porous adsorbents with good adsorption performance to remove residual tetracycline and other antibiotics in water.

Facile design and fabrication of RP/ZnIn2S4 composite photocatalysts with efficient removal of antibiotics under visible-light irradiation

Efficient photocatalysts with visible light irradiation have a bright future in practical environmental remediation. ZnIn2S4 is a promising environmentally friendly visible-light photocatalyst, due to its appropriate narrow band gap and excellent chemical stability. In this research, the RP/ZnIn2S4 composites with flower spheroidal morphology were synthesized by loading RP onto the surface of ZnIn2S4 via a one-pot hydrothermal process. The experimental results show that the tetracycline (TC) degradation efficiency of RP(1 wt%)/ZnIn2S4 was up to 85.1 %, compared with pure RP, ZnIn2S4, and other series of RP/ZnIn2S4 composites. The optimal degradation conditions were as following: 1 wt% RP modification amount, 30 mg catalyst amount, 30 mg/L initial TC solution concentration, and the initial reaction pH of 7. At the same time, good repeatability and stability of RP(1 wt%)/ZnIn2S4 toward TC removal confirm its potential value for practical applications. In addition, the degradation efficiency of RP(1 wt%)/ZnIn2S4 for rifamycin and ofloxacin under the similar conditions was 80.2 % and 65.3 %, respectively, indicating the universal application of RP/ZnIn2S4 for degradation of different antibiotic pollutants. The possible photocatalytic mechanism was proposed based on the trapping experiment and ESR test. The RP(1 wt%)/ZnIn2S4 composite photocatalytic materials with high efficiency and stability are expected to contribute to the exploration of the environmental protection field.

Evaluation of the adsorptive and catalytic properties of sludge-based carbon materials for the efficient removal of antibiotics listed in the European Decision 2020/1161/EU

In this work, sludge from an oily refinery and urban wastewater treatment plant have been used for the synthesis of activated carbons using ZnCl2 and KOH as activating agents. The materials were used as adsorbents and catalysts for the removal of three antibiotics, e.g., sulfamethoxazole (SMX), trimethoprim (TMP) and ciprofloxacin (CPX). The activated carbons have been fully characterized. Thus, the BET surface area of the materials ranged from 183 to 784 m2/g. Qe values of 127.3 mg/g for SMX onto U-ZnCl2; 168.5, and 179.6 mg/g for TMP and CPX, respectively, onto R-KOH were obtained. The best fitting of kinetic data was found by using pseudo-second order (PSO) model, while Freundlich and Liu models successfully fitted the equilibrium adsorption isotherms. SMX, TMP and CPX adsorption mechanisms were governed by pore filling, π-π interactions and H-bonds. R-KOH material was used for wastewater treatment, finding that the adsorption capacity decreased due to a competitive effect. Regarding the Fenton process, the U-ZnCl2 carbon achieved the total SMX degradation after 60 min. In contrast, TMP and CPX showed the highest depletion in only 20 min. The higher performances of the U-ZnCl2 material may be due to a higher C/O ratio and high N and Zn contents. In the experiments with a real aqueous matrix, similar conversions were achieved, although the kinetic constants resulted in slightly lower values. So, it could be stated that adsorption and Fenton oxidation performance were influenced by the different properties of the carbon materials.

L-phenylalanine-assisted construction of hierarchically structured Fe(OH)3@Co2(OH)2CO3 with enhanced catalytic activities for the degradation of persistent organic pollutants

In this work, a flower-like Fe(OH)3@Co2(OH)2CO3 catalyst was prepared via the confinement effects provided by L-phenylalanine, which favored the heterostructure construction of active iron centers (Fe(OH)3) anchored on the Co2(OH)2CO3 nanosheet supports. Benefiting from the created electron-transfer interface and dual metal active sites, the limitation of redox cycling was broken and exhibited highly efficient catalytic activities, the optimal Fe(OH)3@Co2(OH)2CO3 catalyst showed comparable catalytic performance for the degradation of dye (degradation degree of 99% methylene blue and orange II within 18 min). In addition, the prepared catalysts were employed for the efficient removal of antibiotics (tetracycline (98.9%), norfloxacin (92.5%) and doxycycline hyclate (90.2%). Besides, the preferred nanofibrous composite membranes prepared by combination of nanofibrous membranes (NFMs) with Fe(OH)3@Co2(OH)2CO3 catalysts possessed considerable potential for large-scale MB removal (treatment capacity of 238.5 L m−2 and permeability of 191.8 L m−2 h−1 driven by gravity) and stability (182.7 L m−2 of treatment capacity was achieved in the third run). The strategy of construction of rapid interface-redox on the heterogenous catalysts was designed to enhance catalytic performance, which provided a promising chance for the efficiently large-scale removal of dyes and antibiotics.

Performance and mechanisms of photocatalysis of silver phosphate modified by carbon nanosheets doped with both nitrogen and boron for removal of norfloxacin

The photocatalyst technology based on silver phosphate (Ag3PO4) has excellent oxidation ability in the degradation of antibiotic pollutants due to its appropriate energy band structure. However, the high charge recombination efficiency limits the wide application of Ag3PO4. In this study, carbon nanosheets doped with both N and B (NBNS) have excellent charge distribution. The photoactivity of Ag3PO4 was optimized by combining NBNS. After 12 min, Ag3PO4 @NBNS achieved 100% degradation of norfloxacin (NOR), 8.6 times the degradation rate of Ag3PO4 monomer. In addition, NBNS, Ag3PO4 and Ag3PO4 @NBNS were characterized by SEM, TEM, XRD, Raman and XPS. It revealed that there was an intense interface interaction between Ag3PO4 and NBNS, and a built-in electric field (BIEF) was constructed at the interface to achieve rapid separation of photogenerated charges. The DFT calculations results indicated that the doping of B and N could reduce the work function of carbon nanosheets and increase their charge density, which would promote the formation of BIEF between the interface of Ag3PO4 and NBNS. The catalytic reaction mechanism of Ag3PO4 @NBNS was proposed. This work provides a novel photocatalyst for the efficient removal of antibiotics, and sheds light on the use of carbon materials to optimize silver phosphate based photocatalyst, as well as the design of new efficient visible light catalysts.