The present invention provides a catalyst for hydrogen peroxide decomposition with which hydrogen peroxide present in acid-containing water to be treated can be efficiently decomposed at low cost and which is less apt to dissolve away in the water being treated, can be stably used over a long period, and renders acid recovery and recycling possible. The present invention has solved the problems with a catalyst for hydrogen peroxide decomposition which is for use in decomposing hydrogen peroxide present in acid-containing water to be treated, the catalyst including a base and, a catalyst layer that is amorphous, includes a platinum-group metal having catalytic function and a Group-6 element metal having catalytic function and is formed over the base.

The present invention provides a catalyst for hydrogen peroxide decomposition with which hydrogen peroxide present in acid-containing water to be treated can be efficiently decomposed at low cost and which is less apt to dissolve away in the water being treated, can be stably used over a long period, and renders acid recovery and recycling possible. The present invention has solved the problems with a catalyst for hydrogen peroxide decomposition which is for use in decomposing hydrogen peroxide present in acid-containing water to be treated, the catalyst including a base and, a catalyst layer that is amorphous, includes a platinum-group metal having catalytic function and a Group-6 element metal having catalytic function and is formed over the base.

To provide a Sn-based plated steel sheet capable of exhibiting superior corrosion resistance, yellowing resistance, coating film adhesiveness, and sulphide stain resistance without using a chromate film. A Sn-based plated steel sheet of the present invention includes: a steel sheet; a Sn-based plating layer located on at least one surface of the steel sheet; and a coating layer located on the Sn-based plating layer, wherein the Sn-based plating layer contains 1.0 g/m.sup.2 to 15.0 g/m.sup.2 of Sn per side in terms of metal Sn, the coating layer contains zirconium oxide, and a content of the zirconium oxide is 1.0 mg/m.sup.2 to 10.0 mg/m.sup.2 per side in terms of metal Zr, the zirconium oxide includes zirconium oxide with an amorphous structure, and a crystalline layer whose main component is zirconium oxide with a crystalline structure is present on an upper layer of the zirconium oxide with the amorphous structure.

To provide a Sn-based plated steel sheet capable of exhibiting superior corrosion resistance, yellowing resistance, coating film adhesiveness, and sulphide stain resistance without using a chromate film. A Sn-based plated steel sheet of the present invention includes: a steel sheet; a Sn-based plating layer located on at least one surface of the steel sheet; and a coating layer located on the Sn-based plating layer, wherein the Sn-based plating layer contains 1.0 g/m.sup.2 to 15.0 g/m.sup.2 of Sn per side in terms of metal Sn, the coating layer contains zirconium oxide, and a content of the zirconium oxide is 1.0 mg/m.sup.2 to 10.0 mg/m.sup.2 per side in terms of metal Zr, the zirconium oxide includes zirconium oxide with an amorphous structure, and a crystalline layer whose main component is zirconium oxide with a crystalline structure is present on an upper layer of the zirconium oxide with the amorphous structure.

The present invention discloses an electro-deposition process, an electro-deposition bath, and a method for preparing a rare earth permanent magnetic material through electro-deposition. The electro-deposition process is used for depositing a heavy rare earth element on the surface of a sintered R.sup.2-T-B type master alloy, and comprises Step 1: providing an electro-deposition bath, comprising a main salt containing the heavy rare earth element, an induction salt for inducing the heavy rare earth element to deposit, and an organic ionic liquid as the solvent, wherein the main salt is a tetrafluoroborate of the heavy rare earth element; and Step 2: electroplating the sintered R.sup.2-T-B type master alloy in the electro-deposition bath at a temperature of 0 to 200° C. The present invention has the following beneficial effects: deposition of the heavy rare earth element on the surface of the sintered R.sup.2-T-B type master alloy is rapid, so that the electro-deposition process time can be saved, and the production efficiency is improved. In addition, a higher plating thickness of up to 10 to 40 μm can be achieved.

The present invention discloses an electro-deposition process, an electro-deposition bath, and a method for preparing a rare earth permanent magnetic material through electro-deposition. The electro-deposition process is used for depositing a heavy rare earth element on the surface of a sintered R.sup.2-T-B type master alloy, and comprises Step 1: providing an electro-deposition bath, comprising a main salt containing the heavy rare earth element, an induction salt for inducing the heavy rare earth element to deposit, and an organic ionic liquid as the solvent, wherein the main salt is a tetrafluoroborate of the heavy rare earth element; and Step 2: electroplating the sintered R.sup.2-T-B type master alloy in the electro-deposition bath at a temperature of 0 to 200° C. The present invention has the following beneficial effects: deposition of the heavy rare earth element on the surface of the sintered R.sup.2-T-B type master alloy is rapid, so that the electro-deposition process time can be saved, and the production efficiency is improved. In addition, a higher plating thickness of up to 10 to 40 μm can be achieved.

An object of the present invention is to provide a method for purifying efficiently and easily a .sup.226Ra-containing solution obtained when .sup.225Ac is produced from a .sup.226Ra target, a method for producing a .sup.226Ra target by using the purified .sup.226Ra-containing solution obtained by the above purification method, and a method for producing .sup.225Ac including these above methods. The method for purifying a .sup.226Ra-containing solution according to the present invention is characterized by including an adsorption step (R1) of allowing .sup.226Ra ions to adsorb onto a carrier having a function of selectively adsorbing divalent cations by bringing a .sup.226Ra-containing solution (a) into contact with the carrier under an alkaline condition; and an elution step (R2) of eluting the .sup.226Ra ions from the carrier under an acidic condition.

An object of the present invention is to provide a method for purifying efficiently and easily a .sup.226Ra-containing solution obtained when .sup.225Ac is produced from a .sup.226Ra target, a method for producing a .sup.226Ra target by using the purified .sup.226Ra-containing solution obtained by the above purification method, and a method for producing .sup.225Ac including these above methods. The method for purifying a .sup.226Ra-containing solution according to the present invention is characterized by including an adsorption step (R1) of allowing .sup.226Ra ions to adsorb onto a carrier having a function of selectively adsorbing divalent cations by bringing a .sup.226Ra-containing solution (a) into contact with the carrier under an alkaline condition; and an elution step (R2) of eluting the .sup.226Ra ions from the carrier under an acidic condition.

One embodiment of the present invention relates to a production method of a .sup.226Ra target, a production method of .sup.225Ac, or an electrodeposition solution for producing a .sup.226Ra target, and the production method of a .sup.226Ra target includes an electrodeposition step of electrodepositing a .sup.226Ra-containing substance on a substrate by using an electrodeposition solution that contains .sup.226Ra ions and a pH buffer.

One embodiment of the present invention relates to a production method of a .sup.226Ra target, a production method of .sup.225Ac, or an electrodeposition solution for producing a .sup.226Ra target, and the production method of a .sup.226Ra target includes an electrodeposition step of electrodepositing a .sup.226Ra-containing substance on a substrate by using an electrodeposition solution that contains .sup.226Ra ions and a pH buffer.