scholarly journals Effect of Magnesium on the Hydrophobicity of Sphalerite

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1359
Author(s):  
Gloria I. Dávila-Pulido ◽  
Adrián A. González-Ibarra ◽  
Mitzué Garza-García ◽  
Danay A. Charles
Keyword(s):  
Contact Angle ◽  
Zeta Potential ◽  
Zinc Sulfide ◽  
Sodium Carbonate ◽  
Thermodynamic Simulation ◽  
Bulk Solution ◽  
Sulfide Ores ◽  
Recycled Water ◽  
Negative Effects ◽  
Dissolved Species

The use of untreated recycled water has negative effects in the flotation of zinc sulfide ores due to the presence of dissolved species, such as magnesium and calcium. Although it has been found that magnesium is a more potent depressant than calcium, it has not been investigated in this role or for the effect of adding sodium carbonate. The results of an investigation to evaluate the effect of magnesium on the hydrophobicity of Cu-activated sphalerite conditioned with Sodium Isopropyl Xanthate (SIPX) are presented. Zeta potential of natural and Cu-activated sphalerite as a function of the conditioning pH and Cu(II) concentration, respectively, was first evaluated. Later, the effect of pH and presence of magnesium on the contact angle of Cu-activated sphalerite conditioned with SIPX was studied; it was also evaluated the effect of sodium carbonate to counteract the effect of magnesium. Cu-activation enhances the zeta potential of sphalerite up to a concentration of 5 mg/L. Contact angle tests, thermodynamic simulation, and surface analysis showed that magnesium hydroxide precipitates on the sphalerite surface at pH 9.6, decreasing its hydrophobicity. Addition of sodium carbonate as alkalinizing agent precipitates the magnesium in the form of a species that remained dispersed in the bulk solution, favoring the contact angle of Cu-activated sphalerite and, consequently, its hydrophobicity. It is concluded that the use of sodium carbonate as alkalinizing agent favors the precipitation of magnesium as hydromagnesite (Mg5(OH)2(CO3)4∙4H2O) instead of hydroxide allowing the recovery of sphalerite.

scholarly journals Casein phosphopeptide acts synergistically with fluoride to inhibit initial adhesion of Streptococcus mutans to the saliva-coated hydroxyapatite disc

2020 ◽  
Author(s):  
Xiaodie Wang ◽  
Limin Liu ◽  
Xiaoyan Zhou ◽  
Yongbiao Huo ◽  
Jinlong Gao ◽  
...  
Keyword(s):  
Contact Angle ◽  
Zeta Potential ◽  
Streptococcus Mutans ◽  
Water Contact Angle ◽  
Bacterial Adhesion ◽  
Laser Scanning Microscopy ◽  
Water Contact ◽  
Initial Adhesion ◽  
Salivary Pellicle ◽  
Casein Phosphopeptide

Abstract Background Recent preventive strategies for dental caries focus on targeting the mechanisms underlying biofilm formation, including inhibiting bacterial adhesion. A promising approach to prevent bacterial adhesion is to modify the composition of acquired salivary pellicle. This in vitro study investigated the effect and possible underlying mechanism of pellicle modification by casein phosphopeptide (CPP) on Streptococcus mutans (S. mutans) initial adhesion, and the impact of fluoride on the efficacy of CPP.Methods The salivary pellicle-coated hydroxyapatite (s-HA) disc was modified by 2.5% CPP or 2.5% CPP supplemented with 900 ppm fluoride solutions. After cultivation of S. mutans, the adherent bacteria were visualized by scanning electron microscopy (SEM) and quantitatively evaluated using the plate count method. Confocal laser scanning microscopy (CLSM) was used to evaluate the proportions of total and dead S. mutans. The concentrations of total, free, and bound calcium and fluoride in CPP and fluoride-doped CPP solutions were determined. The water contact angle and zeta potential of s-HA with and without modification were measured. The data were statistically analyzed using one-way ANOVA followed by a Turkey post hoc multiple comparison test.Results Initial adhesion of S. mutans to s-HA was inhibited in response to pellicle modification by CPP and fluoride-doped CPP, and the latter was more efficient. CLSM analysis showed that the proportion of dead S. mutans did not differ between the groups. Water contact angle and zeta potential decreased after pellicle modification, and both were lowest in the fluoride-doped CPP group.Conclusions Pellicle modification by CPP inhibited S. mutans initial adhesion to s-HA, possibly by reducing hydrophobicity and negative charge on the s-HA surface, and incorporating fluoride into CPP enhanced its anti-adhesion effect.

scholarly journals Effect of dextrin on flotation separation and surface properties of chalcopyrite and arsenopyrite

2020 ◽  
Author(s):  
Jingshen Dong ◽  
Quanjun Liu ◽  
S. H. Subhonqulov
Keyword(s):  
Contact Angle ◽  
Zeta Potential ◽  
Significant Interaction ◽  
Selective Adsorption ◽  
Surface Adsorption ◽  
Inhibitory Effect ◽  
Chain Structure ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Chemical Adsorption

Abstract The flotation separation and mechanism of dextrin on chalcopyrite and arsenopyrite surface were investigated using micro-flotation tests, zeta potential measurements, infrared spectroscopy, contact angle measurement and surface adsorption experiments. The micro-flotation test showed that dextrin had obvious inhibitory effect on arsenopyrite flotation, but had no inhibitory effect on chalcopyrite flotation. After treating the surface of arsenopyrite with dextrin, the infrared spectra showed that new characteristic peaks, indicating that chemical adsorption and significant interaction between dextrin and arsenopyrite particles. Zeta potential measurements, contact angle measurement and surface adsorption experiments showed that the selective adsorption of dextrin added a large number of hydrophilic groups to the surface of arsenopyrite, but had little effect on chalcopyrite. In addition, the macromolecular chain structure of dextrin may hinder the attachment of collector molecules to arsenopyrite. The combined effect of these two aspects makes the arsenopyrite treated with dextrin lose its hydrophobicity and enables the separation of chalcopyrite and arsenopyrite.

Casein phosphopeptide combined with fluoride enhances the inhibitory effect on initial adhesion of Streptococcus mutans to the saliva-coated hydroxyapatite disc

2020 ◽  
Author(s):  
Xiaodie Wang ◽  
Limin Liu ◽  
Xiaoyan Zhou ◽  
Yongbiao Huo ◽  
Jinlong Gao ◽  
...  
Keyword(s):  
Contact Angle ◽  
Zeta Potential ◽  
Streptococcus Mutans ◽  
Water Contact Angle ◽  
Bacterial Adhesion ◽  
Laser Scanning Microscopy ◽  
Water Contact ◽  
Initial Adhesion ◽  
Salivary Pellicle ◽  
Casein Phosphopeptide

Abstract Background: Recent preventive strategies for dental caries focus on targeting the mechanisms underlying biofilm formation, including inhibiting bacterial adhesion. A promising approach to prevent bacterial adhesion is to modify the composition of acquired salivary pellicle. This in vitro study investigated the effect and possible underlying mechanism of pellicle modification by casein phosphopeptide (CPP) on Streptococcus mutans (S. mutans) initial adhesion, and the impact of fluoride on the efficacy of CPP. Methods: The salivary pellicle-coated hydroxyapatite (s-HA) discs were treated with phosphate buffered saline (blank control), heat-inactivated 2.5% CPP (negative control), 2.5% CPP (CPP) or 2.5% CPP supplemented with 900 ppm fluoride (CPP + F). After cultivation of S. mutans, the adherent bacteria were visualized by scanning electron microscopy (SEM) and quantitatively evaluated using the plate count method. Confocal laser scanning microscopy (CLSM) was used to evaluate the proportions of total and dead S. mutans. The concentrations of total, free, and bound calcium and fluoride in CPP and fluoride-doped CPP solutions were determined. The water contact angle and zeta potential of s-HA with and without modification were measured. The data were statistically analyzed using one-way ANOVA followed by a Turkey post hoc multiple comparison test.Results: Initial adhesion of S. mutans to s-HA was inhibited in response to pellicle modification by CPP and fluoride-doped CPP, and the latter was more efficient. CLSM analysis showed that the proportion of dead S. mutans did not differ between the groups. Water contact angle and zeta potential decreased after pellicle modification, and both were lowest in the CPP + F group. Conclusions: Pellicle modification by CPP inhibited S. mutans initial adhesion to s-HA, possibly by reducing hydrophobicity and negative charge on the s-HA surface, and incorporating fluoride into CPP enhanced its anti-adhesion effect.

scholarly journals Studies of Some Properties and the Structure of Polyethylene Glycol (PEG) Macromolecules Adsorbed on a TiO2 Surface

2001 ◽  
Vol 19 (5) ◽  
pp. 397-407 ◽  
Author(s):  
S. Chibowski ◽  
M. Paszkiewicz
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Zeta Potential ◽  
Surface Charge ◽  
Adsorption Layer ◽  
Bulk Solution ◽  
Ionic Structure ◽  
Solution Interface ◽  
Main Factors ◽  
Presence And Absence

In the studies presented, the influence of the molecular weight of polyethylene glycol (PEG) on the adsorption and electrical properties at the metal oxide/polymer solution interface has been determined. The main factors responsible for the observed changes in the zeta potential and surface charge of titania were determined on the basis of the data obtained. It was demonstrated that changes in the ionic structure of the Stern layer depend on the molecular weight of PEG and its conformation. A possible mechanism for the changes in zeta potential both with pH and molecular weight was proposed on the basis of values of the surface charge difference (Δσ0) and the diffuse layer charge difference (Δσd) as determined in the presence and absence of the polymer. The thickness of the adsorption layer (δ) on the surface of titania was calculated from the zeta potential changes, both in the presence and absence of the polymer. A distinct influence of the PEG molecular weight was noted on the values of the adsorption layer thickness (δ) determined. The structures of the macromolecules in solution and at the solid/solution interface were compared and from the dependencies obtained some changes in the shape and dimensions of the polymer coils on passing from the bulk solution to the interface were proposed.

Mixtures of latex particles and the surfactant of opposite charge used as interface stabilizers – influence of particle contact angle, zeta potential, flocculation and shear energy

Soft Matter ◽  
2014 ◽  
Vol 10 (36) ◽  
pp. 7088-7095 ◽  
Author(s):  
Rémi Deleurence ◽  
Caroline Parneix ◽  
Cécile Monteux
Keyword(s):  
Contact Angle ◽  
Zeta Potential ◽  
Latex Particles ◽  
Opposite Charge ◽  
Particle Contact ◽  
Shear Energy

Using mixtures of latex and surfactant of opposite charges we decouple the effect of the charge and contact angle of the particles on the interface stabilization. We find that the key-parameters are the flocculation state of the particles and the shear energy used to produce the foams.

scholarly journals Specific Adsorption of Aspartic Acid on Iron (III) and Nickel (II) Oxides

2012 ◽  
Vol 14 (4) ◽  
pp. 299
Author(s):  
I.B. Dmitrieva ◽  
A.S. Chukhno ◽  
E.Y. Rodionova ◽  
R.V. Novichkov
Keyword(s):  
Zeta Potential ◽  
Aspartic Acid ◽  
Potentiometric Titration ◽  
Acid Concentration ◽  
Specific Adsorption ◽  
Bulk Solution ◽  
Oxide Surface ◽  
Acid Anion ◽  
Adsorption Time ◽  
Complexation Process

<p>The dependences of zeta – potential and adsorption of aspartic acid on NiO and Fe<sub>2</sub>O<sub>3</sub> oxideswere investigated as a function of aspartic acid concentration, pH and adsorption time using microelectrophoresis and potentiometric titration methods. Shifting of pHIEP (the isoelectric point or IEP) towards the acid zone for Fe<sub>2</sub>O<sub>3</sub> and towards the base zone for NiO in the solutions of aspartic acid in comparison with HCl shows the presence of specific adsorption of aspartic acid anion and cation forms on the surfaces of Fe<sub>2</sub>O<sub>3</sub> and NiO oxides, respectively. The complexation process of Fe(III) ions with aspartic acid in the bulk solution and on the oxide surface was examined by spectrophotometer. It was determined that Fe(III) ions form complexes with aspartic acid in the bulk solution.</p>

scholarly journals A Complete experimental study of oil/water interfacial properties in the presence of TiO2 nanoparticles and different ions

2019 ◽  
Vol 74 ◽  
pp. 39 ◽  
Author(s):  
Ali Khalilnezhad ◽  
Hosein Rezvani ◽  
Parastoo Ganji ◽  
Yousef Kazemzadeh
Keyword(s):  
Contact Angle ◽  
Zeta Potential ◽  
Interfacial Properties ◽  
Optimum Concentration ◽  
Viscosity Reduction ◽  
Wettability Alteration ◽  
Batch Adsorption ◽  
Water Interface ◽  
Oil Viscosity ◽  
Oil Water

Previous studies on Nanoparticles (NPs) application for Enhanced Oil Recovery (EOR) methods have revealed their effective role in the rock wettability alteration, relative Interfacial Tension (IFT) and oil viscosity reduction, formation and stabilization of the emulsions, and reduced asphaltene precipitation, which are all in direct relationship with oil/water interfacial properties. This study focuses on the interfacial properties of oil/water in the presence of Titania NPs and different ions at different pressures and temperatures. For this, different concentrations of TiO2 NPs in the Formation Water (FW) were prepared to monitor the effects of NPs on the oil/water IFT, carbonate rock wettability, zeta potential, and asphaltene adsorption. The results on IFT values indicated that NPs behavior at high pressures and temperatures is completely different, as compared to the ambient conditions, and 1000 ppm NPs introduced the lowest IFT at 600 psi and 60 °C. This reduction is potentially attributed to the asphaltene adsorption at the oil/water interface by TiO2 NPs, which hinders the asphaltene deposition at the interface and in turn IFT increasing. Contact angle results revealed two distinctive behaviors for NPs at high and low concentrations. In other words, with the first interval (below the optimum concentration), an increase in NPs concentration led to a quick wettability alteration toward the water-wet condition, and with the second one (above the optimum concentration), there was an increase in contact angle with an increase in NPs concentration, which is due to the NPs stacking near the rock surface. These results were in good accordance with zeta potential measurements, in which 1000 ppm nanofluid presented the highest stability (zeta potential value of −46.9 mV). Batch adsorption experiments resulted that catalytic TiO2 NPs are capable of adsorbing asphaltene at the oil/water interface. In addition, the results on fitting experimental data to the Langmuir and Freundlich Isotherms showed that the adsorption best fitted Langmuir Isotherm and hence the adsorption type is a monolayer.

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