Preparation of a Phosphate-Modified Flower-Like α-FeOOH Composite and Its Application for Aqueous U(VI) Removal
2018
Zhang, Xiaowen | Jiang, Tianjiao | Xie, Chao | Peng, Ying | Li, Mi | Zhong, Yongming
Goethite is a stable and widespread mineral in soil, which affects the transportation and immobilization of heavy metals in soil. Here, the three-dimensional flower-like goethite (TDFLG) was synthesized by refluxing precipitation method. The modified three-dimensional flower-like goethite (MTDFLG) was prepared by NaH₂PO₄ with dipping method. The obtained samples were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, N₂ adsorption–desorption (BET), and X-ray diffraction (XRD). SEM images showed that the modification of phosphate had no major changes on the morphology of the original sample and the morphology of MTDFLG after adsorbed U(VI) had clearly change. For the goethite and modified goethite, the BET-specific surface area was 229.96 and 203.17 m²/g, respectively. Moreover, the effects of adsorption time, sorbent dose, solution pH, and initial uranium concentration on the uranium adsorption behaviors were investigated using the two materials as adsorbent for the treatment of uranium-containing wastewater. The results showed that MTDFLG had better adsorption capacity than TDFLG on uranium. The increase in uranium removal on MTDFLG was due to the formation of ternary surface complexes (≡FePO₄UO₂). TDFLG and MTDFLG followed the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model, which indicated that uranium adsorption on TDFLG or MTDFLG is mainly based on chemisorption, and the maximum adsorption capacity of two adsorbents is 48.24 and 112.36 mg/g, respectively.
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