New Generation Material for the Removal of Arsenic from Water - Advanced Materials for Agriculture, Food and Environmental Safety - page 68

Table 3.4 Red mud with dif erent parameters.

Adsorbent pH Concentration

range

Capacity (mg/g)
As(III) As(V)

Ref.

Red mud
(RRM)
Red mud
(ARM)

7.25 for
As(III);
3.50 for
As(V)
7.25 for
As(III);
3.50 for
As(V)

33.37- 400.4
μm/L
33.37- 400.4
μm/L

0.663 0.514
0.884 0.941

[64]

Activated
Bauxsol
Bauxsol

4.5
4.5

7.03-220.9 mM
for As(V);
2.04-156.7 mM
for As(III)

0.541 7.642
1.081 -

[68, 69]

Bauxsol 4.5 0.54-20.34

mg/L

- 3.32 [70]

Modii ed
Calcined
Bauxite

7.0 0.5-8.0 mg/L - 1.57 [71-74]

capacity by BFS was 1.40 mg As(III)/g of BFS at 1 mg/L As(III) initial con-
centration. h e oxidation of As(III) to As(V) and its adsorption/precipita-
tion onto BFS was the dominating mechanism [77] (see Table 3.5).

3.1.5.6 Fe(III)/Cr(III) Hydroxide Waste

Chromium(VI) compounds are used as corrosion inhibitors in cool-
ing water systems in industries. Electrolytically generated Fe(II) reduces
chromium(VI) in the wastewater to Cr(III) under acidic conditions. h e
Fe(III)/Cr(III) ions produced in solution are precipitated as Fe(III)/Cr(III)
hydroxide by the use of lime. h e resultant sludge is discarded as waste.
Namasivayam and Senthilkumar [78] adsorbed As(V) from water onto a
Fe(III)/Cr(III) hydroxide waste generated electrolytically in the treatment
of Cr(VI)-containing wastewaters from fertilizer production. Chrome
sludge, a waste material from electroplating, was tested to adsorb As(V)
from aqueous solutions [79]. h e maximum sorption capacity of chrome
sludge for As(V) was 21 mg/g and the results are mentioned in Table 3.5.