La eliminación de metales tóxicos presentes en efluentes líquidos mediante resinas de cambio iónico. Parte XII: Mercurio(II)/H+/Lewatit SP112

Francisco José Alguacil,Esther Escudero

doi:10.3989/revmetalm.160

Abstract

El mercurio(II) puede ser eliminado de disoluciones acuosas acidas mediante la resina de intercambio catiónico Lewatit SP112. Se ha investigado la influencia de distintas variables experimentales sobre la carga del mercurio(II) en la resina: velocidad de agitación (275–1000 min−1), temperatura (20–60 °C), valor de pH del medio acuoso (0–4) y dosificación de la resina (0.05–0.4 g·L−1). La carga de mercurio(II) en la resina disminuye con el aumento de la temperatura (reacción exotérmica) en un proceso espontaneo, mientras que el modelo de núcleo recesivo representa al mecanismo de carga del metal en el rango de temperaturas investigado. Los datos experimentales se ajustan al modelo cinético de segundo orden (275 min−1) o al modelo de pseudo segundo orden (500–1000 min−1), aunque la carga máxima del metal en la resina no depende de la velocidad de agitación. Los datos experimentales se ajustan a la isoterma tipo-2 de Langmuir. Se ha comparado la carga de mercurio(II) con distintas resinas y con nanotubos de carbono de pared múltiple. El mercurio(II) puede ser eluido con distintos eluyentes, pudiéndose obtener mercurio en estado de oxidación 0 a partir de las disoluciones de elución conteniendo al Hg(II).

Highlights

Mercury is, together with gold, silver, lead, copper and iron, one of the six elements known and used by the Mankind from the beginning, and unlike the others, mercury had gained a bad reputation of harmfulness and toxicity, despite the fact that under centuries it had various medical uses
The experimental data fitted to the second order kinetic model (275 min−1) or the pseudo-second order kinetic model (500–1000 min−1), though maximum metal uptake was not dependent on the stirring speed applied to the system
Mercury in the aqueous solutions was analysed by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), whereas mercury loaded onto the resins/adsorbent was calculated by the mass balance

Summary

INTRODUCTION

Together with gold, silver, lead, copper and iron, one of the six elements known and used by the Mankind from the beginning, and unlike the others, mercury had gained a bad reputation of harmfulness and toxicity, despite the fact that under centuries it had various medical uses. Considering only inorganic mercury, organic mercury is another world, this element is basically found in aqueous solutions in the form of Hg2+ cation, or forming a number of complexes i.e. HgCl42-, Hg(CN)42-, Hg(Tu)22+, etc. Following on the series (Alguacil et al, 2002; Alguacil, 2002; Alguacil, 2003; Alguacil, 2017a; Alguacil, 2017b; Alguacil, 2018a; Alguacil, 2018b; Alguacil and Escudero, 2018; Alguacil, 2019a; Alguacil, 2019b; Alguacil, 2019c), in this work the removal of Hg(II) from acidic aqueous solutions by using the cationic exchange resin Lewatit SP112 is investigated. The elution of mercury(II) from metalloaded Lewatit SP112 resin by different eluants is tested, and the precipitation of zero valent mercury as end product of the process

EXPERIMENTAL

RESULTS AND DISCUSSION

Post-treatment of the Hg-bearing eluate

CONCLUSIONS