title: Facilitated transport of Cu with hydroxyapatite nanoparticles in saturated sand: effects of solution ionic strength and composition.
abstract: Column experiments were conducted to investigate the facilitated transport of Cu in association with hydroxyapatite nanoparticles (nHAP) in water-saturated quartz sand at different solution concentrations of NaCl (0-100 mM) or CaCl(2) (0.1-1.0 mM). The experimental breakthrough curves and retention profiles of nHAP were well described using a mathematical model that accounted for two kinetic retention sites. The retention coefficients for both sites increased with the ionic strength (IS) of a particular salt. However, the amount of nHAP retention was more sensitive to increases in the concentration of divalent Ca(2+) than monovalent Na(+). The effluent concentration of Cu that was associated with nHAP decreased significantly from 2.62 to 0.17 mg L(-1) when NaCl increased from 0 to 100 mM, and from 1.58 to 0.16 mg L(-1) when CaCl(2) increased from 0.1 to 1.0 mM. These trends were due to enhanced retention of nHAP with changes in IS and ionic composition (IC) due to compression of the double layer thickness and reduction of the magnitude of the zeta potentials. Results indicate that the IS and IC had a strong influence on the co-transport behavior of contaminants with nHAP nanoparticles.
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
authors.forename: Dengjun
authors.initials: D
authors.lastname: Wang
authors.forename: Marcos
authors.initials: M
authors.lastname: Paradelo
authors.forename: Scott A
authors.initials: SA
authors.lastname: Bradford
authors.forename: Willie J G M
authors.initials: WJ
authors.lastname: Peijnenburg
authors.forename: Lingyang
authors.initials: L
authors.lastname: Chu
authors.forename: Dongmei
authors.initials: D
authors.lastname: Zhou
mesh_terms: D003300:Copper / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry; D007700:Kinetics; D009038:Motion; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D009994:Osmolar Concentration; D011791:Quartz / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D012996:Solutions; D013499:Surface Properties
chemical_list: D004573:Electrolytes; D012996:Solutions; D011791:Quartz; D012822:Silicon Dioxide; D003300:Copper; D017886:Durapatite