Abstract: A method for treatment of mixed electroplating wastewater without a cyanide and a phosphorus-containing reductant without a cyanide and a phosphorus-containing reductant. A ferrous chloride solution is added into electroplating wastewater without a cyanide and a phosphorus-containing reductant. The pH of wastewater is adjusted to 10.5-12. Pollutants such as sodium cyanide and hydroxyl-containing organic amine complexants are oxidized with sodium hypochlorite. Carboxyl-containing organic acid complexants are precipitated. Hexavalent chromium is reduced to trivalent chromium to form chromium hydroxide precipitate. Precipitate is removed by filtering and wastewater is adjusted to pH 4.5-5.5. Heavy metal ions are precipitated with sodium dimethyldithiocarbamate or sodium diethyldithiocarbamate. Precipitate and heavy metal capturing agents are adsorbed with activated carbon followed by removal of precipitate. Wastewater is adjusted to pH 6-8.

Abstract: A method for integrated treatment of electroplating wastewater includes steps of: adjusting and maintaining pH of wastewater at 10.5-12; oxidizing pollutants such as sodium cyanide and hydroxyl-containing organic amine complexants with sodium hypochlorite; precipitating carboxyl-containing organic acid complexants with synergistic effect of ferrous and calcium ions; reducing hexavalent chromium to trivalent chromium and forming chromium hydroxide precipitate; removing precipitate by filtering; adjusting wastewater to pH of 4.5-5.5; precipitating heavy metal ions with sodium dimethyldithiocarbamate or sodium diethyldithiocarbamate; adsorbing precipitate and heavy metal capturing agents with activated carbon; filtering to remove precipitate; adjusting wastewater to pH of 6-8; and destroying aliphatic polyamine complexants and reducing COD using an available biological degradation technique.

Abstract: A hydroxyl graphene-modified plating sealant and a preparation method thereof are disclosed. The plating sealant comprises a film-forming material, a resist, a defoaming agent, a levelling agent, and deionized water; the resist is a nanoscale hydroxyl graphene aqueous solution comprising hydroxyl graphene having a mass fraction of 3.5% to 4% and a pH of 8.0 to 9.5. Nanoscale hydroxyl graphene is used as a resist in the plating sealant of the disclosure, then the hydroxyl groups on hydroxyl graphene can react with the hydroxyl groups of the film-forming material, i.e. silica sol and the silane polymer, by dehydration condensation, thereby significantly improving the performance of the sealing film. The sealing film has higher corrosion resistance and abrasion resistance compared with that prepared by graphene or reduced graphene oxide sealant.

Abstract: A method for combined treatment of electroless copper plating wastewater includes oxidizing hydroxyl-containing organic amine complexants with hydrogen peroxide or sodium hypochlorite to organic acid complexants containing amine group (or amino group) and carboxyl group, precipitating the carboxyl-containing complexants using synergistic effect of ferrous ions and calcium ions and precipitating the copper ions released from the complexes to copper hydroxide precipitate to effectively removing copper. Using this precipitation method to remove complexants in the electroless copper plating wastewater, the problem in the prior art that it is difficult to destroy the hydroxyl-containing organic amine complexant is solved and the COD in the wastewater is effectively reduced.