Zeta potential and viscosity of colloidal silica suspensions: Effect of seawater salts, pH, flocculant, and shear rate

Romero, Cristian P.; Jeldres, Ricardo I.; Quezada, Gonzalo R.; Concha, F.; Toledo, Pedro G.

doi:10.1016/j.colsurfa.2017.10.080

Cited by 54 publications

(26 citation statements)

References 37 publications

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“…These results are in accordance with Romero et al and their work on silica with salts, which demonstrated that the ZP value of silica in absolute decreased with the addition of salts. The addition of salts reduces electrostatic repulsion which facilitates the formation of H bounds, and thus an increase in viscosity occurs [36]. …”

Section: Discussionmentioning

confidence: 99%

Useful In Vitro Techniques to Evaluate the Mucoadhesive Properties of Hyaluronic Acid-Based Ocular Delivery Systems

et al. 2018

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Polymer-based eye drops are the most used drug delivery system to treat dry eye disease (DED). Therefore, the mucoadhesion between the polymer and the ocular mucin is crucial to ensure the efficacy of the treatment. In this context, the present study aimed to evaluate the potential use of in vitro methods to study the mucoadhesion of eye drop solutions and, specifically to evaluate the efficacy of two hyaluronic acid-based formulations (HA), HA 0.15% and 0.30% (w/v) to treat DED. Rheology methods and zeta potential determination were used to study the mucoadhesive properties of both eye drop solutions. All results indicated that interactions occurred between the mucin and the HA, being stronger with HA 0.30%, due to the physical entanglements and hydrogen bounding. In vitro tests on ARPE-19 cell line were performed using a 2D and a 3D dry eye model and the results have shown that pre-treated cells with HA showed a morphology more similar to the hydrated cells in both products, with a high survival rate. The in vitro techniques used in this study have been shown to be suitable to evaluate and predict mucoadhesive properties and the efficacy of the eye drops on relief or treatment of DED. The results obtained from these methods may help in inferring possible in vivo effects.

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Section: Discussionmentioning

confidence: 99%

Useful In Vitro Techniques to Evaluate the Mucoadhesive Properties of Hyaluronic Acid-Based Ocular Delivery Systems

et al. 2018

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“…Impact of inorganic salts on the flocculation process depends on the ion charge. It has been found that, in the case of monovalent or divalent cations, this influence is small, but, in the presence of phosphate ions, a negative effect is revealed [ 73 , 74 , 75 ].…”

Section: Factors Affecting Flocculationmentioning

confidence: 99%

“…Several works have reported effect of salts on the viscosity and ion charge of the flocculated suspensions [ 73 , 74 , 75 ]. Investigations of seawater containing colloidal silica (0.05 wt.%) allowed explaining, along with the influences of viscosity, pH, and shear rate that of the type of electrolyte on the flocculation process [ 73 ]. The water solutions of pH 7 or 9 contained alkali and alkaline–earth metal chlorides in the concentration of 0.5 M. Cationic and anionic acrylamide copolymers were used as flocculants (dose range 0–700 g/ton of dry mass of solid).…”

Section: Factors Affecting Flocculationmentioning

confidence: 99%

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Recent Achievements in Polymer Bio-Based Flocculants for Water Treatment

2020

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Polymer flocculants are used to promote solid–liquid separation processes in potable water and wastewater treatment. Recently, bio-based flocculants have received a lot of attention due to their superior advantages over conventional synthetic polymers or inorganic agents. Among natural polymers, polysaccharides show many benefits such as biodegradability, non-toxicity, ability to undergo different chemical modifications, and wide accessibility from renewable sources. The following article provides an overview of bio-based flocculants and their potential application in water treatment, which may be an indication to look for safer alternatives compared to synthetic polymers. Based on the recent literature, a new approach in searching for biopolymer flocculants sources, flocculation mechanisms, test methods, and factors affecting this process are presented. Particular attention is paid to flocculants based on starch, cellulose, chitosan, and their derivatives because they are low-cost and ecological materials, accepted in industrial practice. New trends in water treatment technology, including biosynthetic polymers, nanobioflocculants, and stimulant-responsive flocculants are also considered.

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“…However, seawater usually contains many inorganic ions (e.g., K + , Na + , Ca + , Mg + , Cl − , and SO 4 2− ) which can change the frothing properties (e.g., froth stability and bubble coalescence) of the pulp as well as the surface properties (e.g., hydrophobicity and electrostatic force) of the minerals particles, further influencing mineral flotability [11,13,17,18]. Laskowski et al [18] found a reduced mineral recovery in aqueous solutions containing primary ions (e.g., Na + , Cl − , Mg 2+ , Ca 2+ , and SO 4 2− ) in seawater.…”

Section: Introductionmentioning

confidence: 99%

Fundamental Studies of SHMP in Reducing Negative Effects of Divalent Ions on Molybdenite Flotation

Wei

et al. 2018

Minerals

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Seawater has been considered as an alternative to freshwater for flotation. However, many ions in seawater were reported to depress molybdenite (MoS2), with the depressing mechanisms being insufficiently understood. In this study, the influence of divalent ions (e.g., Ca2+ and Mg2+) and dispersant on MoS2 flotation was systematically investigated. It was found that the detrimental effects of Ca2+ and Mg2+ on the natural flotability of MoS2 were mainly due to the attachment of formed CaMoO4 precipitates and Mg(OH)2 colloids onto MoS2 surface. However, the addition of sodium hexametaphosphate (SHMP) reduced the negative effects. Various measurements, including contact angle, zeta potential, fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM), were conducted to understand the influencing mechanisms of divalent ions and the beneficial effects of SHMP on MoS2 flotation. In addition, the Extended Derjguin–Landau–Verwey–Overbeek (EDLVO) theory was applied to investigate the total interaction energy between MoS2 particles and formed colloids, revealing that the reduced attraction force between MoS2 and Mg(OH)2 colloids in the presence of SHMP primarily resulted in the increased MoS2 recovery. In addition, SHMP combined with Mg2+ and Ca2+ to form dissolvable complexes, thereby reducing insoluble Mg2+ and Ca2+ compounds or precipitation. Thus, this study demonstrated for the first time two influencing mechanisms of SHMP in improving MoS2 recovery in the presence of Ca2+ and Mg2+.

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Zeta potential and viscosity of colloidal silica suspensions: Effect of seawater salts, pH, flocculant, and shear rate

Cited by 54 publications

References 37 publications

Useful In Vitro Techniques to Evaluate the Mucoadhesive Properties of Hyaluronic Acid-Based Ocular Delivery Systems

Useful In Vitro Techniques to Evaluate the Mucoadhesive Properties of Hyaluronic Acid-Based Ocular Delivery Systems

Recent Achievements in Polymer Bio-Based Flocculants for Water Treatment

Fundamental Studies of SHMP in Reducing Negative Effects of Divalent Ions on Molybdenite Flotation

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