Hybrid Adsorbent for Removal of Cd(II), Cu(II), Pb(II) and Zn(II) from Waters Using Submersible Device

Mesoporous carbon and humic acid - native and oxidized with 5% or 15% hydrogen peroxide - were used to obtain hybrid adsorbents MC-HA, MC-HA5, and MC-HA15, respectively, for removing certain metal ions from water. Fine particles of the hybrid adsorbents were characterized by various methods. The concentration of the functional groups capable of binding metal cations in the hybrid adsorbent increased from 1.2 mmol/g in MC-HA to 1.8 mmol/g in MC-HA5 and MC-HA15. The adsorption capacity depends on pH, and at pH 6.0, it has the following order (mmol/g): Cu(II) (1.0) > Pb(II) (0.65) > Zn(II) (0.46) > Cd(II) (0.38). The adsorption process is fast and reaches the equilibrium at low concentration. The Langmuir isotherm fits the experimental adsorption data better than the Freundlich model. Prepared adsorbents were fixed on a highly porous matrix to obtain a material suitable for simple submersible devices. A high efficiency of multi-metal removal (96.1-100%) and recovery (83.5-100%) by MC-HA5 remained in at least five consecutive adsorption-desorption cycles of model wastewater treatment. The possibility of its use for the remediation of contaminated reservoirs is also shown in a full-scale experiment.