Hydrothermally synthesized tannic acid-copper(I) complex-based nanoparticles for efficient decontamination of lead ions from aqueous solutions

Abstract

In this work, we synthesized a novel wrinkled carbon-Cu2O nanoparticle adsorbent (namely HWC-Cu2O NPs) through a hydrothermal method using tannic acid (TA) and Cu(NO3)2, and then employed it for the removal of Pb2+ from aqueous solutions. The synthesized adsorbent was fully characterized by different techniques such as Fourier Transform Infrared Spectrophotometry (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), Energy dispersive X-Ray (EDX) and X-Ray Diffraction Analysis (XRD). Under the hydrothermal conditions, Cu2+ ions were reduced by TA and then the resulting Cu+ ions (E°Cu2+–Cu+ = + 0.161 V) were coordinated by TA ligands to construct a network of copper(I) complexes on the surface of the nanoparticles. By optimizing the parameters affecting the removal percentage (RP) of Pb2+, it was revealed that the maximum RP (98% for 50 mg L−1 of Pb2+) achieved under the following conditions: pH = 5.5, 10 mg adsorbent and 20 min as contact time. Also, the adsorption data were well fitted to the Langmuir isotherm model, showing that Pb2+ ions tend to occupy the surface of the adsorbent in a monolayer form with a maximum adsorption capacity of 250.0 mg g−1. Also, kinetic models showed that the pseudo first-order kinetics is the best model for the prediction of kinetic behavior. Moreover, HWC-Cu2O NPs was efficiently recovered and reused for five adsorption/desorption cycles. In summary, this adsorbent is a superior system for the Pb2+ decontamination in aqueous samples; its remarkable advantages include high efficiency, short removal time and good reusability.