Functionalized nanocellulose for efficient removal of ammonium impurities from contaminated water

Abstract

Carboxycellulose nanofibers with carboxylate functionality are a promising material for a multitude of applications, including environmental remediation. In this paper, we present an in-depth systematic study on the application of TEMPO-oxidized CNFs for ammonium removal, demonstrating their versatility against a broad range of ammonium impurities (5–5000 ppm) using both simulated and real contaminated water. The efficiency of CNFs was tested under various conditions, including the amount of CNFs, pH, and time. The results showed that CNFs follow both the Langmuir and the Freundlich isotherm models with good fitting, indicating their monolayer as well as multilayer adsorption mechanism. Furthermore, characterization using FTIR, SEM/EDS, and adsorption and kinetic analyses employing various models reveals that chemisorption is the dominant mechanism of ammonium adsorption by CNFs. The Langmuir isotherm model, when fitted to adsorption data gathered for original ammonium impurities in the range of 5–5000 ppm using CNFs, yielded a maximum adsorption capacity of 303.3 mg g⁻¹. Additionally, this study includes a technical application to remove ammonium impurities from real contaminated fish water, with results indicating an average removal efficiency of between 80% and 90%. We have also developed an in-house flotation remediation system (FRS) to address handling and collection issues related to CNFs and used CNFs. Hence, this study presents a comprehensive and sustainable approach to addressing the most significant ammonium nutrient problem, utilizing the most abundant, scalable, and eco-friendly plant-based material.