One-Step Two-Electrode Electrodeposition of Intercalated Layered Double Hydroxide for Effective Uptake of Heavy Metal Ions

In this work, Cu Cr-layered double hydroxide nanosheet (DS-LDH) has been successfully fabricated on a carbon cloth substrate via a facile two-electrode electrodeposition method. The electrodeposition method allows the deposition of well adherent, homogeneous and single phase LDH coatings on electrodes. The resulting DS-LDH was characterized by X–ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Energy-dispersive X-ray (EDX) technique. The DS-LDH coated on the carbon cloth was used for the effective uptake of heavy metals and exhibits superior selectivity as well as a higher adsorption capacity for Hg(II) ions even in the presence of high concentration levels of competitive ions. The Sorption isotherm for Hg(II) agrees with the Langmuir model and thus suggests a monolayer adsorption. The DS-LDH coated on the carbon cloth exhibits a high record saturation Hg(II) uptake capacity of over 2500 mg g-1 and distribution coefficients of 4.10 × 106 mL g-1, which place it at the top of materials known for the uptake of Hg(II). The sorption kinetics for Hg(II) follows a pseudo-second-order model, suggesting a chemisorption binding. Moreover, we observed efficient Hg(II) removal from tap water, well water, river water, and seawater samples. The excellent efficiency in recycling studies and good stability of the coating are other properties of the adsorbent.