Copper-boron-ferrite graphite silica-sol composites

Patent metadata

Field	Value
Publication number	US-2020290900-A1
Application number	US-202016816469-A
Country	US
Kind code	A1
Filing date	Mar 12, 2020
Priority date	Mar 14, 2019
Publication date	Sep 17, 2020
Grant date	—

Abstract

Copper-boron-ferrite (Cu—B—Fe) composites may be prepared and immobilized on graphite electrodes in a silica-based sol-gel, e.g., from rice husks. Different bimetallic loading ratios can produce fast in-situ electrogeneration of reactive oxygen species, H2O2 and .OH, e.g., via droplet flow-assisted heterogeneous electro-Fenton reactor system. Loading ratios of, e.g., 10 to 30 wt. % Fe3+ and 5 to 15% wt. Cu2+, can improve the catalytic activities towards pharmaceutical beta blockers (atenolol and propranolol) degradation in water. Degradation efficiencies of at least 99.9% for both propranolol and atenolol in hospital wastewater were demonstrated. Radicals of .OH in degradation indicate a surface mechanism at inventive cathodes with correlated contributions of iron and copper. Copper and iron can be embedded in porous graphite electrode surface and catalyze the conversion of H2O2 to .OH to enhance the degradation. Inventive cathodes can be stable catalytically after 20 or more cycles under neutral and acidic conditions.

First claim

1 . A method for making an electrode, the method comprising:
applying a silica-based sol gel composite comprising copper, iron, and boron, onto a graphite electrode; and solidifying the sol gel, to obtain a graphite electrode comprising a coating comprising copper, iron, and boron, immobilized in a silica-based sol-gel.

2 . The method of claim 1 , wherein the graphite electrode is a sulfonated graphite electrode (SGE).

3 . The method of claim 1 , wherein the electrode is a cathode.

4 . The method of claim 1 , wherein the silica-based sol gel comprises at least 55 wt. % silica.

5 . The method of claim 1 , wherein the sol gel comprises boron in a range of from 0.1 to 10 wt. %, based on total sol gel weight.

6 . The method of claim 1 , wherein the silica-based sol gel comprises iron in a range of from 0.1 to 30 wt. %, based on total sol gel weight.

7 . The method of claim 1 , wherein the silica-based sol gel comprises copper in a range of from 0.1 to 20 wt. %, based on total sol gel weight.

8 . The method of claim 1 , wherein the silica-based sol gel is prepared by a method comprising:
treating an aqueous silicate solution with iron, copper, and boron; and gelling the sol.

9 . The method of claim 8 , wherein the boron is in the form of boric acid and/or BO 3 3− ,
wherein the silicate comprises at least 75 wt. %, based on total silicates, of sodium silicate, wherein the iron is in the form of an iron (III) salt comprising NO 3 − , Cl − , Br − , I − , ClO 4 − , ClO 3 − , IO 3 − , SiF 6 2− , and/or SO 4 2− , and/or wherein the copper is in the form of an copper (II) salt comprising NO 3 − , Cl − , Br − , I − , ClO 4 − , ClO 3 − , IO 3 − , SiF 6 2 , and/or SO 4 2− .

10 . The method of claim 8 , wherein the aqueous silicate solution further comprises a surface directing agent comprising glycerol and cetyltrimethylammonium bromide.

11 . The method of claim 1 , wherein the silica-based sol uses silica derived from rice husks.

12 . The method of claim 8 , wherein the copper, iron, and boron are provided in a single solution, and
wherein the single solution comprises 1 to 5 M nitric acid, 5 to 30 wt. % iron, 5 to 15 wt. % copper, and 2.5 to 7.5 wt. % boron.

13 . The method of claim 8 , wherein the gelling is brought about by adding a mineral acid to the silicate solution during and/or after contacting the silicate solution with the iron, copper, and boron.

14 . An electrode, comprising:
a sulfonated graphite slab having a thickness in a range of from 1 to 10 mm; a coating, directly contacting the slab, comprising a silica-based sol gel, 0.5 to 30 wt. % iron (III), 0.5 to 10 wt. % copper (II), and 0.5 to 5 wt. % boron.

15 . The electrode of claim 14 , wherein the coating comprises at least 5 wt. % iron (III), at least 2.5 wt. % copper (II), and at least 1.5 wt. % boron.

16 . The electrode of claim 14 , in the form of a cathode.

17 . An electrochemical cell, comprising:
the electrode of claim 16 ; a boron-doped diamond anode comprising a layer of from 1 to 5 μm boron-doped diamond upon silica; and a supply of a gas comprising oxygen, wherein the cell is suitable to conduct an electro-Fenton reaction on one or more organic compounds in water, thereby at least 90% mineralizing the one or more organic compounds.

18 . The cell of claim 16 , wherein the gas is air or at least 50 vol. % oxygen gas.

19 . A method, comprising:
contacting an aqueous solution comprising an organic pharmaceutical, organometallic pharmaceutical, or organic dye compound with the article of claim 16 , thereby degrading the organic pharmaceutical, organometallic pharmaceutical, or organic dye compound.

20 . The method of claim 19 , wherein the organic pharmaceutical, organometallic pharmaceutical, or organic dye compound comprises a beta-blocker, and/or
wherein the water is a hospital waste water.

Assignees

• Univ King Fahd Pet & Minerals

Inventors

• Basheer Chanbasha
• Nsubuga Hakimu

Classifications

• C23C18/1254

  Sol or sol-gel processing · CPC title

• Y02W10/37

  using solar energy · CPC title

• C25B11/065

  Carbon · CPC title

• C25B11/057

  consisting of a single element or compound · CPC title

• C02F1/46109 Primary

  Electrodes · CPC title