Environmental contamination with heavy metals is a growing global concern as metals have adverse impacts on both human health and the ecosystem. Lead (Pb) is one of the most common and toxic metals released into the environment from various industrial activities. Over the last few decades, a growing concern has been raised about the environmental impacts of EDTA and its metal chelates because their biodegradation is very limited to particular conditions. Various biodegradable ligands have recently been introduced and used in various industries and agriculture. Investigation of the reactions of heavy metals with clay minerals in the presence of these ligands in model systems can help to better understand the behavior of the metals in soil environments. In this study, the interactions of Pb with montmorillonite STx-1b in the presence of EDTA and environmental friendly ligands GLDA and MGDA were investigated. This research was conducted in three different studies. In the first study, the adsorption kinetics of Pb at two concentrations of 0.25 and 1 mM on STx-1b in the presence and absence the ligands were investigated. The results showed that the maximum Pb adsorption rate on the STx-1b increased with increasing Pb concentration while the use of ligands decreased the maximum adsorption rate. The Pb adsorption kinetics on the STx-1b was biphasic, with the initial fast phase occurring within 3 h and the slow adsorption phase occurring within 12 h until the equilibrium time. The adsorption kinetics of Pb were described by pseudo-first-order, pseudo-second-order, power function, parabolic diffusion, Elovich, and chemisorption-diffusion models. The best-fitted model was the pseudo-second-order model. The results of speciation performed by the PHREEQC computer model showed that the dominant species in the Pb:GLDA, Pb:MGDA and Pb:EDTA systems were the anionic forms of PbGLDA 2- , PbMGDA - and PbEDTA 2- , respectively. It seems that the formation of these stable chelates in solution resulted in a decrease in Pb adsorption on STx-1b. The decreasing trend of Pb adsorption on STx-1b followed the decrease in the stability constant of the ligands with Pb as EDTA MGDA GLDA. In the second study, equilibrium sorption of Pb, Pb-MGDA, Pb-GLDA, and Pb-EDTA by Montmorillonite STx-1b was investigated. Equilibrium data showed that the Langmuir model has a better explanation of lead absorption on the STx-1b as compared to the Freundlich and Koble-Corrigan models both in the presence and absence of the ligands. The distribution of Pb between the soluble and solid phases varied depending on the metal and ligand concentrations. FE-SEM/EDX, ATR-FTIR, and XRD evidence indicated that Pb and Pb complexes were adsorbed, most likely through physical forces, on both external planar and edge surfaces of the MMT. In conclusion, GLDA and MGDA represented lower ability than EDTA to depress Pb 2+ adsorption on MMT, and hence, lower potential to mobilize Pb in soils and sediments where MMT is a predominant mineral. In the third study, the kinetics of lead desorption from montmorillonite in the presence of GLDA, MGDA, and EDTA ligands was investigated. The results showed that although different kinetic models are capable of describing desorption of Pb and Pb-ligand, the pseudo-second-order model showed the best fits to the data. An increasing incubation time of Pb in the systems from zero time (immediately after saturation with lead) to 30 days resulted in a significant decrease in the proportion of lead desorption in all studied systems. The total quantity of Pb desorbed after 24 h (DQt) and the mean Pb released at eight sampling times (DQm) were quantity parameters calculated desorption for each system to evaluate ligands and aging effects on Pb desorption process. Comparison of the DQt, and DQm values shows that the sequence of these ligands in Pb desorption from STx-1b was GLDA MGDA EDTA, which is consistent with the increasing trend in the stability constants of these ligands with Pb. The initial sorption rate (h) at both concentrations showed an increase in the presence of GLDA, MGDA, and EDTA ligands. The desorption rate Pb decreased significantly when the aging time increased. Key Words : Biodegradable chelating agents; Lead; Kinetic; Isotherm; Desorption Montmorilonite STx-1b.