Ensayo Toxicológico de efluentes líquidos de refinación de oro y la posible remoción de metales pesados Cobre (Cu) y Plomo (Pb) mediante el empleo de Zeolita natural

Abstract

In this study, the adsorption capacity of natural zeolite for the removal of heavy metal ions Cu2+ and Pb2+ present in the effluents of gold refining processes was investigated. The adsorption parameters were evaluated as initial pH (3-6), particle size (595μm-74μm), amount of adsorbent (1-4g), initial concentration (50-400mg/L) and contact time (15-120min), maintaining a constant temperature of 25°C and agitation speed of 150rpm. According to the evaluation conditions for each parameter, lead generally reached removal values between 30 to 100%, while copper values varied between 30 and 80%. The optimal values in this study for the removal of lead and copper metals were: pH: 5-6; particle size: 74μm; amount of adsorbent: 4g and contact time: 30minutes. The following order of selectivity Pb2+>Cu2+ was identified in the entire tests that were carried out during this study. Subsequently toxicological tests were conducted to determine the toxicity of the effluent treated with zeolite on the species of Lactuca sativa (lettuce) and Allium cepa (onion), which were exposed to different concentrations of the effluent (9, 28, 94, 282 and 940mg/L). The results determined that the effluent samples are toxic. Greater sensitivity of the onion was evidenced in the germination tests, while in the evaluation of the root and hypocotyl, there was greater sensitivity for the lettuce seedlings. In the statistical analyzes of variance homogeneity, significant differences were identified among the samples (p <0.05).