Hydroxyapatite/chitosan (HAP/CS) composite adsorbent was prepared by the in-situ co-precipitation method. The physical and chemical characteristics of adsorbents with and without CS were characterized via SEM

XRD

IR

and N2 adsorption-desorption isotherms. The results showed that crystal form of HAP has no change after composition

but the crystallinity was decreased. Moreover

the as-prepared composite has an irregular concave-convex structure with increased surface roughness. The specific surface areas also increased from 106.75m

2

/g to 127.58m

2

/g

and the pore size of composite adsorbent was 10~50 nm

which belongs to mesoporous. Both models

including the Langmuir and the Freundlich

could predict the experimental data conducted. However

the Langmuir model had a better correlation coefficient than the Freundlich model. The kinetic adsorption data showed that the adsorption process follows the pseudosecond- order kinetic. The thermodynamic and kinetics parameters were obtained. Δ

G

0

<

0、Δ

H

0

>

0 and Δ

S

0

>

0 indicated that the adsorption was a spontaneous and endothermic process with increased entropy

and a higher temperature would benefit the adsorption. The adsorption's activation energy (

E

a

)=15.03kJ·mol

-1

and migration energy (

E

)=7.639kJ/mol indicated that the adsorption was mainly physical.