Remoção de metais pesados do lixiviado de aterro sanitário por precipitação e quantificação por voltametria de onda quadrada por redissolução anódica

Abstract

The rapid increase in waste production, driven by the Industrial Revolution, has led to significant environmental challenges, particularly the contamination of soil and water from landfill leachate. This study aims to evaluate the removal of heavy metals (zinc, cadmium, and lead) from landfill leachate through chemical precipitation using the analytical technique of square wave voltammetry by anodic re-dissolution. The study involved sequential stages, starting with adjustments to the electroanalytical method and calibration curve development, followed by precipitation assays with a synthetic metal solution to optimize variables for heavy metal removal. Precipitation experiments were conducted using zinc, cadmium, and lead ions with calcium hydroxide and sodium carbonate, and voltammetric analyses were performed using square wave anodic stripping voltammetry to assess metal concentrations. The study examined the electrochemical behavior of Bi³⁺ using square wave voltammetry, revealing linear relationships between peak current and frequency, indicating reversibility in the reaction. Optimization of parameters such as frequency, step, and pulse amplitude improved the precision and selectivity of the analysis. Bi³⁺ concentration was optimized for maximum electroanalytical response, with a concentration of 1.25 mg L-1 selected. Deposition time was also optimized, with 300 seconds providing the best results. Metal removal efficiency using precipitating agents (Ca(OH)2 and Na2CO3) was analyzed, showing higher efficiency with Na2CO3. The study highlights the significance of pH and agent concentration in the removal process. This study evaluated the removal of heavy metals (zinc, cadmium, and lead) from landfill leachate using chemical precipitation with calcium hydroxide and sodium carbonate. The process achieved high removal rates, particularly for lead (97.97%). Square wave voltammetry was successfully developed for precise quantification, with statistical validation confirming its reliability for this application.