School of Environment and Chemical Engineering, North China Electric Power University , Beijing 102206, P. R. China.
School of Chemistry, Biological and Materials Sciences, East China Institute of Technology , Nanchang, 330013, P. R. China.
Environ Sci Technol. 2016 Apr 5;50(7):3658-67. doi: 10.1021/acs.est.6b00255. Epub 2016 Mar 23.
Graphene oxide (GO) has attracted considerable attention because of its remarkable enhanced adsorption and multifunctional properties. However, the toxic properties of GO nanosheets released into the environment could lead to the instability of biological system. In aqueous phase, GO may interact with fine mineral particles, such as chloridion intercalated nanocrystallined Mg/Al layered double hydroxides (LDH-Cl) and nanocrystallined Mg/Al LDHs (LDH-CO3), which are considered as coagulant molecules for the coagulation and removal of GO from aqueous solutions. Herein the coagulation of GO on LDHs were studied as a function of solution pH, ionic strength, contact time, temperature and coagulant concentration. The presence of LDH-Cl and LDH-CO3 improved the coagulation of GO in solution efficiently, which was mainly attributed to the surface oxygen-containing functional groups of LDH-Cl and LDH-CO3 occupying the binding sites of GO. The coagulation of GO by LDH-Cl and LDH-CO3 was strongly dependent on pH and ionic strength. Results of theoretical DFT calculations indicated that the coagulation of GO on LDHs was energetically favored by electrostatic interactions and hydrogen bonds, which was further evidenced by FTIR and XPS analysis. By integrating the experimental results, it was clear that LDH-Cl could be potentially used as a cost-effective coagulant for the elimination of GO from aqueous solutions, which could efficiently decrease the potential toxicity of GO in the natural environment.
氧化石墨烯（GO）因其显著的增强吸附和多功能特性而引起了广泛关注。然而，释放到环境中的 GO 纳米片的毒性可能导致生物系统的不稳定。在水相，GO 可能与细小的矿物颗粒相互作用，如氯离子插层纳米结晶 Mg/Al 层状双氢氧化物（LDH-Cl）和纳米结晶 Mg/Al LDH（LDH-CO3），它们被认为是用于凝聚和从水溶液中去除 GO 的凝聚剂分子。在此，研究了 LDHs 对 GO 的凝聚作用，作为溶液 pH 值、离子强度、接触时间、温度和凝聚剂浓度的函数。LDH-Cl 和 LDH-CO3 的存在有效地提高了溶液中 GO 的凝聚，这主要归因于 LDH-Cl 和 LDH-CO3 的表面含氧官能团占据了 GO 的结合位点。GO 的凝聚作用与 LDH-Cl 和 LDH-CO3 的凝聚作用强烈依赖于 pH 值和离子强度。理论 DFT 计算的结果表明，静电相互作用和氢键有利于 LDHs 上 GO 的凝聚，这进一步通过 FTIR 和 XPS 分析得到证实。通过整合实验结果，可以清楚地看出 LDH-Cl 可作为一种经济有效的凝聚剂，用于从水溶液中去除 GO，这可以有效地降低 GO 在自然环境中的潜在毒性。
