Novel biomolecule-assisted interlayer anion-controlled layered double hydroxide as an efficient sorbent for arsenate removal
Novel biomolecule-assisted interlayer anion-controlled layered double hydroxide as an efficient sorbent for arsenate removal
复制标题
DOI：
10.1039/c7ta03056h
复制
发表时间：
2017-07
影响因子：
--
通讯作者：
Paulmanickam Koilraj;K. Sasaki;K. Srinivasan
中科院分区：
文献类型：
--
作者：
Paulmanickam Koilraj;K. Sasaki;K. Srinivasan
通过生物分子辅助方法合成纯的含硝酸盐的层状双氢氧化物（LDHs）很难在不产生大量废物的情况下实现。我们第一次展示了使用环境友好的L-精氨酸辅助水热法合成具有受控层间阴离子组成的LDHs，零废物处置。通过PXRD、FT-IR、XPS和离子色谱分析，揭示了LDH的形成机理。在较低的合成温度（90-110 °C）下，甘氨酸介导的水分解导致OH−和[Arg+]-NO3−的形成，从而产生纯的含NO3−的LDH。相反，在高于115 °C的温度下，L-精氨酸发生分解并产生NH 4+和CO2，从而产生含CO 32 −的LDH。在较低温度下获得的固体残留物的FT-IR光谱表明，几种氨基酸在LDH表面上被官能化，并被在较高温度下产生的CO 32 −取代。在100 °C下合成的Mg 2.3Al-LDH和Mg 2Al-LDH从水溶液中吸附砷酸盐的最大吸附容量值分别为1.675和1.972 mmol g−1。与常规制备的LDHs相比，L-精氨酸的功能化增强了对砷酸根的吸附能力。砷酸盐的吸附机理是基于层间NO3−和功能化精氨酸分子的离子交换。总之，化学前体L-精氨酸（本研究中使用的）作为多功能试剂，包括（i）用于LDH合成的沉淀剂，（ii）用于层间阴离子控制的工程师，（iii）功能试剂和（iv）存在于合成介质中的游离NO3−的清除剂。目前的合成方法在合成过程中没有使用危险碱，[Arg+]-NO3−副产物可以用作健康/护肤配方的化学来源，零废物处理，这提供了巨大的好处。
The synthesis of pure nitrate-containing layered double hydroxides (LDHs) via biomolecule-assisted methods is difficult to achieve without producing substantial waste. For the first time, we demonstrated the synthesis of LDHs with a controlled interlayer anion composition using an environmentally friendly L-arginine-assisted hydrothermal method with zero waste disposal. The mechanism of LDH formation was revealed through PXRD, FT-IR, XPS and ion chromatographic (IC) analyses. At low synthesis temperatures (90–110 °C), arginine-mediated water decomposition led to OH− and [Arg+]-NO3− formation and thus produced pure NO3−-containing LDHs. Conversely, at temperatures above 115 °C, L-arginine decomposition occurred and produced NH4+ and CO2, which resulted in CO32−-bearing LDHs. The FT-IR spectra of the solid residues, which were obtained at lower temperatures, indicated that several amino acids were functionalized on the surface of the LDHs and replaced by CO32−, which was produced at higher temperatures. The sorption of arsenate from an aqueous solution on the resulting LDHs showed maximum sorption capacity values of 1.675 and 1.972 mmol g−1 for Mg2.3Al-LDH and Mg2Al-LDH synthesised at 100 °C, respectively. The arsenate sorption capacity was enhanced by the functionalization of L-arginine compared with conventionally prepared LDHs. The mechanism of arsenate sorption was based on the ion-exchange of interlayer NO3− and functionalized arginine molecules. In summary, the chemical precursor L-arginine (utilized in this study) acts as a multifunctional reagent, including (i) a precipitant for the synthesis of LDH, (ii) an engineer for interlayer anion control, (iii) a functional reagent and (iv) a scavenger for free NO3− that is present in the synthesis medium. The current synthesis method did not utilize a hazardous base during synthesis, and the [Arg+]-NO3− byproduct can be used as a chemical source for health/skin care formulations with zero waste disposal, which offers great benefits.