As a low cost and highly efficient adsorption of prevalent phenolic contaminants from aqueous solution of organo-montmorillonite functionalized by containing functional spacer gemini surfactant

This work aimed to prepare organo-montmorillonite (PB-MMT and PD-MMT, namely O-MMT) adsorbent with hydrophobic properties and hydrogen bond acceptor capacity via modification with Gemini surfactants (PB and PD), and to investigate the key role of long alkyl chains and amide bonds in the adsorption behaviors of 4-nitrophenol (4-NP) and 4-chlorophenol (4-CP) in aqueous solutions. The microstructure, morphology and surface propertie of O-MMT were explored by different techniques, including XRD, BET, SEM, FT-IR, TGA and Zeta potential. The results show that the saturated adding amount of PB and PD is 1.0 CEC, and PD with flexible alkyl spacer shows markedly higher loading amount (38.22 wt%) on Na-MTT than PB with rigid spacer (36.35 wt%). The batch experiment results of O-MMT to 4-NP and 4-CP demonstrate that the two are ranked by adsorption capacity as follow: PD-MMT > PB-MMT. Kinetic studies are found pseudo-second-order (R 2  > 0.99) and equilibrium data are fitted well by Freundlich isotherm model (R 2  > 0.99) which indicate the adsorption process is primarily multilayer adsorption. The calculated thermodynamic parameters exhibit that the adsorption processes of 4-NP and 4-CP on O-MMT are physical adsorption and exothermic. Adsorption mechanisms highlighted the synergistic effects of hydrophobic interactions and O-H···N hydrogen bonding as important design criteria for efficient removal of 4-NP and 4-CP from aqueous solutions.