| Abstract |
In the study, post-coagulation sludge was used in the sorption of the Helaktyn Blue F-2R. The sludge was subjected to: (1) drying, or (2) combusting, either (3) oxidizing with H2O2. The effect of pH, the effect of the contact time (and examining the adsorption kinetics), and the adsorption isotherm were examined. The parameters of selected models of adsorption isotherms (Freundlich, Langmuir, Jovanovic, Dubinin-Radushkevich, Sips, and Toth) were determined using nonlinear estimation. In the case of all sorbents strong acidic conditions were required for the adsorption process occurrence (pH 2). According to the sorption kinetics, for all sorbents, the pseudo-first-order model were matching the most to the experimental results, which suggests that the physisorption process occurred. Based on the examination of the intraparticle diffusion model, it can be concluded that the rate of the adsorption process was controlled to a greatest extent by the inner diffusion process than by the film diffusion process. The values of C for all sorbents in the intraparticle diffusion model were positive and greater than 0, which indicates that the intraparticle diffusion was not only the rate-controlling step. Based on the examination of different isotherms' models, the greater sorption capacity was obtained for dried sludge, a little less for the oxidized sludge, and the smallest for combusted sludge. Moreover, the results indicate that the sorbent produced from combusted sludge had the greatest surface heterogeneity, while the lowest - the sorbent obtained from dried sludge. |
