Some Factors Affecting the Removal of Lead(II) Ions from Aqueous Solution by Porous Calcium Hydroxyapatite: Relationships between Surface and Adsorption Properties

Abstract

A porous hydroxyapatite (p-HAp) was prepared and employed for the removal of lead(II) ions at different concentrations from aqueous solution to determine the adsorption properties of p-HAp and compare them with those of a commercial hydroxyapatite (CAp) sample. The kinetic data obtained indicated that the adsorption performances of the adsorbents depended both on their specific surface area and crystallinity. Complexation of the Pb(II) ion on the adsorbent surface favoured the dissolution of hydroxyapatites characterized by a Ca/Pb molar ratio in the 0.85-1.5 range. The maximum adsorption capacity of p-Hap for Pb(II) ions at 30 ± 2 o C was 2.30 mmol/g relative to 1.38 mmol/g for the commercial compound Cap at the same temperature. The higher capacity of p-HAp was explained in terms of its porosity and crystallinity. The Pb(II) ions sorption results could be modelled by the Langmuir and Freundlich isotherms.

Kinetics of adsorption of metal ions on inorganic materials: A review

“…Cd(II), Cu(II) and Pb(II) on smectites (30 min) [89], Cu(II) and Pb (II) on electric furnace slag (480 min) [90], Cd(II) and Cr(VI) on fly ash (120 min) [91], Cu(II), Ni(II) and Zn(II) on Turkish fly ash (120 min) [92], Cr(III) on bentonite and perlite (30 min for bentonite and 900 min for perlite) [93], Co(II) on sepiolite (120 min) [94], Cr(III), Fe(III), Zn(II) and Mn(II) on modified silica gel (20-30 min) [95], Cr(VI) on hydrous titanium oxide (30 min) [96], Hg(II), Pb(II) (90 min) and Cd(II) (75 min) on cation exchanger [97], Cd(II) and Zn(II) on low-grade phosphate (30 min) [98], Cu(II) and Zn(II) on SBA-15 (60 min) [99], Pb(II) on calcium hydroxyapatite (20 min) [100], Cr(III) and Pb(II) on a local clay (30 min) [101], Cu(II) on zero-valent iron (180 min) [102], Cd(II), Pb(II) and Zn(II) on a local clay (180 min) [103], Pb (II) on alginate salts (60 min) [104], Ag(II), Co(II), Cu(II), Ni(II) and Pb(II) (30 min) [105], Cr(III), Fe(III), Mn(II) and Zn(II) on ionimprinted amino-functionalized silica gel (b60 min) [106], Cd(II) on Tunisian palygorskite (40 min) [107], etc.…”

Determination, Modeling and Evaluation of Kinetics of 223Ra Sorption on Hydroxyapatite and Titanium Dioxide Nanoparticles

“…[2]. Several studies focusing on adsorption of various substances onto hydroxyapatite, such as icariin [12], organic dyes [13], Pb 2+ [2,3,14], Cd 2+ [2,15], etc., were already published. They were dealing with contaminant retention and purification.…”

Electrokinetic properties of hydroxyapatite under flotation conditions

“…Apatites have potential for use as lasers and microcrystalline apatites for catalysts (dehydrogenation and dehydration of alcohols), and as an environmental adsorbent of metal and toxic waste removal due to its porous nature and high ion-exchange character (decontamination of soils and aquatic ecosystems from organic and inorganic pollutants) [5,[16][17][18][19][20][21][22].…”