Enhancement of phase separation using a drop coalescer in an aqueous two-phase system

The effect of a drop coalescer on phase separation in a PEG/salt aqueous tw o-phase system (ATPS) in the absence and presence of protein has been inves tigated. Raschig rings of ceramic, PTFE and glass were used as a drop coale scer in order to separate the mixture into two phases. Among the three mate rials PTFE is the most effective in coalescing the dispersed drops, with th e throughput with PTFE being twice that without the coalescer. Random packi ng gives good results for phase separation. Two types of fiber mesh coated with PTFE were also used as drop coalescers, one in a spirally folded form and the other in a three-dimensional lattice-form. Throughput in the PEG/sa lt system with the three-dimensional lattice-form is 1.2 times as high as t hat with the spirally folded form. Throughput with the coalescer formed by compiling PTFE Raschig rings and fiber mesh in lattice form is 1.6 and 1.2 times as high as the case of separate use of the fiber mesh and the PTFE Ra schig rings, respectively. The hydrophobic surface of PTFE in the compiled coalescer has no significant effect on the recovery fraction of the protein in ATPS. (C) 2001 Elsevier Science B.V. All rights reserved.