Surface-Tailored Nanocellulose Aerogels with Thiol-Functional Moieties for Highly Efficient and Selective Removal of Hg(II) Ions from Water

Abstract

Developing an easily recyclable and reusable biosorbent for highly efficient removal of very toxic Hg­(II) ions from bodies of water is of special significance. Herein, a thiol-functionalized nanocellulose aerogel-type adsorbent for the highly efficient capture of Hg­(II) ions was fabricated through a facile freeze-drying of bamboo-derived 2,2,6,6-tetra­methyl­piperidine-1-oxyl (TEMPO) oxidized nanofibrillated cellulose (TO-NFC) suspension in the presence of hydrolyzed 3-mercapto­propyl-trimethoxy­silane (MPTs) sols. Notably, the modified aerogel was able to effectively and selectively remove more than 92% Hg­(II) ions even in a wide range of Hg­(II) concentrations (0.01–85 mg/L) or coexistence with other heavy metals. Besides, the adsorption capacity of the aerogel was not compromised much by the variation in pH values of Hg­(II) solutions over a wide pH range. The fitting results of adsorption models suggested the monolayer adsorption and chemisorptive characteristics with the maximal uptake capacity as high as 718.5 mg/g. The adsorption mechanism of the MPTs-modified TO-NFC aerogel toward Hg­(II) was studied in detail. For the simulated chloralkali wastewater containing Hg­(II) ions, the novel aerogel-type adsorbent exhibited a removal efficiency of 97.8%. Furthermore, its adsorption capacity for Hg­(II) was not apparently deteriorated after four adsorption/desorption cycles while almost maintaining the original structural integrity.

A green l-cysteine modified cellulose nanocrystals biosorbent for adsorption of mercury ions from aqueous solutions

“…37,38 The contents of surface S and N of the adsorbent directly affect its adsorption capacity of Hg(II). 21 The proportions of S and N in CNCs and Lcys-CNCs are performed by elemental analysis in Table 1. The calculated content of surface S and N elements in Lcys-CNCs was 2.80 and 2.77 mmol g À1 , respectively.…”

“…In particular, the negative charge of Lcys-CNCs could further accelerate the arrival of Hg(II) ions on the surface of the adsorbent by electrostatic interaction. 21 Aerword, the active sites decreased due to mercury ions accumulated on the surface of Lcys-CNCs. Therefore, the adsorption rate gradually slowed down, then achieved adsorption equilibrium within 5 min.…”

“…amino group, thiol group) that have strong affinity to Hg(II) ions on the surface of adsorbents can improve their adsorption capacity for mercury ions. 20 Liu and co-workers 21 reported that maximum adsorption capacity was 718 mg g À1 by 3-mercaptopropyltrimethoxysilane (MPTs) modied TO-NFC aerogel. Zhang and co-workers 22 reported that the maximal uptake capacity as high as 543 mg g À1 by triethylenetetramine (TETA) functionalized magnetic poly(glycidyl methacrylate) (PGMA) nano-adsorbent.…”

Carbon Aerogels for Environmental Clean‐Up

“…Carbon aerogels are widely used in heavy metal adsorption because of their porous structure, large specific surface area, high porosity and, most importantly, controllable surface functional groups , , . In earlier times, Meena et al investigated the adsorption of seven kinds of heavy metals (Cd, Pb, Hg, Cu, Ni, Mn and Zn) using carbon aerogel (carbonized from resorcinol formaldehyde (RF) aerogel).…”

Fabrication of Shape‐Memory Aerogel Based on Chitosan/Poly(ethylene glycol) Diacrylate Semi‐Interpenetrating Networks via a Facile and Eco‐Friendly Strategy

“…Aerogels are ultralight materials with porous structure that are produced by replacing the liquid component in the gel by gas. Due to their fascinating characteristics such as low density, light weight, high specific surface areas, and high porosity, aerogels are now regarded as the most promising solid material and are widely applied as pollutants sorbents for environmental remediation applications, piezoresistive sensors, catalyst supports, fire retardants, supercapacitors, microwave absorbing materials, and so on. Based on their components, aerogels are classified as molecular aerogels, inorganic aerogels, and organic aerogels .…”