Calixarene-Based Functional Fabric for Simultaneously Adsorptive Removal of Anionic and Cationic Dyes

This study investigated the adsorptive properties of functionalized fabric containing dimethylaminomethyl calix[4]arene (DMAM-Calix) to remove anionic methyl orange (MO) and cationic Rhodamine B (RhB) dyes in aqueous media. Adsorption studies were performed using a filtration system packed with DMAM-Calix-functionalized fabric (DCF). The results revealed that the cationic and anionic structures work compatibly in a binary mixture medium. Hydrogen bonding, π-π, cation-π, n-π and electrostatic interactions between dye molecules and DMAM-Calix units of DCF were the main factors affecting the adsorption process. Experiments on real wastewater samples of unknown composition confirmed that the approach could successfully remove MO and RhB dyes from real water samples with high efficiency, especially for RhB. Isotherm and kinetic data for MO were mainly represented by the Langmuir model and pseudo-second-order kinetic model, respectively. The adsorption capacities of DCF were found to be about 4.7 mg g^-1 for MO and 1.0 mg g^-1 for RhB at pH 6.0, which were evaluated as satisfactory considering the first use of a calixarene-derived coated fabric as an adsorbent, the anionic-cationic dye selectivity of DCF, and the low cost and ease of application of the method.