Performances and mechanisms of Mg/Al and Ca/Al layered double hydroxides for graphene oxide removal from aqueous solution

• The equilibrium time of GO removal on Mg/Al-LDH and Ca/Al-LDH are no more than 1 h.
• The removal of GO on Mg/Al-LDH and Ca/Al-LDH are almost not influenced by temperature.
• The removal capabilities for GO are: Ca/Al-LDH > CaCl2 > AlCl3 > Mg/Al-LDH.
• The removal mechanisms of GO on Mg/Al-LDH and Ca/Al-LDH are electrostatic attraction and bridging function.

The Mg/Al layered double hydroxides (Mg/Al-LDH) as well as Ca/Al-LDH were successfully synthesized by a facile co-precipitation method and were applied as adsorbents for the efficient elimination of graphene oxide (GO) from aqueous solutions. Experimental data showed that the temperature and ionic strength did not play significant role in GO removal. The interaction of GO with Mg/Al-LDH and Ca/Al-LDH achieved interaction equilibrium in less than 1 h. The removal mechanism of GO on Mg/Al-LDH and Ca/Al-LDH could be explained by electrostatic attraction and bridging function between the two materials, and the removal capabilities were Ca/Al-LDH > Mg/Al-LDH. Based on the experimental results, the Ca/Al-LDH could be a very promising material for efficient elimination of GO from aqueous solutions. Results from this study provided critical information for the transport and potential fate of GO in natural environment.

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