Aluminum Company of America

Zenon Environmental Inc.

Zenon Technology Partnership

Kenneth Paul Goodboy

Mailvaganam Mahendran

Jinhua Bai

Larry F Wieserman

Ake A Deutschmann

Hubert L Fleming

James J Koenig

Luigi Fabbricino

Emmanuel K Saforo

Bradley M Smith

William C Sleppy

Kenneth M Thomas

An asymmetric membrane comprising a tubular polymer film in combination with a tubular braid on which the film is supported, requires the braid be macroporous and flexible, yet sufficiently strong to withstand continuous flexing, stretching and abrasion during use for microfiltration (MF) or ultrafiltration (UF). The specifications for a braid of a long-lived membrane are provided. A membrane is formed by supporting a polymer film in which particles of calcined &agr;-alumina are dispersed, on the defined tubular braid.

Hollow fiber membrane and braided tubular support therefor

A filtration membrane for micro- or ultra-filtration is formed from a complex of PVDF and calcined .alpha.-alumina ('.alpha.-Al') particles, in which complex the particles are reacted and dispersed. The suspended complex is then mixed with a hydrophilic polymer such as polyvinyl alcohol (40%-90% hydrolyzed) referred to herein as HPVA, which reacts with the complex imparting hydrophilicity to the polymer. The novel membrane provides about 50% higher specific flux than a membrane made with the same polymer but without the .alpha.-Al particles. Unexpectedly, the net flux is improved by treating the membrane with a solution of sodium hypochlorite which fails to remove the HPVA from the novel membrane but does remove it from the prior art membrane which does not contain the .alpha.-Al. The preferred membrane comprises a macroporous support coated on its outer surface with a thin tubular asymmetric semipermeable film of polymer containing less than about 50% by weight of .alpha.-Al particles.

Method of making a dope comprising hydrophilized PVDF and

A filtration membrane for micro- or ultra-filtration is formed from a complex of PVDF and calcined .alpha.-alumina ('.alpha.-Al') particles, in which complex the particles are reacted and dispersed. The suspended complex is then mixed with a hydrophilic polymer such as polyvinyl alcohol (40%-90% hydrolyzed) referred to herein as HPVA, which reacts with the complex imparting hydrophilicity to the polymer. The novel membrane provides about 50% higher specific flux than a membrane made with the same polymer but without the .alpha.-Al particles. Unexpectedly, the net flux is improved by treating the membrane with a solution of sodium hypochlorite which fails to remove the HPVA from the novel membrane but does remove it from the prior art membrane which does not contain the .alpha.-Al. The preferred membrane comprises a macroporous support coated on its outer surface with a thin tubular asymmetric semipermeable film of polymer containing less than about 50% by is weight of .alpha.-A1 particles.

Filtration membrane with calcined .alpha.-alumina particles therein

A method and cleaning system is disclosed for cleaning the outer surface of a fouled microfiltration (MF) or ultrafiltration (UF) semipermeable hollow fiber membrane after its initial stable transmembrane flux has been decreased to an unacceptably low level. The method is specifically applicable to any fiber used to withdraw purified water from dirty water, particularly water containing organic matter including beneficial bacteria and/or undesirable inorganic salts, where the viability of the bacteria population is to be maintained. The membrane is cleaned by flowing a cleaning fluid, preferably a biocidal oxidative electrolyte having an oxidizing anion and an associated cation through the clean, permeate-side of the membrane, at low pressure no more than the bubble pressure breakthrough, usually &lt;300 kPa (30 psig) for a MF or UF fiber. Such low pressure is sufficient to diffuse the electrolyte through both, the pores of the membrane and a fouling film which typically includes a biofilm accumulated on the fibers' outer surface, but not enough electrolyte flows through the membrane to kill numerically more than 20% of the living bacteria in the dirty water. This limitation can be met only if the cleaning period is brief. This period is only long enough to oxidize organic matter within the pores and kill essentially all bacteria in the biofilm. Preferably less than 5% of the bacteria population is decimated. As diffusion takes place, pores are again opened, both in the wall of the fiber and through the biofilm, and when the fibers are returned to normal operation, the restored flux is equal to at least 70% of the initial stable flux.

In situ cleaning system for fouled membranes

A process is described for purifying an oil-containing liquid to remove aqueous and solid impurities which comprises passing said liquid through a permeable inorganic membrane previously treated by contacting the membrane with an organic reactant selected from the group consisting of a phosphonic acid, a phosphinic acid, a monocarboxylic acid, a dicarboxylic acid, a boronic acid, a phosphoric acid ester and a precursor which decomposes upon contact with said inorganic membrane to form one of said organic reactants whereby the treated membrane is capable of separating aqueous and solid impurities from hydrocarbons in the oil-containing liquid.

Purification of an oil-containing liquid using a surface treated

A composite HCl adsorbent comprising about 50-95 wt % alumina and about 5-50 wt % Y zeolite wherein the molar ratio of SiO.sub.2 to Al.sub.2 O.sub.3 is about 4.5-6.0. The adsorbent is produced by admixing particles of alumina and acid-treated Y zeolite, agglomerating, aging and activating. The activated composite adsorbent has improved dynamic adsorption behavior for HCl compared with both the alumina and Y zeolite starting materials.

Adsorbent for HCl comprising alumina and acid-treated Y zeolite

An improved Claus catalyst comprising activated alumina in which sodium oxide concentration is controlled to achieve increased sulfur conversion. Sodium oxide is present in an amount greater than 1.0 wt % (1100.degree. C. calcined basis), the remainder being activated alumina. Specific surface area is greater than 100 m.sup.2 /g (BET). The catalyst preferably has a surface area greater than 300 m.sup.2 /g (BET) and an LOI (hydroxyl content as determined by heating from 400.degree. to 1100.degree. C.) between 2.0 and 6.0 wt %.

Activated alumina Claus catalyst having increased sodium oxide content

An improved Claus catalyst comprising activated alumina in which sodium oxide concentration is controlled to achieve increased sulfur conversion. Sodium oxide is present in an amount greater than 0.50 wt % (1100.degree. C. calcined basis), the remainder being activated alumina. Specific surface area is greater than 100 m.sup.2 /g (BET). In a preferred embodiment, sodium oxide content is controlled in the range 1.0 to 2.5 wt %. The catalyst preferably has a surface area greater than 300 m.sup.2 /g (BET) and an LOI (hydroxyl content as determined by heating from 400.degree. to 1100.degree. C.) between 2.0 and 6.0 wt %.

An improved Claus catalyst is provided in the form of activated alumina in which sodium oxide concentration, LOI and surface area of the catalyst are carefully controlled to achieve increased sulfur conversion. Sulfur recovery is enhanced by choosing an alumina catalyst having properties which minimize chemisorption of sulfur dioxide on the catalyst at reaction conditions. Sodium oxide may be present in an amount of 0.1 to 2.5 wt % of the catalyst (1100.degree. C. calcined basis). The catalyst desirably has a surface area greater than 100 m.sup.2 /g (BET) and an LOI (hydroxyl content as determined by heating from 400.degree. to 1100.degree. C.) between 2.0 and 6.0 wt %. A method of producing the catalyst and a method of using the catalyst are also provided.

Method of producing an activated alumina Claus catalyst

A low soda pseudoboehmite gel is provided by reacting a NaAlO.sub.2 solution with a NaHCO.sub.3 solution having a concentration of less than 75 grams/liter and preferably less than 50 grams/liter. The soda content of the resulting AlO(OH) gel can be further lowered by repeated washing and/or redispersing (repulping) in water and/or further neutralization with a carboxylic acid having 1 to 6 carbon atoms.

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Wexford, PA, United States of America

Kenneth Paul Goodboy