Synthesis and adsorption properties for metal ions of crosslinked chitosan acetate crown ethers

Abstract

ABSTRACT:Two novel chitosan derivatives-crosslinked chitosan dibenzo-16-c-5 acetate crown ether (CCTS-1) and crosslinked chitosan 3,5-di-tert-butyl dibenzo-14-c-4 diacetate crown ether (CCTS-2)-were synthesized by the reaction of crosslinked chitosan with dibenzo-16-c-5 chloracetate crown ether and 3,5-di-tert-butyl dibenzo-14-c-4 dichloracetate crown ether with the intent of forming polymers that could be used in hazardous waste remediation as toxic metal-binding agents in aqueous environments. Their structures were confirmed with elemental analysis, infrared spectral analysis, and X-ray diffraction analysis. In the infrared spectra of CCTS-1 and CCTS-2, the characteristic peaks of aromatic backbone vibration appeared at 1595 cm Ϫ1 and 1500 cm Ϫ1 ; the intensity of the NOH and OOH stretching vibration in the region of 3150 -3200 cm Ϫ1 decreased greatly. The X-ray diffraction analysis showed that the peak at 2 ϭ 20°decreased greatly in CCTS-1 and CCTS-2.

Hydrogels based on modified chitosan, 1. Synthesis and swelling behavior of poly(acrylic acid) grafted chitosan

“…These are water insoluble but they swell considerably with the addition of water or aqueous metal salt solutions. Much recent research deals with this topic and its metal chelating capacity [6][7][8][9][10][11][12][13] . This type of material, with a large capacity for water retention, is known as a hydrogel.…”

Adsorption Studies of Pomegranate Peel Activated Charcoal for Nickel (Ii) Ion

“…The values of the monolayer adsorption capacity of the adsorbent q max and the Langmuir constant b were calculated for nickel adsorption by plotting the graph between Ce and Qe and are reported in table 1. The q max value for nickel (II) ions was 10.82 mg/g which is higher from the other adsorbents previously studied for nickel adsorption from aqueous medium [27][28][29][30][31][32] ; for detailed comparison of q max , please see Table 2. According to Freundlich model, value of constants, K and n, are found to be 0.446 and …”

Effects of Grafting Azacrown Ether on Thermal and Swelling Properties of Chitosan Films

“…The selective chelating properties exhibited by crown ethers towards metal ions have led to their incorporation into chitosan polymer matrices to improve capacity for metal ion adsorption [1][2][3], enhance selective pollutant removal [4,5], and thus wastewater remediation [6,7]. While many authors have chemically modified crosslinked chitosan with crown ethers [5,6,[8][9][10][11][12][13][14][15][16][17], and shown the advantage of combining crown ethers with chitosan [5,8,9,18,19], only a few have used the crown ether as the crosslinker for chitosan [7,18,[20][21][22][23][24] and fewer have used the nitrogen containing azacrown ethers [25]. Using the azacrown ether as the crosslinker has the advantage that the consumption of the -NH 2 chelating group of the chitosan might be compensated by the azacrown ether chelating property.…”

“…Furthermore, nitrogen containing azacrown ethers are particularly interesting due to their stronger complexation properties for heavy-metal ions [1,[26][27][28] than the all-oxygen crowns, which strongly complex alkali and alkaline earth metal [26,28]. For example, Ding et al [25] used N,N -diallyl dibenzo-18-crown-6 crown to crosslink chitosan and revealed that these materials performed better in metal ion adsorption than neat Ch owing to the presence of the crown ethers [15,16,22,23]. Structural elucidation of the products suggested that these crown ethers crosslink chitosan, although no report of gel content or network formation was presented in this work and others [10,11,15,16,20,23].…”