Adsorption of Anionic Dye on the Acid-Functionalized Bentonite

Abstract

The efficiency of acid treatment on natural calcium bentonite (natural bentonite) for anionic dye adsorption was investigated using methyl orange (MO) as a probe. Additionally, adsorption experiments were accomplished between the natural bentonite, acidified bentonite, and a cationic dye (methylene blue, MB). Acid functionalization in natural bentonite (RF) was carried out with HCl and H2SO4 acids (RF1 and RF2, respectively). The samples were characterized by chemical analysis, mineralogy, particle size, and thermal behavior with the associated mass losses. The adsorption efficiency of MO and MB dyes was investigated by the effects of the initial concentration of adsorbate (Ci) and the contact time (tc). The acid treatment was efficient for increasing the adsorption capacity of the anionic dye, and the Qmaxexp values measured were 2.2 mg/g, 67.4 mg/g e 47.8 mg/g to RF, RF1 e RF2, respectively. On the other hand, the acid functionalization of bentonite did not significantly modify the MB dye adsorption. The Sips equation was the best fit for the adsorption isotherms. Thus, we found that the acid-functionalized bentonite increases the anionic dye adsorption by up to 8000%. The increased adsorptive capacity of acidified bentonite was explained in terms of electrostatic attraction between the clay surface and the dye molecule.

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

“…To better understand the type of interaction that occurs between the adsorbate and the adsorbent, the experimental data of CV and CR adsorption were fitted to the nonlinear isothermal models of Langmuir, Freundlich, DR and Temkin, corresponding to Equations (3)–(6) respectively [ 89 , 90 , 91 ]: q e = (q max K L C e )/(1 + K L C e ), q e = K F C e 1/n , q e = q D exp(−K DR ε 2 ), ε = R T ln (1 + 1/C e ), q e = (RT/b T ) lnA T + (RT/b T ) lnC e , where C e (mg/L) is the equilibrium dye concentration and q e (mg/g) is the equilibrium dye adsorbed amount. K L (L/mg) is the Langmuir constant representing the activation energy in adsorption and q max (mg/g), which refers to the maximum adsorption capacity.…”

Surface Modification of Attapulgite by Grafting Cationic Polymers for Treating Dye Wastewaters

“…Comparing the fitting results of the two kinetic models, it could be seen that the experimental data were significantly better in accord with the pseudo-second-order kinetic model. This result meant that the adsorption behavior of CM-ATP was chemical adsorption [ 38 ].…”

“…Comparing the fitting results of the two kinetic models, it could be seen that the experimental data were significantly better in accord with the pseudo-second-order kinetic model. This result meant that the adsorption behavior of CM-ATP was chemical adsorption [38]. Isotherm studies of the adsorption process were conducted by using the Langmuir and Freundlich isotherm models, and the results are shown in Figure 8 and Table 3.…”

Development of Scheelite Tailings-Based Ceramic Formulations with the Potential to Manufacture Porcelain Tiles, Semi-Stoneware and Stoneware

“…The chemical composition of raw materials was obtained by X-ray fluorescence (model EDX 720, Shimadzu, Kyoto, Japan). The mineralogical phases were identified by X-ray diffraction (XRD) using a diffractometer (model XRD 6000, Shimadzu, Kyoto, Japan) with Cu-Kα radiation in a 2 theta range from 5° to 60°, an angular step of 0.02, and a counting time of 0.5 s [ 14 ]. The experimental data were collected at room temperature.…”