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

Abstract

Three-dimensional and porous polypyrrole (PPy) aerogels were prepared using a facile two-step procedure in which cryogels were synthesized via the cryopolymerization of pyrrole with iron (III) chloride in the presence of supporting water-soluble polymers (poly(N-vinylpyrrolidone), poly(vinyl alcohol), gelatin, methylcellulose or hydroxypropylcellulose), followed by freeze-drying to obtain aerogels. The choice of supporting polymers was found to affect the morphology, porosity, electrical conductivity, and mechanical properties of PPy aerogels. PPy aerogels were successfully used as adsorbents to remove toxic Cr(VI) ions from aqueous solutions.

Free-Standing Bacterial Cellulose/Polypyrrole Composites for Eco-Friendly Remediation of Hexavalent Chromium Ions

“…However, after gradual saturation of the active sorption sites, the adsorption slowed considerably to a complete stop of the adsorption after the equilibrium point was reached. The continuous and smooth time-dependent adsorption plots suggest monolayer adsorption of Cr­(VI) onto the surface of BC/PPy composites. , Both BC/dry/PPy and BC/wet/PPy composites reached comparable values of the removal efficiency of about 88% and adsorption capacity of about 220 mg g –1 after 48 h (Figure d). The relatively slow adsorption rate can be assigned to the tightly packed and compact morphology of the BC/PPy composites (Figure ).…”

Magnetic Polypyrrole-Gelatin-Barium Ferrite Cryogel as an Adsorbent for Chromium (VI) Removal

“…However, as a result of the conventional chemical synthesis PPy is usually obtained as a powder [31], which can be difficult to remove from the treated solution, when used as an adsorbent. One of the ways of overcoming this problem can be the preparation of PPy cryogels with good mechanical integrity and handling properties [32][33][34][35] that are easily separated from liquid media. These materials can be prepared by oxidative one-step cryopolymerization in the presence of a water-soluble polymer, including gelatin [32,34], nanofibrillated cellulose [33], poly(vinyl alcohol) [35], methylcellulose [35], hydroxypropylcellulose [35] or poly(N-vinylpyrrolidone) [35], which acts as a stabilizer for improving mechanical properties.…”

“…One of the ways of overcoming this problem can be the preparation of PPy cryogels with good mechanical integrity and handling properties [32][33][34][35] that are easily separated from liquid media. These materials can be prepared by oxidative one-step cryopolymerization in the presence of a water-soluble polymer, including gelatin [32,34], nanofibrillated cellulose [33], poly(vinyl alcohol) [35], methylcellulose [35], hydroxypropylcellulose [35] or poly(N-vinylpyrrolidone) [35], which acts as a stabilizer for improving mechanical properties. The macroporous structure and developed surface of PPy-based cryogels facilitate their application for water purification, which has been reported for adsorption of dyes [36], antibiotics [37,38] or Cr(VI) [33,35].…”

“…To the best of our knowledge, there are few works [33,35] describing the adsorption of Cr(VI) by PPy-based cryogels. Minisy et al [33] prepared the cryogels by oxidative polymerization of pyrrole in the presence of a suspension of nanofibrillated cellulose in a frozen medium.…”

“…After the optimization of the material composition, regarding nanofibrillated cellulose content, the highest measured adsorption capacity towards Cr(VI) was found to be 184 mg g −1 . Bober et al [35] prepared PPy-based cryogels by a similar crypolymerization procedure using various polymers, such as gelatin, poly(vinyl alcohol), hydroxypropylcellulose, methylcellulose and poly(N-vinylpyrrolidone) as stabilizers. The materials were used for the detailed study of their applicability as Cr(VI) adsorbents, including adsorption kinetics and isotherms.…”