Highly efficient removal of carcinogenic orange II dye by a pyridine-based calixarene derivative: mechanisms, kinetics, and regeneration

Abstract

This article presents a novel method for removing and recovering the carcinogenic azo dye Orange II from wastewater using a newly synthesized in this work for the first time, pyridine-functionalized calix [4]arene derivative, clx4. Orange II, widely used in industries, poses significant environmental and health risks due to its toxic and carcinogenic properties. The structure of clx4 was characterized by using 1H-NMR spectroscopy, FT-IR, mass, and elemental analysis. Solid-liquid and liquid-liquid extraction studies showed high removal efficiencies, with 86% and 99% of Orange II removed within one hour, respectively. Dye adsorption mechanisms were investigated through stability, complexation, and regeneration studies, confirming the effectiveness of clx4. Macrocyclic clx4 compound was also applied in Bulk Liquid Membrane (BLM) systems, demonstrating rapid and efficient transport of Orange II. Kinetic analysis, based on a model of two consecutive irreversible first-order reactions, provided transport rates, with membrane inlet (k(1)) and outlet (k(2)) rate constants determined through non-linear curve fitting. Maximum flux values for membrane inlet ( \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\:{J}_{d}<^>{max}$$\end{document}) and outlet ( \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\:{J}_{a}<^>{max}$$\end{document}) were calculated, highlighting the system's efficiency. Regeneration studies confirmed the reusability of clx4 over multiple cycles, emphasizing its economic and environmental sustainability. These findings demonstrate clx4 as a promising candidate for the effective removal and recovery of Orange II from industrial wastewater, offering a sustainable solution for environmental remediation.