Removal of Mercury From Aqueous Solutions by ETS-4 Microporous Titanosilicate: Effect of Contact Time, Titanosilicate Mass and Initial Metal Concentration

Mercury is one of the most toxic heavy metals present in the environment and therefore is extremely important develop new, simple and reliable techniques for its removal from aqueous solutions. A recent line of research within this context is the application of microporous materials. The use of these materials for removing heavy metals from solutions may become a potential clean-up technology in the field of wastewater treatment. In this work it is reported the application of microporous titanosilicate ETS-4 as ion exchanger to remove Hg²⁺ from aqueous solution. Under batch conditions, we studied the effect of contact time, titanosilicate mass and initial Hg²⁺ concentration. Only 5 mg of ETS-4 are required to purify 2 litres of water with 50 μg L⁻¹ of metal. Under the experimental conditions, the initial Hg²⁺ concentration and ETS-4 mass have strong influence on the sorption process, and it is proved that 24 h are almost always sufficient to attain ion exchange equilibrium. Langmuir and Freundlich isotherms were used to fit equilibrium experimental results. The kinetics of mercury removal was reliably described by a pseudo second-order model. On the whole, ETS-4 shows considerable potential to remove Hg²⁺ from wastewaters.