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In this paper, the experimental research concerning the impact of the hydrophilic-hydrophobic transition of a polymer exhibiting the Upper Critical Solution Temperature (UCST) onto the crystallization process of inorganic salt is presented. A hypothesis was postulated that under favorable process conditions the sudden change of macromolecules properties and the resulting appearance of insoluble particles will induce the nucleation process of the salt. Since the transition point parameters may be precisely designed, the described mechanism would eliminate the stochastic nature of the crystallization process. Although performed experiments proved that the postulated process mechanism was incorrect, the presence of macromolecules had a significant impact on the crystallization course. The stochastic nature of the process was not eliminated; nevertheless, it seems that a specific point of nucleation was created which was independent of the cloud point temperature (TCP) of the polymer. Moreover, the surface morphology of crystals was changed.

The application of polymers as a tool in the crystallization process is gaining more and more interest among the scientific community. According to Web of Science statistics the number of papers dealing with “Polymer induced crystallization” increased from 2 in 1990 to 436 in 2020, and for “Polymer controlled crystallization”—from 4 in 1990 to 344 in 2020. This is clear evidence that both topics are vivid, attractive and intensively investigated nowadays. Efficient control of crystallization and crystal properties still represents a bottleneck in the manufacturing of crystalline materials ranging from pigments, antiscalants, nanoporous materials and pharmaceuticals to semiconductor particles. However, a rapid development in precise and reliable measuring methods and techniques would enable one to better describe phenomena involved, to formulate theoretical models, and probably most importantly, to develop practical indications for how to appropriately lead many important processes in the industry. It is clearly visible at the first glance through a number of representative papers in the area, that many of them are preoccupied with the testing and production of pharmaceuticals, while the rest are addressed to new crystalline materials, renewable energy, water and wastewater technology and other branches of industry where the crystallization process takes place. In this work, authors gathered and briefly discuss over 100 papers, published in leading scientific periodicals, devoted to the influence of polymers on crystallizing solutions.

In this study, the phase transition phenomena of linear poly(acrylic acid) (PAA) and linear or star-shaped poly(acrylic acid-co-methyl acrylate) (P(AA-co-MA)) in highly concentrated KCl solutions were investigated. The effects of polymer molecular weight, topology, and composition on their phase transition behavior in solution were investigated. The cloud point temperature (TCP) of polymers drastically increased as the KCl concentration (CKCl) and solution pH increased. CKCl strongly influenced the temperature range at which the phase transition of PAA occurred: CKCl of 1.0−2.2 M allowed the phase transition to occur between 30 and 75 °C. Unfortunately, at CKCl above 2.6 M, the TCP of PAA was too high to theoretically trigger the crystallization of KCl. The addition of hydrophobic methyl acrylate moieties decreased the TCP into a temperature region where KCl crystallization could occur. Additionally, the hydrodynamic diameters (Dh) and zeta potentials of commercial PAA samples were examined at room temperature and at their TCP using dynamic light scattering. The salt concentration (from 1 to 3 M) did not impact the hydrodynamic diameter of the molecules. Dh values were 1500 and 15 nm at room temperature and at TCP, respectively.

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Thermosensitive polymers are gaining increasing interest due to their possible applications as drug delivery systems, flotation agents in mineral ore processing or flocculants in wastewater treatment. Lower Critical Solution Temperature (LCST) is a crucial parameter of thermoresponsive polymers. In this work the comparison of four different methods of LCST determination, i.e. transmittance, viscosimetric, Dynamic Light Scattering (DLS) and pH measurement, are presented. They are found to be complementary and each of them is shown to fail under certain condition. For the purpose of this research a cationic copolymer of poly(N-isopropylacrylamide) with diallyldimethylammonium chloride was synthesized. Moreover two reference polymer samples were investigated. [ABSTRACT FROM AUTHOR]

A lumped discrete population balance model has been selected for the verification of the experimental data. Solid aggregates of chalk suspended in vigorously mixed suspension were treated as fractal objects with a mass fractal dimension taken as 2.02. A specially written computer program has been used for determining the evolution of population of aggregates during the course of mixing. The PSD (particle size distribution) results obtained by numerical calculation for fractal and non-fractal approaches have been compared, showing a better fit in the case of the fractal model. The aggregation and breakage rate coefficients were correlated as a function of the average energy dissipation rate in the vibrating mixer. [ABSTRACT FROM AUTHOR]

Aggregation and breakage of solid particles or aggregates suspended in liquid can be found in numerous industrial processes. It is crucially important to predict the evolution of aggregates at any moment during the process. This aim can be achieved by modeling based on solid phase population balances. A lumped discrete population balance model has been selected for the verification of the experimental data. The experiments have been carried out in a laboratory-scale vibrating mixer equipped with a disc-type reciprocating impeller. A reasonably good agreement between the computational and experimental results of PSD data has been obtained. Dependencies between aggregation and breakage rate coefficients and the average energy dissipation rate in the mixer have been shown. [ABSTRACT FROM AUTHOR]

In this paper, the experimental research concerning the impact of the hydrophilic-hydrophobic transition of a polymer exhibiting the Upper Critical Solution Temperature (UCST) onto the crystallization process of inorganic salt is presented. A hypothesis was postulated that under favorable process conditions the sudden change of macromolecules properties and the resulting appearance of insoluble particles will induce the nucleation process of the salt. Since the transition point parameters may be precisely designed, the described mechanism would eliminate the stochastic nature of the crystallization process. Although performed experiments proved that the postulated process mechanism was incorrect, the presence of macromolecules had a significant impact on the crystallization course. The stochastic nature of the process was not eliminated; nevertheless, it seems that a specific point of nucleation was created which was independent of the cloud point temperature (TCP) of the polymer. Moreover, the surface morphology of crystals was changed. [ABSTRACT FROM AUTHOR]

The application of polymers as a tool in the crystallization process is gaining more and more interest among the scientific community. According to Web of Science statistics the number of papers dealing with "Polymer induced crystallization" increased from 2 in 1990 to 436 in 2020, and for "Polymer controlled crystallization"—from 4 in 1990 to 344 in 2020. This is clear evidence that both topics are vivid, attractive and intensively investigated nowadays. Efficient control of crystallization and crystal properties still represents a bottleneck in the manufacturing of crystalline materials ranging from pigments, antiscalants, nanoporous materials and pharmaceuticals to semiconductor particles. However, a rapid development in precise and reliable measuring methods and techniques would enable one to better describe phenomena involved, to formulate theoretical models, and probably most importantly, to develop practical indications for how to appropriately lead many important processes in the industry. It is clearly visible at the first glance through a number of representative papers in the area, that many of them are preoccupied with the testing and production of pharmaceuticals, while the rest are addressed to new crystalline materials, renewable energy, water and wastewater technology and other branches of industry where the crystallization process takes place. In this work, authors gathered and briefly discuss over 100 papers, published in leading scientific periodicals, devoted to the influence of polymers on crystallizing solutions. [ABSTRACT FROM AUTHOR]

In this study, the phase transition phenomena of linear poly(acrylic acid) (PAA) and linear or star-shaped poly(acrylic acid-co-methyl acrylate) (P(AA-co-MA)) in highly concentrated KCl solutions were investigated. The effects of polymer molecular weight, topology, and composition on their phase transition behavior in solution were investigated. The cloud point temperature (TCP) of polymers drastically increased as the KCl concentration (CKCl) and solution pH increased. CKCl strongly influenced the temperature range at which the phase transition of PAA occurred: CKCl of 1.0–2.2 M allowed the phase transition to occur between 30 and 75 °C. Unfortunately, at CKCl above 2.6 M, the TCP of PAA was too high to theoretically trigger the crystallization of KCl. The addition of hydrophobic methyl acrylate moieties decreased the TCP into a temperature region where KCl crystallization could occur. Additionally, the hydrodynamic diameters (Dh) and zeta potentials of commercial PAA samples were examined at room temperature and at their TCP using dynamic light scattering. The salt concentration (from 1 to 3 M) did not impact the hydrodynamic diameter of the molecules. Dh values were 1500 and 15 nm at room temperature and at TCP, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Flocculation process based on water soluble polymers as flocculating agents is still intensively researched nowadays, despite the introduction of these materials about fifty years ago. Dual polymer flocculation or application of new, more sophisticated macromolecules is proposed as a new approach. Simultaneously, more detailed mathematical models of flocculation are developed. The employment of polymer degradation model in population balance equations (PBE) is proposed in the paper. The suspension of chalk in distilled water was flocculated using three types of ultrasonically conditioned commercial flocculants. The experiments were performed using an apparatus for on-line determination of particle size distribution (PSD). The obtained results were compared with simulations using the Class Method. It was proved that the kinetic constant in the aggregation kernel can be described by a function similar to the one showing a change of mean molecular weight of polymer with sonication time. [Copyright &y& Elsevier]

In this paper a novel approach to the flocculation phenomenon was investigated, i.e. application of light-sensitive polymers. A hypothesis was proposed that the energy delivered by an electromagnetic wave will trigger the photo-dimerization reaction, which in turn will lead to the destabilization process via bridging phenomenon. In research two polymers differing in content of light-sensitive component, i.e. cinnamoyl groups, were synthesized by means of conventional free radical copolymerization and postreaction. In the flocculation experiments a model suspension of CaCO 3 precipitate in deionized water was used. The experiments were performed using two different mixer configurations. Unfortunately, the postulated mechanism was proved to be wrong. Although both polymers acted as good destabilization agents directly after injection to suspension, the UV radiation had no impact on the process. [ABSTRACT FROM AUTHOR]

This paper presents results of investigations on the application of CuO-water nanofluids for intensification of convective heat transfer. Performance of nanofluids with 2.2 and 4.0 vol.% CuO NPs (nanoparticles) content were examined with regard to heat transfer coefficient and pressure losses in case of turbulent flow in a tube. Negligible impact of examined nanofluid on heat transfer improvement was found. Moreover, measured pressure losses significantly exceeded those determined for primary base liquid. The observations showed that application of nanofluid for heat transfer intensification with a relatively high solid load in the examined flow range is rather controversial. [ABSTRACT FROM AUTHOR]

Abstract: The influence of temperature on particle size distribution of chalk suspension in the presence of a thermosensitive flocculant based on N-isopropylacrylamide and 3-(acryloyloxy)propanoic acid was investigated. No aggregation was observed at room temperature upon the addition of the polymer. When the system was heated, flocculation took place and the mean particle diameter was found to be temperature dependent. The polymer dosage influence on the process was examined. In higher polymer concentration the investigated process was fully reversible, i.e. aggregates broke upon cooling. The possibility to control particle size by temperature adjustment is discussed and the process'' model is proposed. [Copyright &y& Elsevier]