Tailoring of spherical nanocellulose via esterification with methionine followed by protonation to generate two different adsorbents for mercuric ions and Congo red

• Published in: International journal of biological macromolecules 2024-11, Vol.279 (Pt 2), p.135313, Article 135313
• Main Authors: Chauhan, Sandeep, Jamwal, Pooja, Chauhan, Ghanshyam S., Kumar, Kiran, Kumari, Babita, Ranote, Sunita
• Format: Article
• Language: English
• Subjects: Adsorption; Cellulose - chemistry; Congo red; Congo Red - chemistry; Congo Red - isolation & purification; Esterification; Ions - chemistry; Kinetics; Mercuric ions; Mercury - chemistry; Mercury - isolation & purification; Methionine - chemistry; Nanocellulose; Nanostructures - chemistry; Pine needles; Protons; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - isolation & purification; Water Purification - methods
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.135313

Herein, we report two different adsorbents from spherical nanocellulose (SNC) in successive steps, for the adsorption of Hg2+ ions and Congo red (CR). Cellulose extracted from pine needles was subsequently converted to SNC through mixed acidic hydrolysis. As-obtained SNC was esterified with methionine at C6 of the anhydroglucose unit to produce SNC-methionine ester (SNC-ME). The amino group of methionine residue in SNC-ME was protonated to SNC-PME with positive surface charge. The SNC-ME and SNC-PME were evaluated as Hg2+ ions and CR adsorbents, respectively. The SNC, SNC-ME, SNC-PME, Hg2+-loaded SNC-ME, and CR-loaded SNC-PME were characterized by FTIR, XRD, XPS, Zeta potential, BET, FESEM, EDS, and surface charge analysis. SNC-ME showed Hg2+ ions removal efficiency of 94.8 ± 1.9 % in 40 min, while SNC-PME showed CR removal efficiency of 96.1 ± 3.8 % in 90 min. The adsorption data of both the adsorbents fitted best into pseudo-second order kinetic and Langmuir isotherm. The maximum adsorption capacity of SNC-ME for Hg2+ ions was 211.5 ± 3.1 mg/g and that of SNC-PME for CR was 281.1 ± 7.1 mg/g. The astounding recyclability of the adsorbents for ten repeat cycles with significant cumulative adsorption capacity of 760.9 ± 12.8 mg/g for Hg2+ ions and 758.8 ± 12.7 mg/g for CR endorses their spectacular potentiality for wastewater treatment. SNC was prepared by mixed acidic hydrolysis of cellulose, sourced from vastly available forest biomass, pine needles, and esterified with methionine to get SNC-ME which was later protonated to get SNC-PME. These adsorbents were respectively used to remove Hg2+ ions and anionic dye, Congo red from their sample solutions. [Display omitted]