A study of the distribution of the concentration of mercury ions along a fixed ionite bed in the sorption treatment of water

Resumo

A new approach to the mathematical description of the breakthrough curve by using the space−time concentrations profile of contaminants along the fixed sorbent bed in the process of sorption purification of water is proposed. For the breakthrough concentration C of contaminant in water effluent from the fixed bed, an expression for its time dependence is derived. The space−time concentration profile of mercury adsorbed from a polluted water flow on Amberlite^® GT-73 cationite was determined experimentally. Using the formula derived in the present paper, the time dependence C(t) is calculated, known as a breakthrough curve. The latter was compared with a curve determined experimentally using traditional methods. A close match between the two curves is observed. It is established that, during the adsorption process, adsorbed mercury ions are redistributed between different parts of the fixed bed. It was found that, up to the time of breakthrough (200 min), the concentration of mercury in water flowing out from the fixed Amberlite^® GT-73 bed, ranges within 1−5 μg/L, i.e., is below the maximum permissible concentration, even if the incoming water contains mercury in a concentration of up to 70 mg/L, which corresponds to the typical level of pollution of industrial wastewater.