Search

The copolymer of poli(acrylic acid-co-hydroxyapatite) (PAA-HAP) was prepared and characterized by means of FT-IR and SEM analysis. The adsorptive features of PAA-HAP for $$ {{\text{UO}}_{ 2}}^{{ 2 { + }}} $$ was studied as a function of pH, adsorbent dosage, initial metal ion concentration and temperature. The adsorption isotherm data fitted well to the Langmuir isotherm model. The adsorbed $$ {{\text{UO}}_{ 2}}^{{ 2 { + }}} $$ can be desorbed effectively by 0.1 M HNO3. The maximum adsorption capacities for $$ {{\text{UO}}_{ 2}}^{{ 2 { + }}} $$ of the dry PAA-HAP was 1.86 × 10−4 mol/g. The high adsorption capacity and kinetics results indicate that PAA-HAP can be used as an alternative adsorbent to remove $$ {{\text{UO}}_{ 2}}^{{ 2 { + }}} $$ from aqueous solution.

Poly(N,N-diethylacrylamide-co-acrylicacid) (P(DEA-co-AA)) was synthesized by Free-Radical polymerization. The effects of contact time, solid/liquid ratio, pH value, and initial concentration on the adsorption of Th4+ ions onto P(DEA-co-AA) were investigated. The adsorption was highly dependent on the initial pH and initial metal ions concentration of the solvent. The adsorption kinetic data indicated that the chemical adsorption is a swiftness processes, the adsorption equilibrium could be achieved within 20 min. The adsorption isotherm of the microgels for Th4+ is fitted to the Langmuir isotherm model. Gibbs free enthalpy change was ∆G

We prepared poly(N,N-diethylacrylamide-co-acrylic acid) (P(DEA-co-AA)) microgels which could efficiently remove UO2 2+ from aqueous solutions. In this study, the effect of adsorption parameters such as pH value, adsorbent dose, shaking time, and temperature has investigated. It is found that the pseudo-second-order model is more suitable for our experiment. The adsorption kinetic data indicated that the chemical adsorption was the swiftness processes, the adsorption equilibrium could be achieved within 30 min. And there are very good correlation coefficients of linearized equations for Langmuir isotherm model, which indicated that the sorption isotherm of the hydrogel for UO2 2+ can be fitted to the Langmuir isotherm model. The adsorption process was spontaneous (∆G 0

Polyacrylic acid hydrogel was synthesized by Free Radical polymerization and characterized by means of FTIR. The FTIR results show that the carboxylic groups in the complexes coordinated to the metal ions in the form of two dentate. The effects of contact time, solid/liquid ratio, pH value, and initial concentration on the adsorption of UO2 2+ ions onto polyacrylic acid were investigated. The adsorption of UO2 2+ ions was highly dependent on the initial pH of metal ions solution and initial metal ions concentration. The adsorption kinetic data indicated that the chemical adsorption was the swiftness processes, the adsorption equilibrium could be achieved within 15 min. And there are very good correlation coefficients of linearized equations for Freundlich model, which indicated that the sorption isotherm of the hydrogel for UO2 2+ can be fitted to the Freundlich model. It was found that the maximum adsorption quantity of UO2 2+ was 1,179 mg/g. After five times of repeated tests for the hydrogel it still remained its excellent adsorption.

The copolymers of styrene and maleic anhydride resin (PSt/MA) was synthesized by free radical polymerization and characterized by means of FTIR. It is shown that the PSt/MA copolymer has rather strong coordination ability to UO2 2+ ions by chelation with the carboxylate group, and the microstructures of the U(VI)-PSt/MA complexes can be well controlled. The influence factors on UO2 2+ ions were also investigated and described in detail, such as contact time, solid/liquid ratio, pH value, ethanol content, and initial concentration. It was found that the maximum adsorption quantity of UO2 2+ was 831 mg/g. Experiments show that PSt/MA can recover UO2 2+ ions with high adsorption selectively from a simulated industry solution containing Ca2+ and Mg2+ as impurities. The adsorption kinetic data were best described by the pseudo-second-order equation, indicating that the chemical adsorption was the rate-limiting step. And there are very good correlation coefficients of linearized equations for Langmuir model, which indicated that the sorption isotherm of the PSt/MA for UO2 2+ can be fitted to the Langmuir model. After five times of repeated tests for the hydrogel it still remained its excellent adsorption.

Sorption of thorium (IV) on goethite was investigated as a function of contact time, pH, ionic strength, anions, solid-to-liquid ratio (m/V) and Th(IV) concentration using batch technique. The results showed that the sorption of Th(IV) was strong pH-dependence, and increased from ~10 to ~100% over the pH range of 2.0–4.0, and then kept a constant level in the higher pH range. The sorption of Th(IV) increased with increasing m/V and independent of ionic strength. It was clear that phosphate and FA significantly enhanced Th(IV) sorption on goethite. The sorption and desorption isotherms were investigated at pH 2.90 ± 0.05 and analyzed with Freundlich and Langmuir models, respectively. Compared to Langmuir model, Freundlich model could fit the experimental data better, according to the high relative coefficients.

We have performed a large number of batch sorption experiments of uranyl onto SiO2 and examined the effects of nitrate or ionic strength, phosphate, fulvic acid(FA), phthalic acid (PH), salicylic acid (SA), and cat- echol (CA) on the uranyl sorption onto SiO2. Three sorp- tion edges and three sorption isotherms at ionic strengths 0.05, 0.1, and 0.5 mol/L KNO3 were used to investigate the effect of ionic strength or nitrate on the sorption and the Langmuir, Freundlich, and Dubinin-Radushkevich models are used to simulate the sorption isotherms, respectively. Five sorption edges in the presence of phosphate, FA, PH, SA, and CA were compared with that in the absence of complexing ligand. The results suggest that the effect of complexation of uranyl with nitrate on the uranyl sorption can be negligible and the sorption can be described Fre- undlich and D-R model very well. The positive effect of phosphate on the uranyl sorption was found, though the extent of effect was decreased with increasing pH. The positive effect and the negative effect of FA on the uranyl sorption were found at low pH and high pH ranges, respectively. The sorption edge of uranyl sorption remained unaffected in the presence of PH in the pH 2-10. In the presence of SA, the no effect and the negative effect on the uranyl sorption were, respectively, found at low pH and high pH ranges. The negative effect of CA on the uranyl sorption was found in the pH 2-10.

Sorption of Th(IV) on Zr2O(PO4)2 as a function of contact time, reaction temperature, pH, ionic strength and solid-to-liquid ratio (m/V) is studied under ambient condition by using batch technique. Effects of fulvic acid (FA), phosphate, sulfate and citrate on Th(IV) sorption are investigated in detail. A pseudo-second-order rate equation is used to simulate the kinetic sorption. The removal of Th(IV) increases with increasing pH and hardly depends on ionic strength. Sorption of Th(IV) increases with increasing m/V and reaction temperature. The presence of FA and phosphate enhances the sorption of Th(IV) on Zr2O(PO4)2 while sulfate and citrate decrease the sorption. The Langmuir and Freundlich models are used to simulate the sorption isotherm of Th(IV) on Zr2O(PO4)2 at different temperatures. The thermodynamic data (i.e., ∆H 0, ∆S 0, ∆G 0) are calculated from temperature dependent sorption isotherms. The results suggest that the sorption process of Th(IV) on Zr2O(PO4)2 is spontaneous and endothermic.

Two open-chain crown ethers 2,2'-(ethylenedioxy)bis[(8-quinolyloxymethyl)benzene], (L1), and 2,2'-(ethylenedioxy)bis[(8-quinaldyloxymethyl)benzene], (L2) have been prepared and characterized by using elemental analysis, IR spectra, 1H NMR spectra and positive-ion FAB mass spectra. The extraction of UO22+ and Th4+ by both open-chain crown ethers, L1 and L2 in chloroform as a diluent was studied at 25 °C. Extraction distribution ratios (D) of UO22+ and Th4+ were investigated as a function of pH, lithium picrate concentration, and extractant concentration. Based on the expertimental results, it was found that 1 : 1 complexes were formed involving either UO22+ or Th4+ with L1, and Th4+ with L2. The extractability of L1 for Th4+ is significantly higher than that for UO22+, the extractabilities of L1 and L2 for Th4+ being almost identical. L1 and L2 used here are not feasible for industry because of their relatively low extractabilities for Th4+ at pH