Functionalized chitosan with butylammonium ionic liquids for removal of Cr(VI) from aqueous solution

Abstract

Environmental pollution by heavy metals is currently a problem of great concern for human health. In this context, this study aims to contribute with the synthesis and characterization of chitosan functionalized with three different ionic liquids (n-butylammonium acetate, sec-butylammonium acetate, and tert-butylammonium acetate) followed by its application in hexavalent chromium effluent treatment. The adsorbents synthesized (ChN, ChS, and ChT) were characterized by SEM, EDS, FTIR, BET, RDD, PSD, and XRD techniques. Afterward, the influences of temperature, contact time, and pH on the Cr(VI) adsorption process were evaluated. The solution with pH 3 displayed the highest adsorption capacities (107.31, 104.60, and 107.97 mg.g-1 for ChN, ChS, and ChT, respectively). The kinetic data were better adjusted to the Weber-Morris kinetic model with an ideal time of 2 h. Furthermore, the influence of temperature was evaluated using the Freundlich and Langmuir isotherms, with maximum capacities of 142.05 (ChN), 131.58 (ChS), and 146.63 mg.g-1 (ChT). The adsorbent displayed enhanced adsorption properties in comparison with raw chitosan by an intensification of the electrostatic interaction between amino groups and hexavalent chromium. Finally, the reusability was investigated, and significant results were observed (84.33 ± 4.87%) in the adsorption process after 4 cycles.

Polyvinylсhloride‐based anion exchanger for efficient removal of chromium (VI) from aqueous solutions

“…One can explain this as follows 19,44,45 : Cr (VI) exists in aqueous solution as CrO 4 2− , HCrO 4 − , or Cr 2 O 7 2− , depending on the pH. In the pH range of 1.0–8.0, HCrO 4 − and Cr 2 O 7 2− ions are in equilibrium.…”

“…The SEM image in Figure 2 One can explain this as follows 19,44,45 First order Second order Calculated equilib uptake q e (mg/g)…”

“…In addition, the adsorption capacity of anion exchanger resin PPE-1 for hexavalent chromium ions is compared with other anion exchange materials 13,20,23,45,46 (see Table 4). The data show that the sorption capacity of anion exchange resin PPE-1 exceeds previously published materials by a factor of two or higher, which clearly outlines its highly interesting application potential.…”

Modified Chitosan Forms for Cr (VI) Removal

“…The recommended Cr (VI) limit in drinking water is 0.05 ppm [26,27]. One of the most important effects of Cr (VI), which is a very oxidizing substance, is that it causes lung cancer [28,29].…”

“…Recently, more composite materials containing modified Cts used in chromium removal have been reported. Eliodório et al investigated the synthesis and characterization of Cts functionalized with three different ionic liquids and their application in Cr (VI) waste treatment [28]. Amino groups in Cts are significantly effective in the adsorption mechanism, especially when protonated at acidic pHs.…”