Macromolecular sorbent materials for urea capture

Abstract

Three types of chitosan-glutaraldehyde (Chi-Glu) crosslinked copolymer materials were prepared at various Chi-Glu weight ratios (i.e., 1 : 0.0835, 1 : 0.334, and 1 : 0.585) and variable reaction times. The corresponding Chi-Glu copolymer materials were imbibed in CuSO 4 solution to yield impregnated materials in the form of copolymer/Cu(II) complexes. The copolymer materials were characterized using FTIR spectroscopy and thermogravimetry analysis. Urea sorption isotherms were obtained in aqueous solution at 295 K and pH 7 with pristine chitosan, Chi-Glu copolymers (i.e., 1 : 0.0835 and 1 : 0.585), and the corresponding Chi-Glu/ Cu(II) complexes. The concentration of unbound urea was monitored indirectly using a colorimetric method with p-dimethylaminobenzaldehyde. The equilibrium adsorption data were analyzed using the Sips isotherm model. The uptake of urea with pristine chitosan was 4.7% w/w, whereas Chi-Glu copolymers display increased sorption (Q m ¼ 10.6-17.1% w/w) with increasing glutaraldehyde content. Urea sorption is further enhanced (Q m ¼ 16.3-26.4% w/w) for copolymer Chi-Glu/Cu(II) complexes. The preparation of Chi-Glu copolymers at various conditions illustrates that the sorption capacity and molecular recognition of urea can be systematically tuned via crosslinking and the formation of copolymer/Cu(II) complexes, and these results are related to a previously reported study (Shimizu and Fujishige,

Sequestration of agrochemicals from aqueous media using cross-linked chitosan-based sorbents

“…The incremental swelling with greater cross-linker content parallels the sorption capacity observed for the CGi materials. The incremental swelling observed is consistent with an increased micropore volume as the cross-linker content increases, in agreement with swelling results reported elsewhere (Wilson and Xue 2013).…”

“…The lower decomposition temperature of the CGi materials with greater glutaraldehyde content may relate to greater degrees of vibrational freedom that contribute to an increased heat capacity afforded by the imine linkages. Thermal events that occur below 100°C are attributed to the loss of water and/or residual solvents Wilson and Xue 2013).…”

“…In this study, we report the preparation and characterization of chitosan-glutaraldehyde (CG) (Poon et al 2014;Wilson and Xue 2013) polymers for the sequestration of several model agrochemicals with variable lipophilicity: pentachlorophenol (PCP), 2,4-dichlorophenol (2,4-DCP), 2,4-dichlorophenoxy acetic acid (2,4-D), dicamba and carbofuran (cf. Scheme 1) (Aly and Faust 1965;Crosby 1981;Faust and Aly 1963;Gold and Groffman 1993;Gupta 1994).…”

Design and characterization of chitosan-based composite particles with tunable interfacial properties

“…The adsorptive properties of chitosan-based materials have been 10 widely studied for environmental remediation processes (e.g., removal of heavy metals, 11 inorganics, and organic pollutants in aqueous environments, etc.) (Bhatnagar and 12 Sillanpää, 2009, Guo and Wilson, 2012b, Wilson and Xue, 2013) and in various 13 biomedical applications (Agnihotri, et al, 2004, Casettari, et al, 2012, Kumar, et al, 14 2004). Colloidal particle systems with a variable size range from nm to μm scale have 15 been prepared via electrostatic bonding between chitosan-based materials with an 16 oppositely charged polyelectrolyte such as alginate or polyphosphate (cf.…”

“…Scheme 1) contains β-linked glucosamine and N-acetyl-glucosamine units 3 which may be described as a biopolymer with -cellulose-like‖ structural features. The 4 presence of reactive amine groups enable modular chemical functionalization of this 5 polysaccharide to afford diverse chemically modified forms (Agnihotri, et al, 2004, 6 Casettari, et al, 2012, Kumar, et al, 2004, Wilson andXue, 2013). Chitosan-based 7 materials have attracted attention because of their relatively low cost, high reactivity, 8 tunable physicochemical properties, and good biocompatibility (Durkut, et al, 2006, 9 Lee, et al, 2004.…”