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2 Progress on Chemistry and Application of Chitin and its Derivatives

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REMOVAL OF ALIZARIN RED BY SUPERMACROPOROUS CROSS-LINKED CHITOSAN MONOLITH SORBENTS

100%

Privar Y. , Modin E. , Bratskaya S.

Progress on Chemistry and Application of Chitin and its Derivatives

2019

tom 24

164 - 171

Here, we report the fabrication of supermacroporous monolith sorbents for acidic dye removal via chitosan cross-linking with ethylene glycol diglycidyl ether (EGDGE) in acidic medium at sub-zero temperature. The developed porous structure with the thickness of polymer walls in the range of a few microns and a high content of primary amino groups determined the high sorption capacity of the sorbents toward Alizarin Red in a broad pH range (2–8). Due to the cross-linking via hydroxyl groups of the chitosan, the static sorption capacity of the fabricated materials was higher than that of chitosan flakes, even for sorbents cross-linked at EGDGE:NH2-chitosan with molar ratio 2:1. The monolith sorbents were mechanically stable and supported flow rates up to 300 bed volumes per hour. The breakthrough curve of Alizarin Red sorption showed that the effective dynamic sorption capacity was 283 mg/g, and 100% of the dye could be removed from the solutions with concentration of 100 mg/L. The monoliths can be regenerated with 0.3s M NaOH solution and used in several consecutive cycles of sorption/regeneration without loss of efficacy.

SCREENING OF THE CATALYTIC ACTIVITY OF Pd0 AND Pd2+- SUPPORTED ON CHITOSAN BEADS AND CRYOGELS

75%

Pestov A. , Mekhaev A. , Privar Y. , Prokuda N. , Modin E. , Bratskaya S.

Progress on Chemistry and Application of Chitin and its Derivatives

2018

tom 23

149 - 158

Here, we report the results of screening of the catalytic activity of Pd-containing chitosan beads and cryogels in the cross-coupling reaction, hydrogenation of alkenes, nitro-, and carbonyl compounds and the hydrodechlorination of chlorophenols. Pd0-containing chitosan beads and cryogels show moderate catalytic activity in the reduction of alkenes and nitroaromatics. The conversion of nitroaromatics decreases for substrates with electron-withdrawing substituents, while the conversion of alkenes increases with the activation of carbon-carbon double bonds. For several substrates, a significant difference in kinetics and conversion degrees was observed for Pd nanoparticles supported on chitosan beads and cryogels. It was found that conversion in the hydrodechlorination reaction depends on substrate structure, being higher for substrates containing substituents with a positive mesomeric effect. Pd2+-chitosan catalysts showed high catalytic activity in cross-coupling (Heck reaction) offering the following advantages over known catalytic systems: lower reaction temperature, the selective functionalisation of C-I bonds, and the possibility to perform reactions with iodobenzene without base addition.