Fabrication of magnetically separable 3-acrylamidopropyltrimethylammonium chloride intercalated bentonite composite for the efficient adsorption of cationic and anionic dyes

Decontamination of dye loaded water has become an issue of intensive interest on both, basic research and industrial scale. Herein, we report the fabrication of bentonite/APTMA and Fe₃O₄-bentonite/APTMA adsorbents via a facile synthesis route and commonly available raw materials. The structural and morphological characteristics of the synthesized adsorbents were studied by BET, XRD, FTIR, VSM, SEM, EDX and XPS techniques and were tested for their adsorption capacity for cationic Crystal violet (CV) and anionic Congo red (CR) dyes. Fe₃O₄-bentonite/APTMA exhibited BET surface area and pore volume of 27.8 m²/g and 0.012 cm³/g respectively and superior adsorption than bentonite/APTMA with maximum calculated adsorption capacity of 2286 and 1210 mg/g for CV and CR respectively. Behavior of both the adsorbents revealed the hydrophobic nature of bentonite/APTMA which could be attributed to its lower adsorption capacity as compared to super-hydrophilic Fe₃O₄-bentonite/APTMA. Effect of operating parameters like pH, adsorbent dosage, dye concentration and temperature were studied, and it was observed that the efficiency of adsorbents was further enhanced towards dye removal in the presence of heavy metal ions and in model wastewater which was attributed to the synergistic effect of metal ions during adsorption process. Adsorption process was endothermic with fast reaction kinetics suggesting the predominant occurrence of chemisorption. Adsorption mechanism was dominated by the occurrence of hydrogen bonding and the electrostatic interactions between adsorbent and dye molecules. This study can be of great industrial prospects for the remediation of CR and CV and other similar dyes and organic pollutants from wastewater both, in the presence as well as absence of heavy metals ions.