Strong nanostructured film and effective lead (II) removal by nitro-oxidized cellulose nanofibrils from banana rachis

Abstract

Banana rachis is an abundant and renewable source of cellulose from agricultural wastes. The main focus of the current work is the nanostructured aspects and the potential for removing heavy metals from wastewater using banana rachis cellulose. Highly individualized cellulose nano brils, CNF (length = 1231 nm, diameter = 5.26 nm) with negatively charged carboxylic groups at the C6 position of different degrees of oxidations (DO) were developed through nitro oxidation (NO) followed by simple mechanical treatment. The possibility of understanding the nanostructured aspects and tailoring high puri cation e ciency is discussed. A lm prepared through vacuum ltration of the hydrocolloid suspension was strong (tensile strength = 254 MPa, Young modulus = 10.7 GPa, tensile strain = 5.7%), with the highest strength reaching 334 MPa. The highest puri cation e ciency (compared to other adsorbents in the literature data) was reached at DO = 1.466 mmol/g using an initial Pb (II) concentration of 1000 ppm and followed pseudo-secondorder kinetics. A good relationship between an increased Pb (II) removal to the DO (0.455-1.466 mmol/g) and the NOCNF concentration was observed whereby chemisorption is the primary adsorption mechanism. The NOCNF shows a maximum adsorption capacity of 1667 mg/g at the DO = 0.455 mmol/g based on the Langmuir equilibrium adsorption isotherm. The lm formation property and high Pb (II) removal behavior were attributed to a wellindividualized NOCNF, good dispersion, and high nano bril interaction. The stiff cellulose crystal was successfully preserved even at a high DO with the crystallinity index = 72%.