Fitorremediação de solo contaminado por chumbo: efeitos de agentes quelantes sintéticos e naturais na dessorção,lixiviação e fitoextração

Abstract

Synthetic chelates used in phytoextraction, barely degradate in soil and pose a risk owing metal leaching. Natural organic acids can be an alternative to synthetic chelates thanks to their rapid biodegrability. The study was carried out aiming at evaluating the performance of three synthetic chelators and two natural aliphatic acids in desorbing Pb from a soil contaminated through recycling of battery wastes. Additionally, effects of the amendments on the Pb leaching from soil were also studied. The work comprised two experiments: (1) Pb desorption from soil using the rates of 0, 2, 5, 10, 20 and 30 mmol kg-1 of citric acid and oxalic, EDTA, DTPA and NTA; (2) Pb leaching from soil columns by applying citric acid, oxalic, EDTA, and NTA onto soil at the 0, 10, and 20 mmol kg-1 concentrations. EDTA promoted the highest desorption and leaching, hence is not recommended for phytoextraction programs in the area. High desorption of Pb along with low leaching, qualifies NTA as a potential Pb phytoextraction enhancer for the metal in the field condition. Neither citric acid nor oxalic acid posed risk regarding Pb leaching. On the other hand, they seem little promising for enhancing Pb phytoextraction due to the lowmetal concentration in soil solution.