Leaching And Recovery Of Cr,Ni And Cu From Electroplating Sludge By Sulfonic Acid Group Ionic Liquids

The effective disposal and recycling of electroplating sludge（ES）is an important issue in the construction of"waste-free city"under the background of double carbon,due to annual output of ES is huge and it contains abundant heavy metals（HMs）resources.Chemical leaching is an effective method to dispose HMs in ES.The key to the further development and application of this method is to select an efficient and environmentally friendly leaching agent and explore its mechanism.Considering the advantages of stable chemistry,designability and low synthesis cost of acidic ionic liquids（ILs）,two types of ILs（[Bmim]HSO₄ and[Pr SO₃Hmim]HSO₄）were chosen to leach Cr,Ni,and Cu from ES.In this study,the performance and mechanism of ILs leaching HMs were analyzed,and the process of co-precipitation combined with calcination was adopted to dispose leaching waste solution to recover HMs and explore the recovery mechanism.The main research results are as follows:（1）Both[Bmim]HSO₄ and[Pr SO₃Hmim]HSO₄ can effectively remove HMs from ES.Solid-liquid ratio（S/L）,concentration,reaction time and p H are the key factors affecting the leaching efficiency.With the increase of the amount of two extractants,removal efficiency of HMs was significantly increased（P<0.05）and can be up to 90%.The removal efficiency increased（P<0.05）and tended to be balanced after 1h as reaction time extends.With the increase of p H,the removal efficiency of Cr,Ni,and Cu decreased rapidly（P<0.05）.（2）Quadratic orthogonal regression experiment revealed that the main influencing factor in the leaching process was S/L and concentration.Under the optimal leaching conditions with concentration of 60 g L^-1,S/L of 1:40 and reaction time of 60 min,the removal efficiencies of Cr,Ni and Cu by[Bmim]HSO₄ were 84.3%,78.6%and 89.7%.While[Pr SO₃Hmim]HSO₄remained unchanged and the S/L increased to 1:35,the removal efficiencies of Cr,Ni and Cu were 99.8%,90.1%and 91.3%.（3）X-ray photoelectron spectroscopy confirmed that the leaching agent played an acidic role,Fourier infrared spectroscopy indicated that-OH and SO₄^2-participated in the leaching process,and density functional calculation revealed that Pr SO₃Hmim and SO₄^2-had strong interactions with Cu²⁺,Ni²⁺and Cr³⁺.In general,[Bmim]HSO₄ and[Pr SO₃Hmim]HSO₄ can remove HMs from ES mainly by means of acid leaching,electrostatic attraction and functional chelation.[Pr SO₃Hmim]HSO₄ has the dual action of sulfonic acid and sulfate,so it can achieve efficient removal of HMs（4）Plane hexagonal mixed spinel ferrite powder was prepared by coprecipitation combined with calcination.Target metal elements Cr,Ni and Cu were filled in the lattice of ferrite by wrapping and entrainment.The material shows good soft magnetic properties,and its saturation magnetization is 19.5 emu g^-1 and 8.7 emu g^-1,respectively.According to the cost calculation,the benefit of 800￥t^-1 could be generated by using this ES proposal process.