Removal of cobalt ions from aqueous solutions by polymer assisted ultrafiltration using experimental design approach Part 2: Optimization of hydrodynamic conditions for a crossflow ultrafiltration module with rotating part

Application of shear-enhanced crossflow ultrafiltration for separation of cobalt ions from synthetic wastewaters by prior complexation with polyethyleneimine has been investigated via experimental design approach. The hydrodynamic conditions in the module with tubular metallic membrane have been planned according to full factorial design in order to figure out the main and interaction effects of process factors upon permeate flux and cumulative flux decline. It has been noticed that the turbulent flow induced by rotation of inner cylinder in the module conducts to growth of permeate flux, normalized flux and membrane permeability as well as to decreasing of permeate flux decline. In addition, the rotation has led to self-cleaning effect as a result of the reduction of estimated polymer layer thickness on the membrane surface. The optimal hydrodynamic conditions in the module have been figured out by response surface methodology and overlap contour plot, being as follows: Delta P = 70 kPa, Q(R) = 108 L/h and W = 2800 rpm. in such conditions the maximal permeate flux and the minimal flux decline has been observed. (C) 2009 Elsevier B.V. All rights reserved.