Mr. Patrick Sharrock

Université de Toulouse, Mines ALBI FRANCE

Nacira Belaicha1, Wahiba Lemlikchi1, Med Oimar Mecherri1, Patrick Sharrock2, Ange Nzihou2

Real permeable barrier construction….

Reactive barrier contents:ZVIZeolites, clays,Organic matterCalcium phosphates?

Chanvre Hemp

• hydroxyapatite, Ca5(PO4)3OH,

• fluoroapatite, Ca5(PO4)3F

photo by Alain Darbellay, GGGems.com.

Stable products of calcium and phosphorous

Phosphate ores comprise animal bone residues

Reaction mechanism HYDROXYAPATITE

(Ca5)(PO4)3OH

CONTAMINANTS Zn2+

(Ca,Zn)5(PO4)3OH

Thermodynamically favorable reactions.

(Ca,Pb)5(PO4)3OHPb5(PO4)3BrZn5(PO4)3FCu5(PO4)3OHCd5(PO4)3OHCa5(AsO4)3OH(UO2)3(PO4)2•8H2O

Outersphere

Innersphere

Mineralsurface layers

Water

Adsorption Co-precipitation Surfaceprecipitation

Mechanisms of Metal Interaction at the Mineral-Water Interface

xZn2+ + Ca10(PO4)6(OH)2 (10-x)Ca2+ + Ca10-xZnx(PO4)6(OH)2

Composites tested:

Plaster + hydroxyapatite (HA or duck bone)

Plaster + hydroxyapatite + fibers

use two parts plaster to one part water

Natural porosity of plaster…

Plaster/water ratio (%) MPa Porosity (%) 130 10 55 150 15 46 180 20 37 220 30 28 250 35 23 300 50 17

Experimental set-up for testing porous plaster filter

Flow vs time

0

20

40

60

80

100

120

0 100 200 300 400 500

T, sec

V, m

L

Flow vs Time

0

20

40

60

80

100

120

0 500 1000 1500 2000 2500 3000

T, sec

V, m

L

1% fibers

2% fibers

Mechanical strength of synthetic Ha

Mechanical strength of duck bone calcinated Ha

Tensile strength decreases when bone HA increases

Tensile strength decreases as porous bone HA increases

Plaster-HA composite retains zinc ions

Composite with more HA retains more zinc

Amount of zinc removed decreases with increase in flow rate

Composite material can retain heavy metals and avoid dispersion of fine metal phosphates