Dodecyl sulfate chain anchored mesoporous graphene: synthesis and application to sequester heavy metal ions from aqueous phase

Abstract

Herein, graphene (GN) was synthesized, exfoliated by anchoring dodecyl sulfate chain through hydrophobic interaction over its surface (GN-SDS), and was tested to sequester Cu(II) and Mn(II) ions in single-metal system from aqueous phase. Acid-base titrations and elemental analysis results verified successful dodecyl sulfate chain anchoring over GN-SDS surface. Adsorption/desorption isotherms depicted Type-IV isotherm with H3 type hysteretic loop, confirming mesoporous nature of GN-SDS with BET surface area – 242 m2/g. The ID/IG ratios of GN and GN-SDS obtained by RAMAN spectroscopy were 0.8537 and 0.8540, respectively confirming no distortion in structure during modification. Electrostatic interaction between metal ions and negative surface charge and-/or Cπ electrons of GN-SDS was governing the adsorption process. Maximum Cu(II) and Mn(II) adsorption on GN-SDS was observed at pH 5 and 6, respectively. Rapid Cu(II) and Mn(II) adsorption kinetics accomplishing 80–92% and 87–96%, respectively at varied concentration in 60 min was observed. Maximum adsorption capacities for Cu(II) and Mn(II) on GN-SDS were 369.16 and 223.67 mg/g, respectively. Langmuir isotherm and pseudo-second-order kinetic models were fitted to experimental data. Thermodynamically favorable adsorption process was observed. 30–33% drop in GN-SDS adsorption potential for Cu(II) and Mn(II) after five consecutive regeneration cycles was observed.