Variation Of Zeta Potential Research Articles

Effect of surface corrosion on the zeta potential of copper in acidic solutions

The comprehensive investigation was conducted to analyze the corrosion behavior and surface potential of pure copper surfaces in various acidic solutions. We carried out Zeta potential measurement, electrochemical measurement and in situ Raman spectroscopy to investigate the corrosion process and surface potential of copper in acidic solutions with different pH. It was found that the variation in zeta potential with pH corresponds to the corrosion behavior of copper during this process. In 1mmol / L aqueous chloride media, when the pH is greater than 3.5, unalloyed copper is oxidized to monovalent copper. At this stage, as the pH decreases, the zeta potential gradually increases. When the pH reaches 3.5, the Zeta potential reaches the highest, and the rate of cuprous oxide formation reaches the maximum. When the pH continues decrease, unalloyed copper begins to be oxidized to divalent copper, and the zeta potential will also decrease, the surface charge state shifts to the positive direction. Furthermore, our experimental findings are complemented by Density Functional Theory (DFT) calculations.

Dependence of photocatalytic efficiency of titania-carbon nanotube nanocomposites on optoelectrical properties and colloidal stability

The correlation of photocatalytic efficiency of titania–amorphous (nitrogen doped) carbon nanotubes (TiO2–a(N)CNT) nanocomposites with colloidal and optoelectrical properties of the photocatalysts was investigated. TiO2–aNCNT and TiO2–aCNT exhibited narrow zeta potential variation, high polydispersity index, and large agglomerate size across the pH range 1–8. Despite the poor colloidal stability, TiO2–aNCNT exhibited superior degradation for high molecular weight reactive dyes, RR 120 and Remazol brilliant blue (RBB) with 55 mg.L−1 of RR 120 mineralized under solar irradiation. The photocatalytic performance for TiO2–aNCNT and TiO2–aCNT correlated with the respective energy band gaps 3.01 and 3.14 eV, Ubarch tailing energies. Cyclic voltammetry showed a narrow peak-to-peak separation (ΔEp) of 200.7 V (vs Ag/AgCl) for TiO2–aNCNT thus confirming enhanced electron transfer kinetics. Electron impedance spectroscopy confirmed low charge transfer resistance for TiO2–aNCNT. Herein it is demonstrated that optoelectrical properties are superior in driving photocatalytic reactions.

Development and characterization of ferulic acid-loaded chitosan nanoparticle embedded- hydrogel for diabetic wound delivery

Diabetic wounds present a significant global health challenge exacerbated by chronic hyperglycemia-induced oxidative stress, impeding the natural healing process. Despite various treatment strategies, diabetic foot ulceration lacks standardized therapy. Ferulic acid (FA), known for its potent antidiabetic and antioxidant properties, holds promise for diabetic wound management. However, oral administration of FA faces limitations due to rapid oxidation, stability issues, and low bioavailability. The topical application of FA-loaded chitosan nanoparticles (FA-CSNPs) has emerged as a promising approach to overcome these challenges. Here, we report the development of a sustained-release formulation of FA-CSNPs within a hydrogel matrix composed of Chitosan and gelatin. The FA-CSNPs were synthesized using the ionic gelation method andoptimized through a Central Composite Design (CCD) approach. Characterization of the optimized nanoparticles revealed spherical morphology, a particle size of 56.9 ± 2.5 nm, and an impressive entrapment efficiency of 90.3 ± 2.4 %. Subsequently, an FA-CSNPs-loaded hydrogel was formulated, incorporating chitosan as a gelling agent, gelatin to enhance mechanical properties and cell permeation, and glutaraldehyde as a cross-linker. Comprehensive characterization of the hydrogel included pH, moisture loss, porosity, swelling index, rheology, water vapor transmission rate (WVTR), SEM, TEM, invitro drug release studies, antioxidant activity, antibacterial efficacy, cell cytotoxicity, cell migration studies on L929 fibroblast cell line, and stability studies. The stability study demonstrated negligible variations in particle size, zeta potential, and entrapment efficiency over 60 days, ensuring the stable nature of nanoparticles and hydrogel. This innovative delivery approach embedded within a hydrogel matrix holds significant promise for enhancing the therapeutic efficacy of FA-CSNPs-hydrogel in diabetic wound healing applications.

Poly-3,4-dihydroxybenzylidenhydrazine, a different analogue of polydopamine

Abstract In this article, 3,4-dihydroybenzylidenehydrazine is synthesized for the first time, and its properties as a dopamine analogue for polymerization are investigated. Using an oxidative polymerization reaction, the reaction mechanism as well as the coating ability of the new polymer is determined and compared to that of polydopamine. The polymerization reactions were performed in a mixture of methanol–water with NaIO4 as an oxidation reagent. The polymer was used as a coating on both glass surfaces with a thickness of ∼5 nm as determined by AFM, as well as on TiO2 nanoparticles. For the latter, SEM/TEM and the pH-dependent variation of zeta potential were measured. As a free polymer, poly-3,4-dihydroxybenzylidenhydrazine was investigated by UV-Vis, ss-NMR, and FTIR, and a variety of monomeric units were found in the polymer matrix. The solubility in methanol or DMSO of the monomer and the slight solubility of the polymer allowed us to study the fluorescence and cyclic voltammetry properties for both the monomer and polymer.

Comprehensive effects of microplastics on algae-laden surface water treatment by coagulation-ultrafiltration combined process: Algae cultivation, coagulation performance and membrane fouling development

In coastal areas, the surface water has been simultaneously exposed to the algae blooms caused by eutrophication and the microplastics (MPs) pollution originating from active human activities. As a practical alternative to address these issues in drinking water plant, coagulation-ultrafiltration combined process is still confronted with the limited understanding about the comprehensive effects of MPs on algae-laden surface water (ASW) treatment. Considering the migration of MPs in nature environment and drinking water treatment process, this study first aims to systematically investigate the influence of MPs on algae cultivation, coagulation performance and membrane fouling development. The results of algae cultivation indicate that MPs stimulated the algae activity by 58 % and then constantly suppressed the secretion of protein-like, humic-like and polysaccharide-like metabolites. The variation of particle size distribution and zeta potential confirm that MPs acted as nuclei to facilitate the development of large coagulation flocs with an increasing average size from 82.6 μm to 107.6 μm, during which the negatively charged pollutants were neutralized and removed from ASW. According to the SEM images, MPs could destroy the structure of fouling layer on 50 kDa membranes during the filtration of ASW coagulation effluent. Its synergistic effect with the enhanced coagulation performance and the suppressed EOM secretion contributed to the alleviation of membrane fouling caused by overlapped large-sized foulants. However, the interaction between the enriched organic foulants by MPs and the deposited coagulants on 300 kDa membranes facilitated the development of cake layer, leading to the deterioration of membrane permeability. This study emphasizes the importance in concerning the existence of MPs during the treatment of ASW by coagulation-ultrafiltration combined process and their exact influence in water purification efficiency.

Novel approach for modification of graphene oxide using continuous wave-laser obtained from surgical laser diode

The present investigation employs a modified version of Hummer's method to synthesise graphene oxide (GO), which is subsequently subjected to treatment with a continuous-wave (CW) laser derived from surgical laser diodes for the purpose of performing minimally invasive surgery for 30 s to yield laser-modified GO. XRD analysis was used to look at how CWlaser changed the sizes of crystallites, the distance between planes, and the average number of layers. The study examined the FTIR spectra of graphite oxidation and modification using a CW laser. Changes in the G band, D band, and 2D peaks in the Raman spectra showed disorder and multiple layers. The variations in negative zeta potential were used to analyse colloidal stability in graphite, GO, and laser-modified GO. Different types of dynamic light scattering techniques were used to study electrophoretic mobility, Brownian motion, and electrical double layers. The obtained results exhibited a high degree of agreement with the findings derived from the FTIR spectra. This work examined dielectric and impedance spectroscopy to assess relaxation behaviour that deviates from the Debye model. By fitting curves to the data, we evaluated the dielectric constant, loss, and conductivity. Graphite to laser-modified GO via GO lowered the real component of the dielectric constant at any frequency.

In‐depth study of the mucoadhesive and lubricating properties of Hyalistil SYNFO and other sodium hyaluronate‐based eye drops

Purpose: Several sodium hyaluronate (SH) eye drops formulations are widely used for the management of dry eye disease (DED). Hyalistil SYNFO is an eye drops based on SH and xanthan gum and osmoprotectants (glycine and betaine). The aim of our study was to evaluate viscosity and mucoadhesion profiles of Hyalistil SYNFO with respect to other SH‐based eye drops, and to investigate their ability to protect the corneal surface from dehydration.Methods: The physicochemical properties, in term of viscoelastic and mucoadhesive behaviour, were evaluated by means of a rheometer, TA‐XT2 texture analyzer and zeta potential determination. An in vitro dehydration model was used to demonstrate the lubricant effect of Hyalistil SYNFO compared to other commercially available SH‐based eye drops on human corneal epithelial cells (HCE).Results: The rheological profiles indicated that Hyalistil SYNFO exhibits a viscoelastic behaviour under shear strain showing a characteristic curve owing to its specific molecular properties. Evaluations of detachment force of tested formulations resulting in a strengthening of the mucin‐formulation interface showed that Hyalistil SYNFO exhibited a stronger and significant mucoadhesion calculated as percentage compared to mucin and other SH‐based products. The occurring interaction between formulation and mucin was also demonstrated by the variations in zeta potential measured by the mucin‐eye drops mixture compared to mucin or product alone. The in vitro study on HCE cells demonstrated that Hyalistil SYNFO, compared to others formulation, was able to protect corneal epithelial cells from dehydration.Conclusions: The pseudoplastic profile and increased mucoadhesive strength, due to the presence of both SH and xanthan gum, may lead to an improved residence time of Hyalistil SYNFO on the corneal epithelium ensuring relief during the treatment of DED. Moreover, the effect against dehydration improves eye lubrication and corneal cell protection.

Supercritical Fluid-extracted Citrus aurantium L. var. amara Engl. Essential Oil Nanoemulsion: Preparation, Characterization, and Its Sleep-promoting Effect.

To overcome the defects of Citrus aurantium L. var. amara Engl. essential oil (CAEO), such as high volatility and poor stability, supercritical fluid-extracted CAEO nanoemulsion (SFE-CAEO-NE) was prepared by the microemulsification method. Emulsifiers comprising Tween 80, polyoxyethylenated castor oil (EL-40), and 1,2-hexanediol, and an oil phase containing SFE-CAEO were used for microemulsification. We examined the physicochemical properties of SFE-CAEO-NE and steam distillation-extracted CAEO nanoemulsion (SDE-CAEO-NE), which were prepared using different concentrations of the emulsifiers. The mean particle size and zeta potential were 21.52 nm and -9.82 mV, respectively, for SFE-CAEO-NE, and 30.58 nm and -6.28 mV, respectively, for SDE-CAEO-NE, at an emulsifier concentration of 15% (w/w). SFE-CAEO-NE displayed better physicochemical properties compared with SDE-CAEO-NE. Moreover, its physicochemical properties were generally stable at different temperatures (-20-60℃), pH (3-8), and ionic strengths (0-400 mM). No obvious variations in particle size, zeta potential, and Ke were observed after storing this nanoemulsion for 30 days at 4℃, 25℃, and 40℃, suggesting that it had good stability. The sleep-promoting effect of SFE-CAEO-NE was evaluated using a mouse model of insomnia. The results of behavioral tests indicated that SFE-CAEO-NE ameliorated insomnia-like behavior. Moreover, SFE-CAEO- NE administration increased the serum concentrations of neurotransmitters such as 5-hydroxytryptamine and γ-aminobutyric acid, and decreased that of noradrenaline in mice. It also exerted a reparative effect on the function of damaged neurons. Overall, SFE-CAEO-NE displayed a good sleep-promoting effect.

Magnetically recyclable polydopamine-polyquaternium modified Fe3O4 nanoparticles for demulsification of asphaltene-rich ASP flooding produced water

The asphaltene-rich alkaline-surfactant-polymer (ASP) flooding produced water has been identified with high interfacial stability and severe secondary emulsification, which poses great difficulties in its demulsification process. This leads to an urgent need to develop targeted and efficient demulsifiers. In this research, a novel polydopamine-polyquaternium modified Fe3O4 (PQA-PDA@Fe3O4) nanoparticle integrates the electrical neutralization, interfacial adsorption and magnetic aggregation functionalities was prepared to dispose this emulsion. Primarily, structural and surface properties of the PQA-PDA@Fe3O4 demulsifier were systemically characterized by a series of analytical techniques, which presents its core-shell, hydrophilic and positively charged characters. When employing PQA-PDA@Fe3O4 to treat the produced water that contained 500 mg/L emulsified oil, a demulsification efficiency of 90.5 % was achieved at 200 mg/L dosage. It was found that the PQA-PDA@Fe3O4 nanoparticles could coalesce the fine oil droplets into large and dense aggregates, as demonstrated by the raised fractal dimension values. By monitoring the interfacial properties (interfacial tension, zeta potential and interfacial film elastic modulus) variations, the demulsification mechanism was further explored. The PQA-PDA@Fe3O4 nanoparticle could spontaneously migrate to the oil/water interface and reassemble a loose interfacial film, thus leading the oil droplets destabilization and aggregation. Notably, the magnetic force between the PQA-PDA@Fe3O4 nanoparticles significantly accelerates the oil droplets aggregation and inhibits the secondary emulsification process, so as to achieve the outstanding demulsification efficiency. Moreover, this PQA-PDA@Fe3O4 nanoparticle exhibited acceptable magnetic recyclability. These results provided an effective and alternative protocol to demulsify the asphaltene-rich ASP flooding emulsions.

New insights into the influence of pre-oxidation on membrane fouling during nanofiltration of brackish water considering inorganic-organic complexation and oxidant reduction byproducts

Even though pre-oxidation is usually considered as a promising method to alleviate membrane fouling, information on performance and inner mechanisms of pre-oxidation-influenced membrane fouling during nanofiltration of brackish water is still limited. This study is the first work in which oxidant reduction byproducts and interaction between different pollutants were particularly considered to address these problems. Herein, nanofiltration experiments with different pre-oxidized synthesis brackish water containing inorganic salts and organic pollutants were conducted. Membrane flux results showed that both NaClO and K2FeO4 aggravated membrane fouling, but 0.45 mg/mg TOC KMnO4 mitigated it when simulation results of NICA-Donnan model showed that the complexation between calcium ions and humic acid (HA) was weakened. However, membrane fouling was enhanced by higher dosage of KMnO4. Fourier transform infrared spectrometer using attenuated total reflection (ATR-FTIR) and X-ray diffraction (XRD) spectrum showed that the aggravated membrane fouling was mainly caused by the generation of amorphous manganese oxide, which was oxidant reduction byproduct and had strong capacity for adsorption of HA. Particle size distribution and zeta potential variation indicated that the accumulation of HA could enhance the crystallization process and then the electrostatic attraction between membrane and bulk crystallization was induced. According to SEM images and fitting results of Hermia's models, the already-formed bulk crystallization by 1.90 mg/mg TOC KMnO4 could deposit on membranes more easily, followed by the formation of a denser fouling layer. Overall, the present study provided new insights into the design of reliable pre-oxidation strategies for alleviating membrane fouling during nanofiltration of brackish water.

Insight into sludge dewatering by periodate driven directly with Fe(Ⅱ): Extracellular polymeric substances solubilization and mineralization

The production of waste activated sludge is expanding in tandem with the significant growth in the global population. It is important to explore sludge pretreatment technology to achieve sludge reduction. In this study, deep sludge dewatering was achieved by using Fe2+-catalyzed periodate (Fe2+/PI) conditioning. The result showed that capillary suction time was reduced by 48.27% under the optimum Fe2+ and PI dosages. ·OH, FeⅣ, O2·-, 1O2, and IO3· generated from the reaction between Fe2+ and PI, while ·OH (49.79%) and FeⅣ (47.76%) contributed significantly to sludge dewatering. Investigations of the mechanism revealed that the synergistic action of radical species oxidation and iron species flocculation in Fe2+/PI conditioning led to the mineralization and aggregation of hydrophilic substances in extracellular polymeric substances. The hydrophobic groups on the protein surface were more exposed to soluble extracellular polymeric substances and reduced protein-water interaction. The variations in zeta potential and particle size also verified the presence of a synergistic effect of oxidation and flocculation. The morphology observations revealed that the increased frictional forces generated when water flowed over the raw sludge (RS) surface prevented the rapid passage of internal water. In addition, the hydrophobic and electrostatic interactions in the sludge samples were essential influences that promoted flocculation and sedimentation of the sludge. This research aids engineers by providing a new option to better optimize sludge management while also deepening understanding of the Fe2+/PI conditioning involved in sludge dewatering.

Zeta potential variations in bonding states of fluorocarbon films deposited by plasma-enhanced chemical vapor deposition

The interactions between a solid and a liquid at their interface often produce exotic effects that could be used in energy-related applications. To this end, understanding which properties control the zeta potentials at the interface promises to advance the application of these effects. In this study, we fabricated fluorocarbon films by plasma-enhanced CVD to investigate the interaction of the film with an aqueous solution. We found that the properties of the films can be controlled by the deposition pressure, and the zeta potential correlates with the bonding states within the films. The control of the interfacial potential between the solid material and the aqueous solution can be a factor in maximizing energy output and optimizing device design.

Understanding mucus modulation behavior of chitosan oligomers and dextran sulfate combining light scattering and calorimetric observations

This study reports the fundamental understanding of mucus-modulatory strategies combining charged biopolymers with distinct molecular weights and surface charges. Here, key biophysical evidence supports that low-molecular-weight (Mw) polycation chitosan oligosaccharides (COSs) and high-Mw polyanion dextran sulfate (DS) exhibit distinct thermodynamic signatures upon interaction with mucin (MUC), the main protein of mucus. While the COS → MUC microcalorimetric titrations released ~14 kcal/mol and ~60 kcal/mol, the DS → MUC titrations released ~1200 and ~1450 kcal/mol at pH of 4.5 and 6.8, respectively. The MPT-2 titrations of COS → MUC and DS → MUC indicated a greater zeta potential variation at pH = 4.5 (relative variation = 815 % and 351 %, respectively) than at pH = 6.8 (relative variation = 282 % and 136 %, respectively). Further, the resultant binary (COS-MUC) and ternary (COS-DS-MUC) complexes showed opposite behavior (aggregation and charge inversion events) according to the pH environment. Most importantly, the results indicate that electrostatics could not be the driving force that governs COS-MUC interactions. To account for this finding, we proposed a two-level abstraction model. Macro features emerge collectively from individual interactions occurring at the molecular level. Therefore, to understand the outcomes of mucus modulatory strategy based on charged biopolymers it is necessary to integrate both visions into the same picture.

Combined effects of temperature-dependent properties and magnetic field on electro-osmotic mobility at arbitrary zeta potentials

ABSTRACT We analyze the thermo-electroosmotic mobility of power-law electrolyte solution under the action of a magnetic field in a wavy pattern micro-channel. The flow is driven by the combined effect of the pressure gradient and the electric potential applied externally in the axial direction. The variable properties such as the viscosity, zeta potential, electrical and thermal conductivity of electro-thermal flow are assumed to vary with temperature. The entire flow phenomena have been solved by employing the finite difference method. We have presented the variation of electroosmotic mobility with the effect of Joule heating and applied magnetic field. We have examined the coupling effects of axial velocity, thermal energy, and electric potential function for various values of the temperature-dependent properties. These temperature-dependent property variations lead to developing volumetric flow rates associated with the behavior of the power-law index. The Nusselt number is drastically influenced by the temperature-dependent zeta potential variation in comparison with the Newtonian and shear-thickening fluids. The numerical and analytical solutions are validated with the existing literature and obtained a good agreement.

Stabilization of the oil‐in‐water emulsions of Citrus reticulata essential oil by different combinations of gum arabic/maltodextrin/whey protein

This research aimed to investigate the impact of various wall materials, namely, gum arabic (GA), maltodextrin (MD), and whey protein (WP) on the properties of Citrus reticulata essential oil (CREO) oil-in-water (O/W) emulsions. The wall materials were blended at varied rates to generate seven formulas. The GA showed the highest viscosity at a high shear rate of 80 s−1 (0.024 Pa s) and the highest molecular weight (406.44 KDa). The O/W emulsions showed significant variations in particle size (352.85–664.74 nm), polydispersity index (0.169–0.256), zeta potential (−57.27 to −56.68 mV), surface tension (30.71–43.55 mN/m), and viscosity (0.006–0.097 Pa s). This research showed that combining GA, MD, and WP as wall materials can produce emulsions with better qualities than those made with single-wall materials. Novelty impact statement In this study, the GA, MD, and WP were applied successfully to produce oil-in-water emulsions of CREO. These good properties broaden the applicability of CREO emulsions in foods. This combination is expected to be suitable for producing oil-in-water emulsions for many other essential oils.

Nonlinear Temperature Gradient Focusing of Deoxyribose Nucleic Acid in a Microfluidic Channel With Patterned Surface Charges: A Numerical Study

Abstract We present a numerical analysis of electrophoretic transport of a biological sample, such as, deoxyribose nucleic acid (DNA) via nonlinear temperature gradient within a microfluidic channel having patterned surface charges. The transport of the electrolyte is induced by electroosmotic force by imposing an axial electric field, superposed with the wall electric field via electrodes embedded along the wall of the microchannel. We consider the periodic variation of wall zeta potential in electrokinetic motion of an electrolyte wherein the DNA sample exhibits electrophoretic migration. Temperature dependence of the thermophysical properties of the electrolyte and the electrophoretic mobility and diffusivity of the analyte sample is accounted for in the model to improve its accuracy. Nonlinear longitudinal temperature field along the microchannel is induced via Joule heating by suitably shaping the channel geometry, which enhances the concentration of DNA approximately 270 folds by applying just 500 V DC field with constant zeta potential at the walls. The study further reveals that the concentration of DNA reduces drastically when a periodic wall zeta potential is applied. Results of the study lend to the design of novel electrically actuated bio-microfluidic devices with tunable solute separation and dispersion capabilities.

(Invited) CRISPR-Cas9-Based Cancer Therapy Delivery By Carbon Nanomaterials

Gene therapeutics is a rapidly developing field promising critical advances in finding new vaccines and treatments, as well as genetic adjustments to plants and animal species. This novel area of science may generate treatment pathways for complex diseases such as cancer, Alzheimer’s or sickle cell anemia that can not be easily treated by conventional therapies. Recently developed CRISPR technology can help address these issues, having a power to perform treatment targeted to specific disease mechanisms with little to no adverse effects to the healthy tissue.Many gene therapies require intracellular delivery, and their efficacy can be highly influenced by the choice of the delivery vehicle. Due to their near-infrared fluorescence capabilities and large payload carrying capacity, carbon nanomaterials can be appropriate candidates for this role. Our work utilizes graphene quantum dots (GQDs) and single-walled carbon nanotubes (SWCNTs) as delivery vehicles for several CRISPR-Cas9-based formulations specifically designed to edit out genes related to immortalization and uncontrolled growth of cancer cells. Both of these nanomaterials exhibit visible and near-infrared fluorescence capabilities sufficient for in vitro and in vivo imaging, and, when bound to CRISPR-Cas9 system, are not only expected to transport the therapeutic, but also trace its delivery pathways. In order to warrant more efficient complexation with CRISPR-Cas9 system, GQDs are synthesized bottom-up from cationic polymers and characterized to exhibit stable fluorescence and high biocompatibility at ~1 mg/mL in vitro. Payload attachment is assessed microscopically and reflected by Zeta potential variation upon complexation. Both resulting nanomaterials-delivered formulations show successful target gene scission and intracellular tracking of the gene therapeutic via intrinsic nanomaterial fluorescence. The end goal of this work is to edit out and/or correct aberrant genes in cancer cells making them more susceptible to conventional treatment pathways, thus, ultimately helping improve cancer survival rates.

Characterization of kaolinite aqueous suspensions by acoustophoresis: Influence of crystallinity and of the ratio between basal and lateral surface of grains

The electrokinetic properties of aqueous suspensions of two kaolins were studied using the acoustophoretic method by measuring the ultrasonic attenuation spectrum in a wide frequency range (1–20 MHz). Then, the zeta potential is calculated according to the size distribution of grains. A high state of crystallinity of the kaolinite platelets strongly influences the amplitude and the variation of zeta potential versus the pH due to a high density of hydroxyl surface groups. It was also shown that specific adsorption occurs mainly with the hydroxyl surface groups of the platelet edges by using strong electrolytes (NaOH and HCl) and also organic molecules (Tiron and sodium salt of citrate). The variation of the surface chemical properties of platelets during the amorphous phase formation after temperature treatment of kaolin powder is also studied. The electrokinetic properties of kaolin suspensions treated between 200 and 800 °C successively show an increase in the positive contribution to the zeta potential up to 400 °C for the best-crystallized kaolinite and a decrease in the density of surface hydroxyl groups when the sheets delaminate from 400 °C for the less-crystallized kaolinite. This study shows that the characterization in aqueous suspension of surface properties of kaolinite complements other studies carried out on powder and therefore it makes it possible to choose kaolin as a raw material according to the intended application.

Influence of a plant-based surfactant on improving the stability of iron ore particles for dispersion and pipeline transportation

This investigation addresses the study of the effects of the saponin isolated from the fruits of Sapindus laurifolia (S. laurifolia) as a dispersing and stabilizing agent in the pipeline transportation of iron ore (IO) particles. Two types of IO samples named S1 and S2, which are primarily constituted of hematite (Fe2O3) are taken for the study. The rheological behavior of iron ore water slurry (IOWS) has been studied as a function of saponin dosages, IO concentration, pH, temperature, and the shear rate-shear stress relationship. The isoelectric point of IOWS is calculated by the variation of zeta potential with pH. A suitable mechanism model is given to describe the interaction between S. laurifolia and IO particles. The economic effect of the dispersant has been examined based on slurry head loss, solids conveying rate, hydraulic power need, and specific power consumption (SPC) for the proposed IOWS pipeline to be introduced into commercial operation.

Enhanced selective removal of phosphate in the presence of high-strength nitrate using straw-based anion imprinted biosorbent

To enhance the selective removal and phosphate recycle in the presence of high-strength nitrate, a novel wheat straw anion imprinted biosorbent (SAIB) was prepared by quaternization reaction and ion-imprinting technology. As the concentration of nitrate increased from 50 to 150 mg/L, SAIB exhibited the raising removal efficiencies of 106–112 % for the phosphate and the increasing selectivity coefficients of 1.57–3.93. In contrast, only 2.96–9.17 mg/g of nitrate was removed by SAIB in the binary solvent system, while that of 42.92–75.76 mg/g in the unitary solvent system. Through the analysis of functional groups, variations of solution pH and zeta potential, and theoretical calculation of density functional theory, the adsorption mechanisms of SAIB were coordinated with the electrostatic attraction and anion exchange of the imprinted cavity. The maximum adsorption capacity of SAIB for phosphate calculated from the Langmuir model was 23.86 mg/g at 45 °C and pH = 5. Additionally, the phosphate adsorption efficiency can maintain above 80 % after 4 cycles of regeneration, indicating this biosorbent has good reusability and potentials for soil fertility restoration by properly returning to the field. Overall, this biosorbent of SAIB has a wide range of application prospects in water treatment, such as eutrophication of water bodies, agricultural wastewater, and domestic sewage.