Figure 8
(a) DLVO and XDLVO interaction energy profiles for the SG membrane and polystyrene colloid; I 5 10 mM NaCl, pH 5 5.4. (b) Normalized force vs. piezo scanner position for the SG membrane and a polystyrene colloid-tipped cantilever; I 5 10 mM NaCl, pH 5 5.4.
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Theoretical predictions of interaction energies for several membrane–colloid pairs were made using the classical DLVO theory and an extended DLVO (XDLVO) approach. The XDLVO approach accounts for acid-base (polar) interactions that are not considered in the classical DLVO theory. For all membrane-colloid pairs studied, DLVO interactions were simila...
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This article describes a predictive model to account for the performance of a reverse osmosis (RO) system under the influence of colloidal fouling (using silica particles as model colloids) in terms of transmembrane pressure increase (δTMP) in constant flux operation or flux drop (δJ ) in constant pressure operation. The predictive model considers...
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... XDLVO theory was used to explain the GQD transport in the porous media, through describing the interaction energy profile between nanoparticles and sand media and explain the stability through the energy profile between nanoparticles. The total interaction energy could be described as the sum of van der Waals attraction (VDW), electrostatic repulsion (EL) and Lewis acid-base interaction (AB) (Brant & Childress, 2002), which could be written as: ...
... where A 132 is the Hamaker constant of substances 1 and 2 in solution medium 3. Here 1 represents nanoparticles; 2 represents sands, and 3 represents solutions; h is the separation distance between nanoparticles and sand particles; k is the Boltzmann constant; T is the absolute temperature; ν is the valence of the electrolyte; ⌉ is the electron charge; 0 is the permittivity of vacuum; r is the relative permittivity of the solution; κ is the Debye-Huckel parameter; is the characteristic decay length of AB interactions in solution; ⊣ is the radius of nanoparticle; h 0 is the minimum equilibrium cutoff distance and ΔG h0 is the free energy components per unit area between nanoparticle and sand particle (Brant & Childress, 2002;Wu et al., 2013a). A 132 , i , κ and ΔG h0 can be further written as: ...
Graphene quantum dots (GQDs), characterized by nanostructures with diameters below 10 nm and strong hydrophilicity, exhibit advantageous migration behavior in groundwater environments. The impacts of ionic strength, cation type and pH on the transport of GQDs in porous media diverge from those observed for other nanosized particles. We investigated the cooperative effects of ionic strength (IS, 1 mM NaCl and 100 mM NaCl, 1 mM CaCl2 and 10 mM CaCl2), cation types (Na⁺, Ca²⁺), and pH (4, 7, 9). Through saturated column experiments and numerical modeling, we observed increased GQDs deposition with rising IS, notably enhanced by the presence of divalent cations due to bridging effects and self-aggregation. In the presence of monovalent cations, acidic environment favored the deposition of GQDs, whereas in the presence of divalent cations, an acidic environment with 1 mM CaCl2 was the most favorable for the deposition of GQDs, and shifted to an alkaline condition at 10 mM CaCl2, which may be due to the deprotonation process and the enhancement of self-aggregation. This research sheds light on critical factors governing the environmental behavior of ultra-small nanoparticles and thereby aids in the assessment of their ecological impact.
... However, in the case of the aggregation and the flotation of hydrophobic particles, in order to harmonize the theory and the experiment, it is necessary to apply new mechanisms of long-range surface forces. They are collectively called "non-DLVO" forces in the literature [53][54][55] and are taken into account by the extended DLVO theory (XDLVO [56][57][58]). The relationship between the particle adhesion to the bubble during flotation and the interaction forces caused by the altered structure of the liquid present in the wetting film, i.e., hydrophobic attractive forces, is shown in [41,59], including during gold flotation with xanthogenate [44,60,61]. ...
... However, in the case of the aggregation and the flotat hydrophobic particles, in order to harmonize the theory and the experiment, necessary to apply new mechanisms of long-range surface forces. They are collec called "non-DLVO" forces in the literature [53][54][55] and are taken into account b extended DLVO theory (XDLVO [56][57][58]). The relationship between the particle adh to the bubble during flotation and the interaction forces caused by the altered struct the liquid present in the wetting film, i.e., hydrophobic attractive forces, is show [41,59], including during gold flotation with xanthogenate [44,60,61]. ...
... To determine the diameter of the air bubbles (d b , mm), its dependence (approximation accuracy was R 2 = 0.98) on the pressure drop occurring between the phases (p, MPa) and the outlet hole diameter (d, mm) was in the form of [57]: ...
This work is aimed at the analysis of the development of flotation technology by applying carrier minerals. Based on the concepts of continuum mechanics, a theoretical analysis of the influence of the carrier minerals (wall) on the motion of a single solid particle is provided, taking into account their hydrodynamic interaction (in the case of low Reynolds numbers). A correction was obtained in the form of a ratio of the particle size to its distance from the wall to take into account the influence of the wall on the hydrodynamic force acting on the particle. The influence of the wall is manifested through a rapid approximation of the liquid vortex flow in the gap between the solid wall and the particle to the steady-state mode, accompanied by the suppression of the transverse movement of particles. When the liquid slides along a wall-mounted gas–liquid layer with a reduced viscosity, the liquid flow increases in the interfacial gap, which can be analyzed by a dimensionless correction that includes values describing the properties of a continuous medium (dynamic viscosity) and a disperse phase (geometric particle size). The reason for the decrease in the induction time when gold grains adhere to each other is assumed to be due to the forces of hydrophobic attraction (when the grains have a mirror-smooth surface) and the sliding of the flow along the hydrophobic surface of the particles along the gas layer (when the grains have a rough surface). When polydisperse particles are aggregated, the threshold energy of the fast coagulation was established to be lower than that arising during the interaction of monodisperse particles, whose aggregation requires a large depth of the potential pit. Performing natural experiments on the ore using a rougher concentrate as a carrier material showed that the concentrate yield decreases by 20.52% rel. In the second case, the gold extraction was higher by 4.69% abs. While maintaining the achieved level of gold extraction, the double mixing of the rougher concentrate and the initial feed increased the gold content in the rougher concentrate from 4.97 to 6.29 g/t.
... Indeed, some studies reported that the chemical heterogeneities of the membrane surface may influence the prediction of the adhesion by preventing the prophecy of the distance calculations between the bacterial and substrates surfaces [42]. Moreover, some authors reported that the surface roughness can be involved in contrariness between the experimental adhesion and the theoretical prediction by reducing the repulsive forces, thus making rough surfaces more favorable for microbial adhesion [43]. Furthermore Vadillo-Rodriguez et al [44] reported that the XDLVO theory does not take into account the steric interactions. ...
Pseudomonas aeruginosa is a pioneer bacterium that can initiate biofilm formation in a seawater environment, causing biofouling and biocorrosion. Therefore, understanding the interactions that occur between this bacterium and a commonly used material, 304 stainless steel, in the marine environment is mandatory before attempting to identify methods that can mitigate biofilm development. Thus, in this study, we investigated in one hand the adhesion potential of P. aeruginosa to sea-immersed 304 stainless steel using thermodynamic approach and the Environmental Scanning Electron Microscopy (ESEM) and in the other hand, the effect of the adhesion on the physicochemical characteristics of the stainless steel surface. The contact angle measurements showed that the bacterium has a hydrophilic character, with θw = 9.5 ± 0.4° and ΔGiwi = 20.88 mJ·m⁻², a strong electron-donor character, with γ⁻ = 52.5 ± 0.2 mJ·m⁻², and a weak electron-acceptor character, with γ⁺ = 7.14 ± 0.1 mJ·m⁻². For the substrate surface, we found that sea-immersed 304 stainless steel was hydrophilic and presented a strong electron-donor character and a weak electron-acceptor character. The theoretical prediction showed that the strain exhibited positive value of ΔGXDLVO vis-a-vis the sea-immersed stainless steel which indicates unfavorable adhesion while the ESEM electro-micrograph showed that the bacterium was able to adhere to sea-immersed 304 stainless steel. Furthermore, the results revealed that the physico-chemical properties of the sea-immersed 304 stainless steel surface changed significantly following the bacterial adhesion.
... In addition, according to the Eqs in Table S4, Lewis acid-base interaction energy absolute value is commonly greater than LW and EL energies. It plays a decisive role in the negative or positive characteristics of the total energy [44]. There is hydrophobic attraction energy between two completely non-polar particles (ΔE s-Water-s = − 102 mJ/m 2 ) [45]. ...
ZIF-8 is widely used as a porous crystal material in the field of colloids. Its interfacial interactions are crucial to the performance of colloidal particles. In this paper, the Hamaker constant of ZIF-8 (3.45 ×10⁻²⁰ J) was calculated for the first time by contact angle measurement parameters. The non-retarded Hamaker constant of ZIF-8 (4.66 ×10⁻²¹ J) was calculated using the Lifshitz's theory. Its dispersion in the dipolar (water) and monopolar (toluene) solvent systems was discussed using DLVO theory. The results showed that the energy potential barrier reached +183.9 KBT in the water system. However, the particles tended to be unstable in the toluene system, which did not correspond to the experimental phenomena we observed. Using the XDLVO theory, we took the Lewis acid-base fraction as an object of investigation, and the results showed that the hydrophobic attraction force between particles was 102 mJ/m² in the dipolar solvent (water). In the monopolar system, the steric repulsion was linked to the Lewis acid-base fraction of the particles. XDLVO theory can better describe the dispersion of ZIF-8 particles in different solvents. In future work, it is necessary to consider the Lewis acid-base surface energy due to crystal defects, especially for the interfacial interaction between solvent and particles during the preparation of colloidal suspensions.
... In addition, according to the Eqs in Table S4, Lewis acid-base interaction energy absolute value is commonly greater than LW and EL energies. It plays a decisive role in the negative or positive characteristics of the total energy [44]. There is hydrophobic attraction energy between two completely non-polar particles (ΔE s-Water-s = − 102 mJ/m 2 ) [45]. ...
Knowledge of the fate and transport of metal-organic frameworks (MOFs) in porous media is essential to understanding their environmental impacts. However, to date, the transport mechanisms of MOFs are not fully revealed. Meanwhile, surfactants can promote MOFs dispersion by forming a stable suspension. They also allow MOFs to migrate in the aqueous environment, which would increase the risks of MOFs being exposed to human health and the ecological environment. In this study, the effect of surfactants type and nanoparticle (NP) concentrations (50, 100, and 200 mg/L) were investigated using a sand column to study the transportability of ZIF-8 NPs in saturated porous media. Surfactants used were categorized into three groups, including cationic surfactants (CTAB, DTAB), anionic surfactants (SDBS, SDS), and nonionic surfactants (Tween 80, Tween 20). Experimental results showed that the ionic surfactants significantly increased the transportability of ZIF-8 NPs. Furthermore, a low concentration of NPs tended to break through the column under ionic surfactant conditions, and the maximum effluent recovery of ZIF-8 NPs (50 mg/L) was 87.4% in the presence of SDS. Nevertheless, ZIF-8 NPs tended to deposit in the inlet of the sand column in the presence of nonionic surfactants due to hydrodynamic bridging and straining. This research provides a comprehensive understanding of the deposition mechanism of ZIF-8 NPs as affected by surfactant types and NP concentrations. Most importantly, the study highlights those ionic surfactants had a significant impact on the mobility of ZIF-8 NPs, which arouses attention to the ecological and human health risk assessment related to the manufacturing of MOFs with the aid of various dispersing agents.
... Previous studies investigating colloidal interactions in the soil porous media also observed a similar phenomenon, that the crucial role of AB interactions must not be overlooked (Liu et al., 2019). For both fresh and aged NPs, separation distance when total energy reaches maximum energy barrier in the homoaggregation mode, d m,NP− NP were both smaller than that in the heteroaggregation mode, d m,NP− soil (Fig. 3c-f, Table 1), which also confirms that PS NPs tend to attach onto soil particles instead of forming aggregates as their ultimate fate in the soil solution (Brant and Childress, 2002;Hoek and Agarwal, 2006). Besides, the relatively low d m,NP− soil value with a few nanometers for both fresh and aged NPs also explained why there existed a lagging effect during first few years (Fig. 1b). ...
It is generally believed that the ability of nanoplastics (NPs) to mobilize other contaminants is due to direct adsorption; however, this intuitive belief is questioned in this study when it comes to a historically contaminated soil where mining activities since 1958 have resulted in arsenic (As) and cadmium (Cd) enrichment. Negatively charged polystyrene (PS) NPs were used in this study, which should theoretically stimulate Cd (metal cation) instead of As (negatively charged oxyanion) leaching if direct adsorption accounted for co-transport. Surprisingly, PS NPs enhanced the leaching of As by up to over 5 times (p value < 0.05), but had almost no effect on Cd leaching (p value > 0.05). A novel indirect displacement model was therefore developed to describe the phenomenon of enhanced As leaching. It has been found that negatively charged NPs interacted with As via competition for soil binding sites. Underlying mechanistic insights were further explored via both theoretical calculations with the Extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) approach, and direct characterization using Scanning Electron Microscopy (SEM) and Computed X-ray Microtomography (μCT) showing binding sites and flow channels, respectively. The overall results provide new and valuable insights into NP-metal(loid) interactions in the natural soil environment, which can be integrated in future studies regarding the transport and risk assessment of NPs, and toxic metal(loid)s.
... According to the work in [50], the XDLVO theory does not take into account biological-specific interactions and takes into account only the Lifshitz-van der Waals and acid-base components responsible of first steps of adhesion. Other authors reported that the cause of these significant discrepancies is due to the non-DLVO interactions and physical and chemical heterogeneities [51][52][53]. So, microbial adhesion is a multifactorial phenomenon in which other factors could contribute other than the Lifshitz-van der Waals and acid-base interactions. ...
Despite having been used for ages to preserve wood against several effects (biological attack and moisture effects) that cause its degradation, the effect of vegetable oils on the cedar wood physicochemical properties is poorly known. Thus, in this study, the hydrophobicity, electron-acceptor (γ⁺), and electron-donor (γ⁻) properties of cedar wood before and after treatment with vegetable oils have been determined using contact angle measurement. The cedar wood has kept its hydrophobic character after treatment with the different vegetable oils. It has become more hydrophobic quantitatively with values of surface energy ranged from −25.84 to −43.45 mJ/m² and more electron donors compared to the untreated sample. Moreover, the adhesion of four fungal strains (Penicillium commune (PDLd”), Thielavia hyalocarpa, Penicillium commune (PDLd10), and Aspergillus niger) on untreated and treated cedar wood was examined theoretically and experimentally. For untreated wood, the experimental adhesion showed a positive relationship with the results obtained by the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) approach which found that all fungal strains could adhere strongly to the cedar wood material. In contrast, this relationship was not always positive after treatment. The Environmental Scanning Electron Microscopy (ESEM) has shown that P. commune (PDLd10) and A. niger were found unable to adhere to the wood surface after treatment with sunflower and rapeseed oils. In addition, the results showed that the four fungal strains’ adhesion was decreased with olive and linseed oils treatment except that of P. commune (PDLd10) treated with linseed oil.
... According to the work in [50], the XDLVO theory does not take into account biological-specific interactions and takes into account only the Lifshitz-van der Waals and acid-base components responsible of first steps of adhesion. Other authors reported that the cause of these significant discrepancies is due to the non-DLVO interactions and physical and chemical heterogeneities [51][52][53]. So, microbial adhesion is a multifactorial phenomenon in which other factors could contribute other than the Lifshitz-van der Waals and acid-base interactions. ...
Despite having been used for ages to preserve wood against several effects (biological attack and moisture effects) that cause its degradation, the effect of vegetable oils on the cedar wood physicochemical properties is poorly known. Thus, in this study, the hydrophobicity, electron-acceptor (γ+), and electron-donor (γ−) properties of cedar wood before and after treatment with vegetable oils have been determined using contact angle measurement. The cedar wood has kept its hydrophobic character after treatment with the different vegetable oils. It has become more hydrophobic quantitatively with values of surface energy ranged from −25.84 to −43.45 mJ/m2 and more electron donors compared to the untreated sample. Moreover, the adhesion of four fungal strains (Penicillium commune (PDLd”), Thielavia hyalocarpa, Penicillium commune (PDLd10), and Aspergillus niger) on untreated and treated cedar wood was examined theoretically and experimentally. For untreated wood, the experimental adhesion showed a positive relationship with the results obtained by the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) approach which found that all fungal strains could adhere strongly to the cedar wood material. In contrast, this relationship was not always positive after treatment. The Environmental Scanning Electron Microscopy (ESEM) has shown that P. commune (PDLd10) and A. niger were found unable to adhere to the wood surface after treatment with sunflower and rapeseed oils. In addition, the results showed that the four fungal strains’ adhesion was decreased with olive and linseed oils treatment except that of P. commune (PDLd10) treated with linseed oil.
... Developing highly efficient antifouling membranes needs a better understanding of the foulant-polyamide molecular interactions. From this fundamental aspect, computer molecular simulations can play a critical role [5,[8][9][10][11][12][13]. Many theoretical investigations using molecular dynamics (MD) simulations contributed significantly to the understanding of water transport in membranes and ion rejection during membrane separations [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. ...
... In Fig. 5c and d, we show the coordinated hydration water molecules around the deprotonated M and G alginate monomers, respectively. Direct counting the number of coordinated water molecules on both sides show that there are much less coordinated water molecules on the hydrophobic side (about 4-6) than that on the hydrophilic side (about [10][11][12][13][14] for the M monomer (see Supplementary Information section S1), demonstrating the amphiphilic structural feature of the M monomer. In contrast, the number of coordinated water molecules on both sides of the G monomer are almost equal (about 10-15), indicating that both sides of the G monomer are hydrophilic. ...
Organic fouling of polyamide membrane surfaces with alginate molecules in an aqueous solution is studied through computer molecular simulations. Here, we focus on the molecular binding properties of β-d-mannuronic acid (M) and α-l-guluronic acid (G) alginate monomers on a polyamide membrane surface. Free energy calculations show that M alginate monomers exhibit significant hydrophobic attractions with certain types of benzene ring units in a polyamide chain, though such hydrophobic interactions are not as strong as the ionic bridge binding between the M monomer and the carboxylate group on a polyamide membrane surface. This is in contrast to the fouling behavior of G alginate monomers to which such hydrophobic interactions with a membrane surface do not exist, and the organic fouling is largely attributed to the ionic bridge binding between the G monomer and polyamide carboxylate groups mediated by divalent metal ions. Molecular dynamics simulations of different alginate oligomers near a polyamide surface show that hydrophobic interactions between the M-containing oligomers and polyamide membrane surface result in a much shorter pathway of fouling than that of pure G-oligomers. These hydrophobic interactions, together with the mobility of M monomers on a polyamide chain surface, further reduce the docking time of M-containing oligomers compared to pure G-oligomers, and thus enhance the surface fouling.
... This behaviour demonstrates that long-range electrostatic interactions with the membrane and water molecules were predominant when NP/MPs started to approach the CPAm membranes before shortrange polar interactions became prevalent, repulsing NP/MPs from the surface of the membrane. It was previously demonstrated that hydrophilic membranes immersed in water exhibited short-range repulsive polar forces, resulting in the repulsion or reduced adhesion of colloids such as polystyrene, silica and alumina particles [50,51]. Hence, introducing amine and carboxylic acid polar groups on the surface of the membrane primarily contributed to reducing NP/MPs adsorption, whereas the low polarity of the dimethylsiloxane groups facilitated NP/MPs attraction. ...
Nano/microplastic materials fouling across filtration membranes can impact the performance of filtration systems, which constitutes a critical challenge for water facilities operation. In this study, plasma surface modifications aiming at reducing nano/microplastic materials adsorption on ultrafiltration membranes were investigated. Hydrophilic acrylic acid and cyclopropylamine plasma coatings caused a water flux decline of less than 8% after 6 h of crossflow filtration. Both hydrophilic coatings reduced the percentage of nano/microplastics adsorbed on the membranes by more than 60%. On the contrary, the hydrophobic hexamethyldisiloxane layer had no impact on the cumulative percentage of adsorbed nano/microplastics compared to that of the pristine poly(sulfone) membranes, which culminated at 40%, resulting in a water flux decline of 40% upon filtration for both membranes. The extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory was then applied to the system particle-membrane, which identified polar forces as the predominant intermolecular interactions contributing to membrane fouling. Tuning the hydrophilicity of the membranes was, therefore, a more efficient strategy to reduce nano/microplastic materials adsorption during filtration than tailoring the surface charge of the membranes, showing potential for complex water matrices remediation.
