Removal of Mercury(II) from Aqueous Solutions via Dynamic Column Adsorption

Dynamic column adsorption of mercury(II) from aqueous solutions on an Amberlite GT-73 cationite is studied. Experimental measurements derive the dependences C/C₀ = f(t) (breakthrough curves), where C₀ and C are the concentrations of mercury in the water flow inflowing to the sorbent fixed bed and outflowing from it, respectively, and t is the running time for different thicknesses of the fixed bed, as well as deriving rates of water flow and concentrations of mercury C₀. It is shown that if the breakthrough curves belong to the logistic type, dependences of ln (C₀/C − 1) on t are rectified and have the form ln (C₀/C − 1) = a₀−a₁t, where the parameters a₀ = kq_mM/Q and a₁ = kC₀, k is the rate constant of adsorption, q_m is the dynamic adsorption capacity, M is the weight of the adsorbent, and Q is the volumetric flow rate. By transforming the experimental dependence of the first type to the second type followed by its description using this straight line function, the aforementioned parameters a₀ and a₁ are determined followed by the quantities k and q_m, characterizing the adsorption of mercury on the cationite. It is found that the relative standard deviation is ≤2% for the experimental quantities k and q_m. A formula for the calculation of the service lifetime of the adsorbent maintaining the regulated degree of purification of water is derived. The formula is successfully tested in the experiments on the removal of mercury from water described in this work.