EGTA functionalized magnetic microsphere (Fe 3 O 4 @SiO 2 @EGTA) was prepared for the removal of Cr(III) from highly saline organic wastewater environment. The synthesized adsorbent was characterized with Fourier transform infrared (FTIR), powder x-ray diffraction (XRD), thermogravimetric analysis (TGA) and x-ray photoelectron spectrometry (XPS). The characterization techniques depicted the successful surface modification of magnetic particles (Fe 3 O 4 @SiO 2 ) with the functional groups of EGTA without changing its crystal structure. The maximum adsorption amount of Cr(III) was 25.25 mg ⋅ g −1 at pH 4.0. The Langmuir isotherm was well fitted on the adsorption data, while adsorption equilibrium was achieved in first 15 min, and the equilibrium data well explained by pseudo second order model. The smaller concentrations of inorganic cations (Na + , Ca 2＋ , Mg 2 + ), organic acids (EDTA, Citric acid , Formic acid) and complexing agent with high salt system reduce the adsorption capacity to some extent, but after that the higher concentrations of these competing species have no apparent effect on the adsorption performance. According to the XPS analysis, the carboxyl and amino groups were responsible for the adsorption of Cr(III), while the main mechanism of adsorption were coordination complex and electrostatic interaction. The prepared adsorbent can be readily isolated by external magnetic field and regenerated for several times and still possess higher adsorption performance.
In this work, an outstanding nanolayered tin phosphate with 15.0 Å interlayer spacing, Sn (HPO4)2·3H2O (SnP–H+), has been synthesized by conventional hydrothermal method and first used in the adsorptive removal of Cr(III) from aqueous solution. A number of factors such as contact time, initial concentration of Cr(III), temperature, pH, and ionic strength on adsorption were investigated by batch tests. Moreover, the isothermal adsorption characteristics and kinetic model of Cr(III) onto SnP–H+ were studied. The results showed that the adsorption of Cr(III) by SnP–H+ was in accordance with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. The adsorption capacity of Cr(III) onto SnP–H+ at temperature 40.0 °C and pH 3.0 could reach 81.1 mg g−1. And the distribution coefficient Kd was 23.0 g L−1. Overall, experiments certified that SnP–H+ was an excellent adsorbent that can effectively remove Cr(III) from aqueous solution.
ABSTRACT A novel adsorbent ion-imprinted polymer–silica clay (IIP@SC) was prepared via surface ion imprinting technology by using silica clay (SC) as the support matrix and methacrylic acid as the ionic imprinting monomer. The adsorbent was characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The prepared IIP@SC was applied for recovery of Cr(III) ions from aqueous solution. The selectivity properties of IIP@SC are evaluated. The results showed that the maximum adsorption capacity reached 157.98 mg/g in 30 min when the initial concentration of metal ions was 100 mg/L at pH 6.0. Adsorption kinetic and adsorption equilibrium studies demonstrated that the experimental data fitted well with the pseudo-second-order model and the Langmuir isotherm model. Competitive adsorption study showed that the prepared IIP@SC exhibits an efficient selectivity for Cr(III) ions.The prepared IIP@SC adsorbent can be a promising adsorbents for Cr(III) recovery from aqueous solutions with high selectivity.
危险品化学品经营许可证（带存储）