Tetracycline Removal Efficiency Research Articles

Polypyrrole/cadmium sulfide/nickel hollow fiber as an enhanced and recyclable intrinsic photocatalyst for pollutant removal and high-effective hydrogen evolution

The photocatalysis for environment purification and clean energy production has attracted widespread attention, however, traditional powder-form photocatalysts cannot meet the practical application due to their poor recyclability, especially in slurry system. Here, polypyrrole/cadmium sulfide/nickel (PPy/CdS/Ni) multi-layer hollow fibrous photocatalyst with favorable photocatalytic activity for pollutants removal and hydrogen (H2) evolution was successfully fabricated, which possesses a narrow band gap of ∼1.87 eV and enhanced visible-light photocatalytic activity. The removal efficiency of methylene blue (MB) and tetracycline can reach up to ∼94.76% and ∼76.1%, respectively. Simultaneously, the TOC removal efficiency with regard to MB can reach up to 78.1% and Cd2+ leakage is extremely low (<3 mg⋅L−1). More interestingly, H2 evolution rate of PPy/CdS/Ni hollow fiber is up to as high as 665.7 μmol⋅g−1⋅h−1, which is about 1.43 and 1.86 folds higher than the PPy/CdS/Ni/PET fiber (466.3 μmol⋅g−1⋅h−1) and CdS/Ni/PET fiber (357.1 μmol⋅g−1⋅h−1), respectively. As a fiber-form intrinsic photocatalyst, our catalytic fiber shows great promise for pollutants removal and hydrogen energy production due to its easy-handling and recyclement.

Insights into the adsorption of tetracycline onto cellulose nanocrystal structured MgAl/LDH composite

The present study evaluated for the first time the adsorption potential of cellulose nanocrystal-structured MgAl/LDH (CNC/MgAl-LDH) composite for the removal of tetracycline (TC) from the aqueous phase. The prepared adsorbent was characterized by several physicochemical techniques including SEM, XRD, FTIR, and BET surface area analysis. The CN-MAl-1 composite exhibited a high specific surface area of 101.927 m2 g−1. The adsorption kinetic data is well correlated with the pseudo-second order kinetic model. The Langmuir isotherm model showed an excellent fit to the experimental data with the maximum adsorption capacity of 143.5 and 153.3 mg g−1 at 298 and 318 K, respectively. The thermodynamic studies indicated that the adsorption of TC was spontaneous, favorable, and endothermic with ΔH0 = 25.13 kJ mol−1. After five cycles of regeneration, the TC removal efficiency of the adsorbent remained higher than 90%. The as-synthesized adsorbent showed to be promising and efficient in the removal of TC from aqueous solutions.

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.

Enhanced photodegradation of tetracycline in wastewater and conversion of CO2 by solar light assisted ZnO/g-C3N4

Synthesized graphitic carbon nitride-based (CN) heterojunction photocatalysts are considered as a promising material for photodegradation of organic compounds and CO2 conversion. In this work, ZnO-loaded g-C3N4 (ZnO/CN) heterojunction photocatalyst was investigated for the enhanced photooxidation of tetracycline (TC) and CO2 conversion . After modification, the photocatalysts showed an improvement in the light absorption range and the photogenerated separation rate of electron/hole due to the heterojunction structure of ZnO/CN. The degradation rate of TC was found to be 92.6% within 60 min, while CO production rate was 7.68 μmol/g/h. The rate constants of TC by using ZnO/CN were 0.0812, 0.0539, 0.0336, 0.0249, and 0.0185 min−1, corresponding to the TC level of 1, 10, 30, 50, and 100 mg/L, respectively. The photodegradation rate of TC by ZnO/CN was 5 times higher than that of CN, demonstrating the advantage of heterojunction photocatalyst.The modified ZnO/CN exhibited superior degradation performance of TC and higher CO2 conversion rate than those of unmodified CN. It also exhibited high stability with 82% removal efficiency of TC at the 6th run and the CO2 conversion rate of 71% after reused 5 times.The heterojunction ZnO/CN can be utilized as an efficient material for various photocatalytic applications.

Enhancing visible-light degradation performance of g-C3N4 on organic pollutants by constructing heterojunctions via combining tubular g-C3N4 with Bi2O3 nanosheets

In this paper, a novel heterojunction photocatalyst was prepared by depositing Bi2O3 nanosheets on the surface of tubular g-C3N4 (TCN) using a simple solvothermal method. The photocatalytic activity was assessed using Rhodamine B (RhB) and Tetracycline (TC) as the target contaminant under visible light (λ > 420 nm). Compared with single TCN or Bi2O3, the TCN/Bi2O3 composites exhibited enhanced photocatalytic activity. The TCN/Bi2O3-0.5 photocatalyst, in particular, showed the most superior performance. Its removal efficiency of TC reached 94% in 100 min and that of RhB reached 99% in 60 min, with a rate constant (0.06532 min−1) of degrading RhB of 4.9 and 3.9 times higher than that of TCN and Bi2O3, respectively. The results of photoluminescence, photocurrent, and electrochemical impedance spectrum characterization showed that the composite photocatalysts can significantly improve the separation efficiency of the photogenerated carriers, due to the construction of heterojunctions. A possible mechanism of the degradation of target pollutants by the composite catalyst was proposed. The synergistic effect of the increased specific surface area and the heterojunction formed by interfacial contact between Bi2O3 and TCN was primarily responsible for improving photocatalytic performance.

Removal of tetracycline from water by catalytic photodegradation combined with the microalga Scenedesmus obliquus and the responses of algal photosynthesis and transcription

The antibiotic tetracycline (TC) and its degradation products (TDPs) in degradation solution present serious environmental problems, such as human health damage and ecological risk; thus further treatment is required before being released into the aquatic environment. Furthermore, their environmental impact on microalgae remains unclear. In this study, TC was degraded by photocatalysis using birnessite and UV irradiation, followed by biological purification using the microalga Scenedesmus obliquus. In addition, the photosynthetic activity and transcription of the microalgae were examined to evaluate the toxicity of TC and TDPs. The results show that photocatalytic degradation efficiency reached 92.7% after 30 min, and 11 intermediate products were detected. The microalgae achieved a high TC removal efficiency (99.7%) after 8 days. Exposure to the degraded TC solution (D) resulted in significantly lower (p < 0.05) biomass than the pure TC (T), and S. obliquus in the T treatment showed better resilience than the D treatment. Transcriptomic assays for different treatments revealed differential gene expression mainly involving the photosynthesis, ribosome, translation and peptide metabolic progresses. The up-regulation of photosynthesis-related genes and differential expression of chloroplast genes may be important for S. obliquus to acquire high photosynthetic efficiency and growth recovery when exposed to TC and TDPs. Our study provides a reference for TC removal using a combination of catalytic degradation and microalgal purification, and it is also helpful for understanding the environmental risk of TDPs in natural aquatic environments.

Regulating Lewis acidity and local electron density of iron-based metal organic frameworks via cerium doping for efficient photo-Fenton process

The photo-Fenton performance of Fe-based metal organic frameworks (Fe-MOFs) largely depends on the amount and the local electron density of metal coordinately unsaturated sites (M CUSs). However, a majority of Fe active sites are fully bound by organic ligands leading to decreased Fe CUSs. Additionally, the symmetrical electronic distribution of iron-oxo (Fe-O) clusters and the fast electron-hole recombination are unbeneficial for the directional electron transfer and the following electron accumulation on Fe CUSs. Herein, the structure of Fe-O clusters onto the framework of MIL-88B was controllably regulated via change of Ce doping amount, among which Fe0.8Ce0.2-MIL-88B exhibited highest removal efficiency of tetracycline (TC). That was mainly ascribed to the following two points: for one, the induced ligand missing defects ameliorated the pore structures and generated more M CUSs; for another, the lower electronegativity of Ce than Fe and the role of ligand missing defects as electron trap state collectively increased the local electron density at Fe CUSs. As a result, the increased M CUSs provided more active sites for H2O2 coordination and the highly concentrated electrons density at Fe CUSs afforded the substantial electron donation towards robust H2O2 dissociation into ∙OH. Furthermore, the increased mesoporous size favored highly-efficient utilization of ∙OH. This work provides a facile strategy to improve photo-Fenton performance of Fe-MOFs.

Room-temperature MXene-derived Ti3+ and rich oxygen vacancies in carbon-doped amorphous TiOx nanosheets for enhanced photocatalytic activity

Exploring efficient photocatalysts for photocatalytic degradation is of considerable importance for the long-term mitigation of environmental stress. Although defect engineering is an effective strategy to alter the electronic transport properties and light absorption capacity of TiO2, the synthesis of TiO2 rich in oxygen vacancies (OVs) via a green process at room temperature and with low energy consumption remains a challenge. Herein, amorphous TiO2 nanosheets rich in OVs were prepared by H2O2-assisted room-temperature oxidation of Ti3C2Tx MXene via a bottom-up approach. Notably, small amounts of C and Ti3+ were introduced during the preparation of carbon-doped TiO2 (C-TiOx), which was shown to possess abundant surface functional groups (e.g., –OH, –O, and –F) and two intermediate levels in its bandgap. Comparative experiments demonstrated that OVs play a key role in suppressing the recombination of photogenerated carriers and expanding the light absorption range of the photocatalyst. The unique quasi-two-dimensional structure of C-TiOx features a large number of exposed active sites, which are beneficial for improving its catalytic performance. Tetracycline (TC) was removed from the aqueous solution by the prepared photocatalysts C-TiOx and annealed-TiO2, and the former adsorbed 41.1% of TC. The TC removal efficiency of C-TiOx was 76%, which was higher than that of annealed-TiO2. This approach embodies a new strategy for introducing defects and doping in TiO2. Moreover, it is also thought that C-TiOx possesses promising characteristics suitable for a wide range of potential future applications.

In-situ fabrication of 3D hollow Bi0/OVs-BiOCOOH microspheres with efficient photocatalytic degradation of tetracycline

• Series of Bi 0 /OVs-BiOCOOH photocatalysts with hollow structure were successfully designed and constructed. • The structure–activity relationship between catalyst structure and properties were elucidated. • A possible formation mechanism for the special structure was proposed. • The heterojunctions present excellent activity and stability for photocatalytic TC removal efficiency. Herein, we prepared visible light responsive well-dispersed Bi 0 /OVs-BiOCOOH hollow microspheres through solvothermal method employing colloid carbon nanospheres (CSs) as sacrificial template and reductant. The characterization results show that CSs play multiple roles in the synthesis of hollow Bi 0 /OVs-BiOCOOH microspheres, in which the hollow structure may be caused by the redox reaction of CSs and BiO + during synthesis. The SPR effect of Bi 0 can enrich the photocatalytic performance by promoting the absorption of visible light. Furthermore, a defective energy level can be established by introduction of oxygen vacancies (OVs) on the surface of BiOCOOH, improving photocatalytic capability by accelerating the separation of photogenerated carriers. The degradation performance of Bi 0 /OVs-BiOCOOH for decontamination of tetracycline (TC) is 4.86 times than that of BiOCOOH. Based on the observations, the underlying photocatalytic mechanism of Bi 0 /OVs-BiOCOOH for photodegradation of TC was elaborated.

Investigation of environmentally friendly adsorbent synthesis from eggshell by carbonization, immobilization, and radiation: Box-Benkhen Design and tetracyclin removal

In this study, was conducted to evaluate the applicability of 2.45 GHz electromagnetic radiation (EMR) applied with synthesized zero-valent iron (NZVI) modified immobilized eggshell waste (ESW-NZVI-2.45 GHz) biosorbent for the tetracycline (TC) removal process from aqueous solutions. This composite was synthesized in borohydride reduction method via ethanol using a in atmospheric conditions. Biyosorbent characterized by FTIR, and SEM analyses before and after TC adsorption. Batch experiments were axamined for %TC removal efficiency of ESW-NZVI-2.45 GHz, were conducted utilizing the Response Surface Methodology (RSM), Box-Behnken design. Experimentally, the maximum TC removal efficiency was found to be relatively high %94.61 at an optimum temperature of 20 °C, 2 min EMR time, and Co, 50 mg/L experimental conditions. The TC removal was determined to be appropriate for the pseudo-second kinetic model with the highest R2 value (0.9999). Thermodynamic parameters were calculated for ESW-NZVI-2.45 GHz. The ΔG values indicate that the adsorption process occurs spontaneously, while positive ΔS values indicate an increase in the irregularity at the solid/solution interface. As a result, this study showed that TC removal onto magnetic and irradiated biosorbent ESW-NZVI-2.45 GHz was effectively and optimization of optimum removal conditions studies RSM with high R2 (0.9833) supported.

Boost activation of peroxymonosulfate by iron doped K2−xMn8O16: Mechanism and properties

Among the numerous transition metal catalysts, manganese-based compounds are considered as promising peroxymonosulfate (PMS) catalysts due to their low cost and environmental friendliness, such as cryptomelane manganese oxide (K2−xMn8O16: abbreviation KMnO). However, the limited catalytic performance of KMnO limits its practical application. In this work, iron-doped KMnO (Fe-KMnO) was prepared by one-step hydrothermal method to optimize its catalytic performance. Compared with KMnO/PMS system, Fe-KMnO/PMS system possessed more excellent removal efficiency of tetracycline (TC). Meanwhile, the Fe-KMnO/PMS system also exhibited good practical application potential and excellent stability. The mechanism of Fe-KMnO activation of PMS was further analyzed in detail. It was found that Fe participated in the redox of high-valent Mn, which promoted the activation of PMS. Moreover, The Fe site as an adsorption site enhanced the TC enrichment ability of the catalyst, reducing the mass transfer resistance and further enhancing the TC removal ability of Fe-KMnO/PMS system. This work not only provides an excellent PMS catalyst, but also offers new insights into the mechanism of PMS activation by bimetallic manganese-based catalysts.

The efficient adsorption of tetracycline from aqueous solutions onto polymers with different N-vinylpyrrolidone contents: equilibrium, kinetic and dynamic adsorption.

Extensive use of antibiotics in the world will cause potential risks to human health and ecosystems. The removal of these antibiotics has attracted much attention. Composite materials are growing attention for diverse pollutants separation and removal based on their specific functionality and surface area. In this study, a series of N-vinylpyrrolidone-divinylbenzene polymers (NVPD) with different N-vinylpyrrolidone (NVP) contents were facilely prepared for the adsorption of tetracycline (TC). The effect of polymer surface properties and aqueous solution chemistry (pH, ionic strength, humic acid) on TC adsorption was further studied. The dynamic adsorption and regeneration experiments were also assessed. The results showed that only 25% of NVP was involved in the reaction. When NVP dosage (%) was 75%, polymer (NVPD-g) owned the largest BET surface area (613.23 m2/g) and obtained the maximum TC adsorption capacities (258.76mg/g). In the kinetic, the adsorption between TC and polymers with NVP was controlled by chemical adsorption and intra-particle diffusion. The TC adsorption process of NVPD-g depended on the contribution of the hydrophobic effect, electrostatic interactions, H-bonding, π-πelectron donor-acceptor(EDA) interactions, and cation-π bonding. Moreover, the removal efficiency of TC by NVPD-g was enhanced in the presence of humic acid (HA) in the dynamic adsorption and 1197 BV (2394mL) of TC simulated wastewater can be treated. These findings suggest that NVPD-g has a potential application inthe purification of TC.

Adsorption behaviors of three antibiotics in single and co-existing aqueous solutions using mesoporous carbon

The residual antibiotics detected frequently in aquatic environment may pose a potential threat to human health and ecosystem. Exploring a possible way to remove them from antibiotic polluted-water is a key problem demanding prompt solution. To investigate their adsorption characteristics, three antibiotics including tetracycline (TC), ciprofloxacin (CIP), and sulfadiazine (SDZ) have been removed using sucrose-based mesoporous carbon (SMC) in single and co-existing systems. Characterization revealed that the SMC had a high Brunauer-Emmett-Teller (BET) surface area (1215.48 m2/g), large mesoporous pore size (6.36 nm), and abundant oxygen-containing functional groups, which might offer sufficient adsorption sites for antibiotics. The process of antibiotics adsorption was described well using pseudo-second-order model. The rate constant K2 at various temperatures followed the order 308 K > 298 K > 288 K. This finding suggesting the increase in temperature could promote the removal of antibiotics. The maximum adsorption capacities for TC (232.10 mg/g), CIP (257.30 mg/g), and SDZ (204.28 mg/g) of SMC were obtained using Langmuir isotherm (pH = 4–6, T = 308K, SMC dosage = 10 mg, C0 = 30–40 mg/L). These data implied SMC had the excellent adsorptive property and affinity to antibiotics. In binary systems, SMC offers efficient removal percentages (>90%) for each of the target antibiotic. While the removal efficiencies of TC, CIP, and SDZ by SMC in the ternary system were 90.40, 72.99, and 80.46%, respectively. These results suggested the competition on active sites of SMC happened among the three antibiotics. The affinities of SMC to three antibiotics followed the order TC > SDZ > CIP. The removal of antibiotics by SMC were mainly attributed to the mechanisms including electrostatic interactions, hydrophobic interactions, hydrogen bonding and so on. This study will provide a technical support for antibiotic wastewater treatment.

Mesoporous Ultrathin g‐C3N4 with Surface Defects Activates Peroxodisulfate for Tetracycline Removal under Visible Light: Synergy and Mechanism

AbstractMetal‐free catalysts combined with a persulfate‐based advanced oxidation process (PS‐AOP) are considered to be a promising purification technology. In this study, porous thin layers of g‐C3N4 with nitrogen defects are synthesized by a simple method. Multiple characterization methods demonstrate the porous thin layer structure and the N defects of P‐CNx‐1. Photoelectrochemistry tests show that the combination of morphological modulation and defect engineering produces an excellent photocurrent response. The P‐CNx‐1/PS/Vis system shows the best tetracycline (TC) removal efficiency degrading 74.2% of TC within 90 min, and the degradation kinetics are significantly improved. Optimal degradation conditions such as catalyst dosage, persulfate (PS) dosage, initial TC concentration, and initial pH are investigated. Cyclic and anionic experiments demonstrate the excellent stability of P‐CNx‐1 and its ability to treat complex aqueous bases. Mechanistic experiments show that ˙OH/SO4˙−/˙O2−/h+/1O2 are all involved in the degradation of TC. Liquid chromatography‐mass spectrometry (LC‐MS) suggests possible degradation pathways for TC. This work aims to provide new ideas for the application of metal‐free g‐C3N4 in PS activation.

Broad spectrum driven Y doped BiO2−x for enhanced degradation of tetracycline: Synergy between singlet oxygen and free radicals

The synergy of singlet oxygen and free radicals is crucial to driving organic pollutant degradation in water contain complex natural organic matter. In this study, the rare earth element yttrium doped bismuth oxide (Y-BiO2−x) photocatalyst was prepared by a hydrothermal method. Y doped BiO2−x enables produce oxygen vacancies and possess up-conversion property. The superoxide radicals (O2−), singlet oxygen (1O2), hydroxyl radicals (OH) and hole (h+) play a crucial role in photocatalytic reaction process. The increased 1O2 and hydrogen peroxide are mainly originated from O2−. The degradation efficiency of tetracycline (TC) reached 70.45 % and 40.17 % under Vis and NIR light, respectively. Notably, the TC removal efficiency of Y-BiO2−x maintained 65.92 % in the actual wastewater containing various anions and humic acid (HA), which originate from synergy of singlet oxygen and free radicals. This study provides a new strategy for synergistic singlet oxygen and free radicals to degradation of organic pollutants in complex water matrix.

Peroxymonosulfate-based photocatalytic oxidation of tetracycline by Fe2(MoO4)3/Cd0.5Ni0.5S heterostructure; DFT simulation

The current research is meant to develop novel semiconductor photocatalysts, for the decomposition of tetracycline (TC) as a model organic contaminant in the aquatic environment. The fabrication of Fe2(MoO4)3/Cd0.5Ni0.5S (FMO/CNS) composite has proven to be an effective method for improving the sustainability and photocatalytic activity of Cd0.5Ni0.5S (CNS). Under visible light irradiation, FMO/CNS nanocomposite demonstrated significant PMS activation which led to 1.36 and 1.81 times TC removal efficiency as compared to immaculate Fe2(MoO4)3(FMO) and CNS. FMO/CNS composite potentially promotes the segregation of electron-hole pairs (e−-h+) and exemplifies amazing photocatalytic performance for TC degradation. Its significant photocatalytic activity is due to its unique structure, which includes tiny pores on the surface that confine the PMS molecule to the interface. The FMO/CNS composite has significantly greater piezocatalytic activity than pure FMO and CNS, demonstrating the synergistic effect of FMO and CNS. In the degradation of TC, holes and key reactive radicals (•O2−/•OH/SO4−•) played a major role. Computational studies (DFT) estimates, including the determination of intermediates, confirmed that the hydroxyl addition and C–N cleavage pathways were responsible for TC degradation. As a result, this work delivers a new approach to developing novel photocatalysts with high photocatalytic activity for the abatement of organic contaminants in water.

Cotton-derived 3D carbon fiber aerogel to in situ support Bi2O3 nanoparticles as a separation-free photocatalyst for antibiotic removal

Because of abundant oxygen-based groups, natural cotton is adopted as the precursor to in situ fabricate a three-dimensional (3D) Bi2O3-supported carbon fiber aerogel (Bi2O3/CF). The calcination temperature plays an important role in the crystal composition of Bi species and the specific surface area of the aerogel. When the calcination temperature is 800 °C, the Bi2O3/CF product exhibits the highest tetracycline (TC) removal efficiency, including large adsorbability and superior photocatalytic activity. Furthermore, its 3D porous network architecture provides a multidimensional open framework for the free mobility of solution and rapid diffusion of reactants and products. In the flowing system, the 3D Bi2O3/CF aerogel can implement the continuous and stable elimination of pollutants for a long time, and it does not require any separation operation. Consequently, the 3D Bi2O3/CF aerogel is expected as a promising functional material to massively remove organic pollutants from industrial wastewater.

Digestate of Fecal Sludge Enhances the Tetracycline Removal in Soil Microbial Fuel Cells

The soil pollution of agricultural lands is increasingly being caused by the widely used antibiotic tetracycline (TC) in the animal husbandry industry. Soil microbial fuel cells (SMFCs) provide a promising strategy for the bioremediation of contaminated soil. However, our current understanding of the bioremediation of TC-contaminated soil by SMFC is still limited. Here, we investigated the influence of fecal sludge (FS) digestate on TC biodegradation efficiency and extracellular electron transfer in SMFCs. The addition of FS digestate was beneficial to electricity generation by SMFC, and thus enhanced the removal efficiency of TC in the SMFC. After 25 days, the SMFC with fecal sludge digestate showed a TC removal efficiency of 64.5%, compared to values of 25.2% and 21.4% observed for a SMFC and an open-circuit SMFC operating without the addition of fecal sludge digestate, respectively. Moreover, the addition of FS digestate was favorable for electricity generation by SMFCs, and the average current density and the maximum power density of the SMFC with fecal sludge digestate were 0.054 A/m3 and 8.85 W/m3, respectively. The enrichment of Desulfuromonas and Pseudomonas in the electrode biofilms might account for their high TC removal efficiency and electricity generation. The SMFC with fecal sludge digestate provides a promising approach for the simultaneous disposal of fecal sludge digestate and the bioremediation of antibiotics-contaminated-soil.

Tetracycline removal using microbial cellulose@nano-[formula omitted] by adsorption and heterogeneous Fenton-like processes

In this study, nano-Fe3O4 was anchored on microbial cellulose (MC@nano-Fe3O4) and modified by a high-temperature furnace (MMC@nano-Fe3O4). The prepared nanocomposite was then employed in adsorption and heterogeneous Fenton-Like processes for removing tetracycline (TC) from aqueous solutions. The surface features and morphology of MMC@nano-Fe3O4 were analyzed by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric (TGA), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX), and Brunauer-Emmett-Teller (BET). The results revealed that the MMC@nano-Fe3O4 catalyst is able to adsorb 48 % of TC under optimal conditions (50 mg L-1 TC, pH of 5.0, 0.2 g L-1 MMC@nano-Fe3O4 after 120 min). Afterward, 97.25 % of TC was removed using 2 mM PS after 180 min. The reusability of the catalyst was sequentially examined for up to five runs, and the results demonstrated that TC removal efficiency declined by only 1.47 % after five cycles. Moreover, the mechanism of PS activation by MMC@nano-Fe3O4, isotherm and kinetic of the reaction, and the TC degradation pathway were presented.

Simultaneous Removal of Nitrate and Tetracycline by an Up-Flow Immobilized Biofilter

The removal of nitrate (NO3−-N) and antibiotics in aquaculture tail water is urgent and necessary. A lab-scale up-flow immobilized biofilter (I-BF) filled with polyurethane foam (PUF) carriers and a microbial consortium was developed for simultaneous removal of nitrate and tetracycline (TC). The denitrification and TC removal performance of the I-BF reactor was investigated under different TC concentrations (0, 10, 50, 100 mg·L−1), carbon/nitrogen (C/N) ratio (2, 4, 5, 6) and hydraulic retention times (HRT) (4, 8, 12 h). Simultaneous removal of nitrogen and TC was achieved by the I-BF reactor. Low TC concentration (≤50 mg·L−1) had little effect on nitrogen removal. The denitrification performance of the I-BF reactor was inhibited at high TC load, which may be attributed to the damage of cell membranes and the inhibition of the intracellular denitrification enzymes’ activities. The optimal C/N ratio and HRT were 5 h and 8 h with almost complete denitrification and high TC removal efficiency (73.46%) at influent NO3−-N and TC concentrations of 100 mg·L−1 and 50 mg·L−1, respectively. The I-BF reactor proposed in this study has promising applications such as the treatment of piggery wastewater, aquaculture tail water and pharmaceutical wastewater co-contaminated with nitrate and antibiotics.