Biosorption of Organic Dyes: Research Opportunities and Challenges - Green Chemistry for Dyes Removal from Wastewater - page 303

process. In another study, Cardoso et al. [44] verified that Spirulina platen-
sis was more efficient than commercial activated carbon for the removal of
Reactive Red 120 dye.

8.2.3 Bacterial Biomass

Bacteria constitute a large domain or kingdom of prokaryotic microor-
ganisms [49]. In the last years, bacterial biomass has been tested as bio-
sorbent to remove SODs from aqueous solutions [50-54]. Two general
types of bacteria exist, Gram-positive and Gram-negative. Gram-positive
bacteria are comprised of a thick peptidoglycan layer connected by amino
acid bridges. Imbedded in the Gram-positive cell wall are polyalcohols,
some of which are lipid linked to form lipoteichoic acids. The cell wall of
Gram-negative bacteria is thinner, and composed of only 10-20% pepti-
doglycan. Furthermore, the cell wall contains an additional outer mem-
brane composed of phospholipids and lipopolysaccharides [6,55]. These
chemical functional groups on the cell walls are potential biosorption sites
to interact with SODs [56,57]. The biosorption of SODs by bacterial bio-
mass is an eco-friendly and cost-effective process, since this biomass is
generally obtained in large quantities as residue of full-scale fermentation
processes [52-54]. Table 8.3 summarizes the biosorption capacities of bac-
terial biomass.
In the study of Won et al. [52], the binding mechanisms involved in
the biosorption of reactive dyes onto Corynebacterium glutamicum were

Table 8.3 Biosorption capacities of bacterial biomass.

Bacterial biomass Dye pH T (K) Biosorption

capacity
(mg g -1 )

Reference

Corynebacterium
glutamicum

Basic Blue 3 6.0-9.0 298 50.4 [50]

Corynebacterium
glutamicum

Reactive
Blue 4

2.0 298 184.9 [52]

Corynebacterium
glutamicum

Reactive
Orange 16

2.0 298 156.6 [52]

Corynebacterium
glutamicum

Reactive
Ye l l o w 2

2.0 298 155.0 [52]

Bacillus subtilis Reactive Blue 4 2.0 303 36.3 [53]

Pseudomonas sp. Acid Black 172 3.0 298 2961.2 [54]