Novel application for palygorskite clay mineral: a kinetic and thermodynamic assessment of diesel fuel desulfurization

Adsorption Behavior of Crystal Violet and Congo Red Dyes on Heat-Treated Brazilian Palygorskite: Kinetic, Isothermal and Thermodynamic Studies

“…The second event (125–230 °C) presented a mass loss of 2.46% and is related to the loss of zeolitic water molecules located in the palygorskite channels [ 72 ]. The third event observed between 230–530 °C was attributed to coordinated water loss and condensation of silanol and aluminol groups [ 54 , 80 ], which resulted in a mass loss of 5.26%. The last event occurred at 530–720 °C and showed a mass loss of 11.74% was caused by dolomite decomposition [ 81 ].…”

“…Based on the correlation coefficient values (R 2 ), the Langmuir model was the one that best described the CV and CR adsorption process in the Pal-700T sample, as it exhibited R 2 values closer to the unity. The best mathematical adjusts to the Langmuir model suggest that the adsorption of CV on Pal-700T occurs mainly via the chemisorption process, in which a monolayer of the adsorbate is deposited on the surface of the palygorskite [ 54 , 92 , 93 ]. The higher value of K L means greater interaction between the adsorbent and adsorbate [ 94 , 95 ]; thus, Pal-700T has a greater interaction with CV molecules, while Pal has a lower interaction, which is consistent with the results obtained experimentally.…”

“…After heat treatment at temperatures above 300 °C, the bands at 3612 and 3578 cm −1 disappeared, due to complete dehydroxylation [ 86 ]. The bands related to zeolitic and coordinate water were no longer identified in the spectra of samples calcined above 300 °C, due to losses of zeolitic and coordinate water in the palygorskite structure [ 54 ]. The bands located between 1190 and 975 cm −1 (1190 and 642 cm −1 ) are considered fingerprints of the palygorskite.…”

Kinetics of liquid phase batch adsorption experiments

“…The intercept of the linear regression in Fig. 4 is a significant deviation from 0 and this would be interpreted as evidence of combined surface resistance and internal diffusion (Câmara et al 2020;Kong et al 2016;Lupul et al 2015;Peralta et al 2019;Rincon-Silva et al 2016;Shen et al 2018;Heyden et al 2018), even though if this was the case the intercept should be negative. The positive intercept is actually a result of the fact that the points used are already outside the range where the first term in the series expansion is sufficient to describe the response.…”

“…The fact that this is a very common methodology in adsorption from solution is evidenced by the fact that (Ho and McKay 1998;Cheung et al 2000;Boyd et al 1947a) are cited well over 1000 times. Only considering issues of the journal Adsorption since 2015, 16 contributions reporting parameters based on linearized plots of these empirical models could be found (Câmara et al 2020;Kong et al 2016;Lupul et al 2015;Peralta et al 2019;Rincon-Silva et al 2016;Shen et al 2018;van der Heyden et al 2018;Bartczak et al 2016;Bazargan et al 2017;Ciesielczyk et al 2016;Marques Fraga et al 2020;Hubetska et al 2020;Morales-Perez et al 2016;Popugaeva et al 2019;De Smedt et al 2015;Yuan et al 2019). This shows that significant effort is being devoted to determining the kinetics of adsorption in liquid systems and it is therefore important to be able to interpret these results correctly and arrive at physical parameters that are directly applicable in the design and simulation of adsorption separation processes.…”