Removal of enrofloxacin from aqueous solutions using illite and synthetic zeolite X

Green Synthesis of Fe-Cu Bimetallic Supported on Alginate-Limestone Nanocomposite for the Removal of Drugs from Contaminated Water

In this study Fe-Cu supported on Alginate-limestone (Fe-Cu/Alg-LS) was prepared. The increase in surface area was the main motivation for the synthesis of ternary composites. Scanning electronic microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were used to examine the surface morphology, particle size, percentage of crystallinity, and elemental content of the resultant composite. Fe-Cu/Alg-LS was used as an adsorbent for the removal of drugs such as ciprofloxacin (CIP) and levofloxacin (LEV)from contaminated medium. The adsorption parameters were computed using kinetic and isotherm models. The maximum removal efficiency of CIP (20 ppm) and LEV (10 ppm) was found to be 97.3% and 100%, respectively. The optimal conditions were pH 6 and 7 for CIP and LEV, optimum contact time 45, 40 min for CIP and LEV, and temperature of 303 K. The pseudo-second-order model, which confirmed the chemisorption properties of the process, was the most appropriate kinetic model among the ones used, and the Langmuir model, which was the most appropriate isotherm model. Moreover, the parameters of thermodynamics were also assessed. The results imply that the synthesized nanocomposites can be used to remove hazard materials from aqueous solutions.

Fabrication of graphene oxide/inulin impregnated with ZnO nanoparticles for efficient removal of enrofloxacin from water: Taguchi-optimized experimental analysis

A novel nano-adsorbent zinc oxide impregnated graphene oxide/inulin (ZGI) was prepared for the investigation of the removal efficiency of enrofloxacin. Characterization of the nano-adsorbent was accomplished through Fourier transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with EDS, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The average crystallite size of nanomaterial (ZGI) calculated from XRD data was 14.82 nm. The adsorption of enrofloxacin onto ZGI was performed in batch mode. The variables of adsorption process such as adsorbent dose, pH, contact time and initial concentration of enrofloxacin were optimized by Taguchi method to achieve the maximum removal efficiency. The optimum values of variables were: adsorbent dose = 25 mg, pH = 7, contact time = 60 min and initial concentration = 50 mg/L. The maximum adsorption capacity and removal efficiency of the material for enrofloxacin were 317.83 mg/g and 98.60%, respectively at 303 K. Redlich-Peterson isotherm model was the best fitted among the various isotherm models based on highest R² values (0.9978-0.9981) and lowest χ² (3.43 ×10^-4-2.00×10^-3). Kinetic data followed pseudo-second order model (R² ≥ 0.9974) more accurately as compared to pseudo-first order model (R²≤0.9772). The adsorption mechanism was illustrated on the basis of XPS and Raman studies. Reusability investigation showed that the nano-adsorbent ZGI could be used up to 5 adsorption-desorption cycles with greater than 90% removal efficiency.

Novel Magnetite Nanocomposites (Fe3O4/C) for Efficient Immobilization of Ciprofloxacin from Aqueous Solutions through Adsorption Pretreatment and Membrane Processes

The release of antibiotics into the aquatic environment enhances the drug resistance capabilities of microorganisms, as in large water reservoirs, their concentrations are lesser than their minimum bactericidal concentration, and microorganisms living there become resistant to such antibiotics. Therefore, robust hybrid technologies, comprising of efficient conventional adsorption processes and modern membranes processes, are needed to effectively remove such pollutants from industrial effluents. The present study is an attempt where iron-based magnetic carbon nanocomposites (Fe3O4/C) were prepared from mango biomass precursors and utilized as an adsorbent for the removal ciprofloxacin from wastewater in combination with three types of membranes that are robust but fouled by organic matter. The Fe3O4/C composite was characterized using energy dispersive X-Ray (EDX) technique, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Brunauer Emmett Teller (BET), Barrett–Joyner-Halenda (BJH) surface area, Thermogravimetric (TG)/Thermal differential analysis (DTA) and point of zero charge pH analyses. Initially, batch adsorption experiments were used to determine adsorption parameters. Then the adsorption unit was coupled with membrane pilot plant where the adsorption role was to adsorb CIPRO before entering into the membrane unit to control fouling caused by selected antibiotic. In batch experiments, the equilibrium time was found as 60 min and kinetics data were more favorably accommodated with the pseudo-2nd-order model (R2 = 0.99). Langmuir model (R2 = 0.997) more favorably accommodated the equilibrium data in comparison to other models used such as the Freundlich (R2 = 0.86), Temkin (R2 = 0.91) and Jovanovich (R2 = 0.95) models. The thermodynamic aspects of the adsorption process were also evaluated and the process was found to be spontaneous, feasible and exothermic. The influence of adsorbent dosage and pH, were also investigated, where the optimal adsorption conditions were: optimum pH = 7 and optimum Fe3O4/C dosage = 0.04 g. The CIPRO-loaded nanocomposite was regenerated with NaOH, CH3OH and distilled water several times. Improved percent rejections of CIPRO and permeate fluxes with the membrane/adsorption operation were observed as compared to naked membrane operations. Magnetic adsorbent was found as a best solution of foul control; a defect in the modern robust technology of membranes. However, further experimentation is needed to validate the present findings.

Effects of clay colloids on ciprofloxacin transport in saturated quartz sand porous media under different solution chemistry conditions

Antibiotics, a highly prevalent class of environmental organic pollutants, are becoming a matter of global concern. Clay minerals that are ubiquitous in subsurface environments may play an important role in the fate and transport of antibiotics. Taking ciprofloxacin (CIP) as a model antibiotic, this work explored the role of clay colloids (kaolinite and montmorillonite) on the adsorption and transport of CIP under different chemical solution conditions. The adsorption isotherms showed that montmorillonite colloids had a larger CIP sorption capacity than kaolinite colloids. The results of transport experiments indicated that montmorillonite colloids could promote CIP transport in saturated sand columns, but the addition of kaolinite colloids affected CIP mobility to a much smaller extent. The much stronger transport-enhancement effect of montmorillonite colloids was due to CIP adsorbed strongly to the colloids and desorption hysteresis of colloid-adsorbed CIP, likely stemming from the intercalation of this antibiotic in the interlayer of montmorillonite. Interestingly, transport of clay colloids increased with the increasing pH from 5.0 to 9.0; however, CIP transport decreased with the increasing pH in the presence of clay colloids. The observations were likely attributable to pH-dependent ciprofloxacin adsorption/desorption to clay minerals. Increasing the concentrations of NaCl and CaCl₂ generally decreased the contaminant-mobilizing ability of montmorillonite colloids, mainly by increasing the aggregation of colloids and thus, decreasing the transport of colloid-adsorbed CIP. Moreover, under the test conditions (1 mM NaCl and pH 7.0), the presence of CIP inhibited the transport of clay colloids due to the increase in aggregate size of clay colloids with the addition of CIP. Overall, these findings suggest that clay colloids with high adsorption abilities for antibiotics in the subsurface environment may act as a carrier for certain antibiotic compounds.

Separation of Levofloxacin from Industry Effluents Using Novel Magnetic Nanocomposite and Membranes Hybrid Processes

Magnetic carbon nanocomposite (MCN) was synthesized from waste biomass precursor, pineapple. The prepared adsorbent was characterized using different instrumental techniques and was used to remove levofloxacin (LEV) from effluents. The maximum sorption of LEV was observed at pH 7. Pseudo-2nd-order (PSO) kinetic was found to be the best model that fits well the adsorption kinetics data. For Langmuir adsorption isotherm, the R² value was higher as compared with other isotherms. The Van't Hoff equation was used for thermodynamic parameters determinations. ΔS° (standard entropy) was positive and ΔG° (standard Gibb's free energy) was negative: -0.37, -1.81, and -3.73 kJmol⁻¹ corresponding to 25, 40, and 60°C. The negative values of ΔG° at different temperatures stipulate that the adsorption of LEV was spontaneous in nature and adsorbent has a considerable affinity for LEV molecules. The MCN was then utilized in hybrid way by connecting with ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) membranes in series and as a result enhanced permeate fluxes were observed. The percent retention of LEV molecules was lower with UF membrane and with NF it was 96%, while it was 100% with RO. For MCN/UF and MCN/NF systems, improvement in % retention was recorded.