Optimizing Carbon Dots for Enhanced Lead Removal from Aqueous Solutions: A Novel Approach Using Hydrothermal Synthesis with Tartaric

Abstract

This study explores the synthesis of carbon dots (CDs) using a novel hydrothermal method with tartaric and oxalic acids as precursors. Three distinct samples, CD-1, CD-2, and CD-3, were synthesized with varying precursor ratios (1:1, 1:2, and 2:1) to investigate their impact on the CDs' physicochemical properties and lead ion removal efficiency. Fourier-transform infrared (FTIR) spectroscopy revealed significant surface functionalization, with CD-3 displaying the highest O-H stretching intensity at 3400 cm⁻¹. Transmission electron microscopy (TEM) confirmed quasi-spherical CDs with sizes ranging from 4 to 8 nm, with CD-1 showing the most uniform distribution (5-6 nm average). Raman spectroscopy indicated varying degrees of graphitization, with CD-3 exhibiting the lowest I_D/I_G ratio of 0.85, suggesting a more ordered carbon structure. Notably, CD-1 demonstrated a superior lead ion removal efficiency of 77.2%, significantly higher than CD-2 (27.5%) and CD-3 (71.2%). The optimum precursor ratio was determined to be 1:1 (tartaric acid: oxalic acid) in CD-1, balancing surface functionalization and structural order, thereby enhancing adsorption properties. This study underscores the importance of precursor ratio optimization in tailoring CD properties for environmental remediation applications.