**2. The nature and kinetics of bioadsorption**

#### **2.1 Adsorption isotherm models**

*Advanced Sorption Process Applications*

13 *Sargassum muticum* and *Fucus spiralis* (brown algae)

18 *Fucus ceranoides* and *Fucus serratus* (brown

20 *Laminaria japonica* (washed or oxidized by potassium permanganate)

algae)

35 *Ascophyllum nodosum Fucus spiralis Laminaria hyperborean Pelvetia canaliculata*

*Marine algae used in bioadsorption removal of heavy and lanthanide metals.*

**Number Name of algae Removed metals Ref.** *Sargassum* sp. Cu [9] *Sargassum* sp. Sm and Pr [10] *Spirogyra* spp. Cr [11] *Sargassum vulgaris* Cd and Ni [12] *Sargassum hystrix* Pb [13] *Sargassum natans* Pb [13] *Sargassum hemiphyllum* Ni and Cu [14] *Sargassum wightii* Ni [15] *Sargassum* sp. Cr [15] *Sargassum honeri and S. hemiphyllum* Ho, Dy, Lu, and Yb [16] *Sargassum ilicifolium* Ni and Co [17] *Sargassum* sp. La, Nb, Eu, and Gd [18]

 *Fucus vesiculosus* (brown algae) Cu [20] *Palmaria palmata* (red algae) Cu [20] *Fucus spiralis* (brown algae) Cu [20] *Ulva* sp. (green algae) Cu [20]

19 *Laminaria japonica* Cd, Pb, and Fe [22]

21 *Gracilaria fischeri* Cu and Cd [24] 22 *Gracilaria* sp. Cd, Cu, Zn, Pb, and Ni [25]

 *Pilayella littoralis* Cr, Fe, Al, Cd, Cu, Zn, Co, and Ni [26] *Cladophora crispata* Pb, Cu, Cd, and Ag [27] *Cladophora fascicularis* Cu and Pb [28] *Ecklonia* sp. Cr [29] *Colpomenia sinuosa* Ni and Cu [14] *Petalonia fascia* Ni and Cu [14] *Ulva fascia* Ni and Cu [14] *Padina pavonica* Ni and Cd [12] *Sargassum cymosum* Cr [30] *Turbinaria conoides* Pb [31] *Laurencia obtusa* Cd, Co, Cr, Cu, and Ni [32] *Ulva reticulata* Zn [33]

*Padina* sp. Cd, Cu, Zn, Pb, and Ni [25]

Pd, Zn, and Cd [19]

Cd [21]

Pb [23]

Cu, Ni, Zn, and Ca [34]

**154**

**Table 1.**

An idea about the adsorption process is predicted using the correlation between the pressure or the concentration of adsorbate and the adsorption capacity (X/m) at constant temperature as shown in **Figure 3**.

The amount of adsorbate (X) adsorbed should be normalized by the mass of adsorbent (m) to allow comparison of different materials. From **Figure 1**, it can be predicted that after the saturation point, the number of adsorption sites on the adsorbent is occupied, and the vacancies became limited so that the adsorption does not occur anymore. There are five general types of adsorption isotherms. They are as follows:

**Figure 3.** *Adsorption isotherm.*

• Type I adsorption isotherm (shown in **Figure 2**)

The main characteristics of this type are (i) there is a monolayer adsorption and (ii) it might be explained using the Langmuir adsorption isotherm.
