Removal of lead from aqueous solution by synergistic interaction between LiCoO2 and tourmaline: Synthesis, characterization and mechanism investigation

Abstract

Tourmaline-LiCoO2 composites were synthesized for Pb2+ elimination. The adsorption capacity of Pb2+ was firstly evaluated with varied tourmaline additions and sintering temperatures, and the appropriate values of these two parameters were 0.375 g and 800 °C (TM0.375LCO800), in which the mass ratio of tourmaline/LiCoO2 was about 1:10. The effects of solution pH and foreign cations on the adsorption behavior of TM0.375LCO800 were further investigated, which demonstrate that solution pH and Mn2+ and Ni2+ had little effect, while Cu2+ and Zn2+ had larger effect. Pseudo-first-order kinetic model and Langmuir adsorption isotherm fitted well with the Pb2+ adsorption characteristics on TM0.375LCO800, indicating the chemical adsorption process with an adsorption capacity of 64.01 mg/g. Physicochemical properties of tourmaline, LiCoO2 and tourmaline-LiCoO2 composites were comparatively analyzed by XRD, ATR, SEM, TEM, UV–vis DRS and XPS. It is found that it is the high-temperature transformation of the separate tourmaline and LiCoO2 into interacting states via tourmaline embedment into the LiCoO2 framework that promoted Pb2+ removal. Finally, the Pb2+ adsorption routes are elaborated. This study suggests the potential and eco-friendliness of tourmaline-LiCoO2 composite for removing heavy metal ions from water phase, and also provides scientific implications for the development of tourmaline-LiCoO2 composite for other environmental applications.