School of Environment, Nanjing Normal University, Nanjing 210023, China; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing 210023, China; Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control, Shenzhen 518055, China.
School of Environment, Nanjing Normal University, Nanjing 210023, China.
Sci Total Environ. 2021 Jul 15;778:146189. doi: 10.1016/j.scitotenv.2021.146189. Epub 2021 Mar 3.
The polyphenolic tannic acid (TA) has been widely used in the stabilization and surface modification of nanomaterials. The interaction mechanism of TA with the biogenic nano-hydroxyapatite (nHAP) and its environmental importance, however, are poorly understood. This study explored the adsorption of TA using the green synthesized, eggshell-derived nHAP and implications of this process for the removal of aqueous Cu(II) via batch adsorption experiments, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) investigations. TA adsorption by nHAP was a complex pH-dependent process and significantly correlated with TA molecule speciation and amphoteric properties of nHAP via multiple adsorption modes including surface complexation, electrostatic attraction, and hydrogen bond. The maximum TA adsorption amount was found to be 94.8 mg/g for less crystalline nHAP with lower calcination temperature. In the ternary Cu-TA-nHAP systems, TA promoted Cu(II) adsorption at pH < 5 and reduced Cu(II) uptake at pH > 5. Further studies of the effects of ionic strength and addition sequences, as well as Raman, FTIR, and XPS analyses revealed Cu(II) adsorption on nHAP was mainly dominated by inner-sphere surface complexation. These results can shed light on not only the utility of biogenic nHAP for TA and Cu(II) adsorption but also the evaluation of the effect of TA on the environmental behavior of heavy metals.
多酚单宁酸 (TA) 已被广泛用于纳米材料的稳定和表面改性。然而，TA 与生物源纳米羟基磷灰石 (nHAP) 的相互作用机制及其环境重要性仍知之甚少。本研究通过批量吸附实验、拉曼光谱、傅里叶变换红外光谱 (FTIR) 和 X 射线光电子能谱 (XPS) 研究，探索了使用绿色合成的蛋壳衍生 nHAP 对 TA 的吸附及其对水溶液中 Cu(II) 去除的影响。nHAP 对 TA 的吸附是一个复杂的 pH 依赖过程，与 TA 分子形态和 nHAP 的两性特性密切相关，通过多种吸附模式，包括表面络合、静电吸引和氢键。发现较低结晶度和较低煅烧温度的 nHAP 的最大 TA 吸附量为 94.8 mg/g。在三元 Cu-TA-nHAP 体系中，TA 在 pH < 5 时促进 Cu(II) 吸附，在 pH > 5 时降低 Cu(II) 摄取量。进一步研究离子强度和添加顺序的影响以及拉曼、FTIR 和 XPS 分析表明，nHAP 上的 Cu(II) 吸附主要受内球表面络合控制。这些结果不仅可以揭示生物源 nHAP 对 TA 和 Cu(II) 吸附的应用潜力，还可以评估 TA 对重金属环境行为的影响。
