Adsorption Characteristics of Synthesized Polyelectrolytes onto Alumina Nanoparticles and their Application in Antibiotic Removal.

The present study aims to investigate the adsorption of synthesized poly(2-acrylamide-2-methylpropane sulfonic acid) (PAMPs) onto alumina nanoparticles and their application in the removal of ciprofloxacin (CFX) antibiotic from a water environment. The PAMPs were successfully synthesized and characterized by nuclear magnetic resonance and gel-permeation chromatography methods. The number- and weight-average molecular weights of PAMPs were 6.76 × 105 and 7.28 × 106 g/mol, respectively. The charge reversal of nanoalumina after PAMPs modification from positive to -37.5 mV was determined by ζ-potential measurement, while the appearance of C ═ O and N-H functional groups in PAMPs observed by Fourier-transform infrared spectroscopy confirmed them as the main indicators for adsorption of PAMPs onto a nanoalumina surface. The maximum adsorption capacity of PAMPs onto nanoalumina in 100 mg/L KCl was about 10 mg/g. The adsorption isotherms were fitted well by a two-step adsorption model. Application of PAMPs-modified nanoalumina (PAMNA) in CFX removal was also thoroughly studied. The optimum conditions for CFX removal using PAMNA were found to be pH 6, 10 mM NaCl, contact time 90 min, and adsorption dosage 5 mg/mL. The CFX adsorption isotherms and kinetics were in accordance with the two-step and pseudo-second-order models, respectively. The application for CFX removal in actual hospital wastewater was greater than 80%. The results of this study demonstrate that PAMNA is a new and promising material for antibiotic removal from wastewater.

Adsorption Behavior of Polyelectrolyte onto Alumina and Application in Ciprofloxacin Removal.

This study aims to investigate the adsorption behavior of a strong polyelectrolyte poly(styrenesulfonate) (PSS) onto alumina particles. Adsorption of PSS onto positively charged alumina surface increased with increasing ionic strength, indicating that non-electrostatic and electrostatic interaction controlled the adsorption. The removal of an emerging antibiotic ciprofloxacin (CFX) from water environment using PSS-modified alumina (PMA) was also studied. The removal of CFX using PMA was much higher than that using alumina particles without PSS modification in all pH ranges of 2-11. The removal of CFX reached 98% under the optimum conditions of pH 6, contact time of 120 min, adsorbent dosage of five milligrams per milliliter and ionic strength 104-M NaCl. The adsorption isotherms of CFX at different salt concentrations fit well with a two-step adsorption model, while the adsorption kinetic fit well with a pseudo-second-order model with a good correlation coefficient (R2 > 0.9969). The CFX-removal from a hospital wastewater using PMA was more than 75%. Our study demonstrates that adsorption of PSS onto alumina to modify the particle surface is important to form a novel adsorbent PMA for CFX-removal from water environments.

Synthesis, Characterization, and Modification of Alumina Nanoparticles for Cationic Dye Removal.

In the present study, alumina nanoparticles (nano-alumina) which were successfully fabricated by solvothermal method, were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), and Brunauer⁻Emmett⁻Teller (BET) methods. The removal of cationic dye, Rhodamine B (RhB), through adsorption method using synthesized nano-alumina with surface modification by anionic surfactant was also investigated. An anionic surfactant, sodium dodecyl sulfate (SDS) was used to modify nano-alumina surface at low pH and high ionic strength increased the removal efficiency of RhB significantly. The optimum adsorption conditions of contact time, pH, and adsorbent dosage for RhB removal using SDS modified nano-alumina (SMNA) were found to be 120 min, pH 4, and 5 mg/mL respectively. The RhB removal using SMNA reached a very high removal efficiency of 100%. After four times regeneration of adsorbent, the removal efficiency of RhB using SMNA was still higher than 86%. Adsorption isotherms of RhB onto SMNA at different salt concentrations were fitted well by a two-step model. A very high adsorption capacity of RhB onto SMNA of 165 mg/g was achieved. Adsorption mechanisms of RhB onto SMNA were discussed on the basis of the changes in surface modifications, the change in surface charges and adsorption isotherms.