Our previous work reported that palygorskite has potential for application as metal cations adsorbent due to its chemical and mineralogical properties. In this work, kinetic study and adsorption isotherms were performed in order to evaluate Pb (II) ions adsorption rate, maximum capacity and type of adsorption by using palygorskite as adsorbent. Adsorption tests were performed in batch, using pH of 5, 2 g of palygorskite, 40 mL of synthetic effluent solution and stirring for 1 hour. Kinetic experiments were performed using 34 mg L -1 of a lead synthetic effluent at same mass and pH conditions. Furthermore, after adsorption studies, the sample was characterized by X-ray fluorecence (XRF), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) coupled with Energy-dispersive X-ray spectroscopy (EDS) analysis, in order to verify and understand the interaction of lead ions in palygorskite. The results demonstrated that palygorskite presented an equilibrium time of 10 min with 99.14% of removal, following pseudosecond order kinetic. The maximum adsorption capacity was 21.65 mg g -1 and Gibbs' adsorption-free energy was -21.39 KJ mol -1 , with Langmuir model being the most suitable for adjustment of the data. Thus, its presence was confirmed by characterization techniques, indicating that the metal is distributed homogeneously on palygorskite surface, proving its efficiency as lead ions adsorbent.

Palygorskite is a clay mineral that has several industrial and environmental applications. Palygorskite main deposits in Brazil are located in the municipality of Guadalupe, Piauí. A comparative study was performed with five samples of palygorskite from different locations through ore dressing and chemical and mineralogical characterization, using the XRD, XRF and methylene blue titration techniques. According to the results, there are significant differences in the samples composition. Among them, the most significant difference was the cation exchange capacity (CEC) value, which ranged from 24.0 to 41.0 meq.100 g-1, followed by the content of some oxides and the crystalline phases present. Despite coming from the same region, the samples contained distinct impurities.