Synthesis of Amino-Substituted p-tert-Butylcalix[4]arene for the Removal of Chicago Sky Blue and Tropaeolin 000 Azo Dyes from Aqueous Environment

In this study, we have reported the synthesis of new amino-substituted p-tert-butylcalix[4]arene (3) and its application for the removal of two carcinogenic azo dyes, i.e., Chicago Sky Blue (CSB) and Tropaeolin 000 (TP) from aqueous environment. The newly synthesized calix-ligand 3 is characterized by FT-IR and H-1 NMR spectroscopy as well as elemental analysis. The extraction efficiency of newly calix-ligand 3 for CSB and TP dyes from aqueous media was evaluated through liquid-liquid extraction experiments. The newly synthesized calix-ligand 3 showed outstanding extraction percentage and maximum percent extraction, i.e., 97 and 96 % of CSB and TP dyes was achieved at pH 9, respectively. During the extraction process, effect of various parameters was monitored and found that extraction is highly dependent on pH and salinity. Moreover, cyclic structure, cavity size, functional groups of the calixarene derivative, hydrophobicity, and the ionic property of guest molecules also affect the extraction efficiency. The comparative data prop up calix-ligand 3 as an effective extractant for both CSB and TP dyes.