New Generation Material for the Removal of Arsenic from Water - Advanced Materials for Agriculture, Food and Environmental Safety - page 69

Table 3.5 Blast furnace slag, Fe(III)/Cr(III) hydroxide waste and l y ash with
dif erent parameters.

Adsorbent pH Concentration

range

Capacity (mg/g)
As (III)

Ref.

As(V)

Iron(III) oxide-loaded
melted slag

2.5 20-300 mg/L 2.9-30.1 18.8-78 [75]

Waste Fe(III)/ Cr(III) 4.0 20-100 mg/L - 11.02 [78]

Iron oxide coated sand
Iron oxide coated sand

7.5
7.5

100-800 μg/L
100-800 μg/L

0.006 -
0.028 -

[80, 81]

3.1.5.7 Fly Ash

Coal combustion produces a huge amount of l y ash byproduct, whose
disposal requires large quantities of land and water. Currently, its appli-
cations are limited to civil engineering uses including cement and
brick production and roadbeds. Bottom ash can also serve as an adsor-
bent [80, 81]. Resource recovery from coal l y ash is one of the most
important issues in waste management worldwide. Since the major
chemical compounds contained in l y ash are aluminosilicate, intensive
ef orts have been recently made to utilize this material as an adsorbent
(see Table 3.5).

3.1.5.8 Soils and Constituents

3.1.5.8.1 Soils and Sand
Arsenate [As(V)] adsorption-desorption kinetics were reported on Olivier
loam, Sharkey clay, and Windsor sand, followed by arsenic release using
successive dilutions [82]. h e As(V) retention rate was initially rapid fol-
lowed by gradual or slower retention behavior with increased reaction
time. Manganese greensand was ef ective for removing arsenic to < 25 μg/L
[83]. h e addition of iron was necessary to achieve an el uent arsenic level
of 25 μg/L in the manganese greensand i ltration system. Iron oxide-coated
sand (IOCS) exhibited a high adsorption capacity (136 μg/L). Another
study [84] achieved 285 μg/g of arsenic removal on iron oxide-coated
sand. Sulphate-modii ed iron oxide-coated sand (SMIOCS) was also used
for As(III) and As(V) removal [85]. h e SMIOCS was prepared by coating
BaSO 4 and Fe on quartz sand. h e maximum As(V) removal was obtained
in acidic pHs [86], while maximum As(III) removal was obtained at pH
7-9 [85], as shown in Table 3.6.