Gang Zhang,Wenxia Ma,Yuqin Feng,Ming Yang,Zheng Fang,Yongsheng Yang,Weiyan Yin,Zehao Li
The development of rare earth adsorbents with high adsorption capacity, outstanding selectivity, and excellent reusability is important for the enrichment and recovery of rare earth elements. The adsorption of the rare earth ion Gd(III) by a phosphorylated polyacrylonitrile fiber was investigated. In this work, the adsorbent was synthesized by a simple and cost-effective grafting method using polyacrylonitrile (PAN) fibers as the substrates. The FTIR analysis, SEM, XPS, and TGA indicated the successful synthesis of polyacrylonitrile-phosphite (PAN-Phos) fibers. To evaluate the feasibility of PAN-Phos fibers as the potential adsorbents for Gd(III) removal, a series of adsorption experiments were conducted. The pseudo-second-order kinetic model better illustrated the adsorption of Gd(III) on PAN-Phos fibers, and equilibrium adsorption was achieved within 50 min; the maximum adsorption capacity was 120.9 mg·g–1. The PAN-Phos fibers also exhibited excellent reproducibility after four adsorption cycles. In addition, the results of various analyses indicated that the adsorption mechanism of Gd(III) on PAN-Phos fibers was mainly through the synergistic complexation of secondary amine and phosphoric acid groups. It provided a practicable way for the synthesis and preparation of rare earth adsorbent materials.
Bi 2 MoO 6 hierarchical microspheres (BMO-SP) consisting of monolayer nanosheets with abundant surface oxygen defects and unsaturated Mo sites are constructed for the one-pot synthesis of secondary amine via a photocatalytic coupling reaction of nitrobenzene (NB) and benzyl alcohol (BA). The performance of this photocatalyst is 12 times higher than that of bulk Bi 2 MoO 6 (BMO-bulk). Experiment results and density functional theory calculations reveal that surface oxygen defects induce more unsaturated Mo atoms facilitating the coordination activation of NB and BA molecules through the formation of –N–O···Mo and –C–O···Mo coordination, respectively. The surface oxygen defects also promote the separation of photogenerated carriers. More photogenerated holes transfer to the surface for oxidizing the activated BA while the photogenerated electrons are trapped by oxygen defects for reducing NB. Thus, the photocatalytic performance is markedly improved. This work successfully designs an efficient photocatalyst for the tandem reaction via surface defect engineering.
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