Spectrophotometric Determination of Lead in Wastewater from the Battery Industry Based on the Interaction with EDTA Disodium Salt

Abstract

In addressing the imperative need to assess lead (Pb) concentrations in water due to its heightened toxicity even at minimal levels, this study seeks to overcome challenges in current testing methodologies. Existing approaches often rely on expensive equipment, limiting their accessibility and widespread application. To address this issue, this investigation introduces a simple, rapid, and selective spectrophotometric method for the precise quantification of Pb²⁺ in aqueous solutions. This method is based on the reaction of Pb²⁺ with ethylenediaminetetraacetic acid (EDTA) in an ammonia buffer solution, with an absorption maximum observed at 240 nm. The study was conducted under varying parameters, including EDTA concentration, pH of the medium, the presence of organic compounds, and interference effects. The calibration curve demonstrated linearity within the range of 0.5–20 mg/L, with a correlation coefficient (R²) of 0.999, using an ultraviolet-visible spectrophotometer at a λ_max of 240 nm. The apparent molar absorption coefficient and limit of detection of Pb²⁺ were found to be 2.19 × 10⁴ L/ (mol cm) and 0.44 mg/L, respectively. The relative standard deviation for five replicates was less than 2%. Crucially, interference from other ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cu²⁺, Zn²⁺, Fe²⁺, Co²⁺, Cd²⁺, and Al³⁺) was negligible. The proposed method was successfully applied to determine Pb²⁺ concentrations in battery wastewater samples. The results obtained with the present method were comparable to those from atomic absorption spectroscopy and exhibited high accuracy and excellent precision. These compelling results underscore the method’s efficacy, establishing it as a practical and cost-effective approach for diverse Pb²⁺ determination applications.