Figure. 12.2. Equations and graphical representation of Freundlich, Langm

and Brunuaer–Emmett–Teller (BET) isotherms (adopted from Gadd, 2009;

et al. 2011).

214

Bioremediation for Sustainable Environmental Cleanup

Figure 12.2. Equations and graphical representation of Freundlich, Langmuir and Brunuaer–Emmett–Teller (BET)

isotherms (adopted from Gadd 2009, Park et al. 2011).

in the study with maximum and minimum levels for each parameter (initial metal concentration,

pH, temperature). The CCD methodology is used for the prediction of the impact of different

parameters on the metal remediation process (Podstawczyk et al. 2015). To regulate the adsorption

equilibrium and kinetic behavior of chromium in an aqueous solution, batch mode experiments

were performed for Lyngbya, and maximum metal adsorption capacity was determined. The impact

of other parameters like initial metal ion concentration (10–100 mg/L), pH (2–6) and temperature

(25–45°C) on chromium adsorption were also noted , using Box–Behnken design (BBD) model of

RSM and the optimized conditions (50–60 mg/L initial Cr concentration, 2–3 pH, 45°C temperature)

were computed, when 82% of the metal was extracted from the solution by the alginate immobilized

alga (Kiran et al. 2007b).

The biosorption range of algal cells directly depends on the presence of different functional

groups viz. OH^–, PO3O2, NH2, COOH, SH, etc., on the cell of algae. These groups provide a negative

charge to the cell (Kaplan 2013), which has a strong binding capacity for the positively charged

heavy metals present in the water. These functional groups form a complex or get linked with cell

wall components (teichoic acids, peptidoglycan, polysaccharides and proteins), directly or indirectly

provide metal-binding sites (Volesky and Holan 1995). Biosorption of Cd in Chlamydomonas

reinhardtti occurs in a unique manner, where Cd²⁺ ions form a complex with carboxylic groups

of the algal cells (Adhiya et al. 2002). Covalent bonding and electrostatic attraction are directly

responsible for the adsorption of Ni and Zn on the Chaetophora elegans (Andrade et al. 2005).

Bioremediation of aluminum (Al) follows a different mechanism of sorption on algal cells as it