Foam separation of Cs-137(+) radionuclides coprecipitated with cadmium(II) hexacyanoferrate (Cs-137-CdHCF) particles is investigated in this study using two types of surfactants. The effects of several coprecipitation and foam separation parameters on the recovery percentage and volume reduction of cesium radionuclides are evaluated. The cationic surfactant, hexadecyltrimethylammonium bromide (HDTMA), and the anionic one, sodium lauryl sulfate (NaLS), had the ability to float Cs-137-CdHCF particles at [Cd(II)]/[KHCF] molar ratios of 0.5 and 2, respectively. Recovery percentages of 92% and 88% are obtained in the pH range of 4.7-8.3 and 3.8-9.5 using HDTMA and NaLS, respectively. The addition of stable cesium during the coprecipitation process improved the recovery percentage (98% for HDTMA and 96% for NaLS). The recovery process is very fast where induction time of <15 min (for coprecipitation process) and <5 min (for foam separation process) are sufficient for efficient recovery of cesium radionuclides. The proposed strategy succeeded to efficiently preconcentrate cesium radionuclides from surface water where recovery percentage more than 99% with high volume reduction is achieved using HDTMA. Comparison of the present combined process with previously reported preconcentration processes proved its applicability for preconcentration of cesium radionuclides from water systems. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.