Dispersant Dosage Research Articles

The Preparation of Coal Pitch Slurry with Coking Wastewater

This study explored the feasibility of using coking wastewater and coal pitch powder to make coal pitch wastewater slurry. The medium temperature coal tar pitch powder was prepared by freezing and pulverizing coal tar pitch. The dispersant, JL-C01 medium-breaking emulsifier, had a large adsorption value on the coal pitch surface. At the same time, the Zeta potential on the coal pitch having added dispersant had a big increase. On the basics of that, putting some dispersants and wastewater into the powder under high speed stirring, the coal pitch wastewater slurry was obtained. The slurryability, rheological behavior, and static stability of coal pitch wastewater slurry were investigated at different dispersant dosages and slurry concentrations. The results showed that the apparent viscosity decreased with increasing the shearing rate. The rheological behavior of the slurry exhibited pseudo-plasticity. The biggest slurryability could be up to 70%. When the slurry concentration was 70%, the slurry could be kept for 28 d. At last, considering the test methods for quality of coal water mixture, the combustion analysis of the slurry was carried out and many indexes accorded with the national standard. The low heat value, the ash content, and the volatile matter met the coal water slurry first grade standard, and the sulfur content met the second grade standard.

Gelcasting of fused silica glass using a low-toxicity monomer DMAA

A low-toxicity and water-soluble monomer N,N-dimethylacrylamide (DMAA) was used as gelling agent in gelcasting of fused silica glass. In order to make high solid loading and low-viscosity slurries, acrylic acid-2-acrylamido-2-methypropane sulfonic acid copolymer (AA-AMPS) was selected as dispersant. Zeta potential, pH, dispersant dosage, solid loading and milling time have been investigated to prepare the optimum gelcasting slurries. The results suggest that the best conditions were pH4.8, dispersant dosage 0.1–0.2wt.% and milling time 5h. Gelation of slurries took place with the help of initiator at 65–80°C. Flexural strength of dried fused silica green bodies with only 3.04wt.% polymers reached up to 20.16MPa. Nanometer silica was introduced to boost sinterability by immersing green bodies in the tetraethyl silicate solvent. Bulk density and flexural strength of sintered fused silica bodies without obvious crystallization have been increased to 1.975g/cm3 and 81.36MPa, respectively.

The rheological behavior and stability of Mg(OH)2 aqueous suspensions in the presence of sodium polyacrylate

The magnesium hydroxide (Mg(OH)2) aqueous suspensions were prepared over a wide range of solid loading using sodium polyacrylate (NaPA) as the dispersant. The effects of solid loading, polyelectrolyte concentration, shear rate, temperature and ionic strength on the rheological behavior and stability of Mg(OH)2 aqueous suspensions have been investigated by means of viscosity and sedimentation measurements. The results showed that the apparent viscosity of the concentrated magnesium hydroxide suspensions decreased pronouncedly as the dispersant dosage was increased and reached a minimum as the dispersant concentration exceeded 0.6wt% (based on the dry powder weight). The fitting of shear stress-shear rate dependence curves with several models showed that the suspensions appeared to shift toward a Bingham-plastic flow from the shear thinning flow behavior as the NaPA dosage increased. This suggests that NaPA displays outstanding dispersing and stabilizing effects in the studied system, further evidenced by the sedimentation measurement. In addition, the apparent viscosity was also found to increase with the solid loading in the systems of aqueous Mg(OH)2 suspensions with 0.6wt% NaPA. A maximum solid loading (ϕm) at which the particulate suspensions changed from a fluid-like form into a solid-like form was determined from the ηr−ϕ relationship, using the Krieger-Dougherty model, to be 45vol% and 54vol% at shear rate of 10s−1 and 100s−1, respectively. Ionic strength and temperature also influenced the rheological behavior and stability significantly, such that lower temperature or higher ionic strength could increase the apparent viscosity. Lastly, a possible stabilization mechanism at various NaPA concentrations was discussed based on the adsorption behavior and adsorbed layer conformation of the dispersant on the particle surface.

Selective preparation of Bi2O3 visible light-driven photocatalyst by dispersant and calcination

Abstract Bi 2 O 3 visible light responsive photocatalysts were synthesized by chemical precipitation and consequent calcination process. The as-prepared samples were characterized with XRD, FESEM, UV–Vis and PL methods and their photocatalytic activities were evaluated by degrading malachite green. Last, N-doped β-Bi 2 O 3 with average length of about 252 nm was selectively fabricated under the optimal preparation conditions obtained by investigating influence of dispersant type, dispersant dosage, calcination temperature and time on Bi 2 O 3 crystalline phase, morphology and other performances. The photocatalyst had strong absorption for visible light and efficient separation of charge carrier, which made it a good photocatalyst towards degradation of malachite green. Approximately 96.5% of malachite green was degraded after illumination for 300 min.

Effect on Sedimentation Characteristics of Bentonite Suspension at Different Conditions

To better understand the sedimentation processes of bentonite, the sedimentation characteristic of bentonite suspension was studied by using the sedimentation analysis module of Dynamic Contact Angle Meter and Tensiometer. The results indicated that sedimentation characteristics of bentonite suspension were affected by the concentration and pH values of the suspension together with the dosage of dispersants. The natural sedimentation rates of bentonite suspension declined firstly with prolonging the sedimentation time and soon stabilized after about 50s. The sedimentation weight of particles hardly changed when the concentration ranged from 0.5% to 5.0%, while it increased significantly when ranged from 5.0% to 10.0%. The sedimentation weight and rate were relatively bigger at 4.4, 11.8 than that of 6.0, 7.9, and the maximum values appeared at pH11.8. Adding sodium pyrophosphate could improve the dispersibility of bentonite suspension.

Aqueous gelcasting of silica ceramics using DMAA

A low-toxicity and water-soluble monomer N, N-dimethylacrylamide (DMAA) was used as gelling agent in gelcasting of silica ceramics. In order to prepare high solid loading and low viscosity gelcasting slurries, effects of various parameters such as zeta potential, pH value, dispersant dosage and solid loading on rheological behaviors of the suspensions were investigated. The results suggest that the best conditions are pH 7.7 and dispersant dosage 0.1 wt%. The maximum flexural strength of green bodies with only 2 wt% organics in the slurry could be up to 15.3 MPa. The sintering shrinkage, bulk density, coefficient of linear expansion and flexural strength of sintered ceramics are 5.2%, 1.95 g/cm3, 0.58×10−6 k−1 (200 °C) and 67.4 MPa, respectively. The dielectric constant and loss (1 MHz) are 3.26 and 7.8×10−4, respectively.

The Best Dosage of Polymer Dispersant in WDG by Zata Potential Method

Applied self-prepared GY dispersant into 75% thifensulfuron WDG formulation,only chang the dispersant and filler content, found out the optimal amount of dispersant using zata potential analyzer. The results show that when the dosage of dispersant is 6%, zeta potential to achieve the most negative,75% tribenuron water dispersible granule apparent suspension rate of more than 90%. Zata potentiometric method is a rapid method that decide anionic dispersant dosage.

Aqueous dispersion of red clay-based ceramic powder with the addition of starch

The optimum dispersion and rheological properties of red clay-based ceramic suspension loaded with unary and binary starch were investigated in aqueous medium. The aqueous ceramic suspension was prepared consisting of red clay, quartz, feldspar, and distilled water. Using a polyelectrolyte dispersant (Darvan 821A), the ternary ceramic powder was initially optimized to give the smallest average particle size at 0.8 wt. (%) dispersant dosage as supported by sedimentation test. This resulted into an optimum high solid loading of 55 wt. (%). The addition of either unary or binary starches to the optimized ceramic slurry increased the viscosity but maintained an acceptable fluidity. The mechanism of such viscosity increase was found to be due to an adsorption of starch granules onto ceramic surfaces causing tolerable agglomeration. Correspondingly, the rheological evaluations showed that the flow behaviors of all starch-loaded ceramic slurries can be described using Herschel-Bulkley model. The parameters from this model indicated that all ceramic slurries loaded with starch are shear thinning that is required for direct casting process.

Study on Preparation of Abamectin Microcapsule with Interfacial Polymerization

The abamectin was microencapsulated with interfacial polymerization. The bursa wall materials of Abamectin microcapsule used in the experiment was polyurea which was produced by Tolylene-2,4-diisocyanate (TDI) and hexamethylenetetramine. The stirring speed and the dosage of emulsifier were determined by preliminary experiments, and the technical conditions for abamectin microencapsulation were optimized by orthogonal experiment, meanwhile, the optimal proportion and dosage of bursa wall materials, solvent and dispersant were determined. Encapsulation efficiency was measured by UV spectrophotometer. Results show that the encapsulation efficiency of microcapsules obtained is up to 90%.

Aqueous gelcasting of yttrium iron garnet

Abstract N,N-Dimethylacrylamide (DMAA)/N,N′-methylenebis (acrylamide) (MBAM) system was used in the aqueous YIG (yttrium iron garnet) slurry. YIG powders were prepared by using Y 2 O 3 and Fe 2 O 3 as raw materials through the traditional oxide method. In order to reduce the viscosity and improve the stability of slurries, SD-03 (ammonium polyacrylate) was selected as the dispersant. Zeta potential, pH, dispersant dosage, solid loading and milling time have been optimized. The best conditions were pH 9.86, dispersant dosage 0.2 wt.% and milling time 9 h, which helped to prepare the concentrated slurry with low viscosity and good liquidity. The maximum bending strength of the green body could be up to 13 MPa. The shrinkage and deformation of shaped sintered bodies prepared through gelcasting were small after sintering. The sintering shrinkage, apparent porosity and bulk density were 17%, 0.17% and 5.07 g/cm 3 , respectively. The dielectric constant and dielectric loss were 14.0 and 2.06 × 10 −4 , respectively.

Synthesis of Starch Graft Copolymer Dispersant and its Application Performance in Coal-Water Slurry

In this study, a new starch graft copolymer dispersant for Chinese Shenhua coal-water slurry (CWS) was prepared by radical polymerization using styrene sulfonate (SSS), hydroxyethyl acrylate (HEA) and methyl acrylic acid (MAA) as graft monomers in oxidation-reduction initiator system. The apparent viscosity, static stabilization and rheology of Shenhua coal-water slurry prepared with the dispersant have been were investigated. The experimental results demonstrate that the CWS gives the minimal viscosity of 826 mPas at coal concentration of 66 wt%, dispersant dosage of 0.5 wt% and shear rate of 100 s-1. Bleeding ratio tests indicate the starch graft copolymer can stabilize the slurry. The rheological behavior of the prepared CWS can be described by the pseudo-plastic fluid model. On the basis of the above, the starch graft copolymer dispersant has broad prospect for the application for CWS.

Methods for Improving Slurry Ability of Yangchangwan Bituminous Coal

Yangchangwan (YCW) bituminous of Ningxia is a weakly reductive coal, which was characterized with low ash content, low sulfur content, low H/C and ash fusion, but high moisture, oxygen, inertinite and alkaline earth metal contents, also difficult to make slurry. Influence of dispersant kind and dosage on YCW CWS rheological behavior was studied using 8 dispersants. Examination was conducted in the lab. The results show that the dispersant and its dosage not only influence the apparent viscosity but also the rheological behavior of CWS. Methyl naphthalene acid salt formaldehyde condensation(MF) is the best dispersant for YCW bituminous coal and the optimal dosage is 1%. CWS were also prepared using compounded dispersants of sodium lignosulphonate and Methyl naphthalene acid salt of formaldehyde condensation and in order to investigate the slurry ability of CWS with compounded dispersants. The results show that compounded dispersants have a greater impact on the liquidity and stability of CWS, the optimal ratio of two dispersant is 3:7. Slurry technologies of blended coals were also studied in this paper, YCW bituminous coal with lower slurry ability , lower static s stability and poor theological behavior and Dafeng(DF) anthracite coal with good properties of CWS and the better theological behavior. The effect of the ratios of two coals on the static stability and viscidity of CWS was studied. The results show that CWS is better static stability ability and viscidity when the chemical additive quantity is at 1 parts per hundred and the ratio of two coals is 3:7.The effects of coal blending on the features of coal-water slurry are nonadditivity. It can effectively improve the concentration of coal water slurry, for coal which has difficulty in preparing coal-water slurry.

Synthesis and performance of a comblike amphoteric polycarboxylate dispersant for coal–water slurry

A novel comblike polymer, amphoteric polycarboxylic (AmPC), was designed as a dispersant for coal–water slurry (CWS) and synthesized in aqueous solution from the copolymerization of macromonomer polyethylene glycol-acrylate monoester (PA), sodium p-styrene sulfonate (SSS) and cationic comonomer methacrylatoethyl trimethyl ammonium chloride (DMC). PA was prepared by esterifying with polyethylene glycol (PEG) and acrylic acid (AA) in our laboratory. And then, the molecule structure of amphoteric polycarboxylic dispersant was characterized by means of Fourier transformer infrared (FTIR). Besides, the dispersant was applied in Shenfu coal slurry. By examining the apparent viscosity of the coal slurry using rheometer, the effects of the mole ratio of SSS and PA, amount of cationic monomer DMC, initiator concentration and reaction temperature on the AmPC dispersant performance were discussed. The wetting property of AmPC dispersant on the coal surface and Zeta potential of the CWS with AmPC dispersant was measured. The result shows that the apparent viscosity decrease of amphoteric polycarboxylic dispersant is better than the dispersant in stock which does not have cationic monomer when the dosage of DMC is 5.0wt%. It has been proved that the amphoteric polycarboxylic dispersion agent is suitable for Shenfu coal slurry. When the dosage of AmPC dispersant is up to 0.3wt%, the highest concentration of coal-slurry can reach 65.0wt%. AmPC dispersant with both anionic group and cationic group will provide the better anchoring action with the coal via the adsorption of ion pair. It possesses not only dramatic wetting on coal but also stable steric hindrance so as to disperse coal particles in water.

Synthesis and Evaluation of Starch Graft Copolymer Applied as Dispersant in Coal-Water Slurry

In this paper, a starch-based dispersant for Chinese Shenhua coal-water slurry (CWS) was synthesized by radical polymerization using styrene sulfonate and acrylic acid as graft monomers in oxidation-reduction initiator system. Chemical structure and thermal performance of the copolymer were investigated by Fourier Transform Infrared Spectrum (FT-IR) and Thermogravimetric Analyzer (TGA). The rheological characteristics of the slurry were studied by varying dispersant dosage and shear rate，and the results show, At coal concentration of 66 wt%, dispersant dosage of 0.4 wt% and shear rate of 100 s-1, the CWS gives the minimum viscosity of 848 mPa•s. Bleeding ratio tests indicate the dispersant can stabilize the slurry. Based on the above, the starch-based dispersant has due structure and a bright prospect for the application for CWS.

Dissolution Testing of Acetaminophen Suspension Using Dialysis Adapter in Flow-Through Apparatus: A Technical Note

Dissolution testing is an important tool during drug development, characterization, and quality control of both immediate- and controlled-release formulations. It has been used for evaluating candidate formulations and for understanding possible risks related to specific gastrointestinal factors, potential for dose dumping, food effects on bioavailability, and interaction with excipients (1,2). Recently, dissolution testing has been increasingly used to test dosage forms such as suspensions, soft gelatin capsules, creams and transdermal systems. To test these special dosage forms, special accessories are sometimes required. SOTAX Inc. recently introduced a dialysis adapter for release testing of solution and semisolid formulations. This device, as shown in Fig. 1, facilitates the use of dialysis tubing to sequester a sample in the center of the USP 4 standard 22.6 mm flow cell. The applications with this dialysis adapter are mainly for in vitro release testing of dispersed dosage forms. One publication by Burgess’ group using this method compared dexamethasone release from extruded and non-extruded liposomes (3). Results showed that the USP apparatus 4 method with this dialysis adapter could discriminate between solution, suspension, and liposome formulations of dexamethasone. Fig. 1 Dialysis adapter from Sotax Inc The objective of this study was to evaluate this new dialysis adapter. An acetaminophen suspension drug product and various concentration acetaminophen solution samples were used to compare the flow-through method with and without the dialysis adapter, as well as to compare two different sizes of dialysis membranes. Other parameters such as flow rate, dissolution media, and medium ionic strengths were also studied.

Barrier Coated Drug Layered Particles for Enhanced Performance of Amorphous Solid Dispersion Dosage Form

Amorphous solid dispersions (ASDs) may entail tailor-made dosage form design to exploit their solubility advantage. Surface phenomena dominated the performance of amorphous celecoxib solid dispersion (ACSD) comprising of amorphous celecoxib (A-CLB), polyvinylpyrrolidone, and meglumine (7:2:1, w/w). ACSD cohesive interfacial interactions hindered its capsule dosage form dissolution (Puri V, Dhantuluri AK, Bansal AK 2011. J Pharm Sci 100:2460-2468). Furthermore, ACSD underwent significant devitrification under environmental stress. In the present study, enthalpy relaxation studies revealed its free surface to contribute to molecular mobility. Based on all these observations, barrier coated amorphous CLB solid dispersion layered particles (ADLP) were developed by Wurster process, using microcrystalline cellulose as substrate and polyvinyl alcohol (PVA), inulin, and polyvinyl acetate phthalate (PVAP) as coating excipients. Capsule formulations of barrier coated-ADLP could achieve rapid dispersibility and high drug release. Evaluation under varying temperature and RH conditions suggested the crystallization inhibitory efficiency in order of inulin < PVA ≈ PVAP; however, under only temperature treatment, crystallization inhibition increased with increase in T(g) of the coating material. Simulated studies using DSC evidenced drug-polymer mixing at the interface as a potential mechanism for surface stabilization. In conclusion, surface modification yielded a fast dispersing robust high drug load ASD based dosage form.

Formation of TiO2 photoanodes by simultaneous electrophoretic deposition of anatase and rutile particles for photoassisted electrolytic copper ions removal

The influence of Anatasa/Rutile ratio on TiO2 films, grown by electrophoretic deposition was studied in the photoassisted electrolytic copper ions removal from cyanide solutions. The proper dispersant dosage allowing the simultaneous electrophoretic deposition of Anatase and Rutile was chosen based on electrokinetic measurements; evidenced by the XRD spectra of the formed films. The evaluation of films photoassisted electrolytic copper ion removal showeds that it is possible to enhance the activity of Anatase films by adding some Rutile exploiting the synergetic interaction between these two materials, achieve by its proper deposition.

Research on Coating Dispersion of Liquid Wear-Resistant Decorative Paper

Liquid wear-resistant technology combines original decorative paper and the surface wear-resistant paper into one. Wear-resistant particles are coated directly on the surface of base decorative paper, forming a transparent wear-resistant protective layer. The suspension behavior of ultra-fine A12O3 in the aqueous phase was investigated. The aim was further realizing the good consistency among A12O3, melamine resin and other components. The main influencing factors [viz., dispersant type, dispersant dosage, dispersive methods and pH value] were investigated to get the optimum conditions. The results showed that the stable aqueous suspension of ultrafine A12O3 could be obtained under the following conditions: the concentration of superfine A12O3 5wt%, pH = 9, anionic dispersant APAAA, the amount of dispersant 0.4wt%, ultrasonic suspension time 30min.

Study on Preparation of Super Clean Coal with Selective Flocculation-Flotation Technology on Taixi Anthracite

Based on the coal petrology character of Taixi anthracite, the selective flocculation-flotation preparation of super clean coal is studied. The influences factors of the type and dosage of dispersant, the type and dosage of flocculant, pulp density etc etc on its effect is analyzed, and, through the orthogonal experimental methods, the salience order, interaction, and the optimum combination of the main factors is revealed. The finally test results indicate that we can obtain an ash about 1.29% at a yield of 41.85%％ super clean coal, thus will provide basis for the future super clean coal industrialization.

Fabrication and Preparation of Coal-Water Slurry Dispersant with Amphoteric Polycarboxylate

Coal-water slurry （CWS）dispersant is a key to prepare fine coal-water slurry. A novel amphoteric polycarboxylic (AmPC) dispersant for CWS was copolymerized in aqueous solution by comonomers methacrylate polyglycol monoester (PA), propylene sulfur sodium (SAS) and cationic comonomer methacryloyloxy ethyl trimethylammonium chloride(DMC).Methacrylate polyglycol monoester was prepared by direct esterifying with methacrylate acid (AA) and polyethylene glycol (PEG) in our laboratory. And then, The molecule structure of amphoteric polycarboxylic dispersant was characterized by FTIR. Besides, the dispersant was applied in Shenfu coal slurry. Through examining properties of the coal slurry, the effects of amount of cationic monomer DMC, the concentration of initiator and reaction temperature on dispersant performance were discussed. The result shows that the viscosity reducing of amphoteric polycarboxylic dispersant is better than the dispersant in stock which hasn’t cationic monomer when the dosage of DMC is 5.0wt%. It has been proved that the amphoteric polycarboxylic dispersion agent is suitable for Shenfu coal slurry. When the dosage of AmPC dispersant is up to 0.5wt%, the highest concentration of coal-slurry can reach 65.4wt%.