Zeolite NaX Mass and Propeller Agitator Speed Impact on Copper Ions Sorption

Abstract

Sorption is often carried out in stirred batch reactors without any consideration of how much mixing is sufficient to avoid the effect of diffusion without compromising yield and cost due to overmixing. Therefore, the focus of this work was to study how the maximum sorption capacity, removal efficiency, kinetics and power consumption (P) of the studied process are affected by different mixing speeds, i.e., impeller speed/minimum impeller speed for complete suspension (N/NJS) ratio values and zeolite suspension mass concentrations. Experiments were conducted in a baffled reactor with the propeller at a standard off-bottom clearance. In addition to the experimental studies, numerical modelling approaches were carried out to investigate the sorption process using a transient multiphase computational fluid dynamics model and fitting selected kinetic models. The results show that an increase in zeolite mass leads to a slight increase in the NJS and consequently PJS. The impeller speed affects the velocities, power consumption, kinetics, final amount and removal efficiency of copper sorbed. The experimentally determined kinetic data fit Ritchie’s kinetic model well. However, for two experiments, performed at N/NJS ratios of 0.8 and 0.6, Mixed kinetic model fits better, suggesting that the second-order reaction is suppressed by diffusion. Due to the influence of diffusion, the experimentally determined sorption efficiency decreased from 59.377% to 54.486% and 46.372% for N/NJS ratios of 0.8 and 0.6, respectively.

Effect of NaX Zeolite Mass and Baffle Presence on Copper Sorption

“…With the propeller, the increase in N JS with the zeolite mass in the reactor with baffles and even the values of N JS were almost the same as in this study, although the impeller was slightly larger. 26 This might be related to the results published by Tamburini et al 13 for the Rushton turbine, which indicate that the difference between N JS values in reactors with and without baffles is due to differences in flow patterns produced in those reactors. Thus, the observed similarities and differences might result from the similarities or differences in the flow patterns pro-duced by the SBT, propeller, and PBT impeller.…”

“…Thus, the observed similarities and differences might result from the similarities or differences in the flow patterns pro-duced by the SBT, propeller, and PBT impeller. According to the literature 26 , propeller agitators typically produce an axial flow, whereas SBT impellers are known to produce a radial fluid flow, although this type of impeller does not pump in a true radial direction due to pressure differences between the two sides of the impeller. 17 PBT impeller is known as a "mixed flow agitator" and its size and location in a baffled reactor will result in a more noticeable axial or radial component of flow.…”

“…3,23,24 While the effects of reactor geometry on hydrodynamic conditions and consequently on sorption kinetics, efficiency, and costs did not attract much interest, it was found that reactor geometry indeed affects sorption kinetics, yield, and costs. [25][26][27][28][29] Therefore, the aim of this work was to analyse the hydrodynamic conditions generated by varying the zeolite mass and the presence of baffles, and to investigate their influence on the kinetics and efficiency of copper sorption. To visualise the hydrodynamic conditions in the reactor, the system's behaviour was simulated using ANSYS Fluent v17.2.…”