Efficient removal of carcinogenic azo dyes by novel pyrazine-2-carboxylate substituted calix[4, 8]arene derivatives
In this study, novel pyrazine-2-carboxylate derivatives of calix[4, 8]arene have been synthesised and fully characterised. Furthermore, this study presents removal of carcinogenic azo dyes [Reactive Black 5 (RB5), Trapaeolin 000 (TP), Chicago Sky Blue (CSB), Methyl Orange (MO) and Evans Blue (EB)] from the aqueous solution by solid-liquid extraction using these novel compounds. The maximum sorption of azo dyes was achieved at pH 3. Calixarene derivative (3) showed higher sorption as it formed a more stable complex with azo dyes than calixarene derivative (6). An excellent regeneration for at least five times in sorption capacity indicates that calixarene derivative (3) was highly applicable for the removal of carcinogenic azo dyes from industrial wastewater. The stoichiometric ratio between the calixarene derivatives (3 and 6) and selected azo dyes was estimated through job’s plots.