Dispersant For Coal Water Slurry Research Articles

Carboxyalkylated Lignin as a Sustainable Dispersant for Coal Water Slurry

Carboxyalkylated Lignin as a Sustainable Dispersant for Coal Water Slurry

Resource utilization of polystyrene waste by preparation of high performance dispersant for coal‒water slurry

ABSTRACT In present paper, structures and properties of degradation products of polystyrene (PS) waste were characterized by gel permeation chromatography (GPC), thermogravimetric (TG) analysis, Fourier transform infrared (FT-IR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), and thus the degradation conditions including temperature, time, and assistant type and dosage were investigated and optimized. It is suitable to use 1.0 wt% K2S2O8 as an assistant to degrade PS waste at 300°C for 24 h. Subsequently by sulfonation and neutralization reactions, the degraded PS was prepared into sodium polystyrene sulfonate (PSS), a common dispersant for coal‒water slurry (CWS). The performance of PSS with different molecular weights and sulfonation degrees was studied. Experimental results showed that the PSS with the sulfonation degree of more than 75%, prepared from the degraded PS having number average molecular weight (M n) of about 9000, was appropriate for dispersion and stabilization of CWS suspensions. Additionally, compared with commercial dispersant NSF, the obtained PSS had a better performance for CWS. CWSs prepared with dispersant PSS exhibited pseudo-plastic or shear-thinning rheological behaviors. Combined with coal‒water slurry technology, a new approach is provided for resource utilization of PS waste.

Synthesis and Performance of a Novel Cotton Linter Based Cellulose Derivatives Dispersant for Coal-Water Slurries.

A novel sulfonic-cellulose succinate half ester (S-CSHE) dispersant for coal–water slurry (CWS) was successfully synthesized using cotton linters, sulfamic acid and succinic anhydride in DMF by a one-pot synthesis. The effects of the synthetic condition of S-CSHE as a dispersant for CWS were studied. An S-CSHE with a maximum degree of substitution of 0.98 was obtained under these optimized conditions. The synthesized samples were characterized by GPC, FT-IR spectroscopy, 13C-NMR, and SEM. The molecular weight was from 2.2 × 103 to 1.2 × 104, revealed by GPC; FT-IR spectra analysis revealed characteristic absorptions of the sulfonic-cellulose succinate half ester; SEM images showed smooth cellulose structures, while the S-CSHE had a compact surface. Effects of S-CSHE on the fluidity of application as the dispersants for the CWS prepared from Chinese Zhundong coal were studied further. The CWS application performance investigations showed that S-CSHE can most effectively reduce CWS viscosity, and perform excellent dispersity and stability. When the dosage of S-CSHE was up to 0.5 wt.%, the maximum coal content of CWS may reach 70 wt.%, and the apparent viscosity of CWS was 487 mPa·s. The CWS prepared using S-CSHE (0.38 wt.%) for Zhundong coal showed the rheological characteristics of shear-thinning, and is consistent with the Herschel–Bulkley model. This work found a new route for utilizing cotton linters cellulose and enlarged the selecting range of the dispersant for CWS. It has a positive significance for efficient and clean utilization of Xinjiang Zhundong coal.

Understanding the adsorption behaviors of naphthalene sulfonate formaldehyde in coal water slurry

Naphthalene sulfonate formaldehyde (NSF) has been widely used as a dispersant for coal water slurry (CWS) preparation. However, the adsorption behaviors of NSF on different components were scarcely discussed due to the complex nature of coal. In this study, the adsorption kinetics and isotherms of NSF on the particle surfaces of carbonaceous matter, kaolinite, quartz, pyrite were investigated, along with X-ray photoelectron spectroscopy (XPS) and contact angle meter were conducted to clarify the adsorption mechanism of NSF on each particle surface. The adsorption measurements showed that the saturated adsorption capacities of NSF on the surfaces of kaolinite, pyrite and carbonaceous matter were much higher than that of quartz. Further single-layer adsorption occurred for the NSF adsorbed by all particles except quartz, where multi-layer adsorption was observed. The XPS and contact angle results showed that the interaction between the hydrophobic tail of NSF and carbonaceous matter is mainly attributed to hydrophobic force, concurrently the combination of the hydrophilic groups in NSF with Al elements of kaolinite and Fe elements of pyrite. The findings are significant to elucidate the adsorption mechanism of dispersants on the coal-water interface and proposed a reference for dispersants utilization based on different coal components.

Synthesis of a novel amphoteric copolymer and its application as a dispersant for coal water slurry preparation.

In this work, a novel amphoteric copolymer named Poly(sodium p-styrenesulfonate–co-acrylic acid-co-diallyldimethylammonium chloride) (P(SS-co-AA-co-DMDAAC)) was synthesized via free radical polymerization. Afterwards, P(SS-co-AA-co-DMDAAC) was explored for use as a dispersant in coal water slurry (CWS) preparation. The structure of P(SS-co-AA-co-DMDAAC) was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance. The synthetic conditions were optimized as the feed ratio of AA to SS was 1 : 1 (for Yulin coal) or 1.5 : 1 (for Yili coal), and DMDAAC dosage was 4.0 wt% (for Yulin coal) and 6.0 wt% (for Yili coal) toward total monomers. The performances of P(SS-co-AA-co-DMDAAC) as a dispersant for CWS were evaluated by various technologies, such as apparent viscosity, zeta potential, static stability and contact angle measurements. The results revealed that the optimized dosage of P(SS-co-AA-co-DMDAAC) in CWS preparation was 0.3 and 0.4 wt% for Yulin coal and Yili coal respectively. In this optimum condition, CWS prepared using P(SS-co-AA-co-DMDAAC) as dispersant showed a typical shear thinning behaviour and excellent stability, which are desired in industries. The rheological models also confirmed the pseudo-plastic characteristics of CWS. Finally, compared with the widely used anionic dispersant naphthalene sulphonate formaldehyde condensate (NSF) and poly(sodium p-styrenesulfonate) (PSS), P(SS-co-AA-co-DMDAAC) developed in this work exhibited better slurry making performance. The introduction of cationic functional groups promoted the adsorption of the dispersant, which further enhanced the electrostatic repulsion and steric hindrance among coal particles. Accordingly, the viscosity of CWS decreased and static stability enhanced.

Synthesis of a novel dispersant with topological structure by using humic acid as raw material and its application in coal water slurry preparation

This work reports the synthesis and performance of a novel dispersant for coal water slurry (CWS). The dispersant is derived from humic acid (HA) and has a topological structure, named humic acid-graft-poly(sodium styrene sulfonate) (HA-g-PSSNa). A series of HA-g-PSSNa with simultaneous presence of hydrophobic humic acid skeleton and hydrophilic poly(sodium styrene sulfonate) side chains were synthesized via surface acylation reaction of HA and followed by atom transfer radical polymerization. The structure and chemical composition of HA-g-PSSNa were verified by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Scanning electron microscopy observation suggests that the incorporation of PSSNa segments onto HA skeleton remarkably affects its morphology. The performances of CWS prepared using HA-g-PSSNa, PSSNa, and naphthalene sulfonic formaldehyde condensate (NSF) as dispersants were studied and systematically compared using various technologies. The results show that the slurry-making performance of HA-g-PSSNa enhanced with the increase in the length of PSSNa side chains. In the case of HA-g-PSSNa with appropriate PSSNa chain length, the CWS prepared using HA-g-PSSNa as dispersant exhibits excellent apparent viscosity as well as static stability, even superior to those of PSSNa and NSF. The dispersing and stabilizing mechanism of HA-g-PSSNa is proposed as follows: When used as a dispersant for CWS, HA skeleton provides sufficient hydrophobic interaction to coal surface and drives the adsorption of HA-g-PSSNa molecules. Hydrophilic PSSNa side chains are oriented to water, thus forming a dense electrical layer and steric hindrance surrounding the coal particles. Accordingly, the aggregation of coal particles was suppressed.

β-Cyclodextrin grafted on alkali lignin as a dispersant for coal water slurry

ABSTRACTA modified alkali lignin (AL) was synthesized by introducing β-cyclodextrin (β-CD) into AL with epichlorohydrin (EPI) copolymerization, which resulted in incorporating β-CD with AL by ether linkage. As a dispersant, β-CD copolymerized AL (β-CD-AL) was added into coal water slurry and its efficiency was evaluated. The effects of β-CD content on the performance of β-CD-AL were investigated via analyzing dispersity, zeta potential, and adsorption capacity. The results illustrated that β-CD-AL behaved better dispersion owing to the high slurry concentration at fixed apparent viscosity, which was mainly attributed to the synergistic effects of electrostatic repulsive force and steric hindrance. Steric hindrance originated from the side chain of β-CD gives better stability and less adsorption amount.

Adsorption and dispersion performance of oxidized sulfomethylated kraft lignin in coal water slurry

In this study, oxidized and sulfomethylated lignin (OSL) with the charge density of −4.4 meq/g was used as a dispersant for coal water slurry (CWS). The impact of the OSL on CWS having different particle sizes was fundamentally investigated. The size of particles greatly influenced the adsorption of OSL on coal particles and the rheology and stability of the CWS. The maximum adsorption of OSL was found to be 0.96 mg/g on coal A having the particle size of 22 μm (coal particles with smallest size). OSL improved the wettability of coal by 5–28%. The interfacial tension between coal particle and OSL was reduced from 17 mN/m to 13 mN/m, and the zeta potential of the suspension dropped from −30 mV to −47 mV when 0.96 mg/g of OSL was adsorbed on coal A. The addition of 64 mg/L of OSL to coal A suspension (50 wt%) reduced its viscosity from 1350 to 520 mPa·s. The stability of coal particles was also improved as the destabilization index of CWS was reduced from 4 to 0.2. These results confirmed that the OSL was an effective dispersant for the coal water slurry.

Synthesis of a novel humic acid-based polycarboxylic dispersant for coal water slurry

ABSTRACTA novel humic acid-based polycarboxylic-type (HAP) dispersant for coal–water slurry (CWS) was successfully synthesized in aqueous solution from the copolymerization of HA, acrylic acid and maleic acid. The structure of HAP was characterized by Fourier transform infrared (FTIR), thermogravimetry (TG) and 1H NMR. With HAP as a dispersant for Linfen coal slurry, the effects of the mass ratio of HA and monomer, initiator concentration, reaction temperature and reaction time on the HAP dispersant performance were discussed by examining the apparent viscosity of CWS. The results showed that CWS prepared withHAP dispersant performed excellent dispersity and stability. When the dosage of HAP was up to 0.5 wt.%, the apparent viscosity of CWS was 505 mPa·s. Experiments on the stability of CWS containing 0.5 wt.% HAP demonstrated that the penetration ratio reached 85.45 % after 96 h, which was higher by 12.87 % than that of CWS prepared with HA. And the CWS produced with HAP had lower dewatering rate within the storage time, which was less 1.85 % than that of CWS with HA when the storage time was 72 h. Furthermore, the maximum coal content of CWS with 0.5 wt.% HAP may reached 70 wt.%. This work found a new route for utilizing humic acid and enlarged the selecting range of the dispersant for CWS. It has a positive significance for protection of environment.

Biorefinery lignosulfonates as a dispersant for coal water slurry

Valorization of lignin from biofuel production is the key to developing biorefinery technologies for sustainable and economic utilization of lignocellulosic biomass. Here we present isolating lignosulfonate from the spent liquors of Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses (SPORL)-pretreated lodgepole pine and Douglas-fir forest residue as a dispersant for coal water slurry. The two SPORL pretreatments were conducted at a pilot scale and resulted in very high ethanol yield from the pretreated biomass. Therefore, demonstrating the commercial utility of these lignosulfonates has practical significance. The two isolated biorefinery lignosulfonates (LSs), Na-LS and Ca-LS, both had a molecular weight of approximately 9000 Da. Fundamental lignin properties such as chemical structure, functional groups were analyzed. The two LSs showed slightly better to equal performance in modifying CWS rheology than a commercial dispersant naphthalene sulfonate formaldehyde condensate (FDN), despite they were less sulfonated than FDN. The practical importance of this study is that the pilot-scale pretreatments that produced the two LSs also produced excellent bioethanol yields at high titer without detoxification and washing. This suggests SPORL pretreatment is a promising technology for economic bioconversion of under-utilized woody biomass.

Synthesis of Coal-Water Slurry Dispersant Based on Humic Acid

This paper focused on the preparation of the grafted modification of humic acid (HA) that was used in coal water slurry (CWS). By means of orthogonal experiment, the grafted humic acid was synthesized with acrylic acid (AA) copolymerized with humic acid, using potassium persulfate as the initiator in the reaction system. The structure of copolymer was characterized by ATR-FTIR. And then, the viscosity, liquidity, and stability of CWS used the dispersant based on the modified humic acid were determined through the CWS viscometer and tests of stability. The optimum conditions of synthesis are that the mass ratio of AA and HA is 0.35:1, dosage of initiator is 5%, reaction temperature of is 75°C, reaction time is 2.0h. Besides, when the dosage of active ingredient of the dispersant for CWS was 0.12%, the viscosity of CWS achieved lower.

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%.

Effects of chemical structure on the properties of carboxylate‐type copolymer dispersant for coal‐water slurry

AbstractIn this study, a series of carboxylate‐type copolymer dispersants were prepared. The effects of chemical structures of the copolymer dispersants, including the molecular weight, kind, quantity and ratio of hydrophilic/hydrophobic groups, and side chain length, on the solid loading, apparent viscosity, zeta potential, rheological behavior, and stability of coal‐water slurry (CWS) prepared from Dongtan, Yima, and Datong coals were systematically investigated. The dispersion performance of the copolymer can be improved by adjusting its chemical structures, and the dispersion mechanism was discussed. In addition, a high solid loading CWS with excellent stability toward settling can be achieved by means of the copolymer dispersant and carboxymethyl cellulose sodium salt (CMC‐Na). Experiments have proved that the copolymer has the potential to be developed as a new high‐effective dispersant for CWS. © 2009 American Institute of Chemical Engineers AIChE J, 2009

Application of poly(vinyl alcohol) with an alkyl end group containing anionic groups to coal–water slurry as a dispersant

AbstractAnionic groups were introduced with copolymerization of corresponding vinyl monomers with vinyl acetate into poly(vinyl alcohol) (PVA) with an alkylthio end group. The polymers were investigated as a dispersant for coal‐water slurry (CWM). Anionic groups such as sodium sulfonate and sodium carboxylate enhance remarkably the ability of PVA with an alkylthio end group to disperse coal. Sodium polyacrylic acid with an alkyl end group also showed a good ability of dispersing coal. The order of the ability of dispersing coal in these polymeric dispersants along with sodium napthalene sulfonate formaldehyde condensate (NSF) varied by the kind of coal used. In cases of the polymeric dispersants, the fluidity of coal in terms of dependence of viscosity on shear rate also varied, from dilatency to thixotropy, in accordance with coal used. Impurities in coal as well as surface properties of coal particles might play important roles in the properties of CWM. © 1995 John Wiley & Sons, Inc.

95/00217 Effects of modified poly(vinyl alcohol)s as a dispersant for coal-water slurry

The biodegradability of alkylate compounds in serum bottles was investigated in the presence and absence of ethanol or benzene, toluene, ethylbenzene, and p-xylene (BTEX). The biomass was acclimated to three different alkylates, 2,3-dimethylpentane, 2,4-dimethylpentane and 2,2,4-trimethylpentane in porous pot reactors. The alkylates were completely mineralized in all three sets of experiments. They degraded more slowly in the presence of BTEX than in their absence because BTEX inhibited the microbial utilization of alkylates. However, in the presence of ethanol, their slower biodegradation was not related to inhibition by the ethanol. Throughout the experiments alkylates, ethanol, and BTEX concentrations did not change in the sterile controls.