Ultralight and Superelastic Nanofiber Aerogels with In-Situ Loaded Polypyrrole for High-Efficient Cr(VI) Adsorption

Abstract

Constructing 3-D nanomaterial-based adsorbents with good mechanical properties has attracted increasing attention. This paper reports a simple strategy to prepare ultralight and superelastic 3-D aerogels as efficient adsorbents for heavy metal Cr(VI) in wastewater by in-situ loading of polypyrrole on cellulose acetate nanofibers followed by freeze-drying method. By the way, the cellulose acetate nanofibers are prepared by electrospinning. The obtained aerogel shows obvious 3-D porous and crosslinked structure, in which polypyrrole is uniformly coated on the nanofiber surface. The aerogel shows good mechanical properties with high compressive strength of 14.49 kPa, and can be processed into any desired shape. Due to the advantages of large specific surface area and high porosity, the maximum adsorption capacity of Cr(VI) in wastewater can reach up to 244.65 mg/g. The adsorption process can be described by pseudo-second-order kinetic model and Langmuir isotherm adsorption model, and the reduction-adsorption mechanism of polypyrrole on Cr(VI) is also studied. The present work proposes a high-quality nanofiber aerogel for efficiently adsorbing Cr(VI), which may also hold good potentials in the field of assembled adsorption. Keywords Electrospinning • Nanofiber aerogel • Polypyrrole • Cr(VI) adsorption • wastewater treatmentRecently, aerogels, as a size-controllable lightweight soft materials, have shown obvious development prospects in the field of adsorption. Several functional aerogels, such as silica colloidal aerogels, graphene composite aerogels, and polymer sponges, have recently been used in the field of adsorption. [26][27][28] Although traditional aerogels have the advantages of low density, high porosity, and high specific surface area, they also have inherent limitations of low strength and poor toughness. Nanofiber aerogels were developed and prepared by combining electrospinning technology. [29][30][31] On the basis of retaining the advantages of traditional aerogels, with the strength and toughness of nanofibers, nanofiber aerogels have greatly improved mechanical properties and become an excellent candidate for adsorbents. [32][33][34][35][36][37] Therefore, it is of great significance to explore an economical, environmentally friendly, and shape-designable polypyrrole composite aerogel material for Cr(VI) adsorption.In view of the above contents, the present study reports our success in constructing ultralight and superelastic 3-D nanofiber composite aerogels (PNFA) as efficient adsorbents for Cr(VI) in wastewater by in-situ polymerization of polypyrrole on cellulose acetate (CA) nanofibers followed by freeze-drying method. The obtained PNFA shows high porosity, large specific surface area and environmental stability, and its maximum adsorption capacity of Cr(VI) can reach up to 244.65 mg/g. The PNFA also exhibits good mechanical properties with high compressive strength, and can be processed into any desired shape. This work opens a new avenue for the large-scale production of assembled adsorption de...

Aerogels of Polypyrrole/Tannic Acid with Nanofibrillated Cellulose for the Removal of Hexavalent Chromium Ions

“…PPy-modified eggplant aerogel possessed 27.83 mg g −1 adsorption capacity [41]. Ultralight and super-elastic aerogel of PPy/cellulose acetate nanofibers showed a maximum adsorption capacity of 322.58 mg/g at 45 • C [42].…”

Polypyrrole Aerogels: Efficient Adsorbents of Cr(VI) Ions from Aqueous Solutions

“…PPy, one of the most well-known conducting polymers due to its high electrical conductivity, has easy preparation (it has been synthesized in several forms, e.g., powders, colloids, films, hydrogels, and cryogels), biocompatibility, and excellent environmental stability in ambient conditions [17], and has been widely used as an adsorbent for the removal of Cr(VI) ions from wastewater [5,18,19]. The most desirable PPy absorbents are easily applicable PPy cryogels, hydrogels, and aerogels, which can be effortlessly removed from the solution after the adsorption process is completed [7,20].…”

“…Minisy et al synthesized PPy-nanofibrillated cellulose aerogels, which were three-dimensional (3D), porous, lightweight, and flexible, and showed a 183.6 mg g −1 Cr(VI) ion adsorption capacity with a 98% removal efficiency [7]. Li et al obtained a nanofiber aerogel through the facile polymerization of pyrrole on a 3D cellulose acetate framework, reaching a maximum adsorption capacity of 244.65 mg g −1 for Cr(VI) [19]. Gao et al also produced 3D macroscopic PPy/reduced graphene oxide composite hydrogels, thanks to simultaneous adsorption and chemical reduction, which showed a Cr(VI) ion removal capability of 395 mg g −1 [18].…”