Coagulation Behavior of Graphene Oxide on Nanocrystallined Mg/Al Layered Double Hydroxides: Batch Experimental and Theoretical Calculation Study

Abstract

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.

Complex Roles of Solution Chemistry on Graphene Oxide Coagulation onto Titanium Dioxide: Batch Experiments, Spectroscopy Analysis and Theoretical Calculation

“…Hence, the understanding of the physical and chemical behavior of GO in the natural environment is significantly to evaluate its toxicity to human beings. From the literature survey, the efficient way to lower the GO concentration in water is the coagulation of GO, which forms large agglomerates that can be easily separated by aggregation, filtration or centrifugation121516. Thereby, the coagulation kinetics and stability of GO have been extensively investigated in the literatures4171819, and the results showed that the stability of GO in aqueous solution was strongly influenced by ionic strength and pH values.…”

One-pot synthesis of carbon supported calcined-Mg/Al layered double hydroxides for antibiotic removal by slow pyrolysis of biomass waste

“…Layered double hydroxides (LDHs) are kinds of lamellar inorganic materials which can be described by the general formula [M 1 – x 2+ M x 3+ (OH) 2 ] x + (A n– ) x /n · m H 2 O. M 2+ and M 3+ are divalent (e.g., Mg 2+ , Co 2+ , Ni 2+ , Zn 2+ , Cu 2+ ) and trivalent cations (e.g., Al 3+ , Fe 3+ , Ga 3+ ), respectively; A n– is interlayer gallery anion (e.g., CO 3 2− , Cl − , NO 3 − , SO 4 2− ); and x is the molar ratio of M 3+ /(M 2+  + M 3+ ) and the layer charge will depend on the M 2+ /M 3+ ratio91011. By heating to 450–500 °C, LDHs can be converted into mixed metal oxides (MMOs), which exhibit fine dispersion of metal cations and high surface area.…”

DeepScreen: An Accurate, Rapid, and Anti‐Interference Screening Approach for Nanoformulated Medication by Deep Learning

“…The spectra of LDH showed characteristic peaks: 3526 cm −1 (O—H groups) and 1384 cm −1 (NO 3 − stretching vibration) 21. LDH‐VP16 showed 1610 cm −1 (C=O stretch of carboxyl methyl) and 1485 cm −1 (C=C stretching in the backbone of the aromatic phenyl ring) similar to VP16 and 3526 cm −1 (O—H groups) and 1384 cm −1 (NO 3 − stretching vibration) similar to LDH.…”