Surface treated porous ceramic membranes and method of making same

Claim 2

A treated permeable inorganic membrane having a metal oxide/hydroxide surface and having bonded thereto a substantially monomolecular layer of phosphoric acid ester material, and the bond formed between the oxide or hydroxide group on the membrane and the acid group on the phosphoric acid ester, the ester material selected from the class consisting of: (a) one or more phosphoric acid monoesters having the formula (RO)PO(OH) 2 ; (b) one or more phosphoric acid diesters having the formula (RO) (R'O)PO(OH); and (c) mixtures of same; where R comprises a 1-30 carbon-containing group and R' comprises hydrogen or a 1-30 carbon-containing group.

Claim 3

The treated membrane of claim 1 wherein said monomolecular layer of phosphoric acid ester acid material is chemically bonded to at least 99% of the reactive sites on said surface.

Claim 4

The permeable inorganic membrane of claim 1 wherein said membrane comprises one or more oxide/hydroxides of elements selected from the class consisting of Groups IIIa (Sc and Y), IVa (Ti, Zr, and Hf), Va (V, Nb, and Ta), VIa (Cr, Mo, and W), VIIa (Mn, Tc, and Re), VIII (Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, and Pt), Ib (Cu, Ag, and Au), IIb (Zn, Cd, and Hg), IIIb (B, Al, Ga, In, and Tl), IVb (Ge, Sn, and Pb), Vb (As, Sb, and Bi), an element in the lanthanide series, an element in the actinide series, mixtures thereof, and mixtures of Groups IIa (Be, Mg, Ca, Sr, Ba, and Ra) and VIb (Se, Te, and Po).

Claim 5

The treated membrane of claim 2 wherein said treated membrane has an average pore size of from about 0.1 Å to about 1000 microns in diameter.

Claim 6

The permeable inorganic membrane of claim 2 wherein said membrane is selected from the class consisting of aluminum oxide/hydroxide and zirconium oxide/hydroxide.

Claim 7

The permeable inorganic membrane of claim 5 wherein said membrane comprises aluminum oxide/hydroxide.

Claim 8

The permeable inorganic membrane of claim 6 wherein said membrane has a surface area in the range of 0.1 to 600 m 2 /g.

Claim 9

The permeable inorganic membrane material of claim 5 wherein said membrane comprises zirconium oxide.

Claim 10

The permeable inorganic membrane of claim 8 wherein said porous zirconium oxide has a surface area in the range of 0.1 to 600 m 2 /g.

Claim 11

The permeable inorganic membrane of claim 2 wherein the thickness of said monomolecular layer of phosphoric acid ester material chemically bonded to said metal oxide/hydroxide surface is in the range of 10 to 5,000 Å.

Claim 12

The permeable inorganic membrane of claim 10 wherein the thickness of said monomolecular layer of phosphoric acid ester material chemically bonded to said metal oxide/hydroxide surface is in the range of 3 to 500 Å.

Claim 13

The permeable inorganic membrane of claim 2, wherein said R group of said phosphoric acid ester material contains at least 1 carbon atoms.

Claim 14

The permeable inorganic membrane of claim 2 wherein said R group or said R' group comprises an organic radical selected from long and short chain aliphatic hydrocarbons, aromatic hydrocarbons, carboxylic acids, amines, imides, anilines, pyridines, piperidines, carbohydrates, ethers, alkenes, alkynes, alcohols, nitriles, oximes, organosilicones, sulfur containing organic compounds, perfluoro organic molecules, perchloro organic molecules, perbromo organic molecules and combinations of these groups.

Claim 15

The permeable inorganic membrane of claim 2 wherein said R group or said R' group has a functional group attached to a portion of said organic acid material spaced from the portion of said material bonded to said metal oxide/hydroxide surface and selected from the class consisting of a glucose group, a cyano group, a cyanate group, isocyanate group and thiocyanate group, a phenyl group, a diphenyl group, a tertiary butyl group, a sulfonic group, a benzyl sulfonic group, a halogen group, nitrate group, phosphate group, phospinate group, phosphinite group, phosphonate group, quaternary ammonium salt group and combinations of these groups.

Claim 16

The permeable inorganic membrane of claim 2 wherein the ester material has attached thereto a group selected from the class consisting of --SO 3 H, --N + (CH 3 ) 3 Cl, --COONa, --NH 2 and --CN.

Claim 17

The permeable inorganic membrane of claim 2 wherein said monomolecular layer of phosphoric acid ester material is substantially free of hydroxyl groups after chemically bonding to said metal oxide/hydroxide surface.

Claim 18

A permeable inorganic membrane selected from porous aluminum oxide and zirconium oxide, said membrane having a surface area of from about 0.10 to about 600 m 2 /gram, good chemical stability over a pH range of from 1 to 14, and having bonded to the surface thereof a monomolecular layer of one or more phosphoric acid monoesters having the formula (RO)PO(OH) 2 , where R comprises a 1-30 carbon-containing group, and wherein excess phosphoric acid monoester not bonded to the underlying membrane surface is removed to ensure formation of said monomolecular layer of said phosphoric acid monoester on the surfaces of said membrane.

Claim 19

A permeable inorganic membrane selected from porous aluminum oxide and zirconium oxide, said membrane having a surface area of from about 0.10 to about 600 m 2 /gram, good chemical stability over a pH range of from 1 to 14, and having bonded to the surface thereof a monomolecular layer of one or more phosphoric acid monoesters having the formula (RO)PO(OH) 2 , where R comprises a 1-30 carbon-containing group, and wherein excess phosphoric acid monoester not bonded to the underlying membrane surface is removed to ensure formation of said monomolecular layer of said phosphoric acid monoester on the surfaces of said membrane.

Claim 20

A permeable inorganic membrane selected from porous aluminum oxide and zirconium oxide, said membrane having a surface area of from about 0.10 to about 600 m 2 /gram, good chemical stability over a pH range of from 2 to 12, and having bonded to the surface thereof a monomolecular layer of one or more phosphoric acid diesters having the formula (RO)(R'O)PO(OH), where R comprises a 1-30 carbon-containing group and R' comprises hydrogen or a 1-30 carbon-containing group, and wherein excess phosphoric acid diester not bonded to the underlying surface is removed to ensure formation of said monomolecular layer of said phosphoric acid diester on the surfaces of said membrane.

Claim 21

A permeable inorganic membrane selected from porous aluminum oxide and zirconium oxide, said membrane having a surface area of from about 0.10 to about 600 m 2 /gram, good chemical stability over a pH range of from 2 to 12, and having bonded to the surface thereof a monomolecular layer of one or more phosphoric acid diesters having the formula (RO)(R'O)PO(OH), where R comprises a 1-30 carbon-containing group and R' comprises hydrogen or a 1-30 carbon-containing group, and wherein excess phosphoric acid diester not bonded to the underlying surface is removed to ensure formation of said monomolecular layer of said phosphoric acid diester on the surfaces of said membrane.

Claim 22

A process for bonding a monomolecular layer of one or more phosphoric acid esters to a permeable inorganic membrane selected from the class consisting of Groups IIIa (Sc and Y), IVa (Ti, Zr, and Hf), Va (V, Nb, and Ta), VIa (Cr, Mo, and W), VIIa (Mn, Tc, and Re), VIII (Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, and Pt), Ib (Cu, Ag, and Au), IIb (Zn, Cd, and Hg), IIIb (B, Al, Ga, In, and Tl), IVb (Ge, Sn, and Pb), Vb (As, Sb, and Bi), an element in the lanthanide series, an element in the actinide series, mixtures thereof, and mixtures of Groups IIa (Be, Mg, Ca, Sr, Ba, and Ra) and VIb (Se, Te, and Po) to form a coated membrane having good chemical stability over a pH range of from 1 to 14 which comprises: (a) providing a liquid containing one or more phosphoric acid esters therein selected from the class consisting of: (i) one or more phosphoric acid monoesters having the formula (RO)(OH) 2 ; (ii) one or more phosphoric acid diesters having the formula (RO)(R'O)PO(OH); and (iii) mixtures of (ii) and (ii); where R comprises a 1-30 carbon-containing group and R' comprises hydrogen or a 1-30 carbon-containing group; and (b) contacting the surface of said permeable inorganic membrane with said liquid containing said one or more phosphoric acid esters to form a monomolecular layer of said phosphoric acid ester on said surface; and (c) removing the excess phosphoric acid ester not bonded to the underlying surface to ensure formation of a monomolecular layer of said phosphoric acid ester on the surfaces of said membrane.

Claim 23

A process for bonding a monomolecular layer of one or more phosphoric acid esters to a permeable inorganic membrane selected from the class consisting of Groups IIIa (Sc and Y), IVa (Ti, Zr, and Hf), Va (V, Nb, and Ta), VIa (Cr, Mo, and W), VIIa (Mn, Tc, and Re), VIII (Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, and Pt), Ib (Cu, Ag, and Au), IIb (Zn, Cd, and Hg), IIIb (B, Al, Ga, In, and Tl), IVb (Ge, Sn, and Pb), Vb (As, Sb, and Bi), an element in the lanthanide series, an element in the actinide series, mixtures thereof, and mixtures of Groups IIa (Be, Mg, Ca, Sr, Ba, and Ra) and VIb (Se, Te, and Po) to form a coated membrane having good chemical stability over a pH range of from 1 to 14 which comprises: (a) providing a liquid containing one or more phosphoric acid esters therein selected from the class consisting of: (i) one or more phosphoric acid monoesters having the formula (RO)(OH) 2 ; (ii) one or more phosphoric acid diesters having the formula (RO)(R'O)PO(OH); and (iii) mixtures of (ii) and (ii); where R comprises a 1-30 carbon-containing group and R' comprises hydrogen or a 1-30 carbon-containing group; and (b) contacting the surface of said permeable inorganic membrane with said liquid containing said one or more phosphoric acid esters to form a monomolecular layer of said phosphoric acid ester on said surface; and (c) removing the excess phosphoric acid ester not bonded to the underlying surface to ensure formation of a monomolecular layer of said phosphoric acid ester on the surfaces of said membrane.

Claim 24

The process of claim 19 wherein said step of providing a liquid containing phosphoric acid esters therein further comprises maintaining a concentration of said phosphoric acid esters in said liquid of at least about 0.01 molar.

Claim 25

The process of claim 19 wherein said step of contacting said surface with said liquid containing said phosphoric acid esters further comprises maintaining said contact for from about 0.01 second to about 20 hours.

Claim 26

The process of claim 21 wherein said step of contacting said surface with said liquid containing said phosphoric acid esters further comprises maintaining said contact for from about 0.5 to about 4 hours.

Claim 27

The process of claim 19 wherein said step of contacting said surface with said liquid containing said phosphoric acid esters further comprises maintaining the temperature of the reactants within a range of about 5° to 150° C. during said contacting step.