Synthesis of lanthanum phosphate–carbon nanoparticles using a hydrothermal method and their application for lead ion removal

Abstract

Given the wide range of uses for lanthanum phosphate nanoparticles, a simple and effective production technique is desperately needed. In this work, phytic acid as a source of phosphate and tannic acid as a polyphenol rich material were used as green reagents in a simple hydrothermal method to fabricate lanthanum phosphate–carbon (LaPO₄–C) nanoparticles. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) analysis, Fourier transform infrared (FT-IR) spectrophotometry, and transmission electron microscopy (TEM) were used to characterize the synthesized LaPO₄–C nanoparticles. The outcomes demonstrated the effective synthesis of LaPO₄–C nanoparticles with diameters ranging from 30 to 40 nm. The fabricated LaPO₄–C NPs were then used as adsorbent for the elimination of lead ions (Pb²⁺) from water samples. The best adsorption conditions were found to be pH 5–6, an adsorbent dosage of 8 mg, and a contact period of 40 minutes (more than 90% removal percentage for 50 mg L⁻¹ Pb²⁺). The interpretation of different isotherm models also shows that the adsorption of Pb²⁺ ions onto the LaPO₄–C NPs is a monolayer phenomenon (Langmuir isotherm) with a maximum adsorption capacity of 333.33 mg g⁻¹. Moreover, the adsorption kinetic models represent that the pseudo first order kinetic is the appropriate model for the prediction of the kinetic results.