title: Succinate-bonded pullulan: An efficient and reusable super-sorbent for cadmium-uptake from spiked high-hardness groundwater.
abstract: Chemically modified pullulan was evaluated for its sorption efficiency and selectivity to remove cadmium (Cd) from spiked high-hardness groundwater (GW). Pullulan esterified with succinic anhydride using dimethylaminopyridine showed a fairly high degree of substitution value as confirmed by (1)H NMR spectroscopy. Pullulan succinate (Pull-Suc) was converted into the sodium salt (Pull-Suc-Na). The effect of contact time (5-200min) and pH (2-8) on Cd-uptake by the sorbent (Pull-Suc-Na) was investigated. The sorbent showed more than 90% Cd-removal in first 15min from distilled water (DW) and GW solution, respectively. Comparison of Pull-Suc-Na with other polysaccharidal sorbents suggested its high efficiency (DW 476.2mg/g and GW 454.5mg/g) and selectivity for the removal of Cd by an ion exchange mechanism, which is further supported by the negative Gibbs free energy values calculated from Langmuir isotherms. A Langmuir isotherm kinetic model provided the best fit for the sorption of Cd using Pull-Suc-Na. The sorbent showed a negligible decrease in Cd-uptake over three regeneration cycles. The thermal stability testing of the sorbents indicated that Pull-Suc-Na (sorbent) is more stable than Pull-Suc.
authors.affiliation: Department of Chemistry, University of Sargodha, Sargodha 40100, Pakistan.
authors.forename: Azhar
authors.initials: A
authors.lastname: Abbas
authors.affiliation: Department of Chemistry, University of Sargodha, Sargodha 40100, Pakistan. Electronic address: majaz172@yahoo.com.
authors.forename: Muhammad Ajaz
authors.initials: MA
authors.lastname: Hussain
authors.affiliation: Department of Chemistry, University of Sargodha, Sargodha 40100, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Amin
authors.affiliation: Department of Chemistry, University of Sargodha, Sargodha 40100, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Sher
authors.affiliation: Institute of Inorganic and Analytical Chemistry, Johannes Guttenberg University, Duesbergweg 10-14, 55128 Mainz, Germany. Electronic address: tahir@uni-mainz.de.
authors.forename: Muhammad Nawaz
authors.initials: MN
authors.lastname: Tahir
authors.affiliation: Institute of Inorganic and Analytical Chemistry, Johannes Guttenberg University, Duesbergweg 10-14, 55128 Mainz, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Tremel
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000737:chemistry* / Q000302:isolation & purification*; D005936:Glucans / Q000737:chemistry*; D060587:Groundwater / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D019802:Succinic Acid / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification*; D018508:Water Purification
chemical_list: D005936:Glucans; D014874:Water Pollutants, Chemical; D002104:Cadmium; C009109:pullulan; D019802:Succinic Acid
keywords: Adsorption; Cadmium; Modified pullulan; Succinylation; Thermal stability