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1.
《分离科学与技术》2012,47(13):2201-2219
Abstract The filtration and separation characteristics of iron ore fines have been investigated. The experimental work included: characterization, evaluation of suitable flocculants to enhance settling and dewatering rate, determination of optimum dosages of flocculants, and influence of surfactants on nitration dewatering of both flocculated and unflocculated iron ore fines by vacuum filtration. The results showed that 1) the settling rate can be enhanced many-fold (from 2.52 to 90 m/h) by a suitable flocculant, 2) the residual filter cake moisture content can be reduced from 18.2% without reagents to 12.6% with suitable surfactant dewatering aids while the filtration rate can be enhanced from 4.8 to 97.2 L/h with suitable dewatering filter aids, and 3) the specific cake resistance to filtration can be brought down from 8.6 × 109 to 1.0 × 109 m/kg by using a surfactant sodium petroleum sulfonate at a concentration of 1.47 × 10?3 kg/t. The economics of using flocculant filter aids and surfactant dewatering aids before thermal drying is described and discussed. 相似文献
2.
Naureen Alam 《Fuel》2011,90(1):26-35
A sustainable alternative to tailings dam disposal of coal refuse is mechanical dewatering of tailings, which provides fast production of dry solids and water reuse. In this study, flocculation followed by filtration of coal plant tailings, a new concept in tailings dewatering is investigated in detail. This paper focuses on the effect of preconditioning tailings with varying flocculants and dosages on filtration kinetics and the resultant moisture content of the filter cake. The results show that the cationic flocculant, MAGNAFLOC LT 425, requires a high dosage to produce a low moisture content filter cake and clear filtrate. Optimal sized flocs were produced with the anionic flocculant, MAGNAFLOC 5250, even though the particles are negatively charged. The kinetics of the filtration was dependent on the composition of process water as indicated by supporting sedimentation tests. The concentration of divalent alkali earth metals such as Ca2+ and Mg2+ allow for large floc growth by a bridging mechanism, which involves binding of the polymer and the negativity charged particle. Filtration and settling curves at this dosage were also supported by filter cake analysis using Darcy plots. It was found that the large floc size significantly increases the permeability of the filter cake. Floc size measurements and fractal dimension showed that while the large flocs were produced with anionic flocculant, the flocs produced with the cationic flocculant were small and weak. The results indicate that the optimum dosage and flocculant type for effective and efficient filtration of coal plant tailings is approximately 350 g/t of anionic flocculant at a 35% solids content and 40 kPa filtration pressure. 相似文献
3.
The flocculation of kaolin suspended in a dilute salt solution was studied as a function of the addition of cationic surfactant and cationic polyacrylamide (CPAM) added separately, consecutively, or simultaneously. Cationic polyacrylamide caused flocculation by bridging when added in low concentrations, but at higher concentrations, charge neutralization became the dominant mechanism and the flocculation rate was highly dependent on the charge density of the polymer. Adsorption of sufficient polymer or surfactant (cetyl pyridinium chloride) prevented immediate adsorption of the other, although surfactant could replace polymer after extended agitation. The adsorption of polymer was greatest when small flocs were formed by charge neutralization or by prolonged shaking. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2382–2389, 2002 相似文献
4.
A. Fuangswasdi A. Charoensaeng D. A. Sabatini J. F. Scamehorn E. J. Acosta K. Osathaphan S. Khaodhiar 《Journal of surfactants and detergents》2006,9(1):21-28
This research reports on the adsorption and precipitation of mixtures of anionic and cationic surfactants having single and
twin head groups. The surfactant mixtures investigated were: (i) a single-head anionic surfactant, sodium dodecyl sulfate
(SDS), in a mixture with the twin-head cationic surfactant pentamethyl-octadecyl-1,3-propane diammonium dichloride (PODD)—adsorption
was studied on negatively charged silica; and (ii) a twin-head anionic surfactant, sodium hexadecyl-diphenyloxide disulfonate
(SHDPDS), and the single-head cationic surfactant dodecylpyridinium chloride (DPCI)—adsorption was studied on positively charged
alumina. Whereas the mixed surfactant system of SHDPDS/DPCI showed adsorption on alumina that was comparable to the of SHDPDS
alone, the mixed surfactant system of SDS/PODD showed increased adsorption on silica as compared with PODD alone. The adsorption
of the SDS/PODD mixture increased as the anionic and cationic system approached an equimolar ratio. Precipitation diagrams
for mixtures of single- and twin-head surfactant systems showed smaller precipitation areas than for single-head-only surfactant
mixtures. Thus, the combination of single- and double-head surfactants helps reduce the precipitation region and can increase
the adsorption levels, although the magnitude of the effect is a function of the specific surfactants used. 相似文献
5.
The influence of derivatives of 1,2,4 triazole, 3-amino 1,2,4-traizole (ATA), 3-amino 5-mercapto 1,2,4 triazole (AMT) and 3-amino 5-methylthio 1,2,4 triazole (AMTT) and ionic surfactants cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) on the corrosion control of copper in acidic solution was investigated by gravimetric and electrochemical methods. The combined effect of triazoles and surfactants was also evaluated. Electrochemical parameters like corrosion potentials corrosion current density, corrosion rates and inhibition efficiencies were determined. The results reveal the fact that of all triazoles AMTT shows best inhibition and anionic surfactant SDS protects the surface better than the cationic surfactant CTAB. The polarisation data reveal that all inhibitors behave as a mixed type inhibitor. Adsorption of these inhibitors on the surface of copper is found to obey the Langmuir adsorption isotherm. A marked inhibition synergism effect is shown by all the combinations of triazole and surfactant. 相似文献
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研究了无机和有机絮凝剂对剩余污泥水解和脱水性能的影响。分别投加浓度为20g/L的CaO和CPAM(阳离子型聚丙烯酰胺)调节剩余污泥,溶出的有机质规律如下:溶解性COD(SCOD)的溶出量表现为CPAM>CaO>空白;溶解性蛋白质(SPN)的溶出量表现为CPAM>CaO>空白;溶解性碳水化合物(SPS)的溶出量表现为CaO>CPAM>空白。污泥的脱水性能指标——比阻(SRF)和滤饼含固率的变化分别为:SRF表现为CPAMCaO>空白。从SPN、SPS和SCOD的溶出量、比阻和滤饼含固率的变化说明:加入CaO和CPAM都能改善剩余污泥的水解和污泥脱水性能。 相似文献
8.
The effect of cationic, anionic and neutral surfactants on the mechanical dewatering of a highly decomposed fuelgrade peat has been examined. Surfactant adsorption and zeta potential of the peat particles correlated with dewatering of peat samples. The cationic surfactants had large positive effects on dewatering, the anionic surfactants had a negative effect while the neutral surfactant had no effect. The effects of the surfactants could be explained by charge neutralization and double layer suppression. The cationic surfactants were superior to analogous organic salts because of enhanced interaction by the hydrophobic effect. 相似文献
9.
Navya Antony SreedharanNair Balachandran Puzhavoorparambil V. Mohanan 《Journal of surfactants and detergents》2014,17(4):703-708
The enzyme amylase is one of the hydrolyzing enzymes used in detergent formulation in order to remove soil based on polysaccharides. The effectiveness of the enzyme depends on its compatibility with other ingredients of the formulation. Among the studied additives, comprising anionic surfactants sodium dodecyl hydrogen sulfate (SDS) and dioctyl sodium sulfosuccinate, the cationic surfactant cetyl trimethyl ammonium bromide (CTAB), nonionic surfactants polyoxyethylene sorbitan monooleate and polyoxyethylene octyl phenyl ether, carboxy methyl cellulose and sodium sulfate, only the anionic surfactant SDS and cationic surfactant CTAB showed catalytic enhancement of α-amylase. The kinetic parameters, K m and k cat, showed an increase in catalytic activity in the micellar pseudophase. The decrease in optimum temperature from 55 to 30 °C and the shift in optimum pH from 5.5 to 7 on the addition of SDS and CTAB for the hydrolysis of starch are very favorable to enhance the washing characteristics. 相似文献
10.
Surfactant-Induced Wettability Alteration of Oil-Wet Sandstone Surface: Mechanisms and Its Effect on Oil Recovery 下载免费PDF全文
Baofeng Hou Yefei Wang Xulong Cao Jun Zhang Xinwang Song Mingchen Ding Wuhua Chen 《Journal of surfactants and detergents》2016,19(2):315-324
Different analytical methods were utilized to investigate the mechanisms for wettability alteration of oil-wet sandstone surfaces induced by different surfactants and the effect of reservoir wettability on oil recovery. The cationic surfactant cetyltrimethylammonium bromide (CTAB) is more effective than the nonionic surfactant octylphenol ethoxylate (TX-100) and the anionic surfactant sodium laureth sulfate (POE(1)) in altering the wettability of oil-wet sandstone surfaces. The cationic surfactant CTAB was able to desorb negatively charged carboxylates of crude oil from the solid surface in an irreversible way by the formation of ion pairs. For the nonionic surfactant TX-100 and the anionic surfactant POE(1), the wettability of oil-wet sandstone surfaces is changed by the adsorption of surfactants on the solid surface. The different surfactants were added into water to vary the core surface wettability, while maintaining a constant interfacial tension. The more water-wet core showed a higher oil recovery by spontaneous imbibition. The neutral wetting micromodel showed the highest oil recovery by waterflooding and the oil-wet model showed the maximum residual oil saturation among all the models. 相似文献
11.
Adsorption,Electrokinetic and Stabilizing Properties of the Guar Gum/Surfactant/Alumina System 下载免费PDF全文
Elżbieta Grządka Małgorzata Wiśniewska Vladimir M. Gun'ko Vladimir I. Zarko 《Journal of surfactants and detergents》2015,18(3):445-453
The adsorption of non‐ionic polysaccharide guar gum (GG) in the presence of surfactants (anionic SDS, non‐ionic TX‐100, cationic CTAB and their equimolar mixtures) from their NaCl solutions onto an alumina surface (Al2O3) was studied spectrophotometrically. This study is important in light of the many disagreements concerning the structure and behaviour of mixtures containing polymers and surfactants at the surface of an adsorbent. The presence of surfactant caused an increase in the GG adsorption in all studied systems as a consequence of the formation of complexes. Among the single surfactants the highest increase in the GG adsorption was observed in the presence of CTAB. However, the usage of mixtures of the surfactants caused a much more effective increase in the GG adsorption on the alumina surface because of the synergistic effect of the surfactants. In order to get some information on the structure of the electrical double layer (edl), the surface charge density of alumina was determined and zeta potential measurements were conducted. The obtained data showed that the adsorption of GG or GG/surfactant complexes on the metal oxide surface strongly influences a diffused part of the edl, whereas a compact part of the edl is not affected. The colloidal stability of the alumina suspensions was measured in the presence and absence of GG and surfactants. It was found that GG and the mixtures of GG and surfactants can improve the stability of the suspensions. 相似文献
12.
A novel cationic polyacrylamide modified with fluorinated acrylate had been synthesized of acrylamide (AM), methacryloxyethyl
trimethylammonium chloride (DMC), and 2-(perfluorooctyl)ethyl acrylate (FEA) by free radical micellar copolymerization in
aqueous solution utilizing cetyl trimethylammonium bromide (CTAB) as the surfactant and potassium persulfate (KPS)/sodium
bisulfite (SBS) as the redox initiator. Some factors affecting synthesis, such as the amount of FEA, CTAB, and KPS, were described.
Surface activity and flocculation of the polymer were studied. The results showed that with the incorporation of FEA, the
intrinsic viscosity decreased until the modified polymer was not able to dissolve in water; and with the increase of CTAB
and KPS, the intrinsic viscosity decreased firstly then increased slowly. The polymer exhibited good surface activity in both
water and salt solution. Its flocculation properties were evaluated with kaolin suspensions using a standard jar test. The
results demonstrated the superiority of the copolymer over the no-modified cationic polyacrylamide as a flocculant. 相似文献
13.
The study involves the dynamic evolution of the Briggs–Rauscher (BR) reaction in the presence of various surfactants—SDS (sodium dodecyl sulphate) as anionic, CTAB (cetyl trimethylammonium bromide) as cationic and TritonX‐100 [4‐(1,1,3,3‐(tetramethylbutyl) phenyl polyethylene glycol] as a neutral one in single as well as mixed mode conditions (SDS + TX‐100 and CTAB + TX‐100). The reaction has been monitored potentiometrically at 30 °C under CSTR conditions. These surfactants affect the reaction dynamics to an extent which depends on the nature and concentration of the surfactant and the formation of their self‐assemblies. The experimental findings indicate that the oscillatory behavior of the BR reaction in the presence of surfactants is due to the efficacy of organized surfactant assemblies to selectively distribute the key species involved in the reaction, and their interaction with the counter ions in cases of ionic micelles. The study reveals that the evolution of oscillatory behavior is a characteristic feature of the surfactant. 相似文献
14.
An investigation of the flocculation of silica and alumina suspensions by a series of synthetic flocculants of a wide range of charge density both anionic and cationic in nature has been carried out. The extent of flocculation was determined by measurements of settling rate, sediment volume and supernatant clarity. The effect of the pH of the suspension on the performance of a number of selected polymers has been investigated. In the systems examined, flocculation was largely controlled by the charge carried by the suspended particles and polymer molecules. The dosage/settling rate characteristics of kaolin suspensions flocculated with non-ionic polymers of varying molecular weight are reported. The dosages of non-ionic polymers required for optimum flocculation of kaolin suspensions of varying solids content have been measured. At low particle concentrations bridging is less effective, and is probably reduced due to the adsorption of polymer molecules on to single particles. 相似文献
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17.
M. K. Abd‐El Rahman 《化学工程与技术》2000,23(5):457-461
This work focuses on the dewatering of phosphatic clay waste of Egyptian Abu‐Tartur phosphate ore by flocculation using polyacrylamides to enhance the dewatering rate and recycling of the process water. The experimental program includes sieving, hydrocyclone separation and flocculation of the overflow of hydrocyclone. Results revealed that the coarser fraction larger than 32 micron is enriched with P2O5 whereas the undersize fraction is only clay. Hydrocyclone successfully separates two cuts; the underflow fraction is enriched with phosphate while the other is just clay. By this technique, the P2O5 content is increased from 15.57 % in the feed to 26 % in the underflow cut which constitutes about 39.8 % by weight. Flocculation helps to increase both the settling rate of phosphatic clay waste and recycling the process water. The former criteria increased 37 times by using anionic polyacrylamide (A130) as compared to the natural settling rate of the same waste. Results were explained in the light of a model which suggests that the flocculation mechanism involves two stages: the first stage involves the adsorption of the reagent on the particles whereas the second forms aggregate flocs. Formation of aggregate flocs takes place by tangling the polymer molecules, so that one polymer molecule will be adsorbed at several points on the surface of the particle, leaving loops which may be of varying lengths, projecting out from the surface. Partially covered particles would collide to form bridges. 相似文献
18.
The effect of type of self-assembled system and pH on the efficiency of corrosion inhibition of carbon-steel surfaces 总被引:1,自引:0,他引:1
Erileide Cavalcanti Roberto Alcides de Oliveira Wanderley Neto Carlos Alberto Martínez-Huitle José Luís Cardozo Fonseca Tereza Neuma de Castro Dantas Alexandre Gurgel 《Progress in Organic Coatings》2013
In this work, three surfactants were used in the preparation of self-assembled systems to inhibit acidic corrosion on API5LX Gr X52 carbon-steel surfaces: CTAB (a cationic surfactant), SDS (an anionic surfactant), and C12E9 (a non-ionic surfactant). These surfactants were used in the form of aqueous solutions and in microemulsions. Pseudoternary diagrams were constructed using aqueous phases consisting of 0.5 M NaCl at pH = 2, 4 and 7, butan-1-ol as co-surfactant and kerosene as oil phase. The values of c.m.c., maximum surface excess, minimum surfactant cross-sectional area and free energy of micellization were determined using surface tensiometry. The distinct effects of pH and type of self-assembled system on the efficiency of corrosion inhibition have been elucidated by electrochemical techniques (polarization and Tafel curves). It has been demonstrated that these parameters can significantly affect the results, which depend largely on the mechanism of aggregate adsorption on the metal surface and droplet stability. By establishing the optimal conditions, excellent corrosion efficiencies were found for these systems, even at low surfactant concentrations. 相似文献
19.
Mechanical cake dewatering is always desired to reduce the load on thermal dewatering (drying). Any change in the upstream process such as crystallization can have a significant influence on the filtration as well as cake dewatering characteristics. The present study deals with the effect of hydrodynamics (mixing intensity) during salicylic acid crystallization on the air dewatering characteristics in the subsequent pressure filtration. The mixing conditions during crystallization were varied by using three different types of agitators (anchor impeller [AI], curved blade turbine [CBT], and bar turbine [BT]) and by varying the speed of agitation. The effect of operating pressure and dewatering time on the final moisture content of the cake was also studied. The crystal properties (crystal size and size distribution) were found to vary with the mixing intensity, which further influenced the cake dewatering kinetics as well as the residual moisture content. An AI, which is a laminar flow impeller, produced crystals with a wide size distribution and higher mean particle size, which resulted in cake with high porosity and hence higher moisture content. The high porosity (as well as high cake permeability) caused early air breakthrough, which resulted in ineffective dewatering of cake. Therefore, in this case the residual moisture in cake was found to be higher (27%) even at higher dewatering pressure (1.5 bar gauge) and longer dewatering time (90 s). A BT creates high turbulence during mixing and produced crystals with a relatively narrow size distribution and lower mean particle size, which provided low-porosity cakes. Such cakes could be efficiently dewatered and the final cake moisture content was found to decrease to about 15%, a significant improvement in the filterability of the cake. The dewatering data were modeled according to the correlation between irreducible cake saturation and capillary number for predicting the cake dewatering characteristics (residual moisture as well as dewatering kinetics) and the results were compared with the experimental data. 相似文献
20.
Tianxi Zhang Anping Jiang Joseph H. Harrison Shulin Chen 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(8):1098-1103
BACKGROUND: Use of flocculation in wastewater treatment involves interactions of polymer with suspended solids and some dissolved organic compounds that can have a significant impact on aggregation process. RESULTS: It was found that a strong interaction between cationic compounds and dissolved pigments in anaerobically digested (AD) wastewater occurred. The interactions were investigated by light adsorption of the pigments using a commercial flocculant added in the solutions and through a liquid–liquid extraction method using a model cationic surfactant (CTAB) dissolved in organic solvents. The absorbance of pigments decreased significantly with added cationic flocculant as the pigments and flocculants formed insoluble complexes that were removed by centrifugation. CONCLUSION: The absorbance results indicate that the pigments can form complexes even at high concentrations (e.g. 2000 mg L?1) of the flocculants. In addition, the extraction results demonstrated that pigments in the aqueous phase were transferred into the CTAB organic phase due to a strong interaction between the pigments and CTAB. These results suggest that the pigments present in AD effluent could be a negative factor for the flocculation process, probably resulting in the need for a high dosage of flocculants. Copyright © 2012 Society of Chemical Industry 相似文献