Flocculation of Model Latex Particles by Chitosans of Varying Degrees of Acetylation

and, M. A. Rakib; Hearn, J.

doi:10.1021/la991648w

Cited by 75 publications

(105 citation statements)

References 39 publications

(42 reference statements)

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“…Chitosan has been applied as a flocculant in different colloidal systems, including bacteria [89][90][91], algea [92], latex particles [93] and emulsions [94,95].…”

Section: Emulsion Flocculationmentioning

confidence: 99%

Chitosan: Gels and Interfacial Properties

et al. 2015

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Abstract:Chitosan is a unique biopolymer in the respect that it is abundant, cationic, low-toxic, non-immunogenic and biodegradable. The relative occurrence of the two monomeric building units (N-acetyl-glucosamine and D-glucosamine) is crucial to whether chitosan is predominantly an ampholyte or predominantly a polyelectrolyte at acidic pH-values. The chemical composition is not only crucial to its surface activity properties, but also to whether and why chitosan can undergo a sol-gel transition. This review gives an overview of chitosan hydrogels and their biomedical applications, e.g., in tissue engineering and drug delivery, as well as the chitosan's surface activity and its role in emulsion formation, stabilization and destabilization. Previously unpublished original data where chitosan acts as an emulsifier and flocculant are presented and discussed, showing that highly-acetylated chitosans can act both as an emulsifier and as a flocculant.

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“…Chitosan has been applied as a flocculant in different colloidal systems, including bacteria [89][90][91], algea [92], latex particles [93] and emulsions [94,95].…”

Section: Emulsion Flocculationmentioning

confidence: 99%

Chitosan: Gels and Interfacial Properties

et al. 2015

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“…Flocculation, coagulation and precipitation are chemical pre-treatments that improve the mechanical solid-liquid separation of many suspensions (Gregory, 1973;Smith-Palmer et al, 1994;Ashmore and Hearn, 2000;Nowostawska et al, 2005). In most suspensions, colloidal particles will not aggregate because the particles are negatively charged and repel each other (Gregory, 1989).…”

Section: Precipitation Coagulation and Flocculationmentioning

confidence: 99%

“…Polymer characteristics of importance to polymer bridging are molecular weight and the molecular structure, as large molecules with long tails are capable of catching by-passing particles relatively easily. Charge density is also important, as this affects the number of loops and tails that are formed and the interaction between polymer and particles (Larsson et al, 1999;Ashmore and Hearn, 2000;Bouyer et al, 2001). …”

Section: Theorymentioning

confidence: 99%

Solid—liquid separation of animal slurry in theory and practice. A review

Hjorth

Christensen

et al. 2010

Agron. Sustain. Dev.

335

235

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-Animal slurry contains plant nutrients that are essential for crop production. However, intensive livestock production may lead to a surplus of plant nutrients on farms and, as a consequence, discharge or emission to the environment. In order to ensure that the slurry applied to fields matches the nutrient requirements of the crops, techniques have been developed to reduce the nutrient content of slurry by means of separation. This review discusses the separation technologies used for animal slurry treatment and the physical and chemical processes involved in separation. These processes need to be understood before efficient, reliable and cheap separation technologies that take into account the actual properties of slurry and the likely end-use of the separation products can be developed. A simple separation efficiency expression can be used to assess the efficiency of slurry separation. It is indeed important to measure the amount and composition of the slurry before treatment, the dry-matter-rich fraction and the liquid fraction. The separation efficiency of mechanical separators for the removal of dry matter and phosphorus (P) is ranked as follows: centrifugation > sedimentation > non-pressurized filtration > pressurized filtration. In general, the separation of total N and NH + 4 follows the same pattern, but the separation efficiency is lower than for dry matter and P. Treatment with a flocculant before separation improves separation efficiency significantly. Of the polyacrylamide polymers tested, high-molecular-weight, linear cationic polymers with a medium charge density (20-40 mol%) were found to be the most efficient flocculants. The best mechanical separation techniques for flocculated slurry are screens or filter belts. The separation efficiency of polyacrylamide-treated slurry can be improved by adding a multivalent ion to coagulate particles and for precipitation of phosphorus. Aluminium sulfate (Al 2 (SO 4 ) 3 ) or ferric chloride (FeCl 3 ) seem to be very efficient for improving the mechanical separators. Alternatively, the mineral struvite (MgNH 4 PO 4 ) may be formed by changing the slurry characteristics, such as by the addition of magnesium (Mg) or by increasing the pH to 9. The struvite crystals are removed during solid-liquid separation. The products of the solid-liquid separation may be further treated by evaporation, membrane filtration or ammonia stripping in order to obtain the desired end-products; however, low-maintenance and/or cost-efficient operation of these post-treatments has not yet been demonstrated. The separation should be developed as a whole-system approach, paying attention to parameters such as the value of end-products, environmental consequences and economy.

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“…22 They prepared well-characterized latexes with known amounts of sulfate groups on the surface of the latex particles and correlated the ratio of chitosan amine groups to sulfate groups with the flocculation efficiency, taking into account the acid-base properties of the polymer (by varying the pH). They commented that the flocculation mechanism proceeds by charge neutralization with a contribution from a "charge patch mechanism."…”

Section: Influence Of Degree Of Deacetylationmentioning

confidence: 99%

“…Chitosan dissolved in acetic acid or hydrochloric acid can be used for the uptake of metal cations using polymer-enhanced ultrafiltration 14,15 These interactions of dissolved chitosan with solutes also may be used for the coagulation and flocculation of dissolved contaminants 16 and suspended colloids. 17 Several studies have focused on the use of chitosan for fish processing, 18 in the food industry, 19,20 and in river silt water, 21 latex particles, 22,23 microorganisms, 24,25 and suspensions containing mineral colloids. 17,26 -28 The properties of chitosan, including its cationic behavior and molecular weight, may be used both for charge neutralization (coagulating effect for anionic compounds) and for particle entrapment (flocculating effect).…”

Section: Introductionmentioning

confidence: 99%

Influence of chitosan characteristics on coagulation and flocculation of organic suspensions

Roussy

Vooren²,

Guibal

2005

J of Applied Polymer Sci

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Several samples of chitosan with different degrees of deacetylation and of different molecular weights were tested for the coagulation-flocculation of organic suspensions. Organic suspensions were prepared by mixing mushroom powder with tap water. Experiments were carried out at pH 5, pH 7, and pH 9. Because decreasing the pH reduced the amount of chitosan required to reach the required turbidity, at pH 9, a high concentration of chitosan was required to achieve the required treatment levels, whereas the difference was less significant between pH 7 and pH 5 (the required concentration of chitosan was halved). Though viscosity, correlated to the molecular weight of chitosan, affected treatment performance, its influence on the efficiency of coagulation-flocculation could be substantially reduced by slightly increasing the concentration of the polymer. This is of importance in the processing of industrial effluents: the aging of a chitosan solution, which may cause partial depolymerization, and loss of viscosity, will have a limited impact on process efficiency. The degree of deacetylation also has a limited effect on treatment performance, especially when the degree of deacetylation exceeds 90%.

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Flocculation of Model Latex Particles by Chitosans of Varying Degrees of Acetylation

Cited by 75 publications

References 39 publications

Chitosan: Gels and Interfacial Properties

Chitosan: Gels and Interfacial Properties

Solid—liquid separation of animal slurry in theory and practice. A review

Influence of chitosan characteristics on coagulation and flocculation of organic suspensions

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