Functionalized nanocellulose as a bifunctional material for efficient adsorption of mercuric ions with antimicrobial properties.

To develop a green nanomaterial for specialty applications, spherical nanocellulose (SNC) was functionalized to a semicarbazone‐Schiff base via a polymer analogous reaction. Firstly, SNC was synthesized from cellulose extracted from huge forest biomass, pine needles (PNs). The glucopyranose ring of SNC was oxidatively cleaved at C2–C3 to form SNC‐dialdehyde (SNC‐DA) by periodate oxidation. Both the aldehydic groups generated were reacted with semicarbazide to form a semicarbazone‐Schiff base, referred to as functional spherical nanocellulose (FSNC). All the materials synthesized were characterized by FTIR, FESEM, EDS, TEM, and XRD studies. The FSNC was evaluated as an adsorbent for Hg2+ ions. The adsorption adhered to pseudo‐second order kinetics and Langmuir adsorption isotherm having a maximum adsorption capacity/Lungmuir adsorption capacity of 172.412 mg/g at 60 min. The selectivity of FSNC for Hg2+ ions was confirmed from its appreciable removal (82%) from solution in tap water and 70% with other metal ions. FSNC exhibited bifunctional nature as it possesses antimicrobial activity against bacteria, that is, Gram (+) (Bacillus aereus) and Gram (−) (Escherichia coli and Salmonella typhi), and a fungus Byssochlamys fulva. FSNC showed good recyclability up to eight sorption–desorption cycles. Thus, we have valorized biomass into an eco‐friendly and low‐cost bifunctional material as an adsorbent for Hg2+ ions cum antimicrobial agent. Highlights: Spherical nanocellulose (SNC) prepared via acidic hydrolysis from pine needlesSNC functionalized to semicarbazone‐based bifunctional Schiff baseThe Schiff base is a rapid and efficient Hg2+ ions adsorbentThe Schiff base has good antimicrobial activities against Gram (−) bacteriaBiowaste‐based adsorbent has the potential to sustain the bio‐circular economy [ABSTRACT FROM AUTHOR]