United Kingdom Atomic Energy Authority

Accentus Medical Limited

Aea Technology Inc.

Accentus Plc

Gasrec Limited

Biodynamics Research Limited

Andrew Derek Turner

Nevill J Bridger

Martin Edward Lee Pickford

David Richard Lewis

James Timothy Shawcross

Christopher Peter Jones

Mark D Neville

Martin Edward Pickford

Michael R Hill

Peter C Lovegrove

Richard John Lilleystone

William R Bowen

John S Pottinger

Philip James Agg

Pauline E Ransford

Dennis R Cox

Stuart Anton Legg

George Cutts

Stanley D Derham

Ronald Keith Dawson

James Shawcross

James Merotra

Thomas Campbell Prentice

Jonathon Speed

Richard Lewis David

Martin Edward Lee Pickfrod

In a process for anodizing a metal object (), the metal object () is contacted with an anodizing electrolyte (), and is first pre-anodized so as to grow a thin oxide film on the surface. The microscopic surface area is then deduced from electrical measurements either during pre-anodizing or on the pre-anodized surface. The metal object () can then be anodized. This is applicable when treating an implant to provide a surface that has the ability to incorporate biocidal material such as silver ions. The pre-anodizing uses a low voltage, for example no more than 2. V, and may take less than 120 seconds.

Metal treatment

Metal objects are treated by anodizing (P, SE) the metal object in contact with an acidic solution, and then subjecting the anodized metal object to a reversed voltage (VR). The anodizing is performed in two stages, firstly to passivate (P) with the formation of a surface layer, and secondly to form pits in this surface layer (SE). The second stage (SE) of anodizing is performed at a lower voltage than the first stage (P). After the reversed voltage step (VR) the metal object is then contacted with a biocidal metal-containing solution. Biocidal metal is absorbed into the surface of the metal object, resulting in improved biocidal properties. The lower voltage of the second stage anodizing (SE) results in reduced processing time.

A metal implant for use in a surgical procedure is provided with a surface layer that is integral with the metal substrate, and which incorporates a biocidal material. The surface layer may be grown from the metal substrate, by anodising, and the biocidal material incorporated in it by ion exchange. Alternatively the layer may be deposited by electroplating, followed by diffusion bonding so as to become integral with the metal substrate. In either case, silver is a suitable biocidal material; and both the release rate and the quantity of biocidal material should be low to avoid toxic effects on body cells. Electropolishing the surface before formation of the surface layer is also beneficial, and this may be achieved by electropolishing.

Metal implants

A metal implant for use in a surgical procedure is provided with a surface layer that is integral with the metal substrate, and which incorporates a biocidal material. The surface layer may be grown from the metal substrate, by anodizing, and the biocidal material incorporated in it by ion exchange. Alternatively the layer may be deposited by electroplating, followed by diffusion bonding so as to become integral with the metal substrate. In either case, silver is a suitable biocidal material; and both the release rate and the quantity of biocidal material should be low to avoid toxic effects on body cells. Electropolishing the surface before formation of the surface layer is also beneficial, and this may be achieved by electropolishing.

Metal objects are treated by anodising (P, SE) the metal object in contact with an acidic solution, and then subjecting the anodised metal object to a reversed voltage (VR). The anodising is performed in two stages, firstly to passivate (P) with the formation of a surface layer, and secondly to form pits in this surface layer (SE). The second stage (SE) of anodising is performed at a lower voltage than the first stage (P). After the reversed voltage step (VR) the metal object is then contacted with a biocidal metal-containing solution. Biocidal metal is absorbed into the surface of the metal object, resulting in improved biocidal properties. The lower voltage of the second stage anodising (SE) results in reduced processing time.

A metal object is treated to form an integral surface layer by: (a) immersing the metal object in an anodising electrolyte, and passivating the metal to form an anodised layer on the metal object; (b) continuing the application of a potential to modify the surface layer; (c) then treating the metal object with a chemical reducing agent so a hydrous metal oxide is formed; and (d) then contacting the metal object with a solution containing a biocidal material so as to incorporate biocidal material into the surface layer.

Metal treatment to form a surface layer

A metal implant for use in a surgical procedure is provided with a surface layer that is integral with the metal substrate, and which incorporates a biocidal material. The surface layer is grown by anodizing at a voltage between 50 and 150 V, and the biocidal material incorporated in it by ion exchange. This produces a significantly harder surface than anodizing at low voltage, and generates pits containing ion-absorbing material.

Method of making metal implants

Metal implants () are treated by anodising the surface () in contact with an electrolyte, and then briefly subjecting the anodised surface to a reversed voltage. During a first anodising stage the surfaces are passivated, while during a subsequent anodising stage pits are formed in the passivating surface layer. Rough portions () of the surface, in particular portions produced by plasma spraying of metal powder, are sealed with a watertight cover () during at least part of the anodising process. After rinsing, biocidal metal ions are subsequently absorbed into the surface of the implant. This provides the implant with biocidal properties. The use of the cover () enables a more uniform geometric distribution of biocidal metal ions to be achieved.

Treating a metal implant with a rough surface portion so as to incorporate biocidal material

Metal objects are treated by anodising the metal object in contact with an acidic solution, and then subjecting the anodised metal object to a reversed voltage (compared to the anodising voltage). The thus-treated metal object is then contacted with a biocidal metal-containing solution. Biocidal metal is deposited on the surface of the metal object, resulting in improved biocidal properties.

Method of manufacturing metal with biocidal properties

A process is provided for recovering methane from landfill feed gas and other anaerobic digestors. The process comprising the following steps: firstly treating the feed gas to remove HS; subsequently compressing the gas; and then treating the gas to remove further impurities. Additionally, there is provided a chiller for reducing the temperature of a gas flow. The chiller comprising: a shell arranged to be chilled, a plurality of bores through the shell and through which the gas flows, in use, and forming, together with the shell, a heat exchanger, a tangential inlet to each bore for creating a spiral flow of the gas through the bore, in use. Furthermore, a process is provided for purifying a gas feed using a reversible gas absorber unit comprising two hollow fiber gas/liquid contactors, each of which is arranged to provide a counter-current flow. The process comprising: setting up a partial pressure gradient in the first contactor using a reversible absorber capable of forming an adduct with the gas to be removed, introducing feed gas to the first contactor, forming an adduct of the gas to be absorbed, feeding the adduct to the second contactor, supplying a flushing counter-current flow to the second contactor to liberate the gas, and re-circulating the reversible absorber to the first contactor.

Methane recovery from a landfill gas

The present invention provides a process for the recovery of radiolabelled isotopes from organic substances labelled or contaminated with one or more radiolabelled isotopes, which process comprises: i) adding organic substances labelled or contaminated with a radiolabelled isotope to an acidic aqueous electrolyte containing silver ions as an electrochemically regenerable primary oxidising species; ii) subjecting the acidic aqueous electrolyte to an electric potential; and iii) recovering the radiolabelled isotope from the products of the electrochemical process resulting from the application of the electric potential; wherein the process is carried out at a slight pressure depression.

Recovery process

Using a solution mining procedure, an ore ( ) is treated with a solution of acetic acid and hydrogen peroxide so as to form a leachate containing lead ions. Lead ions (and other metal ions such as zinc and manganese) are stripped ( ) by solvent extraction from the leachate to form separate aqueous solutions. The aqueous solution containing lead ions is treated electrochemically in the anodic compartment of a separated electrochemical cell ( ) to form a precipitate of lead oxide. Manganese dioxide can be produced similarly ( ). A precipitate of zinc hydroxide can be formed in the cathode compartment of a separated electrochemical cell ( ). In the cells ( ) extracting lead ions and manganese ions, the cathode compartment is used to generate hydrogen peroxide (for use in making the leachant), either directly or indirectly.

Electrochemical processing

During filtration, periodic application of a potential difference between an electrically conducting filter medium and counter electrode (as anode) generates a gaseous product at the filter and cleans the filter. To minimise corrosion the counter electrode is of low chromium stainless steel, for example 9% chromium.

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Abingdon, United Kingdom

Andrew Derek Turner