Application of Magnetic Composites in Removal of Tetracycline through Adsorption and Advanced Oxidation Processes (AOPs): A Review

Construction of magnetic MoS2/NiFe2O4/MIL-101(Fe) hybrid nanostructures for separation of dyes and antibiotics from aqueous media

In this study, MoS2/NiFe2O4/MIL-101(Fe) nanocomposite was synthesized by hydrothermal method and used as an adsorbent for the elimination of organic dyes and some antibiotic drugs in aqueous solutions. The synthesized nanocomposite underwent characterization through different techniques, including scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area analysis, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), zeta potential analysis, vibrating sample magnetometry (VSM), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). These results demonstrated the successful insertion of MoS2within the cavities of MIL-101(Fe). The as-prepared magnetic nanocomposite was used as a new magnetic adsorbent for removing methylene blue (MB) and rhodamine B (RhB) organic dyes and tetracycline (TC) and ciprofloxacin (CIP) antibiotic drugs. For achieving the optimized conditions, the effects of initial pH, initial dye and drug concentration, temperature, and adsorbent dose on MB, TC, and CIP elimination were investigated. The results revealed that at a temperature of 25 °C, the highest adsorption capacities of MoS2/NiFe2O4/MIL-101(Fe) for MB, TC, and CIP were determined to be 999.1, 2991.3, and 1994.2 mg g-1, respectively. The pseudo-second-order model and Freundlich model are considered suitable for explaining the adsorption behavior of the MoS2/NiFe2O4/MIL-101(Fe) nanocomposite. The magnetic nanocomposite was very stable and had good recycling capability without any change in its structure.

Magnetic MnFe2O4/ZIF-67 nanocomposites with high activation of peroxymonosulfate for the degradation of tetracycline hydrochloride in wastewater

Advanced oxidation processes (AOPs) based on PMS have been used to degrade various refractory pollutants such as drugs, endocrine disruptors, dyes and perfluorinated compounds due to their wide application range, mild reaction conditions, fast reaction rate and simple operation. In this study, tetracycline hydrochloride (TCH) was degraded based on this method. Magnetic MnFe2O4/ZIF-67 nanocomposites were successfully prepared by a hydrothermal method, which combined the magnetic separation characteristics of MnFe2O4 with the high catalytic activity of ZIF-67 and were used to activate peroxymonosulfate (PMS) to efficiently degrade TCH. Satisfactory removal results were obtained with this simple and readily available material, with 82.6% of TCH removed in 15 min. The effect of different conditions on the degradation effect was investigated, and the optimal catalyst concentration and PMS concentration were determined to be 0.1 g L-1 and 0.2 g L-1, respectively, and all had good degradation effects at pH 5 to 10. XPS, impedance test and radical quenching experiments were used to investigate the degradation mechanism. The results showed that sulfate radical (SO4-˙) was the main active species in the degradation process. In addition, the catalyst has good cyclic stability, which provides a new idea for the removal of TCH in wastewater. It is worth mentioning that the catalyst also has good degradation property for other pollutants.

Preparation of Oily Sludge-Derived Activated Carbon and Its Adsorption Performance for Tetracycline Hydrochloride

Oily sludge-derived activated carbon was prepared using the potassium hydroxide (KOH) activation method using oily sludge as a raw material, and one-factor experiments determined the best conditions for preparing activated carbon. The activated carbon's morphological structure and surface chemical properties were analyzed by scanning different characterization tools, and the adsorption behavior of tetracycline hydrochloride was investigated. The results showed that the optimum conditions for preparing oily sludge-derived activated carbon were an activation temperature of 400 °C, activation time of 30 min, activator concentration of 1 mol/L, and impregnation ratio of 2 mL/g. After activation, the activated carbon had more pores and a more orderly crystal structure arrangement, the specific surface area was 2.07 times higher than that before activation, and the surface was rich in functional groups such as -HO, -C-O, -C=C, and -C-H, which increased the active sites of activated carbon. Physicochemical effects dominated the adsorption process. It belonged to the spontaneous heat absorption process under the quasi-secondary kinetic and Langmuir isothermal models. The maximum monolayer adsorption capacity of KOH-activated carbon was 205.1 mg·g-1.

Batch Experimental Studies and Statistical Modeling for the Effective Removal of Tetracycline from Wastewater Using Bimetallic Zn-Cu-Metal-Organic Framework@Hydrogel Composite Beads

Antimicrobial resistance (AMR) is on an upsurge as more and more broad-spectrum antibiotics are being used haphazardly, resulting in imbalances in the ecosystem and disrupting common/systematic clinical protocols. To combat this issue, metal-organic framework embedded zinc-copper-benzenedicarboxylate@calcium alginate composite beads (Zn-Cu-BDC@CA CBs) were synthesized and utilized for the adsorption of tetracycline (TC) from water. The surface morphology, presence of functional groups, surface area, and thermal stability of Zn-Cu-BDC@CA CBs were evaluated by field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), and thermal gravimetric analysis (TGA), respectively. Batch adsorption experiments were also carried out to optimize the adsorption performance of Zn-Cu-BDC@CA CBs for TC by adjusting the key parameters, including pH of the solution, contact time, adsorbent dosage, temperature, and initial concentration of TC. From the RSM model, 96.8% removal of TC takes place under the optimum conditions (pH = 7.3, mass = 17.2 mg, concentration = 21.3 ppm, time = 3.4 h, and temperature = 31.8 °C), which aligns closely with the experimental batch study, where the addition of 20 mg of adsorbent to a 20 mL TC solution (20 mg/L) at a pH of 7 and a temperature of 27 °C yielded an impressive TC removal efficiency of 96.55% within 180 min. Zn-Cu-BDC@CA CBs possess homogeneous adsorption surfaces, and TC is adsorbed via monolayer chemisorption, according to the results derived from the Langmuir isotherm model and pseudo-second-order kinetic model. The thermodynamic analysis indicated that the adsorption process is both endothermic and spontaneous. In their entirety, the synthesized Zn-Cu-BDC@CA CBs exhibit certain operational advantages, such as simple separation, satisfactory adsorption performance, and decent recyclability, indicating their viability for industrial application of elimination of TC residues from aquatic environments.

Exploring the potential of bacterial-augmented floating treatment wetlands for the remediation of detergent-contaminated water

Due to industrialization and urbanization, the use of detergents inadvertently led to contamination of aquatic environments, thus posing potential threat to aquatic organisms and human health. One of the main components of detergents is linear alkylbenzene sulfonate (LAS), which can cause toxic effects on living organisms, particularly aquatic life in the environment. In this study, floating treatment wetlands (FTWs) mesocosms were developed and augmented with LAS-degrading bacteria. The plant species, Brachiaria mutica (Para grass), was vegetated to establish FTWs and bacterial consortium (1:1:1:1) of Pseudomonas aeruginosa strain PJRS20, Bacillus sp. BRRH60, Acinetobacter sp. strain CYRH21, and Burkholderia phytofirmans Ps.JN was augmented (free or immobilized) in these mesocosms. Results revealed that the FTWs removed LAS from the contaminated water and their augmentation with bacteria slightly increased LAS removal during course of the experiment. Maximum reduction in LAS concentration (94%), chemical oxygen demand (91%), biochemical oxygen demand (93%), and total organic carbon (91%) was observed in the contaminated water having FTWs augmented with bacterial consortium immobilized on polystyrene sheet. This study highlights that the FTWs supported with immobilized bacteria on polystyrene sheets can provide an eco-friendly and sustainable solution for the remediation of LAS-bearing water, especially for developing countries like Pakistan.

Preparation of Chitosan-Modified Bentonite and Its Adsorption Performance on Tetracycline

In this study, chitosan-modified bentonite was synthesized using the coprecipitation method. When the Na₂CO₃ content was 4% (weight of soil) and the mass ratio of chitosan to bentonite was 1:5, the adsorption performance of the chitosan/bentonite composite was best. The adsorbent was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller measurement. Various characterization results demonstrate that chitosan successfully entered the bentonite interlayer and increased layer spacing but did not modify bentonite's laminar mesoporous structure, and the -CH₃ and -CH₂ groups of chitosan appeared on chitosan-modified bentonite. Tetracycline was used as the target pollutant in the static adsorption experiment. The adsorption capacity was 19.32 mg/g under optimal conditions. The adsorption process was more consistent with the Freundlich model and the pseudo-second-order kinetic model, indicating that it was a nonmonolayer chemisorption process. The adsorption process is a spontaneous, endothermic, entropy-increasing process, according to thermodynamic characteristics.

Advances in Remediation of Contaminated Sites

With the development of the social economy, the population has increased sharply, and the land area involved in people’s production and life is also gradually increasing [...]

Tetracycline adsorption on magnetic sludge biochar: size effect of the Fe3O4 nanoparticles

Activated sludge, which is difficult and expensive to treat and dispose of, is a key concern in wastewater treatment plants. In this study, magnetic sludge biochar containing activated sludge and different sizes (14.3, 40.2 and 90.5 nm) of Fe3O4 nanoparticles was investigated as an effective adsorbent for tetracycline (TC) adsorption. Magnetic sludge-based biochar was prepared by a facile cross-linking method and characterized by transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and zeta potential analysis. The adsorption performances of TC on three kinds of adsorbents were investigated. Although 14.3 nm Fe3O4 nanoparticles could be inclined to aggregate and partially filled with pores of biochar, it turned out that magnetic sludge biochar with 14.3 nm Fe3O4 nanoparticles exhibited optimum performance for TC removal with adsorption capacity up to 184.5 mg g-1, due to the larger amounts of functional groups and the change of zeta potential. Furthermore, the adsorption kinetics of TC on three kinds of adsorbents were studied, which implied that the pseudo-second-order kinetic model exhibited the better fit for the entire sorption process.