Polycarboxylate Dispersant Research Articles

Exploring the impact of pH and temperature on TiC nanopowders syntesized via sol-gel and subsequent crystallization by carbothermal reduction method

In the present study, titanium carbide powders with suitable morphology and nanometer particle size were synthesized by the sol–gel method to investigate the parameters affecting the properties of sol and the final powder. The initial sol was prepared in a four-component system of alkoxide-water-alcohol-citric acid based on the chemical process of sol–gel. The study of sol properties showed that pH was the most important factor in the control of sol conditions and particle size so that at low pHs, due to low concentration of OH− ions and reduced viscosity, it was easier to control the particles size. Accordingly, the results of the Dynamics Light Scattering (DLS) showed that at low pHs, the particles size was below 10 nm. According to the zeta potential diagram and by examining the conditions of sol at different pHs, 4.5 was determined as the optimal pH and to prevent the bonding of particles within the sol, ammonium polycarboxylate dispersant was used. The temperature at which particles were formed was determined using Differential thermal analysis (DTA) and Thermal gravimetric analysis (TG). X-ray diffraction (XRD) patterns showed the presence of a completely amorphous phase at 700 °C. It was also observed that with increasing temperature, TiC crystallization started from 1200 °C and ended at 1400 °C. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) micrographs at 1400 °C showed the completely spherical morphology of particles of nanometer size so that no agglomerate was observed.

Molecular dynamics simulations and experimental study of the modification mechanisms of a quaternary amphoteric polycarboxylate dispersant on the rheology of petroleum coke water slurry

Petroleum coke, as a byproduct of delayed coking in oil refineries, can be used as a raw material for gasification to meet the demand for hydrogen in oil refining processes, which can significantly reduce the cost of oil refining while efficiently and cleanly utilizing solid waste. Due to the low ash content of petroleum coke, the feedstock used for gasification is usually petroleum coke water slurry (PWS). However, the rheology of PWS needs to be improved before gasification. In this paper, a quaternary amphoteric polycarboxylate dispersant (PC-4) was synthesized by free radical polymerization with methylallyl polyoxyethylene ether (HPEG-1000), sodium styrene sulfonate (SSS), acrylic acid (AA) and trimethylallyl ammonium bromide (TAB), and for studying the influence of -N(CH3)4+, a ternary polycarboxylate dispersant (PC-3) was also prepared without the -N(CH3)4+ cationic group. The adsorption capacity of PC-4 is about 1.6 times higher than that of PC-3, and PC-4 also leads to an increased zeta potential and stronger hydrophilic modification performance when used to modify Lanqiao petroleum coke (LQ). Therefore, PC-4 is more suitable for enhancing the slurryability and rheological behavior of PWS. Molecular dynamics simulation (MD) was employed to reveal the adsorption mode of PC-4 on the surface of LQ particles. The cation-π interaction between the -N(CH3)4+ ions of the PC-4 molecules and the aromatic structure of the petroleum coke were directly observed in images obtained from the MD simulation. The introduction of -N(CH3)4+ optimizes the adsorption configuration, resulting in a relatively dense and uniform dispersant layer on the LQ particle surface. Finally, the experimental results and MD simulation were integrated to reveal the PWS modification mechanism of PC-4.

Preparation and Utilization of a Comb‐Like Polycarboxylate Dispersant for Organic Pigment

AbstractAs a novel form of carboxylate comb‐like copolymers, SAM‐(m)PEG was prepared by polymerizing styrene (S), acrylic (A), and maleic anhydride (M) to obtain a random copolymer labeled SAM. SAM was then esterified using either polyethylene glycol (PEG) or methyl PEG (mPEG), a waterborne polymer dispersant for dispersing and stabilizing C.I. Pigment Yellow 180 (PY 180). The structures of SAM‐(m)PEG and the ground suspension of PY 180 were characterized by Fourier transform infrared (FT‐IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM), a nanoparticle size analysis, and viscometry. The effects of different branch chains, synthetic formulas, and grinding conditions on the dispersibility of SAM‐(m)PEG were evaluated. In addition, the optical properties of the pigments were investigated after ultrafine grinding. The adsorption mechanism between the SAM‐(m)PEG dispersants and PY 180 particles is also discussed. SAM‐PEG6002 outperformed the other SAM‐(m)PEG dispersants owing to its excellent dispersion and stability. When used as the dispersant, the average particle size (Z‐average) of PY 180 after grinding was 264.6 nm, and the particle size distribution became narrow (PDI=0.089). Moreover, SAM‐PEG6002 effectively maintained the color performance of the pigment, and the product was successfully applied to the pigment coating. Therefore, SAM‐PEG6002 is an effective waterborne polymer dispersant for organic pigments.

Design and evaluation of a novel dispersant with “surface-to-surface” adsorption function for preparing low-rank coal water slurry

It is important to improve the performance of low-rank coal water slurry (CWS) for the development of coal gasification. In this study, to prepare high-quality Shenhua coal water slurry, a novel GON-APEG dispersant with “surface-to-surface” adsorption function was designed and synthesized by grafting the allyl polyoxyethylene ether (APEG) onto the edge of graphite oxide nanosheet (GON) through esterification and emulsion polymerization. The influences of GON-APEG on the properties of CWS, the adsorption isotherm of GON-APEG, and the surface properties of coal were studied, and compared with GON, sodium lignosulphonate (SL), and polycarboxylate (PC) dispersants. The GON-APEG was superior to other dispersants in viscosity-reducing and stabilizing ability. Under the optimum dosage of 0.3 wt%, the maximum coal content of CWS with GON-APEG was 64.5 wt%. All the CWSs with different dispersants belonged to typical yield pseudoplastic fluid. Meanwhile, the adsorption isotherms of four dispersants had a good correlation with the Langmuir model, and the saturated adsorption capacity of GON-APEG was greater than SL and PC dispersants. The GON-APEG decreased the contact angle of water on the coal surface and increased the absolute value of Zeta potential of coal to the greatest extent. The excellent performance of GON-APEG in CWS was due to its strong interaction with coal derived from “surface-to-surface” adsorption mode, which was beneficial to regulate the surface properties of coal. In sum, this study provides a new idea for improving the properties of Shenhua coal water slurry and developing the efficient dispersants in other fields.

Synthesis and performance evaluation of polycarboxylate dispersant for oil well cement

Although polycarboxylate (PCE) is widely used in the concrete industry, its application in cementing engineering is restricted owing to its poor temperature resistance and strong retardation effect on oil well cement. Hence, in this study, a sulfonated polycarboxylate (SPC) dispersant suitable for oil well cement was synthesised by performing free-radical polymerisation using ω-hydroxy polyethylene glycol ether, acrylic acid, and 2-acrylamide-2-methylpropanesulfonic acid as raw materials, and its molecular structure was characterised by using Fourier transform infrared spectroscopy, gel permeation chromatography, and 1H-nuclear magnetic resonance spectroscopy. The rheological properties, thickening curve, and compressive strength of the SPC cement slurry were studied. The hydration products of the SPC cement slurry were analysed by using X-ray diffraction, and the microstructure of the cement stone was examined by using mercury intrusion porosimetry and scanning electron microscopy. The results showed that SPC has good dispersion performance and can effectively reduce the particle size and improve the workability and rheological properties of cement slurry. In addition, SPC has a less retardation effect on the cement slurry than conventional PCE, which can reduce the number of detrimental pores in cement stone, increase compactness, and improve the early compressive strength of cement stone.

Experimental and computational studies of polycarboxylate dispersant effect on the properties of low‐rank coal water slurries

AbstractThe disadvantages of low‐rank coal in the preparation of coal water slurry (CWS) are well known, but the synthesis of suitable dispersants is a promising solution. Polycarboxylate dispersant (PC) is expected to be an efficient CWS dispersant due to its flexible and controllable structure. In this study, a series of binary PC dispersants were synthesized by controlling the ratio of acrylic acid (AA) to sodium styrene sulfonate (SSS), initiator fraction, and temperature, and the optimal PC was selected based on the apparent viscosity of 72# CWS at 100 s−1. The properties of 72# CWS were studied: This CWS exhibited shear‐thinning behavior, >14 static stability, and >55 wt% maximum solid loading, indicating the satisfactory performance of the optimal PC. The experimental results (including adsorption tests and zeta potential measurement) and molecular dynamics simulation showed that PC was effectively adsorbed on the surface of the coal particles by a horizontal multipoint adsorption mode, mainly through the interaction between the hydrophobic groups of the PC molecule and the hydrophobic areas of the coal particles. The hydrophilicity of the coal particles was therefore improved and the stability of their hydration layer was also enhanced, which accounted for the good static stability of 72# CWS. The amount of PC adsorption and the improved absolute zeta potential were associated with the decent properties of 72# CWS. This study is significant for promoting the molecular design of CWS dispersants based on their adsorption behavior.

Interactions of coal pitch with amphoteric polycarboxylate dispersant in coal pitch–water slurry: Experiments and simulations

As the main by-product of coal tar processing, large amounts of coal pitch (CP) are insufficiently utilized. In this study, to realize resource utilization, CP was used to prepare coal pitch–water slurry (CPWS) fuels with the addition of three amphoteric polycarboxylate dispersants (AAD-1, AAD-2, AAD-3). The effects of dispersants on the slurry characteristics were studied. The adsorption of dispersant and the surface properties of CP were also analyzed. Results showed that the AAD-2 with a moderate side-chain length had a better ability to increase the stability and reduce the apparent viscosity of CPWS than others. When the dosage of AAD-2 was 0.5 wt%, the maximum slurry concentration was 53.7 wt%. The adsorption behaviors of three dispersants could be fitted well by the Freundlich model, and the adsorption quantity of AAD-2 was greater than that of two other dispersants. The Zeta potential and wettability of CP were improved to the greatest for AAD-1. To explore the dispersion and stabilization mechanisms, the molecular dynamics simulation and extended DLVO theory were used to discuss the interactions between CP and dispersants, the interaction energy among CP particles. Results showed that the adsorption energy of AAD-2 with CP was the most prominent (-1520.29 kJ/mol), the mobility of water molecules was reduced. Furthermore, in the CPWS with AAD-2, the total interaction energy ΔET was more significant than that of other slurries, which was due to the larger steric hindrance energy from AAD-2. In sum, this research provided an experimental and theoretical basis for preparing slurry with CP and polycarboxylate dispersant.

Effect of molecular composition of comb-like polycarboxylate dispersants on hydrophobic dye dispersion properties

Six different polymers were synthesized to understand the effect of the chemical structure of comb-like polycarboxylates on hydrophobic dye dispersion. They varied in terms of molecular weight and side-chain density. Polymers characterization using Raman spectroscopy confirmed accomplished copolymerization using acrylic acid and tresylated polyethylene glycol. Further characterization indicated half of the polymers are in the range of 20 ± 4 kDa while others are in the range of 10 ± 1 kDa. The application of polymers as a dispersant was evaluated in dye dispersion and ink formulation. It has been found that lower molecular weight polymers resulted in dispersion instability. Moreover, a higher side-chain density of polycarboxylates led to the formation of more stabilized dye dispersions. Effective dispersant adsorption onto the dye particle surface was shown by zeta potential measurement. Also, it was indicated disperse dye solubility increased using the dispersants. The dispersants were successfully applied to ink formulation and the best dispersion stability, lowest dye particle size, lowest viscosity, and lowest surface tension were achieved using the polycarboxylate with the highest molecular weight and the highest side-chain density within the experimental range. Finally, inks were used for sublimation printing on polyester fabrics, and the color characteristics of the printed fabrics were assessed. This study introduces high-performance and cost-effective dispersants for the ink manufacturing, and textile industries.

Interactions of Coal Pitch with Amphoteric Polycarboxylate Dispersant in Coal Pitch–Water Slurry: Experiments and Simulations

Interactions of Coal Pitch with Amphoteric Polycarboxylate Dispersant in Coal Pitch–Water Slurry: Experiments and Simulations

Rheological behavior of oil well cement pastes containing various types of dispersants at different hydration temperatures

This research discusses the effects of different types of oil well dispersants and hydration temperatures on the rheological properties of cement pastes through rheometer. A polycondensate dispersant, AFS and three polycarboxylate dispersants, APC, PCES and MHS, were used at dosages ranging from 0.1% to 0.3% by weight of cement, and three hydration temperatures of 30, 45 and 60 ℃ were selected. The yield stress was calculated by modelling the flow curve through Herschel-Bulkley and Modified Bingham models. Furthermore, the thixotropy of the cement paste involving different dispersants and hydration temperatures was analyzed by hysteresis loop methods. Besides, the small amplitude oscillatory shear (SAOS) test was applied to evaluate rigidification rate of cementitious material, offering useful information for structuration process of cement paste. The results show that the influences of dispersants on rheological behavior are closely related to the molecular structure and the dosage of dispersant, as well as the temperature of hydration. Increasing the dosage of dispersant decreases the yield stress and apparent viscosity, but increases the hysteresis loop area, especially at the lower hydration temperature of 30 ℃. During SAOS measurement, the critical strain of cement paste with dispersants is higher than without dispersant. The storage modulus (G’) continuously increases with hydration time and temperature.

An efficient organosilane-modified polycarboxylate dispersant with excellent dispersing performance and superior wettability for tebuconazole suspension concentrate

The dispersion stability and wettability of suspension concentrates are beneficial for improvement of the utilization rate of pesticides.

Adsorption Properties of Comb-Shaped Polycarboxylate Dispersant onto Different Crystal Pyraclostrobin Particle Surfaces.

The stability of the suspension system of the two crystal forms of pyraclostrobin is evaluated using multiple light technology, and the adsorption performance of polycarboxylate dispersant on the surface of two different crystalline pyraclostrobin particles is compared in combination with XRD, FTIR, XPS, and SEM from the microscopic view. The adsorption kinetics and thermodynamics studies of 2700 on the surfaces of different crystalline forms of pyraclostrobin particles show that the adsorption process of 2700 on the surfaces of pyraclostrobin crystal forms II and IV conform to pseudo-second-order kinetic adsorption model. The Ea values for crystal forms II and IV are 12.93 and 14.39 kJ∙mol−1, respectively, which indicates that both adsorption processes are physical adsorption. The adsorption models of 2700 on the surfaces of pyraclostrobin crystal forms II and IV are in accordance with Langmuir adsorption isotherms. The ∆Gad values of crystal forms II and IV are negative and the ∆Sad values are positive at different temperatures. Therefore, the adsorption processes are spontaneous and accompanied by entropy increase. The results of this study provide an important theoretical basis for the selection of polycarboxylate dispersants in the suspension of pyraclostrobin. This study also provides a reference for the research of polycrystalline pesticide suspension concentrate.

Effect of dispersant types on the rheological and mechanical properties of oil well cement paste with nanosilica

This work evaluated the effect of various types of dispersants on rheological and mechanical properties of nanosilica filled cementitious composites. Three oil well cement dispersants, acetone formaldehyde sulfite (AFS), polycarboxylate (PC) and amphoteric polycarboxylate (APC) with various dosages (0.5%, 1.0% and 1.5% by weight of cement) were utilized to investigate the performance and working mechanism of dispersant in cementitious composites containing nanosilica. Results show that nanosilica adversely affects the rheological properties of cementitious materials, while PC and APC dispersants improve the rheological performance in comparison to AFS dispersant. Besides, cement hydration and microstructure for cement with various dispersants were characterized by Isothermal Calorimeter, X-ray Diffractometer, Thermal Gravimetry and Scanning Electron Microscopy. The PC dispersant with numerous carboxyl groups exhibits retardation of cement hydration, which shows a negative impact on the development of early compressive strength of set cement. The introduction of cationic groups in APC dispersant enhances its dispersion ability and alleviates the retardation from carboxylic groups in PC dispersants, which ensures better dispersion of nanosilica and cement particles and hence better mechanical properties. And all dispersants improve the compactness and microstructure of set cement due to uniform dispersion of nanosilica in cement, and hence advance the development of mechanical properties of nanosilica filled cementitious composites.

An effective recycle way of waste coke ash and coking wastewater for preparing coke ash coking wastewater slurry

The carbon riched coke ash (CA) and organic components riched coking wastewater (CW) recovered from coking plants wastes were utilized for the preparation of coke ash coking wastewater slurry (CACWS), aiming for the fuel and waste reduction and recovery. The effects induced by the properties of CA and compositions of CW on the performances of CACWS, such as slurryability, rheology, stability and dispersant adsorption were investigated and discussed. Characterizations like zeta potentials and contact angles on the surface of CA were also conducted to draw a comprehensive formation mechanism of CACWS. Results showed that the CA was suitable for preparing slurry due to the lack of micropore structures and hydrophobicity in the surface. The maximum content of CA in the as-prepared CACWS could reach 66% and CACWS exhibited non-Newtonian pseudoplastic fluid behaviour. By reducing the particle size distribution, the slurryability of CA could be effectively improved. Although the components in CW enhance the wettability of CA surface, compared with cations in CW, the organic components had more influence on CACWS, which also obviously increased the viscosity of CACWS. The maximum CA content in CACWS (ω = 66 wt%) reduced by 9% comparing to CA water slurry (ω = 75 wt%) which improved the storage stability about 10%. In addition, results show that the dispersant Triton X-405 reduced viscosity and improved stability while in comparison with the anionic polycarboxylate dispersant. Overall, this study may provide an innovative and effective utilization of CA and CW from the coke plants wastes.

Performance Evaluation of Polycarboxylic Acid Dispersant for Oil Well Cementing

The conventional oil-well cement dispersant has the characteristics of poor dispersion at high temperature, poor compatibility with other additives, and environmental pollution during the production process. In this article, with ultra-early strong polyether monomer, acrylic acid, 2-acrylamine-2-methylpropyl sulfonic acid, sodium methacrylate as copolymer monomers, an environmentally friendly polycarboxylic acid dispersant, DRPC-1L, was prepared by the aqueous solution free-radical polymerization. The chemical composition and thermal stability of the synthetic copolymer were characterized by FTIR and TGA techniques. The evaluation results show that DRPC-1L has a wide temperature range (30~210 °C), good salt-resistance and dispersing effect. It can significantly improve the rheological performance of cement slurry, and it is well matched with oil-well cement additives such as fluid loss agent, retarder and so on. Moreover, it is beneficial to the mechanical strength development of set cement, especially the early compressive strength. It can also inhibit the abnormal gelation phenomenon of cement slurry, flash set, that occurs during high temperature thickening experiments, which plays an important role in enhancing the comprehensive performance of cement slurry. Consequently, the novel polycarboxylic acid dispersant has good application prospects in deep and ultra-deep wells cementing.

Synthesis, performance and working mechanism of a novel amphoteric polycarboxylate dispersant without chlorine ion

A series of amphoteric polycarboxylate (APC) dispersants for oil well cement were prepared by free radical polymerization of ω-hydroxy polyethylene glycol (HPEG), maleic anhydride (MA) and [2-(Methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA). The chemical structure of dispersants was characterized by Fourier Transform Infrared Spectrometer (FTIR), 1H-Nuclear Magnetic Resonance (1H NMR) and Gel Permeation Chromatography (GPC). The fluidity, rheology and compressive strength measurements were conducted to evaluate the performance of cement paste with various APC dispersants. The results show that APC dispersants with hydrolysable ester groups and cationic groups enhance dispersing ability, improve rheological property, and promote the compressive strength of cement. Meanwhile, the effect of various APC dispersants on cement hydration was also investigated, which indicate that APC dispersants have a higher adsorption capacity on cement particle than the conventional polycarboxylate (PC) dispersant, resulting in a visible impact on retardation of cement hydration. Besides, APC dispersant notably increases compactness of hardened cement and improves the microstructure of cement, which remarkably enhances mechanical properties of cement paste. Consequently, the APC dispersants show excellent performances in cement paste systems and have great potential for application in oil/gas well cementing.

Dispersion performances and adsorption behavior of novel block polycarboxylate with hybrid side chains in coal-water slurry

A serial of novel block polycarboxylate dispersants (PCDs) with hybrid side chains employing long-short composite side chains for making coal-water slurry (CWS) were synthesized and applied to a low rank coal in the north of China to make slurry. The relationship of the fine structure of side chains and properties of the CWS were investigated. The results show that the apparent viscosity, zeta potential and stability of the CWS are impacted by the molar ratio of short side chain to long side chain of the PCD. Meanwhile, the viscosity reduction, stability property and zeta potentials of the CWSs are increased in accord with the order of adsorption amount of PCD on coal. These facts confirm that the PCD with a molar ratio of the short side chain to long side chain of just over unity more easily forms a larger adsorption amount on the coal surface and has optimal dispersion and stability characteristics. It is helpful to regulate the adsorption behavior of polycarboxylate dispersant to improve its dispersion property. It provides a good pathway to design and prepare a highly effective dispersant for low rank coal.

Introducing reduced graphene oxide to enhance the thermal properties of cement composites

For modern concrete technology, how to control the generation and propagation of thermal cracks is still a challenge. The large temperature gradient between the internal and external surface is primarily responsible for the cracks. The present study successfully develops a new avenue to minimize the temperature difference of cement composites by introducing reduced graphene oxide (rGO). The effective dispersion of rGO in cement matrix is achieved by applying the polycarboxylate dispersant. The incorporation of rGO enhances the thermal properties of mortar, resulting in a lower temperature difference. The uniformity of calculated heat flux and early-age shrinkage of cement composites are improved by adding rGO. Moreover, the mechanical strength slightly increases at 3 days up to doping 0.6 wt % rGO and does not display significant enhancement after 28 days. Obtained results demonstrate doping rGO is a promising approach to reduce the thermal stress and restrain the development of thermal cracks.

Synthesis and hard water resistance mechanism of polycarboxylate dispersant for pesticide water dispersible granules

A new type of dispersant for pesticide water dispersible granules (WDGs), sodium salt of methacrylic acid/styrene/sodium p-styrene sulfonate copolymer (SMSS) was designed and synthesized by by free-radical polymerization in solution. Atrazine WDG was prepared to evaluate the dispersion performances of SMSS. It is found that the as-synthesized dispersant has strong resistance to hard water and high performance, and the suspensibility of 90 wt% atrazine WDG could reach 93.21% and 90.81% in standard hard water and three-fold standard hard water respectively. The hard water resistance mechanism of the as-synthesized SMSS dispersant is proposed as follows: SMSS could inhibit the formation of insoluble calcium polycarboxylate and magnesium salts, and prevent desorption of dispersant molecules from the surface of atrazine particle, thus maintain the suspension stability of WDG in water with high hardness.

Effects of amphoteric polycarboxylate dispersant (APC) and acetone formaldehyde sulfite polycondensate (AFS) on the rheological behavior and model of oil well cement pastes

Two oil-well cement dispersants, Amphoteric polycarboxylate dispersant (APC) and Acetone formaldehyde sulfite polycondensate (AFS) with different dosages (0.10%,0.15% and 0.20% by weight of cement), were used to investigate the rheological performance of cement paste. A simple equipment, six-speed rotational viscometer, was employed to study the relationship between the shear stress and shear rate of the fresh cement paste. Three typical rheological models including Herschel-Bulkley model, Bingham model, and Power-law model, were applied to estimate the yield stress, plastic viscosity and trend of the flow curves. The validity of these rheological models in predicting the rheological properties of cement paste was confirmed by considering the fitting optimization index (R2). Besides, the thixotropic behavior of cement paste with different dispersants was investigated. The results show that the rheological properties of cement paste improve dramatically with either APC or AFS addition. And the APC dispersant with better dispersion behavior is significantly efficient in decreasing the consistency index and increasing the flow behavior index than AFS dispersant. The Herschel-Bulkley model with higher fitting optimization index was found to fit the experimental data best compared with Bingham model and Power-law model. The degree of thixotropy of cement paste with more dispersant addition decreases compared to the reference, which is related to the rheological behavior.