The adsorption properties of a novel gel-type weak acid resin (110-H) for Pb2+ were investigated using chemical methods and IR spectrometry.The optimal adsorption condition of 110-H for Pb2+ is at pH=6.49 in HAc-NaAc medium and the statically saturated adsorption capacity is 485 mg/g at 298 K.Pb2+ adsorbed on 110-H resin can be eluted with 0.025 mol/L HCl quantificationally.The adsorption rate constants determined under the temperatures of 288,298,308 and 318 K are 2.46×10-5,3.82×10-5,4.46×10-5 and 5.71×10-5 s-1,respectively.The apparent activation energy,Ea,is 18.1 kJ/mol and the thermodynamic parameters of adsorption,ΔH=20.9 kJ/mol,ΔS=161 J/(mol.K) and ΔG298 K =-48.0 kJ/mol,respectively.The adsorption behavior of 110-H resin for Pb2+ accords with the Langmuir isotherm.Infrared spectra show that the oxygen atoms of the functional group of resin coordinate with Pb2+ to form the coordination bands.
The sorption behavior and mechanism of a Macroporous weak acid resin, （D155 resin,） for Gd（Ⅲ） were investigated. The statically saturated sorption capacity is 283 mg/g resin at 298 K in HAc-NaAc medium. The Gd（Ⅲ） adsorbed on macroporous weak acid resin, （D155 resin,） could be reductively eluted with the mixed solution of HCl and NaCl, and the elution percentage was as high as 100%. The resin could be regenerated and reused without remarkable decrease in sorption capacity. The apparent sorption rate constant was k298=1.98×10^5 s^-1. The apparent activation energy was Ea=2.78 kJ/mol. The sorption behavior of D155 resin for Gd（Ⅲ） obeyed the Langmuir isotherm. The thermodynamic sorption parameters were △H=33.0 kJ/mol,△S=192 J/mol/K, and △G298=-24.3 kJ/mol. The sorption mechanism of D155 resin for Gd（Ⅲ） was examined by using chemical method and IR spectrometry. The coordination compound was formed between oxygen atoms in the functional group of D155 resin and Gd （Ⅲ）.
The pH dependent sorption of rare earth ions （La（Ⅲ）, Ce（Ⅲ）, Pr（Ⅲ）, Nd（Ⅲ）, Y（Ⅲ）, Sm（Ⅲ）, Eu（Ⅲ）, Gd（Ⅲ）, Tb（Ⅲ）, Dy（Ⅲ）, Ho（Ⅲ）, Er（Ⅲ）, Lu（Ⅲ）, and Yb（Ⅲ）） from HAC-NaAC buffer solution at 298 K by D152 resin containing -COOH function groups were presented. The sorption behaviors of D152 resin for Sm（Ⅲ） were discussed as an example. The effects of operational conditions such as pH, temperature, and contact time were studied. The statically saturated sorption capacity was 510 mg/g resin at pH 6.70 in HAc-NaAc medium at 298 K. The sorption behaviors obeyed the Freundlich isotherm. The capacity value for column study was obtained by graphical integration as 495 mg/g resin. Thomas model was applied to experimental data to predict the breakthrough curve and to determine the characteristic parameters of the column useful for process design.
The sorption behavior and mechanism of a novel macroporous weak acid resin(D113 resin) for Er(Ⅲ) were investigated. The optimal sorption condition of D113 resin for Er(Ⅲ) was pH 6.42 in HAc-NaAc medium. The statically saturated sorption capacity was 272 mg·g-1 at 298 K in HAc-NaAc medium. The Er(Ⅲ) adsorbed on D113 resin could be reductively eluted by the mixed solution of HCl and NaCl. The elution percentage could reach 100%. The resin could be regenerated and reused without apparent decrease of sorption capacity. The apparent sorption rate constant was k298=1.98×10-5 s-1. The apparent activation energy was 8.60 kJ·mol-1. The sorption behavior of D113 resin for Er(Ⅲ) obeyed the Freundlich isotherm and Langmuir isotherm. The sorption parameters of thermodynamics were ΔH=44.0 kJ·mol-1, ΔS=223 J·mol-1·K-1, ΔG298 K=-22.3 kJ·mol-1, respectively. The molar coordination ratio of the functional group of D113 resin to Er(Ⅲ) was 3∶1. The sorption mechanism of D113 resin for Er(Ⅲ) was examined using chemical method and IR spectrometry.
The sorption and desorption properties of La(Ⅲ) on D152 resin were investigated. The influence of operational conditions such as La(Ⅲ) initial concentration, sorbent mass, temperature, solution initial pH and sorption kinetics of La(Ⅲ) were studied. The optimal pH for the sorption was found to be 6.70 in the HAc-NaAc system. The statically saturated sorption capacity is 463 mg·g-1 at 298 K in HAc-NaAc medium. The static sorption data fit to the Freundlich isotherm and Langmiur isotherm. The sorption rate constant is k298 K=1.73×10-5 s-1. The thermodynamic sorption parameters, enthalpy change ΔH, entropy change ΔS and free energy change ΔG298 K of D152 resin for La(Ⅲ) are 15.9 kJ·mol-1, 132 J·K-1·mol-1, -39.4 kJ·mol-1, respectively. Dynamic sorption and desorption experiments have been carried out with the column packed by D152 resin. La(Ⅲ) adsorbed on D152 resin can be quantificationally eluted and the elution percentage is up to 100%.
