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G. Fijałkowska et al.
affects the reduction of sludge transport; thus, the soil erosion process is limited [47–
49]. The macromolecular compounds interact mainly with clay minerals found in
soils or sediments. Adsorbing on the surface of the grains, they affect their properties.
Changing the surface properties of a mineral, soil, or sediment, they affect the fate
of other compounds, i.e., nutrients, heavy metals, and organic substances present in
the surrounding environment [50].
However, from a technical point of view, it is necessary to study the concentrated systems of solid particles. The main problem of this type of system is maintaining adequate dispersion or achieving adequate rheological properties. It is already
known that concentrated suspensions are stabilized or flocculated by the addition
of a polymer, but the role of conformation of the macromolecular compound in
these phenomena remains unclear. This is mainly due to difficulties in measuring
adsorption and determining the conformation of the polymer substance in highdensity systems. However, there are several techniques that allow such research.
These are Fourier-transformed infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), electron spin resonance (ESR), and fluorescence spectroscopy. Using
the fluorescence spectroscopy and ESR technique, the conformation of poly(acrylic
acid) on the solid surface and its effect on the flocculation process was determined.
Based on the obtained results, it was found that the higher the molecular weight of
the polymer is, the greater the degree of coiling of its macromolecules is. The more
developed conformation of the high molecular compound is synonymous with the
formation of a larger number of tails and loops on the surface of the solid, which in
turn increases the efficiency of the flocculation process (creation of more numerous
bridges) [13, 51]. It is also worth mentioning that the research on the impact of
the polyacrylamide molecular weight on the adsorption, and flocculation of suspension process is also important. The higher the molecular weight of the polymer
is, the greater the adsorption capacity is observed. A polymeric substance with a
higher molecular weight is a much better flocculant, because a larger amount of it
is adsorbed on the solid surface. In addition, the conformation of polymer chains
has also been shown to depend on their molecular weight, which is manifested in an
increase in chain length. This promotes the development of polymer macromolecules
conformation and, as a consequence, flocculation efficiency by bridging increases.
Adsorption of polymers such as polyacrylamide and their role in the process
of stabilization and flocculation of dispersed systems has a great scientific interest
[52–61]. The type of action of the macromolecular compound, whether it acts as a
stabilizer or flocculant, is influenced by many factors such as structure, conformation,
solubility, and degree of polymerization [58, 60], as well as the energy of interaction
of polymer chains with a solid surface [62]. Understanding the mechanism of polymer
adsorption is important considering the production of increasingly effective dispersants. So far, many studies on adsorption and the influence of the high molecular
compound presence on the interaction between solid particles have been presented.
These studies concerned: the influence of pH, ionic strength, and the polymer charge
on the adsorbed amount of the macromolecular compound [46, 52, 63–68]; kinetics
of the flocculation process [54]; and the role of polymer conformational changes.
G. Fijałkowska et al.
affects the reduction of sludge transport; thus, the soil erosion process is limited [47–
49]. The macromolecular compounds interact mainly with clay minerals found in
soils or sediments. Adsorbing on the surface of the grains, they affect their properties.
Changing the surface properties of a mineral, soil, or sediment, they affect the fate
of other compounds, i.e., nutrients, heavy metals, and organic substances present in
the surrounding environment [50].
However, from a technical point of view, it is necessary to study the concentrated systems of solid particles. The main problem of this type of system is maintaining adequate dispersion or achieving adequate rheological properties. It is already
known that concentrated suspensions are stabilized or flocculated by the addition
of a polymer, but the role of conformation of the macromolecular compound in
these phenomena remains unclear. This is mainly due to difficulties in measuring
adsorption and determining the conformation of the polymer substance in highdensity systems. However, there are several techniques that allow such research.
These are Fourier-transformed infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), electron spin resonance (ESR), and fluorescence spectroscopy. Using
the fluorescence spectroscopy and ESR technique, the conformation of poly(acrylic
acid) on the solid surface and its effect on the flocculation process was determined.
Based on the obtained results, it was found that the higher the molecular weight of
the polymer is, the greater the degree of coiling of its macromolecules is. The more
developed conformation of the high molecular compound is synonymous with the
formation of a larger number of tails and loops on the surface of the solid, which in
turn increases the efficiency of the flocculation process (creation of more numerous
bridges) [13, 51]. It is also worth mentioning that the research on the impact of
the polyacrylamide molecular weight on the adsorption, and flocculation of suspension process is also important. The higher the molecular weight of the polymer
is, the greater the adsorption capacity is observed. A polymeric substance with a
higher molecular weight is a much better flocculant, because a larger amount of it
is adsorbed on the solid surface. In addition, the conformation of polymer chains
has also been shown to depend on their molecular weight, which is manifested in an
increase in chain length. This promotes the development of polymer macromolecules
conformation and, as a consequence, flocculation efficiency by bridging increases.
Adsorption of polymers such as polyacrylamide and their role in the process
of stabilization and flocculation of dispersed systems has a great scientific interest
[52–61]. The type of action of the macromolecular compound, whether it acts as a
stabilizer or flocculant, is influenced by many factors such as structure, conformation,
solubility, and degree of polymerization [58, 60], as well as the energy of interaction
of polymer chains with a solid surface [62]. Understanding the mechanism of polymer
adsorption is important considering the production of increasingly effective dispersants. So far, many studies on adsorption and the influence of the high molecular
compound presence on the interaction between solid particles have been presented.
These studies concerned: the influence of pH, ionic strength, and the polymer charge
on the adsorbed amount of the macromolecular compound [46, 52, 63–68]; kinetics
of the flocculation process [54]; and the role of polymer conformational changes.