Preparation and adsorptive application of novel superparamagnetic zirconia material

Adsorption Removal of Environmental Hormones of Dimethyl Phthalate Using Novel Magnetic Adsorbent

Magnetic polyvinyl alcohol adsorbent M-PVAL was employed to remove and concentrate dimethyl phthalate DMP. The M-PVAL was prepared after sequential syntheses of magnetic Fe₃O₄ (M) and polyvinyl acetate (M-PVAC). The saturated magnetizations of M, M-PVAC, and M-PVAL are 57.2, 26.0, and 43.2 emu g⁻¹ with superparamagnetism, respectively. The average size of M-PVAL by number is 0.75 μm in micro size. Adsorption experiments include three cases: (1) adjustment of initial pH (pH₀) of solution to 5, (2) no adjustment of pH₀ with value in 6.04–6.64, and (3) adjusted pH₀ = 7. The corresponding saturated amounts of adsorption of unimolecular layer of Langmuir isotherm are 4.01, 5.21, and 4.22 mg g⁻¹, respectively. Values of heterogeneity factor of Freundlich isotherm are 2.59, 2.19, and 2.59 which are greater than 1, revealing the favorable adsorption of DMP/M-PVAL system. Values of adsorption activation energy per mole of Dubinin-Radushkevich isotherm are, respectively, of low values of 7.04, 6.48, and 7.19 kJ mol⁻¹, indicating the natural occurring of the adsorption process studied. The tiny size of adsorbent makes the adsorption take place easily while its superparamagnetism is beneficial for the separation and recovery of micro adsorbent from liquid by applying magnetic field after completion of adsorption.

Modification of Fe3O4 superparamagnetic nanoparticles with zirconium oxide; preparation, characterization and its application toward fluoride removal

Fe₃O₄ superparamagnetic nanoparticles (NPs) modified with zirconia (ZrO₂) were synthesized (Fe₃O₄@ZrO₂) using a chemical co-precipitation method and used as a nanoadsorbent in the removal of excessive fluoride from aqueous solutions.

Nucleation and growth kinetics of zirconium-oxo-alkoxy nanoparticles

Nucleation and growth of zirconium-oxo-alkoxy nanoparticles were studied in a sol–gel process in n-propanol solution in quasi-perfect micromixing conditions.

Application of bifunctional magnetic adsorbent to adsorb metal cations and anionic dyes in aqueous solution

A magnetic adsorbent, amine-functionalized silica magnetite (NH(2)/SiO(2)/Fe(3)O(4)), has been synthesized to behave as an anionic or cationic adsorbent by adjusting the pH value of the aqueous solution to make amino groups protonic or neutral. NH(2)/SiO(2)/Fe(3)O(4) were used to adsorb copper ions (metal cation) and Reactive Black 5 (RB5, anionic dye) in an aqueous solution in a batch system, and the maximum adsorption were found to occur at pH 5.5 and 3.0, respectively. The adsorption equilibrium data were all fitted the Langmuir isotherm equation reasonably well, with a maximum adsorption capacity of 10.41 mg g(-1) for copper ions and of 217 m g g(-1) for RB5. A pseudo-second-order model also could best describe the adsorption kinetics, and the derived activation energy for copper ions and RB5 were 26.92 kJ mol(-1) and 12.06 kJ mol(-1), respectively. The optimum conditions to desorb cationic and anionic adsorbates from NH(2)/SiO(2)/Fe(3)O(4) were provided by a solution with 0.1M HNO(3) for copper ions and with 0.05 M NaOH for RB5.

Kinetics and equilibrium of desorption removal of copper from magnetic polymer adsorbent

This study examined the desorption of copper ions, which were adsorbed on the magnetic polymer adsorbent (MPA) of polyvinyl acetate-iminodiacetic acid (M-PVAC-IDA), by ethylenediaminetetraacetic acid (EDTA). Stage-wise desorptions were applied to remove the Cu(II) ions from the Cu(II) adsorbed M-PVAC-IDA (A-M-PVAC-IDA). About seven desorption runs were needed to regenerate the A-M-PVAC-IDA. The Cu(II) desorbed M-PVAC-IDA (D-M-PVAC-IDA) was then reused to adsorb the Cu(II) ions from the Cu(II) ions-containing solution. The cyclic adsorption and desorption operations (CADOs) were performed to further elucidate the kinetics and equilibria of the desorption system of EDTA/A-M-PVAC-IDA and the adsorption system of Cu(II)-containing solution/D-M-PVAC-IDA. Two simple kinetic models, the pseudo-first-order equation and pseudo-second-order equation, were employed to simulate the kinetic behaviors of adsorption and desorption. With respect to the kinetics of adsorption behavior, the simulated results by both kinetic models exhibit good agreement with the experimental data. However, the adsorption capacities (q(e)) estimated by the pseudo-first-order equation are more accurate in comparison with those simulated by the pseudo-second-order equation. As for the desorption kinetics, the examination of correlation coefficients of model fittings of data shows that the pseudo-first-order kinetic model gives the better agreement for the cases with different initial solid-phase concentrations and can accurately compute the equilibrium concentrations of solid-phase. The values of q(e) after CADOs are consistent with the predicted results via the previous work, evidencing that the adsorption behavior and the characteristics of the regenerated adsorbent of D-M-PVAC-IDA were not altered. In the experiments of desorbing copper ions and CADOs, the desorption isotherm was set up. The Freundlich and Langmuir adsorption (or desorption) isotherms were used to simulate the equilibrium of desorption. The results indicate that the Freundlich equation shows better agreement with the experimental data than the Langmuir equation. The information thus obtained is useful for the better use of M-PVAC-IDA on the removal of heavy mental ions of Cu(II) from the Cu(II) ion-containing water solution with the consideration of its regeneration.