Heavy Metals Leaching from Fluorescent Lamps Physicochemical Treatment Residuals

Abstract

Waste generated during the process of physicochemical treatment of fluorescent lamps contains relatively high quantities of heavy metals. Physicochemical treatment is employed with the aim to concentrate toxic substances present in the lamps. This study attempts to evaluate the leaching properties of treatment residuals. Waste of a similar composition has been not fully researched yet, thus the limited data are available on leaching of heavy metals from residues of similar processes. Concentrations of heavy metals leaching from the residuals into various complex-forming agents (ethylenediamine tetraacetic acid (EDTA), Citric acid, Tartar acid) have been analyzed. EDTA is selected for further kinetics experiments as a complex-forming agent known for its most effective leaching properties as stated in literature on this subject and in most cases practically observed.

Kinetic experiments have shown that almost all water-soluble heavy metals are mobilized from the samples within the period of approximately 20 hours, with time variation for different heavy metals. An increase in the leaching concentrations when using EDTA as a complex-forming agent has been observed. Extraction with EDTA has resulted in heavy metal concentrations ranging from 0.41 mg kg^-1 of dry mass (DM) for Co to as much as 1576.00 mg kg^-1 DM for Zn. Exposure of the samples to different temperatures has revealed the influence of the temperature as an important factor of experimental conditions. The concentration of leaching Hg has increased 3 times after heating the samples in the temperatures from 20^o to 120^oC.