Pullulan/poly(N‐vinylimidazole) cryogel: An efficient adsorbent for methyl orange

Abstract

Pullulan/poly(N‐vinylimidazole) (PNVI) hybrid cryogels were synthesized under free radical polymerization and chemical crosslinking conditions in an alkaline, aqueous solution of pullulan (PUL), N‐vinylimidazole (NVI), ammonium persulfate and epicholorohydrin (ECH) at −18°C. PUL and PNVI cryogels alone were also synthesized under similar conditions. Optimum cryogel formation conditions were determined by considering product yields and gel fractions of the samples. The products were characterized by elemental analysis, FTIR‐ATR spectrometry, Thermal gravimetric analysis, and scanning electron microscopy (SEM) analyses. It has been found that PUL/PNVI hybrid samples bear improved physicochemical properties compared to ECH crosslinked PUL and PNVI samples alone. They act as hydrogels in aqueous medium reaching equilibrium swelling capacity values of the order of 600%. Dried PUL/PNVI cryogels show higher thermal stability than the dried cryogels of the parent polymers and maintain their physical integrity over a prolonged time period. Macroporous morphology was revealed by SEM analysis. Having 54.2 mg/g maximum equilibrium adsorption capacity in 200 ppm methyl orange solution and maintaining 95% of its adsorption capacity at the end of seven consecutive adsorption/desorption cycles, PUL/PNVI cryogel proved to be an efficient and durable dye adsorbent using methyl orange as the model compound in aqueous solution.

Super-Macroporous Pulluan Cryogels as Controlled Active Delivery Systems with Controlled Degradability

“…In addition, Hezarkhani et al prepared pullulan/poly(N-vinylimidazole) (PNVI) cryogels for use in environmental applications, reporting that these cryogels can be used as effective dye adsorbents for wastewater treatment [ 22 ]. Furthermore, hybrid cryogels made of pullulan and poly(N-vinyl imidazole) were created using free-radical polymerization and chemical crosslinking in an alkaline solution containing ammonium persulfate, epichlorohydrin, pullulan, and NVI [ 25 ]. These composite cryogels were utilized to absorb dyes in wastewater treatment.…”

Sonochemical synthesis of inorganic cryogel Ag2Mo3O10@Ag/AgO: structural characterization, antibacterial activity, and dye adsorption properties

“…30 Another category of excellent dye absorbers is hydrogels which have received a lot of attention. 31,32 Hydrogels are typically super-porous networks formed by the solidication of soluble monomers or polymeric precursors at sub-zero temperatures and able to be very effective in removing and absorbing water pollutants through adsorption mechanisms like electrostatic, ion exchange, chemisorption, hydrogen-bonding, hydrophobic, complexation and interactions between target dyes and adsorbents. They are produced with a wide range of morphology and properties that can be designed for specic applications.…”