Improving Extraction Performance of D2EHPA for ImpuritiesRemoval from Spent Lithium-Ion Batteries Leaching Solution byTPC[4]

To reduce reagent consumption, wastewater discharge,and production cost of Mn2+recovery and impurities (Zn2+/Cu2+/Ca2+)removal from an acid leaching solution of spent lithium-ion batteries, amixed extractant (TPC[4]+D2EHPA) was synthesized, and theextraction performances for Mn2+and impurities were systematicallyinvestigated. The synthesis experimental results demonstrated thatTPC[4] can be synthesized in a simple and high yield way with cheapraw materials. Extraction tests indicated that the separation coefficientsof Mn2+,Cu2+, and Zn2+to Ni2+and Co2+by D2EHPA weresignificantly enlarged by the addition of TPC[4], which can mainly beattributed to the enhancement in the differences of binding abilities forcationic complexes with different sizes. Furthermore, the loadingcapacities of Mn2+and impurities (Cu2+,Zn2+) were also enlarged,and the stripping of these cations could easily be achieved with dilute acid. Compared with traditional Mn2+and an impuritiesextraction process with D2EHPA alone, the addition of TPC[4] saved about 10.36% of the saponification alkali (NaOH), 10.36% ofthe washing acid (H2SO4),similar to 20% of the washing water, and more than 4.56% of the organic loss. From both economic andenvironmental perspectives, the mixed solvent of D2EHPA+TPC[4] is an excellent application prospect