Retention of Hg(II) by Solid Mercury Sulfide from Acidic Solution

• Published in: Separation science and technology 1999-02, Vol.34 (3), p.487-499
• Main Authors: HASANY, SYED MOOSA, SAEED, MOHAMMAD MUFAZZAL, AHMED, MUNIR
• Format: Article
• Language: English
• ISSN: 0149-6395; 1520-5754
• DOI: 10.1081/SS-100100662

Mercury sulfide was prepared and characterized by measuring average pore size and surface area. The sorption of mercury onto mercury sulfide was investigated in detail with respect to sorptive medium, agitation time, sorbent and sorbate concentration, and temperature. The maximum sorption of mercury (>99.8) was achieved from 10 −3 M hydrochloric acid solution using 50 mg mercury sulfide for 10 minutes. The sorption data of mercury followed the Langmuir isotherm over the entire concentration of mercury investigated whereas the Freundlich and Dubinin-Radushkevich isotherms were obeyed only up to low and moderate concentrations. Useful parameters like sorption capacity and energy have been evaluated using these isotherms. The variation of the equilibrium constant with temperature has the results ΔH=23.8 ± 3.2 kJ·mol −1 , ΔS = 130 ± 10 J·mol −1 , and ΔG = −13.5 ± 0.4 kJ·mol −1 at 298 K. Among the ions tested, tartrate, fluoride, and citrate increase the sorption whereas Cu(II), Ba(II), Zn(II), Ni(II), Fe(II), and Cr(III) reduce the sorption significantly. Except for Y(III) (∼91%), all the metal ions showed a lower affinity toward HgS, especially trivalent Ho, Fe, Sc, Tm, Ga, Dy, As, and Pr which showed sorption >1 and >10%. The mercury sulfide column can be used to separate Hg(II) from these trivalent metal ions.