Influence of dispersants on coal-water slurry prepared from the solid residue of plasma pyrolysis of coal

This work presents the influence of dispersants on coal-water slurry(CWS),which was prepared from the solid residue of plasma pyrolysis of coal.The effects of dispersant type,solid concentration,dispersant content,and temperature on the rheological properties of CWS are examined.A suitable empirical model regarding the relation between viscosity and temperature is proposed.Through the sedimentation experiment of CWS,dispersants are found to significantly promote the stability of CWS.

Influence of the Precipitating Reagents and Dispersants on the Formation Nano-Aluminum Hydroxide

The influence of the precipitating reagents and dispersants on the formation of nano-aluminum hydroxide from sodium aluminate solution by chemical precipitation was investigated. The influence of the dispersed seeds on the decomposi-tion process was investigated too. The alkaline aluminate solutions were used as original solutions with a concentration of Al2O3 having 14.78 g/dm3, αk—1.6 and127 g/dm3, αk—1.6. For the precipitation processes there were used follow-ing precipitating reagents—solutions HCl, NaHCO3 and NH4HCO3 with a concentration of 80 g/dm3, dispersants—PEG 6000, (NaPO3)6 and Tween 20. For the decomposition process the dispersed seeds and factories seeds were used. Structural studies of the aluminum hydroxide particles were carried out by means of the electron-probe microanalysis and scanning electron microscopy, and phase composition of products was determined by means of X-ray diffraction analysis. Ammonium bicarbonate and Tween 20 were determined as the optimal precipitating reagent and dispersant, correspondingly, resulting in dispersed aluminum hydroxide, which is used as a seed in the decomposition process. It was established that this product in form of dispersed seed considerably reduces the duration of the decomposition process;the maximal decomposition of solution (73.9%) was observed after injection of dispersеd aluminum hydroxide into solution. The final aluminum hydroxide having 90% of particles less than 100 nanometers was obtained within 7 hours of steady decreasing temperature from 70°C to 48°C.

Effect of Mixed Dispersants on Suppression of the Gel Effect during Aqueous Adiabatic Terpolymerization of AM,NaAA,and DMC

Gelation adversely affects the aqueous adiabatic terpolymerization of acrylamide (AM), sodium acrylate (NaAA),and 2-methacryloyloxyethyl trimethylammonium chloride (DMC). Here, the mixed dispersants sorbitan monooleate (Span80) and polyoxyethylene sorbitan monooleate (Tween 80) were introduced to the terpolymerization system in an attemptto mitigate the gel effect. This enabled the preparation of high-performance amphoteric polyacrylamides, which werecharacterized by Fourier-transform infrared spectroscopy and thermogravimetric analysis. The influences of the dispersanttype and content as well as the hydrophilic-lipophilic balance (HLB) on the gel effect were examined, and the mechanismunderlying the suppression of the gel effect was considered. The obtained results indicated that the gel effect can beeffectively mitigated using an aqueous adiabatic terpolymerization system containing mixed Span 80/Tween 80 dispersantsat various contents. In particular, mixed dispersant contents of 0.6%–0.8% with HLB values of 5.0–6.0 afforded the optimalperformance (e.g., high viscosity, fast aqueous dissolution time, and the like).

A comprehensive experimental evaluation of asphaltene dispersants for injection under reservoir conditions

As the efficiency of dispersants with different origins is questionable for each typical oil sample, the present study provides a reproducible and reliable method for screening asphaltene dispersants for a typical asphal- tenic crude oil. Four different asphaltene dispersants （polyisobutylene succinimide, polyisobutylene succinic ester, nonylphenol-formaldehyde resin modified by polyamines, and rapeseed oil amide） were prepared and their performance on two oils from an Iranian field under laboratory and reservoir conditions was studied. A thorough analysis including ash content and SARA tests was performed on the solid asphaltene particles to characterize the nature of deposits. Then a highly efficient carrier fluid, which is crucial when injecting dispersant into the wells, was selected from a variety of chemicals by comparing their solubility. In the next step, using an optical microscope, a viscometer, and a Turbiscan, the screening of dispersants under laboratory conditions was done on a mixture of dead oil and dispersant to evaluate the onset of asphaltene precipitation and its stability when titrating by a precipitant. Finally, two different mixtures of the efficient dispersants, live oil, and carrier fluid were used with the solid detection system （SDS） and the filtration method to examine their effects on the onset pressure of asphaltene precipitation and the asphaltene content of the crude oil under reservoir conditions. The results show that the combination of experimental methods used in this work could be consistently applied to screening asphaltene dispersants. Among the four different dispersants applied here, the dispersant based on nonylphenol-formaldehyde resin modified by polyamines showed the best performance on the available live oils. This chemical modified the onset pressure of asphaltene precipitation of light oil from 4300 psi to about 3600 psi and decreased the precipitated asphaltene of heavy oil by about 30 %.

Influence of polymer dispersants on dispersion stability of nano-TiO_2 aqueous suspension and its application in inner wall latex paint

The effects of SN5040 and polyethylene glycol（PEG） individually and in combination on the dispersion stability of nano-TiO2 aqueous suspension were investigated by ultraviolet-visible absorption spectroscopy. The adsorption mechanism of these dispersants was detected by zeta potential, isothermal absorption and FTIR analysis. It is found that SN5040 is superior for stabilizing nano-TiO2 in aqueous suspension to PEG in basic region, and the optimum mass fraction of SN5040 addition is 3%. In the case of NaCl addition, the optimum value increases with .the increase of NaCl concentration in the solution. When the mixture of SN5040 and PEG is employed, the antagonism appears preponderant. When SN5040 and PEG are added sequentially, the synergistic reaction takes place. The synergistic reaction can be attributed to the mechanism that PEG adsorption decreases the electronic repulsion between SN5040 molecules, which results in the increase of SN5040 adsorption density. PEG is adsorbed by the interaction with the pre-adsorbed SN5040 layer. Furthermore, the modified inner wall latex paint with well dispersed nano-YiO2 suspension is endowed with excellent ultraviolet absorption and antibacterial properties.

Simulation and Experimental Study on the Effect of Dispersants on Soot Aggregation

Diesel engine technology innovation causes excessive soot accumulated in engine oil.Due to its detrimental effect on lubricant and diesel engine,improving the dispersibility of engine oil to restrain soot aggregation efficiently is the key technique for formulations.In this study,the aggregation of soot and interaction between dispersant and soot were investigated by molecular dynamic simulation.It was found that the molecular interaction between the dispersant and the soot aggregation system had a significant influence on disrupting the soot aggregation.Bis-PIBSI was more beneficial to having more interaction sites with soot molecules,while the mono-PIBSI with a high proportion of polar groups had stronger interaction with soot molecules.According to the simulation result,suggestions for use of additives were proposed.Carbon black dispersancy test was exploited to verify the dispersion effect of different dispersants on carbon black.The results indicate that mono-PIBSI and bis-PIBSI added at suitable mixture ratio to lubricant could perform good dispersion ability.

Comparison of toxicity effects of fuel oil treated by different dispersants on marine medaka(Oryzias melastigma) embryo

This study aims to evaluate the subacute toxic effects of oil under different treatments on marine organism by simulating natural contaminative processes. In this study, 120# （RMD15） fuel oil was selected as the pollutant and marine medaka （Oryzias melastigma） embryos as the experimental organism. The developmental toxicity of different volume concentrations （0.05%, 0.2%, 1% and 5%） of water-accommodated fractions, biologically-enhanced water-accommodated fractions, and chemically-enhanced water-accommodated fractions on the embryos in different exposure time （8, 15 and 22 d） were compared and the content of relevant polycyclic aromatic hydrocarbons （PAHs） was studied （in dispersion and in vivo）. The subacute toxic effects were assessed in terms of antioxidant activities of enzymes （superoxide dismutase, catalase and glutathione S-transferase） and the blue sac disease （BSD） indexes.The results showed that the BSD indexes of the treatment groups were significantly higher than the respective control groups and showed positive correlations with both concentration and exposure time. The experiments with three antioxidant enzymes indicated that enzymatic activities of the embryos changed dramatically under the oxidation stress of petroleum hydrocarbons, especially after adding the dispersants. With the increase of petroleum hydrocarbon concentration and exposure time, the three enzymes showed different degrees of induction and inhibition effects.

Stability of aqueous nano-ceramic coatings with two different dispersants

The effects of sodium carboxymethyl cellulose and sodium citrate as dispersants on nano-ceramic aqueous suspension were examined by the measurements of ζ -potential and the sedimentation test. The results show that proper addition of sodium carboxymethyl cellulose or sodium citrate into nano-ceramic coating, exhibits an enhanced dispersion and stability compared with the coating without dispersants. The negative ζ -potential of the particles in the nano-coating increases with the increase of pH value of the coating, and the curve of ζ -pH moves to lower pH range when the dispersants are added into the coating. To ensure that the coating has not only good stability and dispersibility but also no corrosivity to substrate alloy, adding 1.00% sodium citrate into coating with pH value of 7-8 is preferable to adding sodium carboxymethyl cellulose.

Synthesis and properties of hyper-dispersants

The synthesis and properties of three kinds of hyper-dispersants are studied in this paper, which are non-terminated, carboxyl-terminated and polyethylene imine grafted poly（hydroxyl carboxylic acid） ester. The hyper-dispersants are synthesized by the materials of 12-hydroxy-stearic acid, stearic acid and polyethylene imine, which are used to improve the dispersion properties of nano titanium dioxide （nano-TiO2） in low-concentration resin solution system. The influences of hyper-dispersants on the viscosity and stability of the system are studied. It is found that polyethylene imine grafted hyper-dispersant has the best dispersion performance in nano-TiO2 dispersion system, and the optimal content of the hyper-dispersant is 4%.

Influence of Dispersants on Flow Ability of Colloidal Alumina Bonded Corundum Castables

In order to make corundum castables satisfy more severe service conditions in high temperature industries,colloidal alumina due to the same main component with corundum castables was introduced for a pure binding system.The influence of three dispersants(citric acid,FS10 and urea)on the flow ability of colloidal alumina bonded corundum castables was researched to choose a suitable dispersant for solving the shaping problem.In order to further understand the influence of dispersants on the flow ability and the mechanism,the rheological property and Zeta potential value of the colloidal aluminadispersant system and the matrix-colloidal alumina-urea-water system were tested.The results show the castables added with the urea have the best flow ability,and the appropriate addition of the urea is 0.5%.

Interfacial properties of oil spill dispersants and their effects on dispersion effectiveness

Ｉｎｔｅｒｆａｃｉａｌ ｐｒｏｐｅｒｔｉｅｓ ｏｆ ｏｉｌ ｓｐｉｌｌ ｄｉｓｐｅｒｓａｎｔｓ ａｎｄ ｔｈｅｉｒ ｅｆｆｅｃｔｓ ｏｎ ｄｉｓｐｅｒｓｉｏｎ ｅｆｆｅｃｔｉｖｅｎｅｓｓＩｎｔｅｒｆａｃｉａｌｐｒｏｐｅｒｔｉｅｓｏｆｏｉｌｓｐｉｌｌｄ...

Development of High Efficient and Low Toxic Oil Spill Dispersants based on Sorbitol Derivants Nonionic Surfactants and Glycolipid Biosurfactants

Dispersants, usually blending with several surfactants and a solvent, are used to enhance oil spill dispersion as small droplets in water column. Although there is growing acceptance of dispersants as a counter measure to marine oil spills around the world, the two major issues with the dispersants are their toxicity to marine life and dispersion effectiveness (DE) for crude-oil, especially for heavy oil. To develop more efficient and less toxic dispersants, two kinds of sorbitol derivant nonionic surfactant (polysorbate 85 and sorbeth-40 tetraoleate), two kinds of glycolipid biosurfactants (rhamnolipid and sophorolipid) and less toxic solvent ethylene glycol butyl ether were chosen in this study, and two dispersant formulations were optimized by uniform design methods. Effects of dispersant-to-oil ratio, temperature, salinity and pH on the performance of the two optimized dispersants were investigated. The two dispersants had high dispersion effectiveness (DE) for heavy crude oil, while both dispersants keep high DE at the dispersant-to-oil ratio below 1:25 and the temperature above 5 ℃. In addition, the two dispersants also performed well in a wide range of salinity and pH values. Finally, toxicity tests revealed that the two dispersants showed low toxicity to two kinds of fish (Danio rerio and Microgobius gulosus).

Clarification of the dispersion mechanism of three typical chemical dispersants in lithium-ion battery (LIB) slurry

This paper mainly clarified the dispersion mechanism of three typical chemical dispersants which are polyethylene glycol octylphenyl ether(Triton X-100,T-100),polyethylene pyrrolidone(PVP)and carboxymethyl cellulose(CMC)within lithium-ion battery(LIB)slurry.Initially,the optimum amounts of T-100,PVP and CMC are selected from 0%,0.5%,1.5%and 2.5%by evaluating the impedance of LIB slurry in the case of adding each typical chemical dispersant with EIS method.Moreover,the impedance spectrum of three different slurry samples which are PVDF-NMP solution,LiCoO_(2) slurry and Carbon Black(CB)slurry with the optimum amount of each dispersant are also investigated.After using SEM and C element distribution images of LIB slurry to verify the correctness of the dispersion mechanism of each dispersant,it is concluded that the dispersion CMC with its optimum amount 1.5%is the best one to promote the formation of conductive paths and CB-coated LiCoO_(2) network structure within LIB slurry,which has the considerably potential to improve the performance of LIB.

Facile Fabrication of High-performance Polyimide Nanocomposites with in situ Formed“Impurity-free”Dispersants

Polyimide/carbon black（PI/CB） nanocomposite films were fabricated via the direct ball-milling method with poly（amic acid）（PAA）, the precursor of PI, as an in situ formed impurity-free dispersant. FTIR and Raman spectral results reveal that, besides physical adsorption, chemical grafting of PAA chains onto the CB surface occurs during the ball-milling process. Comparative studies show that introduction of various commercial dispersants improves the dispersion of CB. However, the mixtures exhibit poor reproducibility, unstable electrical properties, and decreased tensile strength; these issues may be attributed to interfacial pollution brought about by differences in the chemical structures of the dispersant and the matrix. The impurity-free dispersant is effective not only in ensuring the uniform dispersion of CB particles but also in enhancing filler-matrix interfacial adhesion. High-molecular weight PAA chains are effective reagents for impurity-free modification and can therefore be used to improve the electrical and mechanical properties of the resultant composite.

Design and Application of Novel Dispersants for Coatings and Other System

1 Results Dispersants are defined as liquids or gases that can be added to a mixture to promote dispersion or to maintain dispersed particles in suspension. A good dispersant not only helps to provide good dispersion, but also good performance, stability and rheological properties. Therefore, dispersants are widely used in many applications such as coating, ink, electronic materials, plastics, and so on[1]. There are different ways to categorize the many dispersants available on the market. From a molec...

Strong synergy between physical and chemical properties:Insight into optimization of atomically dispersed oxygen reduction catalysts

Atomically dispersed catalysts exhibit significant influence on facilitating the sluggish oxygen reduction reaction(ORR)kinetics with high atom economy,owing to remarkable attributes including nearly 100%atomic utilization and exceptional catalytic functionality.Furthermore,accurately controlling atomic physical properties including spin,charge,orbital,and lattice degrees of atomically dispersed catalysts can realize the optimized chemical properties including maximum atom utilization efficiency,homogenous active centers,and satisfactory catalytic performance,but remains elusive.Here,through physical and chemical insight,we review and systematically summarize the strategies to optimize atomically dispersed ORR catalysts including adjusting the atomic coordination environment,adjacent electronic orbital and site density,and the choice of dual-atom sites.Then the emphasis is on the fundamental understanding of the correlation between the physical property and the catalytic behavior for atomically dispersed catalysts.Finally,an overview of the existing challenges and prospects to illustrate the current obstacles and potential opportunities for the advancement of atomically dispersed catalysts in the realm of electrocatalytic reactions is offered.

Alkyl dimethyl betaine activates the low-temperature collection capacity of sodium oleate for scheelite

The impact of alkyl dimethyl betaine (ADB) on the collection capacity of sodium oleate (NaOl) at low temperatures was evaluated using flotation tests at various scales. The low-temperature synergistic mechanism of ADB and NaOl was explored by infrared spectroscopy, X-ray photoelectron spectroscopy, surface tension measurement, foam performance test, and flotation reagent size measurement.The flotation tests revealed that the collector mixed with octadecyl dimethyl betaine (ODB) and NaOl in a mass ratio of 4:96 exhibited the highest collection capacity. The combined collector could increase the scheelite recovery by 3.48% at low temperatures of 8–12℃. This is particularly relevant in the Luanchuan area, which has the largest scheelite concentrate output in China. The results confirmed that ODB enhanced the collection capability of NaOl by improving the dispersion and foaming performance. Betaine can be introduced as an additive to NaOl to improve the recovery of scheelite at low temperatures.

Oxygen‑Coordinated Single Mn Sites for Efficient Electrocatalytic Nitrate Reduction to Ammonia

Electrocatalytic nitrate reduction reaction has attracted increasing attention due to its goal of low carbon emission and environmental protection.Here,we report an efficient NitRR catalyst composed of single Mn sites with atomically dispersed oxygen(O)coordination on bacterial cellulose-converted graphitic carbon(Mn-O-C).Evidence of the atomically dispersed Mn-(O-C_(2))_(4)moieties embedding in the exposed basal plane of carbon surface is confirmed by X-ray absorption spectroscopy.As a result,the as-synthesized Mn-O-C catalyst exhibits superior NitRR activity with an NH_(3)yield rate(RNH_(3))of 1476.9±62.6μg h^(−1)cm^(−2)at−0.7 V(vs.reversible hydrogen electrode,RHE)and a faradaic efficiency(FE)of 89.0±3.8%at−0.5 V(vs.RHE)under ambient conditions.Further,when evaluated with a practical flow cell,Mn-O-C shows a high RNH_(3)of 3706.7±552.0μg h^(−1)cm^(−2)at a current density of 100 mA cm−2,2.5 times of that in the H cell.The in situ FT-IR and Raman spectroscopic studies combined with theoretical calculations indicate that the Mn-(O-C_(2))_(4)sites not only effectively inhibit the competitive hydrogen evolution reaction,but also greatly promote the adsorption and activation of nitrate(NO_(3)^(−)),thus boosting both the FE and selectivity of NH_(3)over Mn-(O-C_(2))_(4)sites.

Tunable dispersion relations manipulated by strain in skyrmion-based magnonic crystals

We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. Especially, the allowed bands and forbidden bands in dispersion relations shift to higher frequency with strain changing from compressive to tensile,while shifting to lower frequency with strain changing from tensile to compressive. We also confirm that the spin wave with specific frequency can pass the magnonic crystal or be blocked by tuning the strains. The result provides an advanced platform for studying the tunable skyrmion-based spin wave devices.

Pipeline thickness estimation using the dispersion of higher-order SH guided waves

Thickness measurement plays an important role in the monitoring of pipeline corrosion damage. However, the requirement for prior knowledge of the shear wave velocity in the pipeline material for popular ultrasonic thickness measurement limits its widespread application. This paper proposes a method that utilizes cylindrical shear horizontal(SH) guided waves to estimate pipeline thickness without prior knowledge of shear wave velocity. The inversion formulas are derived from the dispersion of higher-order modes with the high-frequency approximation. The waveform of the example problems is simulated using the real-axis integral method. The data points on the dispersion curves are processed in the frequency domain using the wave-number method. These extracted data are then substituted into the derived formulas. The results verify that employing higher-order SH guided waves for the evaluation of thickness and shear wave velocity yields less than1% error. This method can be applied to both metallic and non-metallic pipelines, thus opening new possibilities for health monitoring of pipeline structures.