title: Adsorption properties of cross-linked cellulose-epichlorohydrin polymers in aqueous solution.
abstract: Cellulose was cross-linked with epichlorohydrin (EP) at variable levels (CLE-0.5, CLE-2 and CLE-4), where CLE-i denotes the cellulose to EP mole ratios. The cross-linked products were characterized by TGA and FT-IR spectroscopy, pH at the point of zero charge (pHpzc), water swelling, and dye-adsorption methods employing two types of dyes [phenolphthalein (phth) and p-nitrophenol (PNP)]. The characterization methods provide evidence of cross-linking of cellulose in accordance with variations in surface area, PZC, available surface hydroxyl groups, and thermal stability when compared against pristine cellulose. The pHpzc of the sorbent materials was ∼ 6.5 indicating a negative surface charge occurs above pHpzc. The cross-linked polymers possess greater swelling properties relative to pristine cellulose. Detailed adsorption studies were carried out at pH 9 for cellulose and CLE-i with five types single component carboxylate anions [2-hexyldecanoic acid (S1), trans-4-pentylcyclohexanecarboxylic acid (S2), 2-dicyclohexylacetic acid (S3), adamantane carboxylic acid (S4), and cyclohexane carboxylic acid (S5)] at 295 K. The uptake properties of PNP with cellulose and CLE-i were also compared at pH 5 and 9, respectively. CLE-2 had the highest uptake of PNP (Qm=1.22 × 10(-1)mmol/g, pH 9) and S1 (Qm=4.27 mg/g) while cellulose and CLE-4 had the strongest binding affinity (1.43 L/mmol and 5.90 × 10(-2)L/mg), respectively. Uptake of PNP by CLE-0.5 at pH 5 (Q m=5.30 × 10(-2)mmol/g) was higher than uptake at pH 9 (Qm=3.11 × 10(-2)mmol/g). Sorption of CLE-4 with S1, S2 and S3 showed that relative uptake of the surrogates had the following order: S3>S2>S1, where S2 had the strongest binding affinity to CLE-i. CLE-2 had the highest sorption capacity towards Si in an equimolar mixture with evidence of molecular selective uptake. At pH 9, low uptake was mainly related to electrostatic repulsion between the negatively charged sorbent surface and the carboxylate head groups of Si.
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada.
authors.forename: Inimfon A
authors.initials: IA
authors.lastname: Udoetok
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada.
authors.forename: Raquel M
authors.initials: RM
authors.lastname: Dimmick
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada. Electronic address: lee.wilson@usask.ca.
authors.forename: Lee D
authors.initials: LD
authors.lastname: Wilson
authors.affiliation: Water Science and Technology Directorate, Environment Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5, Canada.
authors.forename: John V
authors.initials: JV
authors.lastname: Headley
mesh_terms: D000327:Adsorption; D002482:Cellulose / Q000737:chemistry*; D003116:Color; D004811:Epichlorohydrin / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D020113:Phenolphthalein / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D012996:Solutions; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D011108:Polymers; D012996:Solutions; D014867:Water; D004811:Epichlorohydrin; D020113:Phenolphthalein; D002482:Cellulose
keywords: 2,2-dicyclohexylacetic acid (PubChemCID: 3661562); 2-hexyldecanoic acid (PubChemCID: 32912); Adamantane carboxylic acid (PubChemCID: 13235); Aliphatic carboxylate anions; Cellulose; Cross-linking; Cyclohexane carboxylic acid (PubChemCID: 7413); Epichlorohydrin (PubChemCID: 7835); Isotherm; Naphthenic acids; P-nitro phenol (PNP) (PubChemCID: 980); Surrogates; Trans-4-pentylcyclohexylcarboxylic acid; p-Nitrophenolate