Manganese is a crucial metal for various industrial applications, particularly in the production of batteries. For example, NMC, one of the most commonly used cathode materials in lithium-ion batteries (LIBs), contains manganese (Ju et al. in Chem Eng J 466:143218, 2023 [1]). Therefore, there have been notable efforts to recycle batteries to recover valuable metals like manganese, minimize waste, and reduce the environmental impact of batteries (Li in Sep Purif Technol 306:122559, 2023 [2]). Eutectic freeze crystallizationEutectic freeze crystallization (EFC) is a technique employed to recover metal salts from aqueous solutions. EFC can provide significant benefits over traditional methods such as evaporative crystallization, including lower energy consumption and decreased operational corrosion (Randall et al. in Desalination 266(1–3):256–262, 2011 [3]). This study investigates the recovery of manganese as manganese sulfate heptahydrate from diluted sulfuric acid solutionsAcid solutions using EFC. Additionally, at increased temperatures, manganese sulfate heptahydrate crystals produced by EFC transform into a pentahydrate and subsequently into a monohydrate. The experimentally observed transition temperatures were compared with those estimated using the OLI Stream Analyzer software.