Titanium implanted hydroxyapatite nanoaggregates : facile synthesis and lead removal properties

Abstract EN

Hydroxyapatite-titanium composite had been successfully synthesized by hydrothermal thermal treatment for significantly enhanced removal of lead from wastewaters.

A description was given for preparation these aggregates that were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).

The results suggest that titanium implantation on hydroxyapatite surface was achieved mainly through dissolution-precipitation interactions and a parallel slight substitution of phosphate group with titanium in TiO4-; 4 form.

XRD Data exhibited a change in the unit cell and a shift in peak position of HAP with presence of Ti.

Also, formation of a new titanium phosphate compound was detected.

SEM observation showed that granule TiO2 crystals were nucleated and grown on the surface of rod-like HAP nanoparticles.

Batch studies were performed to evaluate the influences of parameters like contact time, pH value, initial concentration and desorbing eluents on the efficiency of lead removal and recovery.

The removal process was initially fast and maximum removal was attained within 90 min of contact.

The equilibrium sorption capacity (qe) attained the values 444 and 472 mg g-1 for sorption of Pb(II) onto HAP-Ti(OH)4 and HAP-TiO2, respectively.

Lead removal was highly sensitive to pH value and a maximum removal was achieved at initial pH range 3–6.

Different specific sorption mechanisms were hypothesized to participate in lead immobilization to definite extents varied with changing the hydrolysis species of lead.

The sorption date fit Langmuir model, and thermodynamically the prepared composites are feasible sorbents retain Pb(II) ions through a favorable and spontaneous sorption process.