Bis-imidazolium linked covalent organic network effectively removes arsenate from water and wastewater containing phosphates

Abstract

Sustainable water management is crucial due to increasing pollution and the depletion of freshwater resources. Despite the vital role water plays in human survival, many people worldwide still lack access to safe drinking water. Among various contaminants, arsenic and phosphorus-based oxoanions present significant environmental and health risks due to their high toxicity and mobility in different ecological conditions. Developing innovative and efficient materials for water contamination is essential, especially those focused on removing toxic heavy metal oxo-anions. In this report, we present the development of a bis-imidazolium-based covalent organic network (IC-CON) that effectively removes and recovers arsenate and phosphate from water. This dicationic linker-based polymer demonstrates remarkable selectivity for arsenate and phosphate ions, even in the presence of other competing anions. Although IC-CON effectively captures both arsenate and phosphate ions, it shows a stronger preference for arsenate, making it ideal for removing arsenate from phosphate-rich water systems. Interestingly, the IC-CON polymer exhibits anion-responsive morphological transformations that enhance its chemical properties. The maximum arsenate adsorption capacity (Q_max) is 698 mg g⁻¹, while 503 mg g⁻¹ for phosphate. These high adsorption capacities and rapid kinetics underscore the efficiency of IC-CON in removing these harmful contaminants, making it a promising solution for environmental remediation and wastewater treatment.