Cationic and Anionic Dye Adsorption on a Natural Clayey Composite

Abstract

One of the main challenges for environmental sciences today is the effective treatment of dye-laden industrial effluents. This work aimed to study the potential of an untreated (natural occurring clayey composite) red clay (RC) for the adsorption of a cationic dye Basic Navy Blue 2RN (CNB) and anionic dye Drimaren Yellow CL-2R (ADY). We evaluated the effect of pH, dye concentration, and adsorbent concentration on the removal effectiveness to study the absorption process. Also, we studied the adsorption process by analyzing the feasibility of several known adsorption isotherms and kinetic models. The results show that at a pH of less than 4, the CNB and ADY removal percentages were 97% and 96%, respectively. At a pH greater than 8, the CNB and ADY removals were 75% and 25%, respectively. The CNB adsorption happened by chemisorption of a monolayer on iron-containing particles (IPs). In congtrast, the ADY adsorption occurred by monolayer physisorption on kaolinite particles (KPs) and Na, K-rich Laumontite particles (LPs). The Langmuir isotherm model fits very well with CNB experimental data. The Temkin model shows the best fit between the isotherm function and the ADY dye-adsorption data. The pseudo-second-order kinetic model fits the CNB and ADY dye-adsorption data on RC particles. The heterogeneous composition of naturally occurring clay favors different adsorption mechanisms and opens an avenue for the separation process’s engineering.

Removal of Anionic and Cationic Dyes Present in Solution Using Biomass of Eichhornia crassipes as Bioadsorbent

“…It was also observed that there is an increase in the percentage of removal with the increase in the amount of mass of the adsorbent, since the adsorption of both dyes increases due to the increase in the area available for the exchange process between the solution and the surface until reaching the equilibrium. This type of behavior has been reported in other studies with different adsorbents [ 2 , 13 , 22 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ]. This analysis allows us to understand and know the limitations due to mass transfer, so this particularly important parameter must be considered [ 2 , 13 , 23 , 33 ].…”

“…After the adsorption of GV and PR with both bioadsorbents ( Figure 9 ) it was possible to notice that all the peaks disappeared exception of the signals at 14.7 and 21.9°, this effect is assigned to crystallinity increment of the materials increases [ 34 , 48 , 49 ]. The lattice parameters were also shown in Table 12 .…”

“…On the other hand, for GV adsorption the opposite occurs, since the decrease for the Ca/Si ratio present in WLW and NWL was 60.58 and 17.59%, respectively, and for the C/O ratio, it was 55.32 and 19.71%, respectively, which indicates that the cationic nature of the dye, together with these functional groups, are the ones in charge promoting better removal than in the case where WLW was used. The results allow us to mention that there could be more than one adsorption mechanism involved, such as (i) electrostatic forces, (ii) intervention of functional groups present on the surface, and (iii) ion exchange [ 45 , 46 , 47 , 48 , 49 ].…”

“…The different bands observed represents the functional groups detected on the surface of WL. In this spectrum, the stretching vibration found at 3300 cm −1 is related to the OH group and the bonds corresponding to lignin, cellulose, and hemicellulose, while at the signal 2921 cm −1 it is assigned to the symmetric and asymmetric vibrations of the C-H bond of the methyl and methylene groups on the surface [ 38 , 48 , 49 ]. The band at 2859 cm −1 is assigned to the stretching of CH groups of lignin [ 45 ].…”

“…The band at 2859 cm −1 is assigned to the stretching of CH groups of lignin [ 45 ]. The bands at 1628 and 1536 cm −1 correspond to the stretching vibrations of the C=O carboxylic bond and lignin, respectively [ 32 , 38 , 48 ]. There is a peak at 1413 cm −1 corresponding to the vibration of aliphatic compounds (CH 2 and CH 3 ) and methoxy group (O-CH 3 ) [ 45 ] whilst the peaks at 1320, 1240, and 1013 cm −1 are attributed to the symmetry vibration of the stretching of the COO- bond, to the presence of the C-H bond of the aromatic group and the stretching vibration of the C-OH bond of the groups’ alcoholics, lignin and carboxylic acids, respectively (40,60).…”