Laboratory of Applied Chemistry and Environment, Department of Chemistry, Faculty of Science, Ibn Zohr University, Agadir, Morocco.
Laboratory of Materials Nanoarchitectonics, Faculty of Chemical Engineering and Environment Protection, Technical University of 'Gheorghe Asachi' of Iasi, Iasi, Romania.
Environ Sci Pollut Res Int. 2020 Dec;27(36):45767-45774. doi: 10.1007/s11356-020-10444-5. Epub 2020 Aug 15.
Layered double hydroxides (LDHs), known as a class of anionic clays, have attracted considerable attention recently due to their potential applications in different areas as catalyst materials, energy materials, and adsorbent materials for environmental remediation, especially for anionic pollutant removal. In this study, magnesium aluminum layered double hydroxide (MgAl-LDH) was synthesized by two methods: standard coprecipitation and urea hydrolysis. Their textural properties and morphologies were examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and differential (DTG) analysis, and point of zero charge (pH). The specific surface area was calculated from BET adsorption equation. The results indicated that the crystallinity and the regularity of the samples prepared by urea hydrolysis were much preferable to those prepared by the coprecipitation method. Their sorption properties toward phosphate were investigated and the experimental evidence showed that, at the initial concentration of 100 mg L and at room temperature, the LDH synthesized by urea hydrolysis had a percentage removal of 94.3 ± 1.12% toward phosphate ions while 74.1 ± 1.34% were uptaked by LDH synthesized by coprecipitation method, suggesting that the crystallinity affects the sorption capability. The sorption mechanism indicates that phosphate ions could be sorbed onto LDHs via electrostatic attraction, ligand exchange, and ion exchange.
层状双氢氧化物（LDHs），又称阴离子粘土，由于其在不同领域作为催化剂材料、能源材料和环境修复吸附材料的潜在应用而受到广泛关注，特别是用于阴离子污染物的去除。在本研究中，通过两种方法合成了镁铝层状双氢氧化物（MgAl-LDH）：标准共沉淀法和尿素水解法。通过 X 射线粉末衍射（XRD）、扫描电子显微镜（SEM）、能谱（EDS）、傅里叶变换红外光谱（FTIR）、热重（TG）和差热（DTG）分析以及零电荷点（pH）对其结构和形貌进行了考察。比表面积由 BET 吸附方程计算。结果表明，与共沉淀法相比，尿素水解法制备的样品结晶度和规则性要好得多。研究了它们对磷酸盐的吸附性能，实验结果表明，在初始浓度为 100mg/L、室温下，尿素水解法合成的 LDH 对磷酸盐离子的去除率为 94.3±1.12%，而共沉淀法合成的 LDH 的吸附率为 74.1±1.34%，表明结晶度影响吸附能力。吸附机理表明，磷酸盐离子可以通过静电吸引、配体交换和离子交换吸附到 LDHs 上。
