Utilization of Cucurbit[6]uril as an effective adsorbent for the remediation of Phthalocyanine and Procion golden yellow dyes

Abstract

The present study explores the utilization of the major product Cucurbit[6]uril (CB[6]) a macrocyclic host cavitand formed during synthesis of Cucurbit[ n ]urils, as a cost-effective adsorbent to remove C.I. Reactive orange 12 (RO-12) and C.I. Direct blue 199 (DB-199) dyes from effluent water. The effects of various parameters such as dye concentration, pH, adsorbent dosage, contact time, temperature and metal ions on the adsorption are thoroughly investigated. The performed isotherm calculations suggest the Langmuir to be the suitable isotherm model for adsorption of both dyes with maximum adsorption capacity 230 mg/g of RO-12 and 240 mg/g of DB-199 at room temperature. Kinetic studies reveal that the adsorption follows the pseudo-first-order kinetics for both the dyes. Thermodynamic calculations suggest that adsorption of both the dyes to be an enthalpy-driven and spontaneous. The analytical and density functional theory-based calculations were used to explain adsorption mechanism. These analyses revealed that adsorption process is dominated by the electrostatic interactions of the dye and CB[6]. In addition, A three-layer artificial neural network (ANN) model is used to predict the percentage of dye removal. A cascade Forward Back Propagation (CFBP) ANN was used with Levenberg–Marquardt algorithm (LMA), a linear transfer function (purelin) at output layer and a tangent sigmoid transfer function (tansig) in the hidden layer with 50 neurons. • CB[6] was utilized efficiently to remove Phthalocyanine and Reactive class of dye. • Adsorption behavior, isotherms, dynamics, and thermodynamics were studied. • Molecular mechanism of dyes adsorption on CB[6] was evaluated. • Adsorption mechanism were investigated by means of TGA, IR and DFT calculations. • Artificial neural network model was used to predict the percentage of dye removal.