Remoção de dureza cálcica utilizando processo de troca iônica

Abstract

In this work, the adsorption of Calcium (Ca+2 ) in cationic resin of the brand Amberlite IR-120 was studied. Equilibrium and kinetics experiments were carried out to determine the effect of resin mass (10 to 200 mg), agitation (100 to RPM), initial concentration (50 to 250 mg L1 ) and temperature (15 to 45ºC) on the removal efficiency. For the studies of equilibrium and adsorption kinetics, non-linear models combined with error functions, such as coefficient of determination (R2 ) and squared sum of residues (SQR) were used to evaluate compatibility between kinetic models (pseudo-first order, pseudo-second order, Elovich) and isothermal adsorption equations (Langmuir and Freundlich). The IR-120 resin was characterized by scanning electron microscopy with X-ray energy dispersion spectroscopy (SEM-EDS), laser granulometry, nitrogen adsorption-desorption isotherms (BET) and infrared spectroscopy with attenuated total reflection (ATR-FTIR). Using the Langmuir model, the maximum Ca+2 adsorption capacity was calculated at 150 mg g1 . According to the R² values of the kinetic models, it can be concluded that the pseudo-first order model showed the best fit for all experimental data. The tests indicated the best conditions as: temperature of 25ºC, mass of 0.12 g of resin and agitation of 230 RPM. The results suggest that IR-120 can be a promising adsorbent for Ca+2 removal.