Abstract
Dissolved air flotation (DAF) process has been widely used for many applications including waste water treatment. For the purpose of heavy-metal removal, this study will implement several commercial polymers as collectors in DAF process. The investigated polymers are polyvinyl alcohol, polyethylene glycol, and chitosan which will be used as separation-enhancing agents in the air flotation process. On the other hand, the studied heavy metals are zinc chloride, lead(II) nitrate, manganese(II) chloride, nickel chloride, and cadmium chloride. Different parameters have been studied in this work such as the concentration and types of collectors, modification of polyvinyl alcohol, and the type and concentration of the heavy metals.
The results showed that chitosan was generally better than the other investigated polymers in affecting the removal of Cd (29%), Ni (27%), Mn (31%), and Pb (29%). The removal of Zn was not consistently high for any type of polymers, although it was less with chitosan. Polyvinyl alcohol was modified by carboxylation and the modified polymers were found to be more effective at removing the smaller metals such as Ni (30%), and Zn (28%), and less effective at removing the larger metals Cd (24%) and Pb (29%) at heavy concentration of 250 ppm. (C) 2015 Elsevier Ltd. All rights reserved.