Tetracycline Adsorption Process Research Articles

Efficient Removal of Tetracycline from Water by One-Step Pyrolytic Porous Biochar Derived from Antibiotic Fermentation Residue.

The disposal and treatment of antibiotic residues is a recognized challenge due to the huge production, high moisture content, high processing costs, and residual antibiotics, which caused environmental pollution. Antibiotic residues contained valuable components and could be recycled. Using a one-step controllable pyrolysis technique in a tubular furnace, biochar (OSOBs) was produced without the preliminary carbonization step, which was innovative and time- and cost-saving compared to traditional methods. The main aim of this study was to explore the adsorption and removal efficiency of tetracycline (TC) in water using porous biochar prepared from oxytetracycline fermentation residues in one step. A series of characterizations were conducted on the prepared biochar materials, and the effects of biochar dosage, initial tetracycline concentration, reaction time, and reaction temperature on the adsorption capacity were studied. The experimental results showed that at 298 K, the maximum adsorption capacity of OSOB-3-700 calculated by the Langmuir model reached 1096.871 mg/g. The adsorption kinetics fitting results indicated that the adsorption of tetracycline on biochar was more consistent with the pseudo-second-order kinetic model, which was a chemical adsorption. The adsorption isotherm fitting results showed that the Langmuir model better described the adsorption process of tetracycline on biochar, indicating that tetracycline was adsorbed in a monolayer on specific homogeneous active sites through chemical adsorption, consistent with the kinetic conclusions. The adsorption process occurred on the surface of the biochar containing rich active sites, and the chemical actions such as electron exchange promoted the adsorption process.

Novel activated carbon derived from a sustainable and low-cost palm leaves biomass waste for tetracycline removal: Adsorbent preparation, adsorption mechanisms and real application

Palm leave biomass waste was converted into a new activated carbon through facile chemical activation and pyrolysis. The prepared activated carbon (KAC) was characterized by X-Ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), surface area analyzer (BET), and point of zero charge (pHPZC) measurement. KAC was used as an adsorbent to remove emerging contaminant tetracycline (TC) from water, and systematic TC adsorption studies (i.e. kinetics, isotherm, and thermodynamic) were performed. Moreover, density functional theory (DFT) was applied to simulate the TC adsorption process. The adsorption kinetics data corroborated the pseudo-second-order model perfectly. The maximum monolayer adsorption capacity was 132.94 mg g−1 at 25 °C. According to the thermodynamics study, the adsorption process of TC was favorable and endothermic, while the process increased the randomness of molecules at the interface between water and solid. TC adsorbed onto KAC via π-π interaction, H-bonding, electrostatic interaction, and pore-filling. TC adsorption mechanism elucidated by DFT calculations showed good agreement with the experimental findings. The reusability of KAC in real wastewater was also tested for three cycles. This study shows that converting of the abundant palm leaves biomass waste into a valuable adsorbent for TC removal is promising.

Synthesis and Characterization of a Magnetic Molecular Imprinted Polymer for Tetracycline Quantification in Food Samples

AbstractIn the present work, we synthesized and tested a magnetic molecularly imprinted polymer (mag‐MIP) sensor for the detection of tetracycline in food samples. High‐performance liquid chromatography (HPLC) and spectrofluorometry were employed for tetracycline determination. The mag‐MIP was polymerized on the surface of Fe3O4@SiO2 magnetic nanoparticles using the following substances: 4 mmol of methacrylic acid as the functional monomer, 20 mmol of ethylene glycol dimethacrylate (EGDMA) as the cross‐linking agent, 82.5 mg of benzoyl peroxide as the radical initiator, and 30 ml of acetonitrile as the solvent. The physicochemical characteristics of the proposed mag‐MIP, including adsorption capabilities and selectivity, were studied and compared with those of a magnetic non‐molecularly imprinted polymer (mag‐NIP). The analytical curve was constructed in the range of 1.0×10−5–8.0×10−5 mol L−1, LOD: 3.3×10−6, LOQ: 1.1×10−5 mol L−1. The results obtained from the adsorption analysis showed that the highest adsorption capacity of the mag‐MIP at equilibrium was 8.247 mg g−1 and that the tetracycline adsorption process followed the Langmuir adsorption isotherm model and pseudo‐second‐order reaction kinetics. The proposed mag‐MIP also exhibited good results when subjected to fluorescence analysis; an increase in tetracycline concentration resulted in an increase in the adsorption capacity, and this led to the effective removal of tetracycline with the reduction of fluorescence intensity. The applicability of the proposed mag‐MIP was evaluated in honey, cow milk, and egg samples through recovery tests conducted using samples containing spiked tetracycline concentration at two different concentration levels (1.7×10−5 and 2.5×10−5 mol L−1), where we obtained recovery percentages in the range of 73.2–87.2 % (HPLC) and 90.5–103.7 % (spectrofluorometry).

Engineering of 3D architectures with yttrium on reduced-graphene oxide nanosheets for effective co-adsorption of tetracycline and phosphate

Effective removal of composite pollutants containing antibiotic and phosphorus is still facing challenges for the wastewater treatment. In this study, yttrium-hydroxide component was loaded onto the surface of reduced GO nanosheets via low-temperature hydrothermal method, to synthesize the 3D YrGO architectures. The optimized YrGO-8 hydrogels showed the maximum adsorption capacity of 226.45 mg/g for tetracycline (TC), and 33.403 mg/g for phosphate, which was higher than many other reported adsorbents. The characterization results demonstrated that the rGO nanosheets were successfully crosslinked by Y(III) to form a porous 3D structure, which was beneficial to the mass transfer and active sites exposure. The adsorption behaviors of TC or phosphate was suppressed by the co-existing phosphate ions or TC, with slower adsorption rate and lower adsorption amount. Importantly, column adsorption analyzed by Thomas model illustrated the rate basis of YrGO-8beads to capture TC/phosphate in an adsorbate diffusion rate. Moreover, the 3D YrGO-8 remained stable and high reusability in multi-uptake-release rounds via pH regulation. The mechanism study suggested that the sequence of adsorption process of TC followed the order of hydrogen bond (HB) > π – π electron donor–acceptor (EDA), n − π EDA > Y(III) bridging interactions, while the uptake of phosphate formed Y-O-P inner-sphere complexes prior to HB. This study proposes a novel insight into the development of 3D architectures for effectively simultaneous treatment of composite TC and phosphate pollution.

Green synthesis of manganese ferrite magnetic nanoparticle and its modification with metallic-organic frameworks for the tetracycline adsorption from aqueous solutions: A mathematical study of kinetics, isotherms, and thermodynamics

In the current investigation, MnFe2O4/ZIF-8 nanocomposite was generated as a magnetic nanoadsorber using the extract of Dracocephalum plant and characterized by XRD, FTIR, VSM, BET, FESEM, EDS-mapping, TEM, XPS, TPD-NH3, and TGA analyses. Also, to determine its efficiency in the adsorption process of tetracycline, the effect of pH (3–9), nanocomposite dose (0.025–2 g/L), initial pollutant concentration (5–100 mg/L), contact time (5–200 min), and temperature (5–50 °C) were studied. The results of the morphological properties of the magnetic nanocomposite confirmed the spherical shape of this nanoadsorber with an average size of 54 ± 31 nm. BET analysis showed that modification of MnFe2O4 material with ZIF-8 as a new nanoadsorber leads to excellent modification of SBET (143.8 m2/g) and VTotal (0.44 cm3/g). The highest removal efficiency of tetracycline in optimal conditions (pH = 7, contact time = 120 min, nanocomposite dose = 1.5 g/L, and temperature = 20 °C for a tetracycline concentration of 20 mg/L) was 90.11%. As the temperature increased, the removal efficiency increased from 40.46% to 95.06% during 120 min, which indicates that the adsorption reaction is endothermic. In addition, the data obtained from the isotherms of Langmuir (R2 = 0.958), Freundlich (R2 = 0.534), and Temkin (R2 = 0.747) showed that the tetracycline adsorption is monolayer and on the homogeneous surface of the synthesized magnetic nanoadsorber. The elimination process of tetracycline by nanoadsorber followed the pseudo-second order model (R2 = 0.998). Investigating the effect of interfering ions also confirmed the decrease in the adsorption efficiency. Also, the investigation of the reusability of the synthesized magnetic nanoadsorber in tetracycline adsorption indicates that after eight cycles, the efficiency decreases by %16.51. According to the results, the magnetic nanocomposite synthesized in this work can be a suitable and economical adsorber for the removal of tetracycline from aqueous environments.

Modified biochar activated by traditional Chinese medicine extract and its removal of tetracycline

Traditional Chinese medicine (TCM) has been widely used during the outbreak of Covid-19 in the past few years, causing waste of resources and environmental pollution. This paper will convert TCM into porous carbon-based materials through pyrolysis technology, and then combine it with TCM extract activator to synthesize a new type of adsorbent. The two main ingredients of Chinese patent medicine “Lianhua Qingwen Capsules”, Honeysuckle and Forsythia suspensa, will be used as raw materials. After the two herbs are crushed, the leachate is extracted, and the remaining residue is collected. The dried residue is activated and carbonized at high temperature to generate biochar. Further, the biochar will be soaked in TCM extraction liquid to load active ingredients. The adsorption mechanism of tetracycline (TC) by TCM biochar was explored based on the adsorption kinetics and adsorption isotherm fitting results. The microstructure, surface functional groups and crystal structure of TCM biochar will reveal the material properties of the adsorbent. The results show that compared with biochar without extract activation, the adsorption effect of combined biochar (BC-C) with the proportion of “Lianhua Qingwen Capsules” is greatly improved. BC-C has richer surface functional groups through TCM extract loading, which provides superior TC adsorption capacity (36.92 mg/g). The adsorption process of TC by TCM biochar follows the pseudo-second-order adsorption kinetic model and Freundlich adsorption isotherm model. The adsorption mechanism mainly involves pore filling, hydrogen bonding, electrostatic interaction and π-π interaction.

Comparative study by microwave pyrolysis and conventional pyrolysis of pharmaceutical sludge: Resourceful disposal and antibiotic adsorption

Compared with conventional pyrolysis, microwave pyrolysis has superior heat transfer performance and promotes the decomposition of organic matter. The paper focuses on the harmless treatment and resource utilization of pharmaceutical sludge (PS) by microwave heating and conventional heating methods. The experimental results showed that the conventional pyrolysis gas is dominated by CO2, CO and H2. For microwave pyrolysis gas, the “microwave effect” promoted secondary cracking of volatile fractions and increases the content of CH4, CxHy, H2 and CO through condensation, aromatization, and dehydrogenation. Conventional pyrolysis oils contained the highest percentage of oxygenated compounds. However, high-temperature microwave radiation accelerated the cleavage of polar oxygenated molecular bonds and long-chain hydrocarbons, thereby increasing the aromatics content of pyrolysis oils. The solid residues obtained from microwave pyrolysis is highly graphitized and porous, with a surface area of 146.2 m2/g. Furthermore, the solid residue was rich in pyridine-N and pyrrole-N that could be utilized for adsorption and catalysis. The MA-600 removes up to 99% of tetracycline (TC) in 6 h. It was also found that the adsorption process of TC by the two pyrolysis residues was consistent with the proposed secondary and Freundlich models.

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

Tetracycline decontamination from aqueous media using nanocomposite adsorbent based on starch-containing magnetic montmorillonite modified by ZIF-67

In the present study, starch/zeolitic imidazole framework-67 (ZIF-67) modified magnetic montmorillonite nanocomposite adsorbent to remove tetracycline (TC) as an emerging antibiotic-based contaminant from aqueous media. The surface properties of the adsorbents were investigated using FTIR, XRD, SEM, EDX-Map, XPS, TEM, BET, and VSM analysis. The specific surface area of MMT, St/MMT-MnFe2O4, and St/MMT-MnFe2O4-ZIF-67 magnetic nanocomposite samples were found to be 15.63, 20.54, and 588.41 m2/g, respectively. The influence of pH, adsorbent amount, initial TC concentration, temperature, contact time, and coexisting ions on TC elimination was explored in a batch adsorption system. The kinetic and equilibrium data were well matched with the pseudo-second-order and Langmuir isotherm models, respectively. The maximum monolayer adsorption capacities of TC were obtained to be 40.24, 66.1, and 135.2 mg/g by MMT, St/MMT-MnFe2O4, and St/MMT-MnFe2O4-ZIF-67 magnetic nanocomposite adsorbents, respectively. Also, thermodynamic studies illustrated that the TC adsorption process is exothermic and spontaneous. Furthermore, the magnetic nanocomposite adsorbent St/MMT-MnFe2O4-ZIF-67 showed good reusability and could be recycled for up to five cycles. This excellent adsorption performance, coupled with the facile separation of the magnetic nanocomposite, gave St/MMT-MnFe2O4-ZIF-67 a high potential for TC removal from aqueous media.

Facile and green synthesis of recyclable, environmentally friendly, chemically stable, and cost-effective magnetic nanohybrid adsorbent for tetracycline adsorption

Antibiotic contamination of water sources, particularly tetracycline (TC) contamination, has emerged as one of the global issues that needs action. In this research, ZnCoFe2O4@Chitosan (Ch) as a magnetic nanohybrid adsorbent was synthesized using the microwave-assisted co-precipitation method, and their efficiency for the TC adsorption process was investigated. FESEM (Field Emission Scanning Electron Microscope), EDX (Energy Dispersive X-ray), Mapping and line Scan, XRD (X-Ray Diffraction), FTIR (Fourier Transform Infrared Spectrometer), VSM (Vibrating Sample Magnetometer), Thermogravimetric analysis (TGA) and BET (Brunauer Emmett Teller) techniques were used to check and verify its physical and chemical properties. The removal of TC via the adsorption process from synthetic and real wastewater samples was investigated. The factors determining the TC adsorption process, comprising tetracycline concentration (5–30 mg/L), adsorbent dosage (0.7–2 g/L), contact time (2–45 min), and pH (3–11), were evaluated. The removal effectiveness for the synthetic sample and the real wastewater sample was 93 % and 80 %, respectively, under the ideal TC adsorption process parameters of pH 3, adsorbent dosage 1 g/L, TC initial concentration 5 mg/L, and contact time 30 min. According to kinetic and equilibrium studies, the adsorption of TC by ZnCoFe2O4@Ch follows pseudo-second-order kinetics and the Freundlich isotherm. Additionally, it was determined through the analysis of thermodynamic data that the process of exothermic adsorption is spontaneous and is followed by a decrease in disorder (ΔH = −15.16 kJ/mol, ΔS = −28.69 kJ/mol, and ΔG = −6.62 kJ/mol). After five cycles of recovery and regeneration, the ZnCoFe2O4@Ch magnetic nanocomposite was able to remove 65 % of the TC pollutant and had good chemical stability. The results showed that the magnetic nano-adsorbent ZnCoFe2O4@Ch is a novel magnetic nano-adsorbent with high adsorption capacity that can be utilized to eliminate pharmaceutical contaminants from aqueous solutions.

Artificial Neural Network [ANN] modeling for tetracycline adsorption on rice husk using continuous system

In this work, Tetracycline (TC) was dynamically adsorbed from aqueous solution using Raw Rice Husk (RRH). The removal of TC from various aqueous solutions was done continuously using a fixed bed column that was filled with RRH. It was investigated how various flowrates, bed heights, and TC concentrations impact the performance of the adsorption breakthrough. The dynamic TC adsorption process was modeled using an artificial neural network (ANN). Various error analysis techniques, such as the correlation coefficient, mean square error (MSE), and error histogram (R2) for the training, testing, and validation data, were employed to compare the model's predicted data with experimental data. The Artificial Neural Network (ANN) model that was utilized to predict TC adsorption using raw rice husk demonstrated a robust correlation coefficient of 0.999, This shows how well the trained model performed in predicting the TC adsorption process.

Adsorption performance on tetracycline by novel magnetic adsorbent derived from hydrochar of low-rank coal and sewage sludge

Herein, a novel magnetic tetracycline (TC) adsorbent (S3C7-Fe) was prepared by co-hydrothermal carbonization (HTC) of sewage sludge (SS) and low-rank coal (LC) combining with K2FeO4 modification. The adsorption performance at different conditions, adsorption kinetics, isotherms and thermodynamics were investigated. The results showed that S3C7-Fe exhibited high TC removal efficiency over a wide pH range (2∼11) and a high coexisting ion concentration range (50∼200 mg/L), and the maximum equilibrium adsorption capacity could reach to 884.04 mg/g. TC adsorption process by S3C7-Fe fitted the Langmuir and pseudo-second-order models, and the adsorption process was homogeneous and dominated by chemisorption. The π-π EDA interaction between the S3C7-Fe and TC molecular was the main mechanism, and pore filling, hydrogen bonding and cation-π complexation also contributed to the adsorption. Besides that, the microscopic interface interaction mechanism between the adsorbent and TC was analyzed both at molecular and electronic levels through theoretical calculations by density functional theory and frontier orbital theory. Interestingly, the results indicated that the oxygen and nitrogen containing functional groups in the adsorbent surface facilitated TC adsorption, and increasing the relative content of COOH and pyrrolic N could be the most effective pathway for improving adsorption capacity.

Enhanced adsorption performance of tetracycline in aqueous solutions using Mg-Al-LDH/AC nanocomposite

Water contamination with antibiotics promotes environmental antibiotic resistance. Tetracycline(TC), commonly used in agriculture, pollutes water and enables bacteria to develop resistance genes. Mg-Al-layered double hydroxides/Activated carbon (Mg-Al-LDH/AC) nanocomposite effectively removes tetracycline from water in this study. The synthesized adsorbent was characterized using Brunauer–Emmett–Teller (BET), Fourier-transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDS) tests, and exhibited a large surface area of 105.46 m2/g, a total pore volume of 0.4571 cm3/g, and an average pore diameter of 27.99 nm. The optimal conditions for eliminating TC using the Mg-Al-LDH/AC nanocomposite were determined via the central composite design response surface methodology (CCD-RSM) approach. The responses were evaluated using a second-order polynomial multiple regression model, which was found to be a satisfactory fit to the data based on the analysis of variance (R2 = 0.9690, R2Adj = 0.9478, and R2Pred = 0.9042). The ideal conditions were identified as pH = 5.1, 0.11 g of adsorbent, a TC concentration of 50 mg/L, and a contact time of 90 min. The adsorption isotherms showed that TC elimination follows the Langmuir model with a maximum adsorption capacity of 106.4 mg/g and a high R2 value of 0.9986. The kinetics of the TC adsorption process was found to fit the pseudo-second-order model with a correlation value of 0.9997. The values of ΔG, ΔH, and ΔS for TC were determined to be 1.90 kJ/mol (at 333.15 K), −41.97 kJ/mol, and −0.131 kJ/(mol·K), respectively. Additionally, the study showed that ionic strength did not affect the effectiveness of TC removal, and the adsorbent was effective in removing TC antibiotics in a range of ionic strengths. Finally, the study found that adding 20% by weight of AC to LDH resulted in the best TC removal efficiency.

A novel Fe-biochar from polyporaceae for enhancing tetracycline removal in water

The production of residues has expanded quickly with the growth of herbal medicine. Chaga mushroom (Inonotus obliquus) is a notable medicinal fungi belonging to the polyporaceae. The Chaga mushroom is a potential raw material for biochar preparation due to its porous structure. In this study, a carbothermic reduction method was used to prepare iron-loading biochar (Fe-BC) from Chaga mushroom residues. The Fe-BC was used as an adsorbent and catalyst to eliminate tetracycline (TC) from water. The specific surface area of the Fe-BC is 473.33 m2/g, and the major pore size of the Fe-BC varied from 0 to 3 nm. The effects of initial concentration, temperature, pH, ionic strength, and water source on TC adsorption were explored. The pseudo-second-order model and Langmuir model can describe the TC adsorption process, and the adsorption is endothermic and spontaneous. The maximum adsorption capacity of the Fe-BC for TC is 183.81 mg/g. The maximum TC removal reached more than 90% when the hydrogen peroxide (H2O2) was added. It can be predicted that high-quality adsorbent and catalyst can be obtained from the residues of polyporaceae for water pollution control.

Hydrothermal Pretreatment of KOH for the Preparation of PAC and Its Adsorption on TC.

The environment has been heavily contaminated with tetracycline (TC) due to its excessive use; however, activated carbon possessing well-developed pores can effectively adsorb TC. This study synthesized pinecone-derived activated carbon (PAC) with high specific surface area (1744.659 cm2/g, 1688.427 cm2/g) and high adsorption properties (840.62 mg/g, 827.33 mg/g) via hydrothermal pretreatment methods utilizing pinecones as precursors. The results showed that PAC treated with 6% KOH solution had excellent adsorption properties. It is found that the adsorption process accords with the PSO model, and a large amount of C=C in PAC provides the carrier for π-πEDA interaction. The results of characterization and the isothermal model show that TC plays a key role in the adsorption process of PAC. It is concluded that the adsorption process of TC on PAC prepared by hydrothermal pretreatment is mainly pore filling and π-πEDA interaction, which makes it a promising adsorbent for TC adsorption.

Application of a novel adsorbent UiO-66 modified by Ce to tetracycline removal in water bodies

In the present work, Ce-UiO-66, namely cerium-organic framework was prepared through rapid one-step solvothermal method, uncovering it potency to effectively get rid of tetracycline (TC) from an aqueous solution. The morphology and structure of Ce-UiO-66 materials were characterized by typical traditional methods such as FESEM, XRD, FTIR, and XPS. The process performance in terms of TC removal was investigated at different operating conditions. Specifically, when the dose, pH value, adsorption time, and temperature were 20 mg, 9, 180 min, and 25 ℃ respectively, the removal effect of TC was the best. The adsorption process of TC was described using the Freundlich model and the quasi second order model, respectively. The removal efficiency of TC by UiO-66 before modification was only 40.37%, and the adsorption amount was 44.38 mg⋅g−1, while the removal efficiency of TC adsorption by Ce-UiO-66 could reach about 90% under the optimal adsorption conditions, and the maximum adsorption amount was 86.95 mg⋅g−1. The data showed that Ce-UiO-66 exhibits good TC adsorption performance. And TC adsorption process was spontaneous and endothermic multi molecular layer chemical adsorption. Ce doping increased the quantity of active sites, and promoted the synergistic effects of electrostatic attraction, π-π conjugation, and hydrogen bonding between the adsorbent and TC, thus improving the adsorption effect of TC. As everyone knows that the application of UiO-66 in the adsorption field can be broadened by doping other metal ions, which prove that the metal skeleton adsorption material has broad development prospects in the next few years.

Effective adsorptive removal of tetracycline from aqueous solution by Zn-BTC@SBC derived from sludge:Experimental study and density functional theory (DFT) calculations

Overuse of tetracycline (TC) has caused serious damage to aquatic environment. Developing sustainable and efficient removal technologies for TC is of great significance to eliminate its ecological risks. In this study, a novel zinc metal organic framework porous biochar composite (Zn-BTC@SBC) derived from sludge was the first time synthesized and employed for adsorptive removal of TC from water.The adsorption process of TC followed the Elovich and Temkin model and the maximum capacity of Zn-BTC@SBC to adsorb TC was 125.9 mg/g. Characterization analysis demonstrated that the greater adsorption capacity of Zn-BTC@SBC was ascribed to its larger surface area, pore volume and abundant oxygen-containing functional groups. The fitting results showed that both chemisorption and physical adsorption predominated the adsorption process of TC on Zn-BTC@SBC. Further material characterization (FTIR and XPS) and density functional theory (DFT) calculations at the molecular level suggested that the good adsorption performance of Zn-BTC@SBC on TC might be due to chemisorption dominated by oxygen-containing functional groups, which included π-π conjugation, H-bonding and electrostatic interaction. And it was a spontaneous, endothermic and randomness increasing reaction. Both ion species/strength and solution pH significantly affected the adsorption capacity of Zn-BTC@SBC for TC. The natural water samples with complex composition (lake and river water) still showed 71.27–76.37 % of TC adsorbed. The used Zn-BTC@SBC was capable of maintaining its stable adsorption capacity by NaOH regeneration. This study demonstrated that Zn-BTC@SBC was a promising practicability in removal of TC and workable approach for sustainable utilization of sludge.

Porous biochar derived from walnut shell as an efficient adsorbent for tetracycline removal

In this study, a high-performance porous adsorbent was prepared from biochar through a simple one-step alkali-activated pyrolysis treatment of walnut shells, and it was effective in removing tetracycline (TC). The specific surface area (SSA) of potassium hydroxide-pretreated walnut shell-derived biochar pyrolyzed at 900 °C (KWS900) increased remarkably compared to that of the pristine walnut shell and reached 1713.87 ± 37.05 m2·g−1. The maximum adsorption capacity of KWS900 toward TC was 607.00 ± 31.87 mg·g−1. The pseudo-second-order kinetic and Langmuir isotherm models were well suited to describe the TC adsorption process onto KWS900. The KWS900 exhibited high stability and reusability for TC adsorption in the presence of co-existing anions or cations over a wide pH range of 1.0–11.0. Further investigations demonstrated that the proposed adsorption mechanism involved pore filling, hydrogen bonding, π–π stacking, and electrostatic interaction. These findings provide a valuable reference for developing biochar-based adsorbents for pollutant removal.

Biocrystal-encased manganese ferrite coupling with peroxydisulfate: Synergistic mechanism of adsorption and catalysis towards tetracycline removal

Biocrystal-encased manganese ferrite (BC@MnFe2O4), an adsorption/catalytic bifunctional catalyst, was synthesized for peroxydisulfate (PDS) activation and tetracycline (TC) removal. Under the optimal conditions (PDS 6.0 mM, pH 7.0, dosage 0.30 g L−1, and TC content 20.0 mg L−1), the TC removal efficiency reached 85.11% and maintained 79.07% after four cycles. Furthermore, inorganic anions (H2PO4− > HCO3− > NO3− > SO42− > Cl−) and natural organic matter (HA) inhibited TC elimination to varying degrees. Compared with the MnFe2O4 nanorods, BC@MnFe2O4 effectively alleviated the side effects caused by particle aggregation and reduced metal ion leaching. Adsorption kinetic and isotherm results exhibited that the adsorption process of TC on MnFe2O4 and BC@MnFe2O4 were better fitted with the pseudo-second-order and Langmuir models. The analyses of quenching experiment, electron paramagnetic resonance, and X-ray photoelectron spectroscopy demonstrated that Fe and Mn sites exposed on the BC@MnFe2O4 served as the catalytic centers for PDS activation, and OH, SO4−, and 1O2 were crucial reactive oxidant species contributing to the rapid TC degradation. Based on the determination of TC degradation intermediates, three possible degradation pathways were proposed, and TC was converted to small molecules via hydroxylation, demethylation, deamidation, dehydration, and other reactions. This study offers novel insights into the synergistic effect of adsorption and catalysis by inorganic-biological hybrid design, and gives inspiration for the construction of high-performance catalysts in organic wastewater treatment.

Adsorption modeling of tetracycline removal by multi-walled carbon nanotube functionalized with aspartic acid and poly-pyrrole using Bayesian optimized artificial neural network

BackgroundThe high use of tetracycline (TC) for the prevention and treatment of diseases has led to the formation of unknown compounds and various metabolized products of TC in aquatic environments. It seems that compounds containing carbon nanotubes have a good performance as an adsorbent for TC removal. MethodsMulti-Walled Carbon Nanotubes doped with aspartic acid (Asp) and polypyrrole (PPy) were synthesized to adsorb TC. The adsorbent morphology and its corresponding physicochemical properties were characterized by FTIR, XRD, FESEM, EDS and BET analysis. The adsorption capacity was investigated as a function of adsorbent dosage, pH, temperature, contact time, and initial concentration. Significant findingsThe maximum adsorption capacity was 34.50 mg/g, for an adsorbent dosage of 0.005 g, pH = 5, contact time of 60 min, and the temperature of 25℃. Reusability studies demonstrate that the removal efficiency of adsorbent after seven cycles has been more than 70%. Also, An Artificial Neural Network was developed to predict the adsorption capacity of the adsorbent. ANN performance was enhanced using Bayesian Optimization as the hyperparameter tuning scheme and 11 hyperparameters of the network as the decision variables. The improved ANN performance demonstrated a remarkable ability to model the adsorption process of TC (RMSE=0.33 and R2=0.9996).