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A reduced graphene oxide (H-rGO)/TiO2-composite (H-TiO2@rGO) as a catalyst for photocatalytic degradation of rhodamine B (Rh B) and methyl orange (MO) was prepared by hydrothermal treating a dispersant of TiO2 nanoparticles with sizes of 5-10 nm and GO obtained by the Hummers method from coal-based graphite in water. Compared with the M-TiO2@GO and M-TiO2@rGO composites by a wet mixing method, results indicated that the TiO2 nanoparticles in H-TiO2@rGO were uniformly decorated on both sides of rGO sheet, forming a stacked-sheet structure while apparent aggregation of TiO2 nanoparticles was found in both M-TiO2@GO and M-TiO2@rGO. Therefore, H-rGO@TiO2 had the highest catalytic activity towards degradation of Rh B and MO under visible light irradiation among the three, where the incorporation of rGO into TiO2 helps to narrow the band gap of TiO2, inhibit the recombination rate of electron–hole pairs and provide conductive networks for electron transfer.

Large quantities of lignin are produced as by-streams via chemical pulping and emerging biorefinery processes. These lignins are typically water-insoluble; however, they can be converted into a water-soluble form by chemical modifications. A novel LigniOx technology solubilizes lignin using alkali-O2 oxidation. The product can be used for bio-based dispersants. This study evaluated the biodegradability of alkali-O2 oxidized kraft, organosolv, and hydrolysis lignin. The oxidized lignins exhibited higher biodegradation in soil and in aquatic environments in comparison to a commercial kraft lignin and a commercial lignosulfonate. In soil, the biodegradabililties of oxidized lignins were 19 to 44%, whereas the reference lignins exhibited only 5 to 12% conversion to CO2. Biodegradation of the oxidized lignins and references in the aquatic environment increased in a similar order as in the soil environment, although the degradation in each sample was slightly smaller, than in the soil. The improved biodegradability of the oxidized lignins was due to the altered chemical structure of lignin. Compared to the untreated lignin, the oxidized lignin contained structures formed in aromatic ring opening reactions, making the lignin more accessible to microbial degradation. In addition, the oxidized lignin contained carbon originating from small organic compounds, which are easily biodegradable

Oil spills pose significant environmental risks, particularly in cold seas. In the Baltic Sea, the low salinity (from 0 to 2 up to 18) affects the behaviour of the spilled oil as well as the efficiency and ecological impacts of oil spill response methods such as mechanical collection and the use of dispersants. In the present study, mussels (Mytilus trossulus) were exposed under winter conditions (5 °C) to the water-accommodated fraction (WAF) of Naphthenic North Atlantic crude oil prepared by mechanical dispersion or to the chemically enhanced fraction (CEWAF) obtained using the dispersant Finasol OSR 51 at salinities of 5.6 and 15.0. Especially at the lower salinity, high bioaccumulation of polycyclic aromatic hydrocarbons was recorded in mussels in the CEWAF treatments, accompanied by increased biomarker responses. In the WAF treatments these impacts were less evident. Thus, the use of dispersants in the Baltic Sea still needs to be carefully considered. Research of this study was conducted for the EU project GRACE, which received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 679266. This study also received funding from the Academy of Finland, OILRES, Grant no. 289238. Genotoxicity and cytotoxicity studies were funded by the Research Council of Lithuania through the project ACTIS S-MIP-17-10. Dr. Jari Nuutinen (SYKE) is thanked for the PAH analyses.

Resumen En esta investigación se presentan los resultados de la aplicación de aceite de coco (Cocos nucifera) como estabilizantede asfaltenos y el efecto del calentamiento en su desempeño en una muestra de petróleo del Estado Monagas (Venezuela). El aceite de coco se sometió a ll temperaturas entre 25 y 200 °C, para luego prepararse 12 mezclas con gasoil. Se determinó el umbral de floculación de los asfáltenos a muestras de 10 mL de petróleo dosificadas con 8µL de cada mezcla, aplicando volúmenes sucesivos de n-Heptano hasta observar los agregados en un microscopio óptico y el punto de dispersión aplicando volúmenes sucesivos de Xileno hasta observar la disolución de los agregados. Se determinó el Índice de Inestabilidad como la razón entre el punto de dispersión y umbral de floculación. Se aplicó análisis ANOVA para establecer la significancia del efecto de la temperatura sobre el Índice de Estabilidad. Se concluyó que las mezclas de aceite de coco y gasoil aumentan la estabilidad de los asfaltenos al ser aplicadas a la muestra de petróleo, sin embargo, la temperatura tiene efecto estadísticamente significativo. El efecto del aceite fue positivo hasta la muestra calentada a 130 °C, perdiendo su efecto a partir de esa temperatura. Abstract This research presents the results of the application of coconut oil (Cocos nucifera), as a stabilizer of asphaltenes and the effect of warming on their performance, in a sample of Monagas state oil, Venezuela. The coconut oil was subjected to 11 temperatures between 25 and 200° C, and then 12 mixtures with diesel oil were prepared. The flocculation onset of the asphaltenes was determined to samples of 10 mL of petroleum dosed with 8µL of each mixture, applying successive volumes of n-heptane until observing the aggregates in an optical microscope and the dispersion point applying successive volumes of Xylene up to observe the dissolution of the aggregates. The Instability Index was determined as the ratio between the dispersion point and the flocculation onset. ANOVA analysis was applied to establish the significance of the effect of temperature on the Stability Index. It was concluded that mixtures of coconut oil and diesel increase the stability of asphaltenes when applied to the oil sample, however the temperature has a statistically significant effect. The effect of the oil was positive until the sample heated to 130 °C, losing its effect from that temperature.

The dispersion of nanomaterials in lubricating oil plays an important role in the lubrication and wear-resistance properties. In this work, supramolecular layered double hydroxides (LDHs) were prepared and added to lubricating oil with different dispersants. The content of key elements in the samples was measured by an oil element analyzer, and the dispersion properties of different samples were studied. The friction coefficient of the samples was measured by high-frequency linear vibration (SRV), and the morphology and composition were characterized by SEM to study the antiwear performance and action mechanism of LDH. The oxidation induction time of the samples was measured by RBOT to study the antioxygenic properties of LDH in lubricating oil. The results show that LDH can be well-dispersed in lubricating oil with the action of specific dispersants. After adding LDH, the antiwear performance of lubricating oil was improved, as a uniform and dense protective film was formed on the friction surface.

Porous diatomite ceramics with hierarchical pores and high apparent porosity (50.29–56%) were successfully fabricated via direct stereolithography. The pre-ball-milling time, dispersant type and dispersant concentration were systematically investigated to prepare diatomite pastes with high solid loading, low viscosity and a self-supporting effect. The results showed that a pre-ball-milling time of 24 h was more suitable to prepare diatomite pastes with high solid loading, and Span80 at 2 wt% was the optimal dispersant to obtain 40 vol% diatomite paste with a low viscosity and a self-supporting effect. To restrain the formation of defects, a heating rate as low as 0.2 °C/min was allowed to control the pyrolysis rate in the multistage debinding process. At sintering temperatures ranging from 900 °C to 1000 °C, porous diatomite ceramics exhibited a typical bimodal porosity, high apparent porosity and great flexural strength.

Two small molecular dispersants (SMD-1 and SMD-2) with different charge densities of phosphate as the adsorption group were synthesised by the reaction of polyetheramine, phosphorous acid and formaldehyde. The structure and molecular weights of these two synthesised phosphated superplasticisers (PSPs) and a commercial polycarboxylate superplasticiser (PCE) were characterised by Fourier transform infrared spectroscopy and gel permeation chromatography. The dispersing, adsorption and hydration behaviours with the addition of potassium sulfate (K2SO4) to the cement paste were also analysed. The experimental results showed that, compared with the conventional comb-shaped PCE, the linear structure of the PSPs provided lower dispersing ability but better fluidity retention. The addition of potassium sulfate had an obvious negative effect on the dispersing ability of PCE, while the effect on the PSPs was slight. The adsorption isotherms indicated that, with the addition of 2 wt% potassium sulfate, the competitive adsorption between sulfate ions and PCE was enhanced: the saturated adsorption of PCE decreased by 10.37%, whereas the PSPs were less affected, with the saturated adsorption of SMD-1 only decreasing by 2.32%. Isothermal calorimetry measurements showed that the PSPs showed excellent retarding ability and could delay the hydration process of cement.

This study examines the electrophoretic deposition of Yb2Si2O7 particles on SiC substrates to produce Environmental Barrier Coatings. To prepare crack-free and homogeneous green coatings, the effect of the solvent, dispersant concentration, and pH were investigated. Ethanol provided a well-dispersed suspension and crack-free coating which was shown by sedimentation tests and microstructure analysis. The effect of the dispersant concentration was investigated with zeta potential measurement and microstructure analysis with a concentration above 0.5 g/L resulting in higher ionic strength and producing cracked and uneven coatings. The ionic strength was also associated with the powder packing density with larger indentation impressions measured for loosely packed coatings. The deposition rate depended on the suspension properties influenced coating integrity with delamination evidenced by analysing the current density drop during deposition. Sintering of the green coatings having different densities and microstructure showed their importance in the preparation of uniform and dense sintered coatings.

Hypothesis Flow curve measurement is commonly used to characterize the flow behavior of concentrated suspensions. However, dynamic changes in the suspension inner microstructures under highly sheared conditions have not been correctly understood even though they strongly affect the measured shear stress. We hypothesize that the real particle dynamics during shearing could be effectively revealed by a systematic investigation that combines macroscopic flow curve measurements with operando microstructural observation employing an optical coherent tomography (OCT) apparatus and surface interaction measurements with the colloidal probe atomic force microscopy (AFM) method. Experiments The model system was spherical SiO2/toluene suspensions stabilized by polyethyleneimine (PEI) partially complexed with different fatty acids. Inner structures of the suspensions during flow curve measurements were observed by the OCT technique. The surface-surface interactions in toluene were analyzed using the colloidal probe AFM method. Findings Operando OCT observations revealed that during flow curve measurements, the suspensions can have completely different microscopic flow modes depending on the fatty acid species complexed to PEI and the solid concentrations. These microscopic flow modes could not be recognized using the typical flow curve measurements alone. The different flow modes can be explained by surface interactions measured by the colloidal probe AFM method.

By surface modification with APTMS, spontaneous coagulation casting (SCC) of fused silica based on Isobam was achieved and the possible coagulation and molding mechanism is proposed. Through the interaction between the polar groups on the Isobam molecular chain and the incorporated –NH2 groups on the surface of the silica particles, Isobam molecular chains were adsorbed on the surface of particles, which initiate the formation of flocs and the solidification of the suspension. The addition of dispersant TMAH results in the hydrolyzation of Isobam, forming more –COO–, which effectively improves the fluidity and stability of the suspension. Then the zeta potential, rheological properties and coagulation behavior of the suspension were systematically investigated and the fused silica suspension with high solid content (up to 52 vol%), low viscosity and good coagulation properties were prepared at 1.8 wt% TMAH and 0.5 wt% Isobam dosage. After sintering at 1260 °C for 4 hours, the fused silica ceramics (50 vol% solid content) shows a high bending strength of 61.59 MPa, the lowest dielectric loss tanδ of 8.46 × 10-4 and the dielectric constant of 3.72. Thus, this work provides a simple and effective method for preparing fused silica and other ceramics with negative surface charge by Isobam SCC.

After oil spills occur, dispersed oil droplets can collide with suspended particles in the water column to form the oil-mineral aggregate (OMA) and settle to the seafloor. However, only a few studies have concerned the effect of chemical dispersant on this process. In this paper, the mechanism by which dispersant affects the surface properties of kaolin as well as the viscosity and oil-seawater interfacial tension (IFTow) of Roncador crude oil were separately investigated by small scale tests. The results indicated that the presence of dispersant impairs the zeta potential and enhances the hydrophobicity of kaolin. The viscosity of Roncador crude oil rose slightly as the dosage of dispersant increased while IFTow decreased significantly. Furthermore, the oil dispersion and OMA formation at different dispersant-to-oil ratio (DOR) were evaluated in a wave tank. When DOR was less than 1:40, the oil enhancement of dispersant was not significant. In comparison, it began to contribute when DOR was over 1:40 and the effect became more pronounced with the increasing DOR. The adhesion between oil droplets and kaolin was inhibited with the increasing DOR. The size ratio between oil droplets and particles is the significant factor for OMA formation. The closer the oil-mineral size ratio is to 1, the more difficultly the OMA forms.

This paper proposes a comparative study of two techniques of granulation of a submicronic alumina powder with high binder content slurries, by spray drying and freeze granulation for the preparation of mixed granules. First, the viscosity and flow index of the suspensions are given as a function of dispersant, solid and binder contents versus alumina content, and the data are analysed in order to give a predictive model in a wide range. Suspensions with varying viscosities (7–208 mPa.s), densities (1.31–1.76) and surface tensions (23–40 mN/m) were then granulated. The first observations reveal the importance of the content and the molar mass of the binder: when they are too high, the freeze granulation fails and filaments are produced instead of granules due to extensive stretching of the molecular chains of the binder during spraying. Then through a theoretical analysis of the phenomena leading to granulation, an original dimensionless number is proposed to describe the evolution of the granule size as a function of suspension formulation. This number is related to the Reynolds and Weber number and is able to predict the granule size over a wide range (20–500 μm for freeze granulation, and 5–30 μm for spray drying). Spray drying leads to smaller granules with various shapes, from full shape to hollow or donut-like, whereas freeze granulation leads to bigger but spherical granules with a microporosity, and a size easier to predict as no drying shrinkage is observed.

In this present work, nanosize zinc oxide particles were prepared via modest coprecipitation synthesis route. Powder X-ray diffraction pattern was applied for calculating the size of crystallites in the prepared sample. Fourier Transform Infra-Red spectrum established the Zn-O bands at 539 and 433 cm−1 in nano ZnO sample. The structural analysis was done using Scanning Electron Microscopy (SEM) studies for ZnO nanoparticles. Ultrasonicated two step procedure was followed to disperse the produced nanoparticles in the combination of water (60%) and ethylene glycol (40%) to produce ZnO nanofluids with five different particle volume fractions from 0.0125% to 0.1%. To overcome the stability problem and uniform distribution of nanoparticles within the fluid, Cetyl Trimethyl Ammonium Bromide (CTAB) dispersant was added within the suspension while preparation. The investigation results of viscosity, density as well as thermal conductivity at various temperatures showed the enhanced results than the base fluid combination. Huge improvements in thermophysical properties leads the ZnO nanofluid as an alternate working liquid in heat transferring systems.

Polymer nanocomposites which possess outstanding antimicrobial efficacies are potential materials for food packaging applications. Amidst the several biodegradable synthetic polymers, Polyvinyl alcohol exhibits excellent biocompatibility and are very economical. A new hybrid composite based on Polyvinyl alcohol with GO and reduced rGO with Potassium Chloride as salt spacer was synthesized using solvent cast method. The antibacterial activity of the prepared films was explored against Pseudomonas aeruginosa (ATCC 7903) Escherichia coli (ATCC 8739) Campylobacter jejuni (ATCC 29428) Staphylococcus aureus (ATCC 6538). The antifungal activity was studied against Candida albicans (ATCC 10231) Trichodermaharzianum (ATCC 90237) Aspergillus Niger (ATCC 6275). Polymer nanocomposite with GO as dispersant (4 wt%) have shown inhibitory activity with respect to P. aeruginosa, E. coli and C. jejuni. Polymer nanocomposite with rGO as dispersant (4 wt%) have inhibitory activity against E. coli, C. albicans and against P. aeruginosa using well diffusion method.

Porous materials manufactured by freeze-casting are demonstrating potential application as oxygen carriers for the production and purification of hydrogen, or anode material for lithium-ion batteries. However, to obtain the required pore morphology and sufficient mechanical strength, the suspension processing parameters must be controlled. Fe2O3 nanoparticles/camphene suspensions were fabricated using stearic acid as the dispersant agent showing a low-viscosity (130 mPa·s) with a high solid volume fraction (0.3). Suspensions show a shear-thinning behavior according to the Sisko model and a maximum packing fraction of 0.569 estimated from a zero porosity sample. A modified Krieger and Dougherty model was introduced to incorporate the influence of the particle-aspect ratio. The Fe2O3 scaffolds manufactured by freeze-casting shown a gradient pore size along the freezing direction, which was diminished with the solid volume fraction, the compression strength was improved with the pore size reduction and fitted according to the minimum solid area model.

Traditional water-based dyeing of polyester textiles usually generates burdensome processes and a great deal of wastewater, which can no longer meet the green and sustainable developments in the textile dyeing industry. In the silicone waterless dyeing system, polyester textiles can be dyed with disperse dye without water. However, the dyeing performance of polyester textiles is influenced by the dispersant. In this study, the relationship between the properties of dispersants and disperse dyeing performance was studied. When the amount of dispersant NNO (2-Naphthalenesulfonic acid) was 1.2%, the exhaustion of disperse red 177 and the final K/S value of the dyed fabric improved to 94.18% and 14.73, respectively. However, the exhaustion of disperse red 177 was reduced from 90.73% to 82.61%, and the final K/S value of the dyed fabric was decreased from 14.77 to 14.01 when the dosage of MF (Naphthalenesulfonic acid) was 1.2%. Compared with different dyeing systems, the final uptake of disperse red 177 was 93.81% and 94.18% in traditional water-based and silicone waterless dyeing systems and the K/S value of the dyed fabric was almost the same. The washing and rubbing fastness (wet and dry) of the dyed fabric were found to be at a level of 4 or 4–5, and the light fastness of the dyed fabric was 3–4. If only the dispersant was added in the silicone waterless dyeing system, there was no leveling problems on dyed samples. Moreover, the maximum absorption wavelength of disperse red 177 was not changed after adding the dispersant. With an increasing amount of dispersant NNO, the solubility of the dye in the silicone solvent decreased, but it increased with an increasing amount of dispersant MF. In the relationship between dye exhaustion and dye solubility in a silicone waterless dyeing system, the exhaustion of dye was linearly and inversely proportional to the dye solubility. A dispersant with better hydrophilicity can decrease the solubility of the dye in dyeing media, and the dyeing performance of dye is better. Compared with previous studies, the exhaustion of dye was consistent with the ClogP value (hydrophobic constant) of the dyeing accelerant. Therefore, a dispersant with high hydrophilicity can reduce the solubility of dye and improve the exhaustion of disperse dye in a silicone waterless dyeing system. Moreover, the color fastness of the dyed fabric did not change before and after adding the dispersant.

Poloxamers (known by the trade name Pluronic®) are triblock copolymer surfactants that contain two polyethylene glycol blocks and one polypropylene glycol block of various sizes. Poloxamers are widely used as nanoparticle dispersants for nanotoxicity studies wherein nanoparticles are sonicated with a dispersant to prepare suspensions. It is known that poloxamers can be degraded during sonication and that reactive oxygen species contribute to the degradation process. However, the possibility that poloxamer degradation products are toxic to mammalian cells has not been well studied. We report here that aqueous solutions of poloxamer 188 (Pluronic® F-68) and poloxamer 407 (Pluronic® F-127) sonicated in the presence or absence of multi-walled carbon nanotubes (MWNTs) can became highly toxic to cultured cells. Moreover, toxicity correlated with the sonolytic degradation of the polymers. These findings suggest that caution should be used in interpreting the results of nanotoxicity studies where the potential sonolytic degradation of dispersants was not controlled.

The influence of the multi-component composition of cotton and polyester dyeing baths was investigated in a DCMD process using a PTFE membrane, aiming to water reclamation from textile wastewater. The process was evaluated with each auxiliary, solutions combining auxiliary and dye, and residual water from pilot-scale dyeing baths. The salts used in the cotton dyeing bath did not influence the DCMD process, resulting in a similar rejection rate and permeate flux to those in dye solutions. The formic acid employed in the polyester dyeing bath resulted in high permeate fluxes but decreased the permeate quality by almost 33%. The surfactants (detergent and dispersant) demonstrated the most harmful behavior in the process, evidenced by a complete membrane wetting. An absence of synergy of the dyes and auxiliaries influencing the DCMD process was verified for the textile dyeing wastewater. This work enabled identifying the influence of each dyeing bath component in the rejection rate and permeate flux, allowing to find alternatives in mitigating the remaining gaps involving DCMD operation and the MD membranes. This work contributes to consolidating this promising technique in water reclamation from textile wastewater, encouraging research on membrane development and modification or integrated operations involving MD.

The increase of harmful carbon monoxide (CO) caused by incomplete combustion can affect human health even lead to suffocation. Therefore reducing the CO discharged by vehicles or factories is urgent to improve the air quality. The spinel cobalt (II, III) oxide (Co3O4) is an active catalyst for CO abatement. In this study, we tried to fabricate dispersing Co3O4 via the dispersion-precipitation method with acetic acid, formic acid, and oxalic acid as the chelating dispersants. Then, the asprepared samples were calcined at 300 ºC for 4 h to obtain active catalysts, and assigned as Co(A), Co(F) and Co(O) respectively, the amount of the dispersants used are labeled as I (0.12 mole), II (0.03 mole) and III (0.01 mole). For comparison, another CoAP sample was prepared via alkaliinduced precipitation and calcined at 300 ºC. All samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), scanning electron microscope (SEM), and nitrogen adsorption/desorption system, and the catalytic activity focused on the CO oxidation. The influence of chelating dispersant on the performance of abatement of CO was pursued in this study. Apparently, the results showed that the chelating dispersant can influence the catalytic activity of CO abatement. An optimized ratio of dispersant can improve the performance, while excess dispersant lessens the surface area and catalytic performance. The series of Co(O) samples can easily donate the active oxygen since the labile Co–O bonding and indicated the preferential performance than both Co(A) and Co(F) samples. The nanorod Co(O)-II showed preferential for CO oxidation, T50 and T90 approached 96 and 127 ºC, respectively. Also, the favorable durability of Co(O)-II sample maintains 95% conversion still for 50 h at 130 ºC and does not emerge deactivation.

Amyloid-fibers help to maintain the structure of infectious biofilms. Disassembly of amyloid-fibers contributes to biofilm-dispersal in the blood-circulation, from which bacteria should be cleared by the host immune system. However, often the immune system is insufficiently prepared for increasing bacterial concentrations in blood, causing septic symptoms. Here, poly(ethylene glycol)/poly(beta-amino ester), pH-responsive micelles are prepared for co-delivery of (-)-epigallocatechin-3-O-gallate (EGCG) as a dispersant. Hydrophilic EGCG can not be loaded in the micellar core, but is cross-linked in the micellar shell through pH-reversible, boronic-ester binding. Disassembly of micelles under acidic biofilm conditions facilitates release of EGCG and dispersal of biofilm-bacteria. When core-loaded with ciprofloxacin, in-shell EGCG prevents ciprofloxacin-leakage at physiological pH. Bacterial killing by core-loaded ciprofloxacin in Staphylococcus aureus biofilms is enhanced when released in combination with EGCG in vitro and in vivo. In mice, micelles with in-shell EGCG self-target after tail-vein injection to an infection site, yielding dispersal of pathogens with mild septic symptoms and bacterial killing by the immune system. Septic symptoms disappear slightly faster when micelles are additionally core-loaded with ciprofloxacin. Thus, micelles with in-shell EGCG yield balanced biofilm dispersal inducing only mild septic symptoms, which is good news in an era of increasing antibiotic-resistance.

Characterization of carbon black (CB) nanomaterials is required in industrial and research areas. Hence, in this study, asymmetrical flow field flow fractionation coupled to UV–vis and DLS detectors in series (AF4-UV–vis-DLS) was studied to evaluate the CB dispersion behavior in polymeric and biological dispersants, given the relevance of these media in practical applications. Under the experimental conditions, the results indicated that polymeric and biological dispersions showed size distributions with hydrodynamic diameters of 404 and 175 nm, respectively, for a particle core diameter of 40 nm. The polymeric dispersant provided lower stability as a function of time than that achieved by the biological dispersant. AF4 allowed separation of different core-sized CB (40, 69, and 72 nm) according to their hydrodynamic size using cross-flow rates of 0.5 mL·min–1 and 1 mL·min–1 for polymeric and biological dispersants, respectively. The dilution of the polymeric dispersion with different real water matrices produced a dramatic loss of dispersion stability, this effect being negligible in the case of biological dispersions.

During continuous casting of steel billets, mould lubrication is provided by addition of oil in case of open casting and mould powder is used during close casting. Open casting of steel billets has hazards like mould spitting of liquid metal whereas in case of close casting the sequence length is less incurring more refractory consumption. To get combined advantages of both, a new class of lubricant has been developed by dispersing mould powder in oil using nonionic dispersants. The characteristics of this suspension are studied extensively to evaluate all required properties for plant operation. The result of plant studies shows, (1) reduction in liquid metal spitting by 60% and thence reducing hanger breakout, (2) heat extraction in the mould is reduced by 14% and (3) no entrapment of mould powder found in the billet. This can be used as an alternative to close casting and hence increasing sequence length.

Nowadays, 3D polymer-derived silicon oxycarbide ceramics (SiOC) can be fabricated by the stereolithography method successfully. However, due to their intrinsically poor ceramic content and the large thermal shrinkage during the pyrolysis, it is difficult for the bulk 3D polysiloxane precursors to be pyrolyzed into dense 3D-ceramics. Herein, the ceramic content of the photocurable polysiloxane precursors was increased by adding a large amount of SiO2 powders into the low solid content epoxy-acrylic siloxane. After being added with proper dispersant, the viscosity of the high solid loading polysiloxane/SiO2 slurry can reach a proper level. Bulk 3D-silica ceramics with the wall-thickness around 8 mm can be conveniently fabricated from the polysiloxane/SiO2 slurry by stereolithography and a two-step sintering process. The addition of a proper sintering aid NaF can promote the 3D-PSO/SiO2 precursor to be converted into dense and crack-free 3D-silica ceramics with good mechanical proprieties.

The goal of this research is to fabricate pure transparent yttria ceramics through gel casting and vacuum sintering. A specific processing method has been used and optimized for this purpose. A pure yttria nanopowder was synthesized as the starting material to produce pure transparent ceramics through a low-temperature sintering process. It was attempted to minimize the undesirable nanopowder hydration by using the as-synthesized yttria nanopowder and a rapid deagglomeration and slurry preparation process. The synthesized nanopowders were deagglomerated to enhance the efficiency of both powder shaping and sintering stages. Carrageenan was used as the gelling agent because it is a low-cost and abundant material, and because the temperature is the only catalyst needed for its gelation; therefore, it is possible to control its gelation to obtain high-density and pure optical ceramics. The effect of the deagglomeration method and the processing parameters, including the amounts of dispersant, gelling agent, solid loading, pH, and deagglomeration time, on the rheology of slurry, density, and microstructure of the obtained green yttria ceramics was examined and optimized in order to obtain high solid loading nanoyttria suspensions of 38 vol%, which is more than those obtained in many of the previous investigations. The precise gelling temperature and time were measured, and green gel cast ceramics with a density of 63 % of the theoretical density were produced. A rapid deagglomeration and slurry preparation method was used instead of using a conventional planetary ball-milling approach to minimize the risk of the hydrolysis of yttria nanopowder. No sintering aid was necessary, and transparent yttria ceramics with 99 % of the theoretical density were produced after vacuum-furnace sintering at 10-2 mbar and 1715 °C.

Waterborne polyurethane (WPU) and Ag NPs have been applied widely in packaging. However, WPU was susceptible to the contamination due to high moisture absorption, and the stability of Ag NPs in matrix polymers was still low. To resolve this problem, chitosan (CS) was used as the dispersant to synthesize CS/Ag NPs composites in this work, and then they were mixed with WPU to prepare CS/Ag-WPU films. CS macromolecules provided the carriers for Ag NPs with a diameter of about 2.5 nm, and Ag NPs were dispersed stably in WPU. Compared with pure WPU film, as-prepared CS/Ag-WPU films had a higher thermal stability at low temperature, and the crystal size for WPU increased after introducing CS/Ag NPs. Importantly, the water contact angle for CS/Ag-WPU-5 increased to 54.2° from 27.5° implying that the hydrophobicity was improved. In addition, CS/Ag-WPU composites exhibited an excellent inhibitory effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Antibacterial performances of most samples were improved with the crease of the concentration of CS, and the inhibitory effect on S. aureus was preferred. Therefore, as-prepared CS/Ag-WPU films in this paper have a potential application in antibacterial packaging field.

The current investigation is focused on the assessment of combustion, performance, and emission parameters of VCR compression ignition engine working with ZnO nanoparticles dispersed Baheda (Terminalia bellirica) oil biodiesel (BOBD20). The ZnO nanoparticles were considered at the accompanying extents, for instance, 50, 75, and 100 ppm. Besides, a 1:1 proportion of dispersant (QPAN80) was blended to ZnO nanoparticles. The entire experimentation was performed at four compression ratios such as 16.5:1, 17.5:1. 18.5:1, and 19.5:1, respectively. The ZnO nanoparticle dispersed BOBD20 has shown tremendous outcomes. The dispersant added fuel was shown encouraging outcomes than regular diesel and biodiesel. Among all, the BOBD20 + ZnO75 + DSP 75 was revealed better outcomes concerning the operating characteristics. Further, the positive impact was perceived with increasing compression ratio and attained encouraging outcome at CR19.5:1. For BOBD20 + ZnO 75 + DSP 75 and at CR19.5:1, the higher BTE and least BSFC were obtained was 34.89% and 0.305 kg/kWh. Similarly, the highest combustion quantities for instance CP and NHRR were seen as 72.52 bar and 61.22 J/°CA, respectively. Finally, the minimum emissions of CO, UHC, and NOx, were 0.08%, 25 ppm, and 932 ppm, respectively for BOBD20 + ZnO75 + DSP75.

Magnetic nanoparticles (MNPs) are widely investigated to evaluate their efficacy for therapeutic carriers, biosensors, contrast agents, therapeutic agents (hyperthermia generators), antimicrobial agents, etc., in extracellular space. When MNPs are used for biomedical applications, the nanoparticles are usually dispersed in phosphate buffer saline or body fluids. Bare MNPs tends to agglomerate and aggregate due to high specific surface energy and magnetic dipolar interactions. Further non-specific adsorption of proteins and salts on bare MNPs leads to collapse of colloidal properties. In order to mitigate the above problems, bare MNPs are ligated with biocompatible dispersants for colloidal stability. Majority MNPs are ligated with dispersants such as oleic acid, oleylamine, dopamine derivatives, zwitterionic compounds and polyethylene glycol, to obtain surfactant ligand monolayer on MNPs. Sometimes, polymers are also used as capping agent or encapsulation material. Surfactant monolayer can further be functionalized with therapeutics, proteins, immunoreceptor, etc., for a specific application. Hence one need to understand biocompatible properties, especially cytotoxicity, of nanoparticles with different dispersant monolayers. In addition, biocompatibility testing is also important because the presence of extractable chemical compounds and agents from synthesis process may influence biocompatibility. Cytotoxicity is most sensitive of the biocompatibility tests and is useful for evaluating these types of harmful reactions. Effect of dispersants on cytotoxicity of MNPs are not reviewed in the literature. The effect of various dispersant on cytocompatibility of various MNPs are systematically presented here. Among all, polyethylene glycol polymer is a universal dispersant with high colloidal stability and very low cytotoxicity. Short-chain zwitterionic surfactant ligands are next best dispersants.

This study introduces a comprehensive and cost-effective approach to diagnose and treat the asphaltenes precipitation problems in different downhole conditions. The proposed approach has been successfully applied in two oil wells (Well-I, and Well-II) located in the Western Desert of Egypt. The two wells produce oil of moderate to high oil gravity with low asphaltenes content using Electrical Submersible Pumps (ESP). In such operating conditions, solid deposits caused blockage at the pump intake and within the pumping stages in the two wells. This blockage led to a sharp decrease in oil production rate and a significant increase in the operating cost. The existing failure analysis procedure was not able to accurately identify the reasons for the blockage; accordingly, the treatment operations were unsuccessful. On the contrary, applying the proposed approach accurately (1) identified the type of the solid deposits, (2) solved the problem using proper treatment option with minimum cost, and (3) improved the oil production rate. The laboratory tests of the fluid and solid deposits showed that (1) the asphaltenes were unstable in the crude oil and acted as a glue for other minerals, and (2) the blockage was successfully diagnosed to confirm that the two wells had asphaltenes precipitation problem. The laboratory tests were extended to select optimum asphaltene dispersant for wells treatments. The field application results showed a significant increase in the oil production rate from 700 to 1600 STB/D in Well-I and from 470 to 1500 STB/D in Well-II. Moreover, the operating cost decreased considerably from 2.01 to 0.43 $/STB in Well-I, and from 4.37 to 0.52 $/STB in Well-II after applying the proposed approach.

In response to food packaging improvements, this study investigates changes in mechanical and thermal barrier properties of pigment-based paper coatings when cellulose nanocrystals (CNC) and cellulose nanofibers (CNF) are added to the formulation. Stable dispersions of all coating components were formed between pH 7–9 (zeta potential > |30 mV|) except CNF, which favored stable dispersions at higher pH. Hydrodynamic diameters (Dh) of CNC and CNF decreased when interacting with calcium carbonate ions (Ca2+ and CO32-); however, latex binder and dispersant diameters were unaffected by the presence of CaCO3 in solution. Thermal barrier performance was quantified by measuring ΔT across coated samples, with and without nanoparticle additives. Both CNC and CNF additives significantly contributed to the ΔT measured, with the best result recorded for 2 wt% CNF, pH 7, and a drying rate of 25 °C/min. This sample recorded 37 ± 6 °C higher than the ΔT for baseline coatings (without additive). Dynamic mechanical analysis (DMA) showed a higher storage modulus for all samples containing CNC and/or CNF compared with the baseline coating, suggesting a material with greater resistance to deformation from applied load. Higher dissipation energy was also observed; however, lower tan delta values suggest improved mechanical properties with both additives.

The GuLF STUDY is investigating health outcomes associated with oil spill-related chemical exposures among workers involved in the spill response and clean-up following the Deepwater Horizon disaster. Due to the lack of dermal exposure measurements, we estimated dermal exposures using a deterministic model, which we customized from a previously published model. Workers provided information on the frequency of contact with oil, tar, chemical dispersants applied to the oil spill and sea water, as well as the use of protective equipment, by job/activity/task. Professional judgment by industrial hygienists served as a source of information for other model variables. The model estimated dermal exposures to total hydrocarbons (THC), benzene, ethylbenzene, toluene, xylene, n-hexane (BTEX-H), polycyclic aromatic hydrocarbons (PAHs), and dispersants in GuLF DREAM units (GDUs). Arithmetic means (AMs) of THC exposure estimates across study participants ranged from 0.9) for most of the substances in oil but were lower for some of the substances in tar. These data were linked to the study participants to allow investigation of adverse health effects that may be related to dermal exposures.

The avoidance and mitigation of energy wastage have attracted increasing attention in the context of global warming and climate change. With advances in materials science, diverse multifunctional materials with high thermal conductivity have shown excellent energy-saving potential. In this study, a hybrid film exhibiting high thermal conductivity with excellent stretchability and washability was prepared. First, a simple surface modification of boron nitride (BN) was performed to realize a modified boron nitride (BNOH) filler. Next, an organic dispersant was synthesized to enhance the dispersion of BNOH and graphene nanoplatelets (GNPs) in the proposed composite. Subsequently, a simple procedure was used to combine the dispersed GNPs and BNOH fillers with thermoplastic polyurethane (TPU) to fabricate a hybrid structure. The hybrid films composed of BNOH–GNP/TPU with a dispersant exhibited a high thermal conductivity of 12.62 W m–1 K–1 at a low filler loading of 20 wt.%. This hybrid film afforded excellent stretchability and washability, as indicated by the very small thermal-conductivity reduction to only 12.23 W m–1 K–1 after 100 cycles of fatigue testing and to 12.01 W m–1 K–1 after 10 washing cycles. Furthermore, the cooling and hydrophobicity properties of the hybrid film were enhanced when compared with neat TPU. Overall, our approach demonstrates a simple and novel strategy to break the passive effect of traditional commercial cooling clothing by combining a high-thermal-conductivity film with an active cooling source to amplify the cooling effect and develop wearable cooled smart clothes with great commercial potential.

Assembly processes in marine microbial communities amended with crude oil and chemical dispersant are poorly understood and even more so when biosurfactants are used. We set up a microcosm experiment in which microbiome structure was analyzed using 16S rRNA gene amplicon sequencing and six null models to better understand and quantify the mechanisms and patterns controlling the assembly of a marine crude oil degrading microbial community in the presence of chemical dispersant or rhamnolipid biosurfactant. Although each null model quantifies different aspects of the community assembly, there was a general agreement that neither purely stochastic nor purely deterministic processes dominated the microbial communities, and their influence was variable over time. Determinism was dominant in the early phase of incubation, while stochasticity was prevalent in the middle and late stages. There was faster recruitment of phylogenetically distant species in the dispersant‐amended community compared to oil‐only or rhamnolipid‐amended communities. This analysis provides important insights of how chemical dispersants and rhamnolipid influence microbial communities' dynamics and identified which groups may be excluded—an important consideration for biodegradation process and oil spill response., Assembly processes in marine microbial communities amended with crude oil and chemical dispersant are poorly understood and even more so when biosurfactants are used. We used a comprehensive set of null models approaches to test traditional macroecological concepts in the context of microbial metagenomics in order to understand and quantify the mechanisms and patterns controlling the complexity of microbial ecology Our results advance the understanding of how chemical and biogenic dispersants affect the ecological processes in marine microbial community response to crude oil.

The effect of the salt composition of water (model aqueous solutions of NaCl and artificial sea salt Instant Ocean, as well as water from the Pechora Sea) on the effectiveness of oil spill dispersants determined in laboratory conditions is studied. The efficiency of dispersants (Finasol OSR 52, Slickgone NS and Slickgone EW) was evaluated three samples of crude oil produced in the Russian Federation. Those oil samples of different composition and properties were used at fixed values of the dispersant-oil ratio (1:10), water temperature (20 ± 2°C) and salinity (35 ± 2%). It is shown that the effectiveness of the oil spill disper­sant depends on the nature (composition) of water in which the oil is dispersed, other things being the same. An anomalous behavior of one of the oil samples was found when it was dispersed in an aqueous so­ lution of NaCl under the action of Finasol OSR 52 and Slickgone EW Good convergence of the numerical values of the efficiency of dispersants was obtained when testing them in an aqueous solution of artificial sea salt Instant Ocean and in the water of the Pechora Sea. It is noted that to assess the effectiveness of dispersants in laboratory conditions, it is advisable to use water of the natural object in which this disper­sant is planned to be used. Moreover, the possibility of using an aqueous solution of the artificial salt when its salt composition is similar to that for real sea water was noted.

Kraft lignin is an underutilized material mainly combusted in the pulping industry. Its conversion to value-added products for further end-use applications is limited due to its insolubility in water. In this work, the modification of kraft lignin (KL) was conducted through oxidation and carboxymethylation to generate anionic water-soluble lignin (OKL, and CMKL, respectively). The results indicated that these biopolymers acted as effective dispersants in an aluminum oxide suspension. Subsequently, generated biomaterials were polymerized with acrylamide monomer to generate flocculants (i.e., OKL-AM and CMKL-AM) for the aluminum oxide suspension. The properties of polymers were characterized extensively, and the polymerization of OKL and CMKL with acrylamide increased the molecular weight (Mw) of the biomaterials from 16 × 103 and 28 × 103 to 684 × 103 and 387 × 103 g/mol, respectively. Flocculation studies under stirring revealed that the chord length of aluminum oxide particles increased substantially by treating the suspension with the OKL-AM polymer. The reflocculation analysis provided further insight into the reversibility and high strength of formed flocs. Our results confirmed that by following a one-step reaction, a lignin-based dispersant could be generated, and further polymerizing the biomaterials (i.e., dispersants) would make it a valuable flocculant. This investigation confirms a versatile and environmentally friendly pathway to convert a waste material (i.e., lignin) to a green dispersant and flocculant.

In this study, the relationship between the physicochemical properties of kaolin slurries and their particles produced by spray drying to obtain FCC matrices was discussed. Eight aqueous slurries were prepared with 40 wt.% solids using two types of kaolin (K1 and K2) and sodium silicate solution as the dispersant. Additionally, nitric acid at 5.0 wt.% was used to adjust the pH in the range between 6 and 8. Both kaolin sources were characterized by X-ray diffraction and scanning electron microscopy. The K2 kaolin had a higher crystallinity of kaolinite and smaller particle size in comparison with K1. Likewise, while K2 showed 4 well defined bands of hydroxyl groups in the infrared spectrum at 3688, 3666, 3653 and 3620 cm−1, the K1 IR spectrum consisted of two sharp signals at 3692 cm−1 and 3620 cm−1 and two poorly developed bands at 3666 cm−1 and 3653 cm−1. These features intimately related to their structure were shown to have an effect on the morphology of the particles obtained during the drying process; in the case of the K1 slurries, these led to the formation of microspheres, and on the contrary, from K2 slurries mushroom head shape particles were formed. Furthermore, the average diameter (D50) of the particles increased with the increase of the amount of the binder in the slurry. Thus, the results show that a less crystalline kaolin favors the formation of microspherical particles during the spray drying process that allows a better control of the FCC matrix produced to be used in in-situ zeolite Y crystallization on kaolin particles.

Increasing occurrence of intrinsically antimicrobial-resistant, human pathogens and the protective biofilm-mode in which they grow, dictates a need for the alternative control of infectious biofilms. Biofilm bacteria utilize dispersal mechanisms to detach parts of a biofilm as part of the biofilm life-cycle during times of nutrient scarcity or overpopulation. We here identify recent advances and future challenges in the development of dispersants as a new infection-control strategy. Deoxyribonuclease (DNase) and other extracellular enzymes can disrupt the extracellular matrix of a biofilm to cause dispersal. Also, a variety of small molecules, reactive oxygen species, nitric oxide releasing compounds, peptides and molecules regulating signaling pathways in biofilms have been described as dispersants. On their own, dispersants do not inhibit bacterial growth or kill bacterial pathogens. Both natural, as well as artificial dispersants, are unstable and hydrophobic which necessitate their encapsulation in smart nanocarriers, like pH-responsive micelles, liposomes or hydrogels. Depending on their composition, nanoparticles can also possess intrinsic dispersant properties. Bacteria dispersed from an infectious biofilm end up in the blood circulation where they are cleared by host immune cells. However, this sudden increase in bacterial concentration can also cause sepsis. Simultaneous antibiotic loading of nanoparticles with dispersant properties or combined administration of dispersants and antibiotics can counter this threat. Importantly, biofilm remaining after dispersant administration appears more susceptible to existing antibiotics. Being part of the natural biofilm life-cycle, no signs of "dispersant-resistance" have been observed. Dispersants are therewith promising for the control of infectious biofilms. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Increasing occurrence of intrinsically antimicrobial-resistant, human pathogens and the protective biofilm-mode in which they grow, dictates a need for the alternative control of infectious biofilms. Biofilm bacteria utilize dispersal mechanisms to detach parts of a biofilm as part of the biofilm life-cycle during times of nutrient scarcity or overpopulation. We here identify recent advances and future challenges in the development of dispersants as a new infection-control strategy. Deoxyribonuclease (DNase) and other extracellular enzymes can disrupt the extracellular matrix of a biofilm to cause dispersal. Also, a variety of small molecules, reactive oxygen species, nitric oxide releasing compounds, peptides and molecules regulating signaling pathways in biofilms have been described as dispersants. On their own, dispersants do not inhibit bacterial growth or kill bacterial pathogens. Both natural, as well as artificial dispersants, are unstable and hydrophobic which necessitate their encapsulation in smart nanocarriers, like pH-responsive micelles, liposomes or hydrogels. Depending on their composition, nanoparticles can also possess intrinsic dispersant properties. Bacteria dispersed from an infectious biofilm end up in the blood circulation where they are cleared by host immune cells. However, this sudden increase in bacterial concentration can also cause sepsis. Simultaneous antibiotic loading of nanoparticles with dispersant properties or combined administration of dispersants and antibiotics can counter this threat. Importantly, biofilm remaining after dispersant administration appears more susceptible to existing antibiotics. Being part of the natural biofilm life-cycle, no signs of "dispersant-resistance" have been observed. Dispersants are therewith promising for the control of infectious biofilms. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

The formation of surface multilayer structures, induced by the addition of multivalent counterions in dilute surfactant solutions, has been widely observed in a range of anionic surfactants. The phenomenon is associated with the ability to manipulate surface properties, especially in the promotion of enhanced surface wetting, and in the presence of an extensive near surface reservoir for rapid surface delivery of surfactant and other active components. Hypothesis. In the single alkyl chain anionic surfactants, such as sodium dodecysulfate, SDS, sodium alkylethoxylsulfate, SAES, and alkylestersulfonate, AES, surface multilayer formation is promoted by trivalent counterions such as Al3+, and is generally not observed with divalent counterions, such as Ca2+ or with monovalent counterions. In the di-alkyl chain anionic surfactant, dodecylbenzenesulfonate, LAS, surface multilayer formation now occurs in the presence of divalent counterions. It is attributed to the closer proximity of a bulk lamellar phase, resulting in a greater tendency for surface multilayer formation, and hence should occur in other di-alkyl chain anionic surfactants. Experiments. Aerosol-OT, AOT, is one of the most commonly used di-alkyl chain anionic surfactants, and is extensively used as an emulsifying, wetting and dispersing agent. This paper reports on predominantly neutron reflectivity, NR, measurements which explore the nature of surface multilayer formation of the sodium salt of AOT at the air-solution interface with the separate addition of Ca2+ and Al3+ counterions. Findings. In the AOT concentration range 0.5 to 2.0 mM surface multilayer formation occurs at the air-solution interface with the addition of Ca2+ or Al3+ counterions. Although the evolution in the surface structure with surfactant and counterion concentration is broadly similar to those reported for SDS, SAES and AES, some notable differences occur. In particular the surfactant and counterion concentration thresholds for surface multilayer formation are higher for Ca2+ than for Al3+. The differences encountered reflect the greater affinity of the di-alkyl chain structure for lamellar formation, and how the surface packing is controlled in part by the headgroup structure and the associated counterion binding affinity.

On the cusp of a miniaturized device era, a number of promising methods have been developed to attain large-scale assemblies of micro- and nanoparticles. In this study, a novel method is proposed to firmly capture dispersed microparticles of nominal sizes of 10 μm on a two-dimensional array (1.0 × 1.0 mm2) of through-pores on a surface. This is obtained by dispensing a droplet of the particle dispersion on the pores, which drains by applying a vacuum-driven force at the backside of the pores. The assembled particles are captured on the surface in a reversible way, making them available for direct manipulation and inspection, or subsequent transfer of the particles to a second surface. The relevant process parameters dispersant concentration, dispersant type, particle properties, and pitch distance d, are optimized to obtain (near-)perfect ordered particle arrays. Furthermore, to significantly improve the quality of the particle assembly, washing steps are added to remove excess particles from the surface. Silica or polystyrene (PS) particle assemblies with an error ratio (ER) as low as 0.2% are obtained, demonstrating the universality of the proposed method. For the smallest pitch, d = 1.25 μm, even with optimal process parameters, higher ER-values (=1.1%) are obtained.

Obtaining winter diesel fuel is an expensive and complex process, in which paraffinic hydrocarbons are removed from the fuel. Today, the consumption of winter diesel fuel in Russia has reached its maximum, and the volume produced is not enough to meet the needs of the Russian market. Therefore, obtaining winter diesel fuel from summer grades, by adding a depressant additive, remains relevant. The most common depressants are ethylene vinyl acetate copolymers. The effectiveness of depressant-dispersant additives depends on the fractional and group hydrocarbon composition of diesel fuel. Also, the physicochemical characteristics of the paraffins contained in the fuel play an important roleDuring long-term storage of fuel, depressants do not prevent fuel stratification. Therefore, together with a depressant additive, a paraffin dispersant is used, the composition of such additives includes mainly amides and imides of mono- and dicarboxylic acids. Dewaxol 7801 depressant and dispersant additive is a specially selected composition based on surfactants and copolymers in a hydrocarbon solvent. The use of this additive makes it possible to improve the low-temperature performance of diesel fuel without affecting other properties. From the low-temperature properties of diesel fuel, we have chosen the limiting filterability temperature, since it is this temperature that characterizes the real working conditions. When the maximum filterability temperature is reached, the n-paraffin crystals reach sizes exceeding the pore diameters of the filters, the fuel is not pumped through the fine filters of the high-pressure fuel pump, and the fluidity of the fuel deteriorates. The article shows the effect of Dewaxol 7801, a depressant-dispersant additive, on summer diesel fuel, in various concentrations and when the fuel is heated from 40 to 60 degrees in steps of 10 degrees.

Water-based ZnO nanofluids were prepared via the two-step method, and the influences of dispersant type and mass fraction on the stability and particle size distribution of the nanofluids were investigated. The spectral transmittances of the nanofluids were obtained by a UV-Vis-NIR spectrophotometer. Thermal conductivities of the nanofluids with various mass fractions were measured at different temperatures and a fitted nonlinear correlated equation was established for low-concentration application and compared with existing models. The photothermal conversion performance of the nanofluids was evaluated by theoretical and experimental methods at three optical depths. The results showed that, CTAB as the dispersant provides better physical stability of water-based ZnO nanofluids than SDBS or GA does. Effect of the temperature on the nanofluid thermal conductivity is remarkable with the increase of nanoparticle mass fraction, especially in the range 55°C to 75°C. The maximum thermal conductivity of the studied nanofluids is 0.9488 W/(m·°C) at 75°C, 43.61% higher than that of water. The minimum thermal conductivity of the studied nanofluids is 0.6376 W/(m·°C) at 25°C, 5.16% higher than that of water. The photothermal conversion performance of the nanofluids is quite good with a maximum average absorption efficiency of 0.47, 135% higher than that of water (η=0.2), and the maximum SAR is 527.5 W/g.

French Guiana heavily relies on high-cost imported materials to sustain its strong population growth and construction demand. Local alternatives such as earth concrete are needed to reduce the use of conventional concrete. It is currently unknown if tropical soils are suitable for non-cement stabilized earth construction and especially what are the characteristics of these soils. In this study, 14 soils were characterized (particle size, EDS-SEM, FTIR, color) and evaluated as building materials on earth mortar prismatic specimens. For each soil, physical and mechanical mortar properties were evaluated based on two formulations of equivalent plastic consistency, with or without dispersant (0.5% of dry mass). The results show that hardened mortar properties were driven by water content at fresh state, particle size, and Fe and Al-oxide content. Water content directly correlated with fine-grains content and negatively impacted all mortar properties. The use of dispersant reduced water content and considerably improved compressive strengths, reaching up to 4 MPa. Compressive strength positively correlated with Fe and Al content and could be predicted by soil color. Overall, the characterized soils demonstrated good mechanical aptitude when mixed with a low level of dispersant, indicating a high potential for construction, particularly for metal oxide-rich soils., Academic Journal of Civil Engineering, Vol 40 No 2 (2022): Special Issue - NoMaD 2022

The application of chemical dispersants aims to stimulate microbial oil degradation by increasing the bioavailability of oil compounds. Overall, nine microcosms were prepared (three for each treatment) using treated sediment with (i) dispersant (d: 25 ppm), (ii) oil (500 ppm), and (iii) with oil + dispersant (500: 25 ppm), respectively. There are also three control microcosms containing only water and sediment without petroleum. Then, we analyzed bacterial abundance, total hydrocarbon, biological oxygen demand (BOD5), and chemical oxygen demand (COD) in each microcosm. Bacterial response density was significantly affected after 40 days of exposure; it was higher in the control microcosm and d (> 24.103 cell/l) than in the other treatments. The index of total hydrocarbons was equal to 53 mg/kg dw in oil and 56 mg/kg dw in oil + dispersant. The higher BOD5 found in oil and in oil + d shows the increased amount of oxygen consumed, which indicates enhanced bacterial activity. Microcosms treated with dispersant had higher COD than the others, but the dispersant did not stimulate microbial hydrocarbon degradation.

Large quantities of lignin are produced as by-streams via chemical pulping and emerging biorefinery processes. These lignins are typically water-insoluble; however, they can be converted into a water-soluble form by chemical modifications. A novel LigniOx technology solubilizes lignin using alkali-O2 oxidation. The product can be used for bio-based dispersants. This study evaluated the biodegradability of alkali-O2 oxidized kraft, organosolv, and hydrolysis lignin. The oxidized lignins exhibited higher biodegradation in soil and in aquatic environments in comparison to a commercial kraft lignin and a commercial lignosulfonate. In soil, the biodegradabililties of oxidized lignins were 19 to 44%, whereas the reference lignins exhibited only 5 to 12% conversion to CO2. Biodegradation of the oxidized lignins and references in the aquatic environment increased in a similar order as in the soil environment, although the degradation in each sample was slightly smaller, than in the soil. The improved biodegradability of the oxidized lignins was due to the altered chemical structure of lignin. Compared to the untreated lignin, the oxidized lignin contained structures formed in aromatic ring opening reactions, making the lignin more accessible to microbial degradation. In addition, the oxidized lignin contained carbon originating from small organic compounds, which are easily biodegradable

The development of composites from 1D and 2D nanocarbon building blocks, namely carbon nanotubes and graphene layers, with enhanced properties or novel functionalities is an emerging challenge in material science. Herein, we developed a colloid-based approach using surfactants and polymers to non-covalently functionalize multiwalled carbon nanotubes (MWNTs) and graphene nanoplatelets (GnPs), and to fabricate GnP@MWNT nanocomposites via an electrostatic-driven assembly process in aqueous solution. In the assembly process, two building methods were used and compared (bulk mixing and adapted layer-by-layer assembly), using surfactant and polymer/surfactant combinations as the dispersants for the initial nanomaterials. After their characterization by scanning electron microscopy, Raman spectroscopy and BET analysis, the nanocomposites were evaluated as electrocatalysts for the oxygen reduction reaction (ORR). Results show that the type of the dispersant (namely the presence of polymer) plays a more relevant role than the specific building method in almost all the ORR parameters. Further, the nanocomposites show selectivity toward the 2-electron pathway oxygen reduction for the electrochemical production of hydrogen peroxide. The development and optimization of further nanocomposite electrocatalysts can be pursued using this type of versatile and robust assembly method.

Nanocellulose is a renewable material with excellent properties. At present, nanocellulose powder is mainly prepared by high-cost spray drying, which severely limits its output and quality. In this paper, we propose an innovative method to prepare dispersible nanocellulose powder by simple precipitation and conventional evaporation. Potassium acetate was added to CNC (a kind of nanocellulose) suspension to precipitate and purify CNC. The added potassium acetate was dissolved in ethanol and removed. Then dispersible nanocellulose powder can be obtained by simple evaporation. In CNC purification, we discussed the combination of different electrolytes and CNCs. It was found that although the monovalent electrolytes lead to weak aggregation with CNC, the resulting dry CNC powder had the best dispersion. In CNC drying, we discussed the effects of different dispersants and different drying methods on the forming of dry CNC powder. It is revealed that ethanol is the best dispersant tested in this paper because it can only form a single hydrogen bond with CNC and is easy to evaporate. In the evaporation of CNC and ethanol mixture, it will not lead to the aggregation of CNC fibers. It is hopeful that the new method may greatly reduce the cost of the preparation of nanocellulose powder.

Polypropylene (PP)/poly(benzyl methacrylate) (PBzMA) composite particles were prepared by dispersion polymerization of benzyl methacrylate (BzMA) in the presence of PP particles without a conventional dispersant. The polymerization process yielded a stable emulsion of composite particles with a "currant bun"-like morphology consisting of a PBzMA core and PP bumps, indicating that the PP particles operate as colloidal stabilizers. Conversely, when BzMA was replaced with styrene as the monomer, dispersion polymerization yielded a large amount of aggregates. Finally, a stable emulsion was formed by copolymerizing a small amount of methyl methacrylate (MMA) with styrene. This result suggested that PP must interact with a second polymer to prepare stable composite particles. The surfaces of the PP particles, which are highly hydrophilic due to their carboxyl groups, were involved in the attachment and stabilization of the polymer precipitated in the medium. A film prepared from the obtained PP/PBzMA composite particles was highly hydrophobic and strongly adhesive to a PP sheet.

This study reports an approach to reutilize ceramic polishing waste as a multifunctional additive for coatings. A stable aqueous dispersion of the ceramic polishing waste was prepared with ceramic polishing waste, water, and an appropriate dispersant. The process of preparation was investigated by particle size, dynamic viscosity and XRD analysis. Moreover, a series of coatings containing various stable dispersions, consisting of ceramic polishing waste, resin, and other additives, were made for conducting the contrast ratio, the hardness, the adhesion power, the film bending test, the scrub resistance and the corrosion resistance test. The test results showed that as a multifunctional additive for coatings, the dispersion from ceramic polishing waste added can significantly enhance the properties of polymer film and the white paint film. However, the optimum addition amount of the dispersion varies with the types of polymers and white paints.