Improvement of the sorption behavior of aluminum silicate composite toward 134Cs and 60Co radionuclides by non-living biomass of Chlorella vulgaris

Cesium and cobalt radioactive isotopes (Cs-134 and Co-60) are dangerous to human health due to their long half-life about 2.1 and 5.3 year, respectively. Developing a new composite used as an efficient sorbent for these is an urgent requirement for radioactive waste management. Herein, preparation of different materials such as aluminum silicate (AS), cultured of Chlorella vulgaris (NCV) alga, and aluminum silicate/Chlorella vulgaris (AS/NCV) composite 3:1 were prepared by wet chemical technique and used to remove the Cs-134 and Co-60 radionuclides. Different analytical techniques were used to characterize the prepared sorbents as SEM, TEM, XRD, BET, TGA/DTA, FTIR particle size analyzer, and pore size distribution. The factors affecting the sorption process as pH, temperature, contact time, and weight of adsorbent were studied. The sorption process was found to follow a pseudo-second-order mechanism. The monolayer capacity for Cs-134 radionuclide onto the aluminum silicate, non-living Chlorella vulgaris biomass, and aluminum silicate/Chlorella vulgaris composites are 66.67, 83.54, and 90.11 mg/g, respectively, and for Co-60 radionuclide are 59.31, 91.99, and 99.24 mg/g, respectively. The values of thermodynamic parameters indicate that the sorption process is endothermic and spontaneous.