Synthesis, performance, and mechanisms of strontium ferrite-incorporated zeolite imidazole framework (ZIF-8) for the simultaneous removal of Pb(II) and tetracycline

Application of apophyllite and thomsonite natural zeolite as modified adsorbents for the removal of zinc from acid mine drainage

Materials composed of natural zeolite have the potential to serve as highly effective adsorbents in the treatment of wastewater. The present study explores zeolite resin-based Apophyllite and Thomsonite as adsorbents for removing Zinc from acid mine drainage solution. The characteristics of the natural zeolites (Apophyllites and Thomsonite) are investigated using X-ray diffraction, Fourier-transform infrared spectroscopy and Field emission scanning electron microscopy analysis. The removal of Zinc from AMD is explored, and the influence of metal ion concentration, resin dose, and pH is investigated using a batch exchange resin-based experimental method. Maximum zinc removal occurs in the pH range of 2-6 with an initial zinc content of 50-250 mg/L and a resin dosage of 25-700 mg/L, indicating that the adsorption process is pH-dependent. Various isotherm models, including those proposed by Freundlich and Langmuir as well as Redlich-Peterson, Dubinin, and Temkin, are used to verify the results of the experimental research. All these isotherm models' constants are determined. Both resins showed different sorption efficiencies at different operating conditions. However, highest Zn removal efficiency of 86.2% was observed for the Thomsonite zeolite resin whereas Apophyllite zeolite resin showed maximum Zn uptake of 81.6%. Thus, Thomsonite was found to be an effective sorbent.

Bimetal doped Cu-Fe-ZIF-8/g-C3N4 nanocomposites for the adsorption of tetracycline hydrochloride from water

Bimetal doped Cu-Fe-zeolitic imidazole framework-8 (ZIF-8)/graphitic carbon nitride (GCN) (Cu-Fe-ZIF-8/GCN) nanocomposites were prepared via one-pot and ion-exchange methods. The main influencing factors, such as adsorbent concentration, TC concentration, initial pH, and coexisting ions, were evaluated in detail. Due to the suitable pore structures and the presence of multiple interactions on the surface, the nanocomposite showed a high adsorption capacity up to 932 mg g-1 for tetracycline hydrochloride (TC), outperforming ZIF-8 by 4.8 times. The adsorption kinetics and adsorption isotherm were depicted in good detail using pseudo-second-order kinetic and Langmuir models, respectively. Thermodynamic calculation revealed that the adsorption of the nanocomposite under experimental conditions was a spontaneous heat absorption process, and was primarily driven by chemisorption. After four cycles of use, the nanocomposite retained 87.2% of its initial adsorption capacity, confirming its high reusability and broad application prospects in removing tetracycline-type pollutants from wastewater.

Fabricating Materials of Institute Lavoisier-53(Fe)/zeolite imidazolate framework-8 hybrid materials as high-efficiency and reproducible adsorbents for removing organic pollutants

Environmental pollution by emerging contaminants has become an urgent problem. Herein, novel binary metal-organic framework hybrids were constructed from Materials of Institute Lavoisier-53(Fe) (MIL-53(Fe)) and zeolite imidazolate framework-8 (ZIF-8) for the first time. A battery of characterizations were employed to determine the MIL/ZIF hybrids' properties and morphology. Furthermore, the MIL/ZIF towards toxic antibiotics (tetracycline, ciprofloxacin and ofloxacin) were studied to explore their adsorption abilities. The present work disclosed that the obtained MIL-53(Fe)/ZIF-8 = 2:3 possessed an eminent specific surface area with an admirable removal efficiency of tetracycline (97.4%), ciprofloxacin (97.1%) and ofloxacin (92.4%), respectively. The tetracycline adsorption process conformed to the pseudo-second-order kinetic model and this process was more compatible with the Langmuir isotherm model with the highest adsorption capacity of 215.0 mg g^-1. Moreover, the process of removing tetracycline was proved to be spontaneous and exothermic by the thermodynamic results. Furthermore, the MIL-53(Fe)/ZIF-8 = 2:3 towards tetracycline exhibited significant regeneration ability. The effects of pH, dosage, interfering ions and oscillation frequency on tetracycline adsorption capacity and removal efficiency were also investigated. The primary factors contributing to the decent adsorption ability between MIL-53(Fe)/ZIF-8 = 2:3 and tetracycline included electrostatic, π-π stacking, hydrogen bonding and weak coordination interactions. Additionally, we also investigated the adsorption ability in real wastewater. Thus, the proposed binary metal-organic framework hybrid materials can be deemed a promising adsorbent in wastewater purification.

Optimal preparation of a core-shell structural magnetic nanoadsorbent for efficient tetracycline removal

As emerging contaminants, tetracyclines pose a severe threat to aquatic environments and human health. Therefore, developing efficient approaches to remove tetracyclines from water has attracted a large amount of interest. Herein, a novel core-shell structural magnetic nanoadsorbent (FSMAS) was facilely prepared by graft copolymerization of acrylamide (AM) and sodium p-styrene sulfonate (SSS) monomers on the surface of vinyl-modified Fe₃O₄@SiO₂ (FSM). From single factor experiments, the optimal graft copolymerization conditions were concluded to be the following: initiator concentration = 1.2‰, reaction pH = 9, monomer molar ratio = 7 : 3. The surface morphology, microstructure and physicochemical properties of as-prepared FSMAS were fully evaluated by different characterization techniques, including SEM, TEM, FTIR, XPS, XRD and VSM. The adsorption performance of FSMAS towards tetracycline hydrochloride (TCH) was systematically studied by batch adsorption experiments. Results showed that the adsorption capability of the adsorbent was largely enhanced after graft copolymerization. The removal rate of TCH by FSMAS reached 95% at solution pH = 4.0, almost 10 times higher than FSM. Besides, the adsorption process of TCH by FSMAS was very efficient, 75% of pollutant could be adsorbed after only 10 minutes, attributed to the stretch of polymer chains and the strong affinity provided by abundant functional groups. Furthermore, TCH-loaded FSMAS was easily regenerated with HCl solution, the regeneration rate was higher than 80% after five adsorption-desorption cycles. Superior adsorption capability, fast solid-liquid separation speed and satisfactory reusability demonstrated the great potential of FSMAS in practical tetracycline removal.