Lead removal from water using carboxycellulose nanofibers prepared by nitro-oxidation method

Carboxycellulose nanofibers were extracted from untreated jute using a simple nitro-oxidation method based on nitric acid/sodium nitrite. The characteristics of nitro-oxidized carboxycellulose nanofibers (NOCNF) with low crystallinity (35%), high carboxylate content (1.15 mmol/g) and high surface charge (− 70 mV) made them an excellent substrate for Pb(II) ion removal from water. For example, a low concentration of NOCNF suspension (0.23 wt%) could remove a wide range of Pb(II) ions ranging from 50 to 5000 ppm in a short time-interval (< 5 min) at room temperature and pH ~ 7, where the adsorption efficiency of NOCNF was found to be 2270 mg/g based on the Langmuir isotherm analysis. The high removal efficiency of NOCNF was due to the combined effects of adsorption (dominated at Pb(II) concentration ≤ 1000 ppm) and mineralization of lead hydroxide (Pb(OH)₂) crystals at high Pb(II) concentration (> 1000 ppm). Evidence of nanoscale lead hydroxide crystallization, induced by the lead(II)-NOCNF aggregated scaffold, was confirmed by FTIR, UV–visible spectroscopy, SEM/EDS, WAXD and TEM measurements.