Calixarenes: A Versatile Source for the Recovery of Reactive Blue-19 Dye from Industrial Wastewater

The present work demonstrates the comparative extraction efficiency of p-tert-butylcalix[4]arene (1) and its derivatives (2-4) toward a series of some selected reactive dyes such as Reactive Black-5 (RB-5), Reactive Blue-19 (RB-19) and Reactive Red-45 (RR-45). The study elaborates effectiveness of different anchoring groups present on the periphery of calix[4]arene platform and highlights the importance of preorganization concerning the application of supramolecular chemistry in separation science and technology. It has been observed that compound 4 shows good extraction efficiency toward RB-19 among the selected reactive dyes. Enhanced extraction efficiency was observed with the addition of NaCl at pH 7. The proposed extraction mechanism through inclusion complexation was confirmed by log-log plot analysis, which shows 1:1 complexation between 4 and RB-19. The solvatochromic response of 4 in various solvents of different polarities showed good response in methanol. The log K of complex was found as 5.2. The complex formation between 4 and RB-19 has also been confirmed by FT-IR spectroscopy. The recovery of 4 and RB-19 dye was achieved at pH 8 that signifies the reusability of 4 again and again.