The invention relates to an electrode for electrolytic processes, in particular to an anode suitable for oxygen evolution comprising a valve metal substrate, a catalytic layer, a protection layer consisting of oxides of valve metals interposed between the substrate and the catalytic layer and an outer coating of oxides of valve metals. The electrode of the invention is particularly suitable for processes of cathodic electrodeposition of chromium from an aqueous solution containing Cr (III).

The invention relates to an electrode for electrolytic processes, in particular to an anode suitable for oxygen evolution comprising a valve metal substrate, a catalytic layer, a protection layer consisting of oxides of valve metals interposed between the substrate and the catalytic layer and an outer coating of oxides of valve metals. The electrode of the invention is particularly suitable for processes of cathodic electrodeposition of chromium from an aqueous solution containing Cr (III).

A method and equipment for removing ammonia nitrogen from electrolytic manganese residue are provided in the technical field of solid waste resource utilization. The method includes following steps: step 1: adding phosphate and magnesium salt into electrolytic manganese residue leachate and fully reacting, where after the phosphate and the magnesium salt are added, n (Mg):n (N):n (P)=1.1-1.3:1:1 in the electrolytic manganese residue leachate; step 2: on a basis of the step 1, adjusting pH of the electrolytic manganese residue leachate to alkalinity, and stirring and reacting for 10-30 min; and step 3: on a basis of the step 2, filtering the electrolytic manganese residue leachate to obtain purified leachate and struvite respectively.

A method and equipment for removing ammonia nitrogen from electrolytic manganese residue are provided in the technical field of solid waste resource utilization. The method includes following steps: step 1: adding phosphate and magnesium salt into electrolytic manganese residue leachate and fully reacting, where after the phosphate and the magnesium salt are added, n (Mg):n (N):n (P)=1.1-1.3:1:1 in the electrolytic manganese residue leachate; step 2: on a basis of the step 1, adjusting pH of the electrolytic manganese residue leachate to alkalinity, and stirring and reacting for 10-30 min; and step 3: on a basis of the step 2, filtering the electrolytic manganese residue leachate to obtain purified leachate and struvite respectively.

A method of producing manganese metal or EMD by leaching a source of manganese with a solution comprising sulfuric acid to form a leach solution, adding one or more sulfides generated in a sulfide recycle stage to the leach solution in order to form sulfide precipitates comprising heavy metal sulfides, removing the sulfide precipitates from the leach solution, feeding the leach solution to one or more electrolytic cells, subjecting the purified leach solution to electrolysis so as to deposit manganese metal or EMD, reacting the sulfide precipitates with an acid to generate H.sub.2S, producing one or more sulfides from the H.sub.2S for recycle. Methods of producing manganese metal and a purified manganese sulfate solution are also provided.

A method of producing manganese metal or EMD by leaching a source of manganese with a solution comprising sulfuric acid to form a leach solution, adding one or more sulfides generated in a sulfide recycle stage to the leach solution in order to form sulfide precipitates comprising heavy metal sulfides, removing the sulfide precipitates from the leach solution, feeding the leach solution to one or more electrolytic cells, subjecting the purified leach solution to electrolysis so as to deposit manganese metal or EMD, reacting the sulfide precipitates with an acid to generate H.sub.2S, producing one or more sulfides from the H.sub.2S for recycle. Methods of producing manganese metal and a purified manganese sulfate solution are also provided.

An electrochemical process implements, in a decoupled manner, a first step of electrolysis of an electrolyte to produce gaseous oxygen in a chamber and a second step of electrochemical conversion of H+ ions into gaseous hydrogen in a chamber which contains a liquid phase and a gas phase not dissolved in the liquid phase. Gaseous hydrogen produced in the conversion step is partly present in the gaseous headspace of chamber and as bubbles in the electrolyte, and partly dissolved in the electrolyte which is saturated with hydrogen. The electrolyte has at least one redox pair (A/B) forming at least one intermediate vector enabling the decoupling of the first and second steps. The interface between the gas and liquid phases is increased during the second step to accelerate the diffusion, from liquid phase to gas phase, of the dissolved hydrogen able to supersaturate the electrolyte. Pressurized gaseous hydrogen is then collected.

The method includes two technological segments (i) a reduction segment and (ii) an oxidation segment that are interconnected by various support technological processes for the regeneration of solutions and gases and heat recuperation. The reduction segment includes an electrolysis that is performed from a solution of chloride salts of an energy carrier. During the electrolysis, these elements reduce to a lower oxidation state, solidify on the electrodes or precipitate to a solid state. The solid substance thus obtained is the energy carrier that can be stored outside of the electrolyser until a need for additional energy emerges. During the electrolysis, chlorine gas develops that is collected and dissolved in water. An HCl solution is regenerated, which is used in the oxidation segment. Oxygen is released in this process. The energy that has thus been stored in the oxidation potential of the energy carrier is released during a spontaneous chemical reaction between the energy carrier and the HCl solution in the oxidation segment. In this chemical reaction, the oxidation state of the chemical elements which constitute the energy carrier is increased to an oxidation state identical to that from before the beginning of the electrolysis. The reaction product hydrogen is formed that represents a high calorific fuel. This fuel can be immediately converted to heat or electrical energy, without a need for intermediate storage, by known methods. Only water enters the entire method, oxygen and hydrogen leave, while the cycle is closed/cyclic for the remaining substances.

An electrolytic cell and a method of electrochemical oxidation of manganese(II) ions to manganese(III) ions in the electrolytic cell are described. The electrolytic cell comprises (1) an electrolyte solution of manganese(II) ions in a solution of at least one acid; (2) a cathode immersed in the electrolyte solution; and (3) an anode immersed in the electrolyte solution and spaced apart from the cathode. Various anode materials are described including vitreous carbon, reticulated vitreous carbon, woven carbon fibers, lead and lead alloy. Once the electrolyte is oxidized to form a metastable complex of manganese(III) ions, a platable plastic may be contacted with the metastable complex to etch the platable plastic. In addition, a pretreatment step may also be performed on the platable plastic prior to contacting the platable plastic with the metastable complex to condition the plastic surface.

An electrolytic cell and a method of electrochemical oxidation of manganese(II) ions to manganese(III) ions in the electrolytic cell are described. The electrolytic cell comprises (1) an electrolyte solution of manganese(II) ions in a solution of at least one acid; (2) a cathode immersed in the electrolyte solution; and (3) an anode immersed in the electrolyte solution and spaced apart from the cathode. Various anode materials are described including vitreous carbon, reticulated vitreous carbon, woven carbon fibers, lead and lead alloy. Once the electrolyte is oxidized to form a metastable complex of manganese(III) ions, a platable plastic may be contacted with the metastable complex to etch the platable plastic. In addition, a pretreatment step may also be performed on the platable plastic prior to contacting the platable plastic with the metastable complex to condition the plastic surface.