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

Removal of tetracycline antibiotics from agricultural wastewater efficiently using natural attapulgite functionalized MIL-53(Fe): adsorption mechanism and thermodynamic study

An excessive utilization of tetracycline antibiotics (TCs) in aquaculture and livestock farming significantly threatens human health and the vitality of aquatic environments. In this work, we used a one-pot hydrothermal approach with APT@MIL53-X hybrid material to achieve the selective removal of TC and OTC from agricultural wastewater. APT@MIL53-X showed significant chemical stability in the 3-10 pH range. Analysis of the adsorption results using adsorption kinetics, adsorption isotherm studies and adsorption thermodynamics indicated the presence of a monolayer physicochemical adsorption process with a maximum equilibrium adsorption of 600.43 mg g-1 for TC (removal efficiency of 93.5%) and 537.71 mg g-1 for OTC (removal efficiency of 91.4%). The elimination of TCs was not significantly impacted by the common buffer system of solution or the presence of water. Furthermore, a number of characterization techniques, including FT-IR and XPS, suggested that electrostatic interactions, π-π stacking, and hydrogen were potential adsorption processes. APT@MIL53-X showed stable recycling performance, maintaining a stable adsorption amount and chemical stability after six adsorption-desorption cycles of use, which proved that APT@MIL53-X has application possibilities for the agricultural wastewater treatment process. This study illustrates that APT@MIL53(Fe)-X hybrid material offers a novel method for the selective and effective elimination of agricultural wastewater.

Unraveling Ofloxacin Behavior in Aqueous Environments: Molecular Dynamics of Colloidal Formation and Surface Adsorption Mechanisms

Ofloxacin, a commonly prescribed antibiotic, raises serious environmental concerns due to its persistence in aquatic systems. This study offers new insights into the environmental behavior of ofloxacin and its interactions with carbon-based adsorbents with the aim of enhancing our understanding of its removal mechanisms via adsorption processes. Using a comprehensive computational approach, we analyzed the speciation, pKa values, and solubility of ofloxacin across various pH conditions, accounting for all four microspecies, including the often-overlooked neutral form. Our findings indicate that clustering of ofloxacin in water is influenced not only by solubility but also by electrostatic repulsion, dipole creation, and π-π interactions. At extreme pH levels, clustering is primarily driven by Coulombic forces and strong π-π interactions between different ofloxacin molecules. Density functional theory (DFT) was employed to optimize the molecular structures, and molecular dynamics (MD) simulations explored interactions among ofloxacin, water, and carbon surfaces. Hybrid Reverse Monte Carlo (HRMC) simulations were used to determine the disordered structure of an activated carbon cloth (ACC), specifically, KIP1200 (Dacarb company, France), for use in MD simulations. KIP1200 contains a small amount of oxygen (less than 2%), which supports our assumption of a predominantly carbon-based structure. Surface interactions were found to vary significantly depending on the ofloxacin form. The neutral form exhibited strong π-π interactions with flat surfaces, whereas the zwitterionic form displayed a greater affinity for curved surfaces. On KIP1200, adsorption was pH-dependent: acidic conditions enhanced adsorption due to reduced repulsion, while adsorption decreased under basic conditions. The aromatic rings in ofloxacin, combined with the high electronegativity of its fluorine atoms, played a critical role in facilitating adsorption through π-π interactions. These results deepen our understanding of ofloxacin microspecies, colloid formation, and adsorption mechanisms under diverse conditions.

Bio-based adsorption foam composed of MOF and polyethyleneimine-modified cellulose for selective anionic dye removal

With the increase of sustainable development goal, the bio-based adsorption materials with high and selective dye removal are important for water treatment in the dyeing industry. In this paper, a bio-based adsorption foam composed of metal-organic frameworks (MOF) and polyethyleneimine (PEI)-modified cellulose was prepared by a three-step process, i.e., PEI modification of cellulose fibers (PC), MOF decoration of PEI-modified cellulose (MIL-53@PC), and in-situ foaming with polyurethane. PEI modification provides cellulose fiber with more active sites for both dye adsorption and MOF bonding. We found that MIL-53 crystals were tightly bonded on the surface of PC through hydrogen bonding. Because of the abundant adsorption sites (e.g., amines, iron oxide group), the MIL-53@PC demonstrated high adsorption capacity and selectivity for anionic dye (e.g., 936.5 mg/g for methyl orange) through electrostatic interaction and hydrogen bonding. Finally, MIL-53@PC particles were blended with a waterborne polyurethane prepolymer to prepare a three-dimensional hydrophilic foam (MIL-53@PC/PUF), which not only maintained high adsorption capacity and selectivity of MIL-53@PC and also improved its recyclability and reusability. The MIL-53@PC/PUF offers a promising solution for dye wastewater treatment.

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.

Calcined Bean Dregs-Hydrocalumite Composites as Efficient Adsorbents for the Removal of Ofloxacin

Calcined bean dregs-hydrocalumite composites were prepared through in situ self-assembly of hydrocalumite on the surface of bean dregs and used for the adsorption of ofloxacin from water. The adsorbents were characterized by scanning electron microscopy, X-ray powder diffraction, and N2 physical adsorption. The results showed that the adsorption performance of calcined bean dregs-hydrocalumite composites for ofloxacin was much better than that of a single bean dreg carbon or calcined hydrocalumite. The effects of preparation and adsorption conditions on the adsorption property of calcined bean dregs-hydrocalumite for ofloxacin were also investigated. The adsorption ratio of ofloxacin reached up to 99.93% using 4 g·L-1 adsorbent dosage with 20 mg·L-1 initial concentration of ofloxacin at 30 °C in 2 h. The adsorption process mainly occurred in the first 5 min. In addition, the adsorption of ofloxacin by calcined bean dregs-hydrocalumite was more in line with pseudo-second-order dynamics and the Langmuir isotherm model.