Superior adsorption of cationic dye on novel bentonite/carbon composites

Abstract The principal objective of this work was to modify the surface of natural bentonite for enhanced adsorption of cationic dyes. In this regard, novel bentonite/carbon composites were synthesized through two routes. Ferrocene/ p ‐xylene mixture was used as carbon source through (1) hydrothermal decomposition and (2) spray routes during the calcination of sodium‐bentonite (Na‐B) to deposit carbons on the surface of Na‐B. Samples were characterized using scanning electron microscopy (SEM) with energy dispersive spectroscopy, X‐ray diffraction (XRD), Fourier‐transform infrared, and N 2 adsorption at −196°C. Cationic neutral red (NR) dye was used to investigate the adsorption capacity of the samples. SEM and XRD profiles showed that the first route deposited carbon with orthorhombic structures, whereas the second yielded carbons with hexagonal shapes like rods on Na‐B. The specific surface areas and the total pore volumes of the composites were considerably increased in comparison with matrix of bentonite. The products gave superior adsorption of NR dye, for example, 145 mg/g onto B‐C2 and attained good reusability of adsorbent where 90% of NR dye was removed on the third run at pH 5 and temperature of 25°C. These results affirm that the prepared composites are promising as novel adsorbents for the purification of water containing cationic dyes.