| 铌酸盐改性钛酸纳米片对水中Cd(Ⅱ)的吸附行为及机制 |
| 摘要点击 1975 全文点击 532 投稿时间：2017-06-12 修订日期：2018-01-12 |
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| 中文关键词 钛酸盐 铌酸盐 Cd(Ⅱ) 吸附 离子交换 回用 |
| 英文关键词 titanate niobate Cd(Ⅱ) adsorption ion-exchange reuse |
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| 中文摘要 |
| 采用温和水热法合成了负载铌酸盐纳米粒子的钛酸纳米片（Nb-TNS），并应用于水体中重金属离子Cd（Ⅱ）的吸附去除.XRD、TEM和SEM等多种表征证实了新合成的复合材料为未卷曲成管的纳米片状结构.Nb-TNS对Cd（Ⅱ）的吸附机制为Cd（Ⅱ）阳离子与层间Na+的离子交换.Nb-TNS对Cd（Ⅱ）的吸附动力学过程很快，60 min内即可达到吸附平衡，且符合准二级动力学方程.吸附等温线符合Langmuir模型，且对Cd（Ⅱ）的理论最大吸附量高达287.9 mg·g-1.高pH利于Nb-TNS对Cd（Ⅱ）的吸附，原因是带负电的材料表面易于通过静电作用捕集Cd（Ⅱ）阳离子进而发生离子交换，而酸性环境会抑制Cd（Ⅱ）吸附.共存离子Na+和Ca2+抑制Cd（Ⅱ）在Nb-TNS上的吸附，主要因为共存离子与Cd2+竞争吸附位点所致.腐殖酸（HA）对Nb-TNS吸附Cd（Ⅱ）抑制作用较小.经HNO3处理，Cd（Ⅱ）离子易从Nb-TNS上解吸，NaOH再生后，Nb-TNS的-ONa位点恢复.由于Nb-TNS简易的合成方法、对金属阳离子的高效去除效果及可再生性能，在重金属废水修复领域具有很好的应用前景. |
| 英文摘要 |
| Niobate-modified titanate nanosheets (Nb-TNS) were synthesized through a hydrothermal method and used to remove Cd(Ⅱ) from water. TEM and SEM characterizations indicated that the new nanocomposites were non-curled nanosheets. XRD showed that the material was composed of sodium tri-titanate and niobate, and titanate was the primary component. Ion exchange between Cd2+ and Na+ in the interlayers of the Nb-TNSs was the dominant mechanism for Cd(Ⅱ) adsorption, leading to good adsorption performance. The material exhibited rapid adsorption kinetics for Cd(Ⅱ), reaching equilibrium within 60 min, and the data fit well with the pseudo-second order model (R2=1). The maximum adsorption capacity of Cd(Ⅱ) was 287.9 mg·g-1, according to the Langmuir isotherm model, which was larger than that of most of traditional adsorbents. Higher pH promoted adsorption because the negatively charged material could capture Cd(Ⅱ) cations more easily. Co-existing inorganic ions (Na+and Ca2+) were unfavorable to the adsorption of Cd(Ⅱ) by Nb-TNS owing to the competition for adsorption sites. In addition, a slight inhibition effect on the adsorption in the presence of humic acid (HA) was found. Cd(Ⅱ) was efficiently desorbed from Nb-TNS after HNO3 treatment, and -ONa sites were restored with NaOH treatment. Considering its simple synthesis method, high removal efficiency for heavy metals, and good reusability, Nb-TNS is a promising material for remediation of areas contaminated by heavy metals. |
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