Method for electrochemical synchronous synthesis of urea and struvite using nitrogen and phosphorus pollutants and waste gas field

A method for electrochemical synchronous synthesis of urea and struvite using nitrogen and phosphorus pollutants and waste gas, comprising the following steps:

• Step 1:
• preparing an anode material using RuO2, IrO2, and Ti4O7, and using graphite as a cathode to construct a dual-chamber type H-type electrolytic cell;
• introducing sewage containing nitrogen and phosphorus and magnesite into an anode region, and connecting a power source to perform an electrocatalytic oxidation reaction;
• wherein a specific method for preparing the anode material using RuO2, IrO2, and Ti4O7 in Step 1 is:
• using nickel foam as a substrate material of an electrode;
• taking equal mass of RuO2, IrO2, and Ti4O7 to be added into a distilled water/ethanol dispersant;
• performing ultrasonic dispersion to a uniform ink-like state;
• and adding conductive adhesive for coating onto a treated titanium plate to obtain a RuO2, IrO2, and Ti4O7 nickel foam anode material;
• wherein a main reaction formula in Step 1 is:
• organic nitrogen→NO3−+NO2−
• organic phosphorus→PO43−
• magnesite→Mg2+;
• Step 2:
• preparing a metal-loaded In(OH)3 nanomaterial;
• on a basis of the electrolytic cell in Step 1, using the In(OH)3 nanomaterial to replace the anode prepared by RuO2, IrO2, and Ti4O7 to become a new cathode, and using graphite as a new anode;
• introducing waste gas containing carbon dioxide into a cathode region;
• and exchanging positive and negative electrodes and connecting a power source to perform an electrocatalytic reduction reaction to obtain urea and struvite;
• wherein a preparation method of the metal-loaded In(OH)3 nanomaterial in Step 2 is:
• ultrasonically dispersing In(OH)3 powder in deionized water;
• adding a compound of metal M for stirring;
• and adding a sodium carbonate solution to obtain a suspension;
• and after filtering, washing, and drying, calcining to obtain a metal M-loaded In(OH)3 nanomaterial;
• wherein the metal M is Fe, Mn, or Co;
• wherein a main reaction formula in Step 2 is:
• 2NO3−+CO2+18H++16e−→NH2CONH2+7H2O
• CO2+2NO2−+14H++12e−→NH2CONH2+5H2O
• NH4++Mg2++PO43−+6H2O→Mg(NH4)PO4·6H2O.