Electrical double-layer effects on the deposition of zeolite A on surfaces

Oonkhanond, Bovornlak; Mullins, Michael E.

doi:10.1016/j.jcis.2004.08.170

Cited by 14 publications

(8 citation statements)

References 6 publications

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“…The xylene isomer separations have indicated that the pure silicalite membranes synthesized by in situ crystallization give a higher separation efficiency (α p -xylene/ o -xylene = ∼8.9) than that on the zeolite membranes synthesized by secondary growth from solutions having Si/Al ratios from 40 to 65. Similar influences of aluminum contents on the intercrystalline structure of zeolite membranes were also reported in the literature . It is more likely that the enhancement in ion rejection for ZSM-5 membranes is caused by a strong surface charge rather than molecular sieving .…”

Section: Resultssupporting

confidence: 81%

Enhanced Water Permeation of Reverse Osmosis through MFI-Type Zeolite Membranes with High Aluminum Contents

Liu

McPherson

et al. 2007

Ind. Eng. Chem. Res.

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MFI-type zeolite membranes with different Si/Al ratios were synthesized by seeding and secondary growth. Several factors including alkalinity, synthesis time, and Si/Al ratio were varied to optimize the synthesis conditions. Ion separation of 0.10 M NaCl solution by zeolite membranes was investigated through a cross-flow reverse osmosis system. The aluminum content was found to play an important role in zeolite growth and reverse osmosis separation performance afterward. Membrane hydrophilicity and surface charge measured by the contact angle and particle ζ-potential were found to be strongly dependent on the aluminum composition of the membranes. Both water flux and ion rejection increased considerably as aluminum ions were incorporated into the zeolite framework with a water flux increase from 0.112 to 1.129 kg/m2·h and ion rejection improvement from 90.6% to 92.9%. The enhancement in ion separation and water flux for high aluminum ZSM-5 membranes was further analyzed by enhanced water affinity on the membrane surface and restricted ion permeation in confined spaces.

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Section: Resultssupporting

confidence: 81%

Enhanced Water Permeation of Reverse Osmosis through MFI-Type Zeolite Membranes with High Aluminum Contents

Liu

McPherson

et al. 2007

Ind. Eng. Chem. Res.

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“…The equilibrium of forces as a new model, i.e., electrostatic repulsion, van der Waals attraction, and mechanical separation, defines the critical gel formation in the system with a linear, but slow coagulation rate. Consequently, the electrostatic repulsion absence may be compensated by mechanical shear to stabilize a coagulating slurry and to control the coagulation period 24.

true \frac{F}{R_{normaleff}} = \underset{normalVan normal normalder normal normalWaals}{\underset{︸}{- \frac{A}{6 h}}} + \underset{normalElectrostatics}{\underset{︸}{4 π ε_{0} ε ζ^{2} e^{- κ normalh}}} + \underset{normalMechanics}{\underset{︸}{α \overset{\cdot}{γ}}} \overset{!}{\overset{︷}{=}} 0

…”

Section: Resultsmentioning

confidence: 99%

“…The calculations originate from the Derjaguin‐Landau‐Verwey‐Overbeek (DLVO) theory 24 and include the following side conditions: Interacting silica particles from water glass show a diameter of approximately 1 nm (silicate). The viscosity of gelled slurries is focused due to the drastic viscosity increment. To stablish a minimum strain rate for the stability of the slurry a 110 % value of the minimum viscosity was used. The critical strain rate value defines the force equilibrium. …”

Section: Resultsmentioning

confidence: 99%

Peptization Control of Composite Materials Containing Water Glass for Spray Drying of Catalysts

et al. 2021

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Silica‐based composite particles are complex catalyst materials that are widely used in petrochemistry. The preparation of particles that are well defined in form, composition, and chemical and rheological behavior by spray drying of suspensions remains an important industrial challenge. Here, zeolite HY, kaolin, and the cheap binder water glass are used. Experimental and model regimes of slurry peptization are analyzed based on their pH value, zeta potential, and mixing speed to control the process. The results show a pseudoplastic behavior of the silica slurries for zeta potential below 20 mV, which is explained by surface charge, hydroxyls, and pH‐dependent coagulation. Thus, a quick acidification of the slurry, additional mechanic shear, and subsequent pH control during spray drying enable control of peptization kinetics.

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“…Zeolite membranes synthesized from a wide range of aluminum content show high ion rejection for 0.10 M NaCl solution (r i >90%). Both the xylene isomer separation and gas permeation study indicated that zeolite membranes synthesized from an aluminum-containing solution have poor intercrystalline growth [32]. It is more likely that the enhancement in ion rejection for ZSM-5 membranes is caused by strong surface charge rather than the molecular sieving [33].…”

Section: Surface Chemistry and Ion Separationmentioning

confidence: 99%

Treating Coalbed Natural Gas Produced Water for Beneficial Use By MFI Zeolite Membranes

Lee

Li²

2008

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Desalination of brines produced from oil and gas fields is an attractive option for providing potable water in arid regions. Recent field-testing of subsurface sequestration of carbon dioxide for climate management purposes provides new motivation for optimizing efficacy of oilfield brine desalination: as subsurface reservoirs become used for storing CO 2 , the displaced brines must be managed somehow. However, oilfield brine desalination is not economical at this time because of high costs of synthesizing membranes and the need for sophisticated pretreatments to reduce initial high TDS and to prevent serious fouling of membranes. In addition to these barriers, oil/gas field brines typically contain high concentrations of multivalent counter cations (eg. Ca 2+ and SO 4 2-) that can reduce efficacy of reverse osmosis (RO). Development of inorganic membranes with typical characteristics of high strength and stability provide a valuable option to clean produced water for beneficial uses.Zeolite membranes have a well-defined subnanometer pore structure and extreme chemical and mechanical stability, thus showing promising applicability in produced water purification. For example, the MFI-type zeolite membranes with uniform pore size of ~0.56 nm can separate ions from aqueous solution through a mechanism of size exclusion and electrostatic repulsion (Donnan exclusion). Such a combination allows zeolite membranes to be unique in separation of both organics and electrolytes from aqueous solutions by a reverse osmosis process, which is of great interest for difficult separations, such as oil-containing produced water purification. v The objectives of the project "Treating Coalbed Natural Gas Produced Water for Beneficial Use by MFI Zeolite Membranes" are: (1) to conduct extensive fundamental investigations and understand the mechanism of the RO process on zeolite membranes and factors determining the membrane performance, (2) to improve the membranes and optimize operating conditions to enhance water flux and ion rejection, and (3) to perform long-term RO operation on tubular membranes to study membrane stability and to collect experimental data necessary for reliable evaluations of technical and economic feasibilities.Our completed research has resulted in deep understanding of the ion and organic separation mechanism by zeolite membranes. A two-step hydrothermal crystallization process resulted in a highly efficient membrane with good reproducibility. The zeolite membranes synthesized therein has an overall surface area of ~0.3 m 2 . Multichannel vessels were designed and machined for holding the tubular zeolite membrane for water purification. A zeolite membrane RO demonstration with zeolite membranes fabricated on commercial alpha-alumina support was established in the laboratory. Good test results were obtained for both actual produced water samples and simulated samples. An overall 96.9% ion rejection and 2.23 kg/m 2 .h water flux was achieved in the demonstration. In addition, a post-synthesis modification method u...

show abstract

Electrical double-layer effects on the deposition of zeolite A on surfaces

Cited by 14 publications

References 6 publications

Enhanced Water Permeation of Reverse Osmosis through MFI-Type Zeolite Membranes with High Aluminum Contents

Enhanced Water Permeation of Reverse Osmosis through MFI-Type Zeolite Membranes with High Aluminum Contents

Peptization Control of Composite Materials Containing Water Glass for Spray Drying of Catalysts

Treating Coalbed Natural Gas Produced Water for Beneficial Use By MFI Zeolite Membranes

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