Densities, Viscosities, and Liquid Diffusivities in Aqueous Piperazine and Aqueous (Piperazine + N-Methyldiethanolamine) Solutions Derks, P.W.J.; Hamborg, E.S.; Hogendoorn, J.A.; Niederer, J.P.M.; Versteeg, G.F.; Journal of Chemical & Engineering Data 2008, 53, 1179-1185