Realizing highly effective and selective enrichment of radioactive Cs(I) in complex environmental systems and exploring the microscale adsorption mechanism of Cs(I) on adsorbing material is the key point for developing highly efficient materials for Cs(I) adsorption. In addition, the low cytotoxicity of materials is essential for practical applications and environmental protection. In this study, the controlled assembly of bentonite carrier with a highly selective substance of Cs(I) is prepared by in-situ synthesis method in order to construct a low-toxic functional clay material with high adsorption capacity and selectivity of Cs (I) in complex environmental systems. The efficiency of the zinc hexacyanoferrate(III)-grafted magnetic bentonite (denoted as ZHF/MB) composite was evaluated in adsorption isotherm studies, kinetics analyses, and selectivity tests by using the batch technique. The toxicity of the ZHF/MB composite was evaluated through in vitro cytotoxicity assays using human hepatic cells (HepG2 cells). The results revealed that the ZHF/MB composite had not only a higher adsorption capacity (1.638 mmol/g, 60 degrees C) for Cs+ ions than a number of other natural and manmade materials but also no cytotoxicity in human cells. In addition, the ZHF/MB composite showed excellent selectivity for Cs' with a removal efficiency of over 90% from solution (m/V = 0.4 g/L, [Mn+](initial) = 10 mg/L, Mn+= Cs+, Ni2+, Sr2+,Co2+). The promising safe toxicology profile, remarkable Cs' adsorption efficiency, and excellent selectivity of the ZHF/MB composite demonstrate its great potential for using as a decorporation agent for radioactive cesium remediation. The implementation of this research will provide new adsorption materials and method for radioactive Cs(I) waste management. (C) 2020 Elsevier Inc. All rights reserved.