Identifying the Removal Efficiencies of As3+ in Wastewater by Functionalized Nanocellulose

Abstract

Nanocellulose (NC) gains significant attention as a promising candidate in water purification and environmental remediation studies due to its superior chemical and physical properties. The present study explored the capacity of removing the hypertoxic As3+ in wastewater, with the use of NC after functionalization, namely sulfonation, phosphorylation, and xanthation. Cellulose was extracted through an alkaline treatment followed by bleaching with NaOCl from Panicum maximum, which is an invasive plant in Sri Lanka, selected as the cellulose source. Acid hydrolysis on extracted cellulose with 50% sulfuric acid, 85% phosphoric acid, and 21.9 % hydrochloric acid results in sulfonated, phosphorylated, and nonfunctionalized NC respectively. Xanthation on non-functionalized NC with NaOH and CS2 results xanthated NC. Functionalized NC was separately fabricated on each filter paper with 50 mg loading and allowed to filter the As3+containing water through it. The As3+ concentrations in the medium were determined by the colour intensity of formed I2 with the reduction of IO3-, which corresponds to the oxidation of As3+ into As5+ in an acidic medium, with the aid of UV-Vis spectroscopy. Among the functionalized NC, the sulfonated NC has shown the highest removal efficiencies in 200 ppm, 150 ppm, and 100 ppm As3+ concentrations with removal percentages of 46.8,38.4, and 50.1. Further advancement of this work can reach the development of bio-degradable and affordable columns for As3+ removal. Dynamic Light Scattering results of sulfonated, phosphorylated, and non-functionalized NC were 295.7 nm, 271.4 nm, and 320.9 nm respectively, indicating that the particle sizes were in the nanoscale range.