Marine Macro
597
Part D | 24.1
24. Marine Macrophytes: Biosorbents
Chiara Pennesi, Fabio Rindi, Cecilia Totti, Francesca Beolchini
Biosorption is a biological method suggested as
a cheaper and more effective technique for heavy
metal ion removal and recapture from aqueous
solutions such as industrial wastewater. A large
range of biomass, principally bacteria, algae,
seagrasses, crab shells, yeasts, and fungi have
received increasing attention for heavy metal ion
removal and recovery. In particular, through this
method, nonliving aquatic macrophytes (i. e.,
macroalgae and seagrasses) can be used for heavy
metal removal due to their large availability,
easy regeneration, and low costs. In recent years,
macrophytes have been shown to be able to
remove pollutants by surface adsorption or by
bioaccumulation, incorporating metals into their
tissues or storing them in a bound form. The
type of biomass used in the treatment procedure
can make a significant difference for the removal
of pollutants. Furthermore, the knowledge of
metal kinetic biosorption parameters for nonliving
macrophytes has become crucial for treatment
design to improve the efficiency of metal removal
in artificial systems for their recycling. In this
chapter, the properties of dried macrophytes in
the treatment of wastewater and their cell wall
and cuticle compartments are described. More24.1 Marine Macrophytes............................. 597
24.1.1 The Algae ................................. 597
24.1.2 Marine Benthic Green Algae
(Chlorophyta, Ulvophyceae) ........ 598
24.1.3 The Red Algae (Rhodophyta). ...... 598
24.1.4 The Brown Algae
(Heterokontophyta,
Phaeophyceae). ......................... 599
24.1.5 Seagrasses ................................ 600
24.2 Heavy Metals: Definition and Toxicity ... 601
24.3 Biosorption ......................................... 601
24.3.1 Cell Wall of the Algae ................. 602
24.3.2 Seagrass Cuticles........................ 604
24.3.3 Macrophytes: Key Chemical
Functional Groups ..................... 604
24.3.4 Chemical and Physical
Mechanisms.............................. 605
24.4 Biosorption Experiments: Procedure ..... 606
24.4.1 Biosorption: Kinetic Curves......... 606
24.4.2 The Langmuir Adsorption
Isotherm .................................. 606
24.5 Conclusions ......................................... 606
References................................................... 607
over, the procedures for biosorption experiments
are analyzed.
24.1 Marine Macrophytes
The term macrophytes indicates aquatic organisms capable of performing oxygenic photosynthesis that are
sufficiently large-sized to be observed with the bare
eye. They typically grow submerged or floating in riverine, estuarine, and marine coastal environments, where
they play a key role as primary producers. Marine
macrophytes form the bulk of the photosynthesizing
biomass in coastal habitats; they belong to two different groups, indicated with the common names of algae
and seagrasses.
24.1.1 The Algae
The term algae designates the complex of all
oxygenic photosynthesizers other than embryophyte
plants [24.1]. As such, algae represent a heterogeneous
assemblage of organisms belonging to many separate
evolutionary lineages, which in modern classifications
are distributed in no less than four eukaryotic supergroups (Archeplastida, Chromalveolata, Excavata,
Rhizaria) [24.2]. Due to such vast evolutionary diver-
597
Part D | 24.1
24. Marine Macrophytes: Biosorbents
Chiara Pennesi, Fabio Rindi, Cecilia Totti, Francesca Beolchini
Biosorption is a biological method suggested as
a cheaper and more effective technique for heavy
metal ion removal and recapture from aqueous
solutions such as industrial wastewater. A large
range of biomass, principally bacteria, algae,
seagrasses, crab shells, yeasts, and fungi have
received increasing attention for heavy metal ion
removal and recovery. In particular, through this
method, nonliving aquatic macrophytes (i. e.,
macroalgae and seagrasses) can be used for heavy
metal removal due to their large availability,
easy regeneration, and low costs. In recent years,
macrophytes have been shown to be able to
remove pollutants by surface adsorption or by
bioaccumulation, incorporating metals into their
tissues or storing them in a bound form. The
type of biomass used in the treatment procedure
can make a significant difference for the removal
of pollutants. Furthermore, the knowledge of
metal kinetic biosorption parameters for nonliving
macrophytes has become crucial for treatment
design to improve the efficiency of metal removal
in artificial systems for their recycling. In this
chapter, the properties of dried macrophytes in
the treatment of wastewater and their cell wall
and cuticle compartments are described. More24.1 Marine Macrophytes............................. 597
24.1.1 The Algae ................................. 597
24.1.2 Marine Benthic Green Algae
(Chlorophyta, Ulvophyceae) ........ 598
24.1.3 The Red Algae (Rhodophyta). ...... 598
24.1.4 The Brown Algae
(Heterokontophyta,
Phaeophyceae). ......................... 599
24.1.5 Seagrasses ................................ 600
24.2 Heavy Metals: Definition and Toxicity ... 601
24.3 Biosorption ......................................... 601
24.3.1 Cell Wall of the Algae ................. 602
24.3.2 Seagrass Cuticles........................ 604
24.3.3 Macrophytes: Key Chemical
Functional Groups ..................... 604
24.3.4 Chemical and Physical
Mechanisms.............................. 605
24.4 Biosorption Experiments: Procedure ..... 606
24.4.1 Biosorption: Kinetic Curves......... 606
24.4.2 The Langmuir Adsorption
Isotherm .................................. 606
24.5 Conclusions ......................................... 606
References................................................... 607
over, the procedures for biosorption experiments
are analyzed.
24.1 Marine Macrophytes
The term macrophytes indicates aquatic organisms capable of performing oxygenic photosynthesis that are
sufficiently large-sized to be observed with the bare
eye. They typically grow submerged or floating in riverine, estuarine, and marine coastal environments, where
they play a key role as primary producers. Marine
macrophytes form the bulk of the photosynthesizing
biomass in coastal habitats; they belong to two different groups, indicated with the common names of algae
and seagrasses.
24.1.1 The Algae
The term algae designates the complex of all
oxygenic photosynthesizers other than embryophyte
plants [24.1]. As such, algae represent a heterogeneous
assemblage of organisms belonging to many separate
evolutionary lineages, which in modern classifications
are distributed in no less than four eukaryotic supergroups (Archeplastida, Chromalveolata, Excavata,
Rhizaria) [24.2]. Due to such vast evolutionary diver-