Effective Thallium(I) Removal by Nanocellulose Bioadsorbent Prepared by Nitro-Oxidation of Sorghum Stalks

• Published in: Nanomaterials (Basel, Switzerland) Vol. 12; no. 23; p. 4156
• Main Authors: Chen, Hui, Sharma, Priyanka R, Sharma, Sunil K, Alhamzani, Abdulrahman G, Hsiao, Benjamin S
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 24.11.2022; MDPI
• Subjects: Adsorbents; Adsorption; Aquatic organisms; Atomic force microscopy; Biomass; Cellulose; cellulose nanofibers; Cost analysis; Data analysis; Developing countries; Drinking water; Energy efficiency; Health aspects; Hemodialysis; Ions; LDCs; Lignin; Lignocellulose; Methods; Mineralization; Nanocrystals; nitro-oxidation; Oxidation; Oxidation process; Oxidation-reduction reaction; Raw materials; Sodium; Sorghum; sorghum stalks; Spectrum analysis; Thallium; Thallium oxides; thallium removal; Transmission electron microscopy; Water purification; Zeta potential; Massachusetts; United States > US; Africa; thallium removal; cellulose nanofibers; sorghum stalks; nitro-oxidation
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano12234156

Thallium(I) (Tl(I)) pollution has become a pressing environmental issue due to its harmful effect on human health and aquatic life. Effective technology to remove Tl(I) ions from drinking water can offer immediate societal benefits especially in the developing countries. In this study, a bio-adsorbent system based on nitro-oxidized nanocellulose (NOCNF) extracted from sorghum stalks was shown to be a highly effective Tl(I) removal medium. The nitro-oxidation process (NOP) is an energy-efficient, zero-waste approach that can extract nanocellulose from any lignocellulosic feedstock, where the effluent can be neutralized directly into a fertilizer without the need for post-treatment. The demonstrated NOCNF adsorbent exhibited high Tl(I) removal efficiency (>90% at concentration < 500 ppm) and high maximum removal capacity (Qm = 1898 mg/g using the Langmuir model). The Tl(I) adsorption mechanism by NOCNF was investigated by thorough characterization of NOCNF-Tl floc samples using spectroscopic (FTIR), diffraction (WAXD), microscopic (SEM, TEM, and AFM) and zeta-potential techniques. The results indicate that adsorption occurs mainly due to electrostatic attraction between cationic Tl(I) ions and anionic carboxylate groups on NOCNF, where the adsorbed Tl(I) sites become nuclei for the growth of thallium oxide nanocrystals at high Tl(I) concentrations. The mineralization process enhances the Tl(I) removal efficiency, and the mechanism is consistent with the isotherm data analysis using the Freundlich model.