title: [Impact of particle size and morphology on zinc cation adsorption by hydroxyapatite and dentifrice containing hydroxyapatite].
abstract: OBJECTIVE
  To study the influence of particle size and morphology on zinc cation adsorption by hydroxyapatite (HA) and dentifrice containing HA.
  
  
  METHODS
  Four HAs with different particle sizes and morphologies, HA-containing dentifrice and blank dentifrice were prepared into suspensions of serial concentrations. Zinc ion solutions with an initial concentration of 10 mg/L was mixed with the suspensions and kept for 24 h for adsorption reaction. The zinc ion concentration in the supernatant was measured by inductively coupled plasma emission spectrometer and the sorption rate of zinc ion was calculated.
  
  
  RESULTS
  HA and HA-containing dentifrice with various particle sizes and morphologies were all capable of absorbing zinc ions from simulated waste water, and the adsorption rate of HA-containing dentifrice was 3%-10% higher than that of HA. HA with a particle size of 12 µm and a spherical morphology showed the strongest adsorption ability, followed by short bar-shaped HA with a particle size of 30 µm. Both Langmuir and Freundlich equation could simulate the sorption processes of HA dentifrice, while only Langmuir equation could simulate the sorption processes of HA.
  
  
  CONCLUSIONS
  Incorporation of HA in dentifrice can enhance zinc ion adsorption capacity of the material. The particle size and morphology of HA both affect the adsorption of zinc ions, and 12-µm HA particle with a spherical morphology has the best adsorption ability.
authors.affiliation: Department of Endodontics, Affiliated Stomatological Hospital of Southern Medical University and Guandong Provincial Stomatological Hospital, Guangzhou 510515, China.E-mail: yangjzh2010@163.com.
authors.forename: Jian-Zhen
authors.initials: JZ
authors.lastname: Yang
authors.forename: Xiao-Qing
authors.initials: XQ
authors.lastname: Shen
authors.forename: Cheng-Xia
authors.initials: CX
authors.lastname: Liu
authors.forename: Ping-Ping
authors.initials: PP
authors.lastname: Xu
mesh_terms: D000327:Adsorption; D003802:Dentifrices / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D010316:Particle Size; D012996:Solutions; D015032:Zinc / Q000737:chemistry*
chemical_list: D003802:Dentifrices; D012996:Solutions; D017886:Durapatite; D015032:Zinc