Non-conventional Adsorbents for Dye Removal - Green Chemistry for Dyes Removal from Wastewater - page 367

Table 10.2 ( Cont .)

Adsorbent Dye S a q max Reference

Sepiolite (Turkey) Reactive Red 239 50.5 108.8 [60]

Sepiolite (Brazil) Astrazon Red 108 [83]

Sepiolite (Spain) Basic Red 46 107 106 [83]

Sepiolite (Turkey) Basic Blue 9 322 79 [84]

Sonicated sepiolite
(Turkey)

Basic Blue 9 487 128 [84]

Treated diatomite
(Jordan)

Basic Blue 9 572.9 126.6 [85]

a surface area (in m 2 g -1 )

onto diatomite, showed that this naturally occurring material could sub-
stitute the use of CAC as an adsorbent due to its availability and low cost,
and its good adsorption properties. Al-Ghouti et al . [57] also investigated
the feasibility of using diatomite for the removal of the problematic reac-
tive dyes and concluded that clay materials were efficient adsorbents. Tsai
et al . [62] demonstrated that the beer brewery waste mostly consisting of
diatomite could be directly used as a porous adsorbent mainly based on its
pore properties. Clay materials can be modified to improve their adsorp-
tion capacity. Ozdemir et al . [60] investigated the modification of sepiolite
to adsorb a variety of azo-reactive dyes, and showed that the adsorption
capacities are substantially improved upon modifying its surface with qua-
ternary amines. The adsorption capacity of kaolinite can also be improved
by purification and by treatment with NaOH solution [55]. The acid-treated
bentonite showed a higher adsorption capacity than non-modified benton-
ite [61,56]. It is evident from the literature survey that clay materials may
be promising adsorbents for environmental and purification purposes [3].

10.4 Siliceous Materials

The use of natural siliceous materials [86] such as dolomite, perlite, alunite,
and glasses for wastewater is increasing because of their abundance, avail-
ability and low price, and interesting adsorption properties (Table 10.3).
Walker et al. [70] previously proposed dolomite, both a mineral and a rock,
as adsorbent for dye removal. The structure can be visualized as alterna-
tive layers of calcite and magnesite [87]. Outstanding removal capability
of dolomite to uptake dye was obtained [70]. A comparison was made