(US4602987-A)      Extracting oxygen from a fluid environment which is contacted with a membrane. A carrier fluid contacts the other surface of the membrane and continuously removes oxygen passing through the membrane. The carrier fluid passes first to an oxygen removal zone and then is regenerated in an electrochemical cell.    Carrier fluid can be a protoporphyrin its alkyl ester or a herne/1-methylimidazole complex formed of carbon or P.T.F.E. covered with gold or platinum.    ADVANTAGE -   Arrangement can provide oxygen e.g. for a fuel cell, engine or consumption by a human being. (36pp)e    (US4609383-A)      Appts. for extracting oxygen from an environment in contact with the appts., comprises (a) a container having an inlet, an outlet, and an oxygen-permeable membrane which together, at least in part, define an inner space of the container, the membrane having a first surface adapted to be in contact with the environment and a second surface facing the interior space, (b) a carrier fluid in contact with the second surface of the membrane in the container, and (c) a non-proteinaceous oxygen-binding cpd. contained in the carrier fluid, the cpd. comprising a tetradentate chelating molecule, a metal ion chelated in the molecule and a nitrogenous base chelated to the metal ion.    Pref. (c) comprises a protoporphyrin or alkyl ester thereof.    ADVANTAGE -   Oxygen is extracted from a fluid at a rate higher than that previously available. (12pp)c    (US4629544-A)      A ligand is reversibly removed from a carrier by contacting fluid contg. a binding-state carrier with ligand with an electrochemical electrode so that the carrier undergoes redox reaction to enter the non-binding state and release the ligand, removing the free ligand, contacting the fluid with a second electrode to perform a reverse reaction and return to the binding state, and contacting with a ligand source for this to bind to the carrier.    The electrodes are parallel plates of PTFE or carbon covered with a thin layer of gold or platinum. Electrode compartments are pref. no mroe than 5 mm thick and are separated by a ligand-permeable membrane, pref. a composite member of silicone rubber and porous polysulphone.    USE/ADVANTAGE -   Partic. for removing oxygen from a heme/1-methylimidazole complex carrier, does not require the use of chemicals or a vacuum, and does not use a significant fraction of the energy which can be generated by using the released oxygen in a fuel cell or combustion engine. (21ppp)a    (US4761209-A)      Novel appts. for extn. of O2 from environment surrounding it, comprises a container having (a) an O2-permeable membrane forming at least part of the inner space of the container, which has a surface adapted for contacting the environment and a second surface facing the interior; (b) a first electrode compartment of an electrochemical cell; (c) a second electrode compartment of the electrochemical cell; and (d) means for removing O2 from cell.    Container is adapted such that a fluid confined within it passes from (b) to (d), from (d) to (c), from (c) to (a), and from (a) to (b). Pref. appts. has a pump for circulating fluid through interior.    ADVANTAGE -   High rate of O2-extn. is obtd. (37pp)    (JP2573479-B2)      Extn. of O2 from a fluid is effected by (a) contacting the fluid with an outer surface of an O2-permeable membrane whose whose inner surface is in contact with a carrier fluid in a closed container, where the carrier fluid contains an O2 carrier in a binding state such that it binds to O2 diffusing through the membrane to form a complex; (b) transporting the complex-contg. carrier fluid to a 1st electrode compartment of an electrochemical cell forming part of the closed container; (c) electrochemically modifying the O2 carrier to an oxidn. state with less binding affinity for O2, thus releasing free O2 into the carrier fluid and producing a non-binding O2 carrier; (d) removing O2 from the carrier fluid; (e) transporting the carrier fluid to a 2nd electrode compartment forming part of the closed container; and (f) 2nd electrode compartment forming part of the closed container; and (f) electrochemically modifying the O2 carrier to regenerate its binding state. Also claimed is a process similar to steps (b)-(f) for reversibly removing a ligand from a ligand carrier.    USE/ADVANTAGE -   The process may be used to extract O2 from air or water, e.g. for consumption in a fuel cell or engine or by humans or animals. Oxygen can be extracted at higher rates than in known processes; e.g. the O2 concn. can be increased from 7 ppm in sea water to 860 ppm in the carrier fluid.    (JP2688165-B2)      Extn. of O2 from a fluid is effected by (a) contacting the fluid with an outer surface of an O2-permeable membrane whose whose inner surface is in contact with a carrier fluid in a closed container, where the carrier fluid contains an O2 carrier in a binding state such that it binds to O2 diffusing through the membrane to form a complex; (b) transporting the complex-contg. carrier fluid to a 1st electrode compartment of an electrochemical cell forming part of the closed container; (c) electrochemically modifying the O2 carrier to an oxidn. state with less binding affinity for O2, thus releasing free O2 into the carrier fluid and producing a non-binding O2 carrier; (d) removing O2 from the carrier fluid; (e) transporting the carrier fluid to a 2nd electrode compartment forming part of the closed container; and (f) 2nd electrode compartment forming part of the closed container; and (f) electrochemically modifying the O2 carrier to regenerate its binding state. Also claimed is a process similar to steps (b)-(f) for reversibly removing a ligand from a ligand carrier.    USE/ADVANTAGE -   The process may be used to extract O2 from air or water, e.g. for consumption in a fuel cell or engine or by humans or animals. Oxygen can be extracted at higher rates than in known processes; e.g. the O2 concn. can be increased from 7 ppm in sea water to 860 ppm in the carrier fluid.