Novel Heterogeneous Extraction Methods for Adiponitrile Electrolyte Recycling

Electrohydrodimerization of acrylonitrile (AN) to adiponitrile (ADN) is considered to be one of the largest and most successful electrochemical processes. The reutilization of electrolytes and the ease of removal of ADN from the electrolyte have emerged as critical challenges in this process. However, the current methods to recover the electrolyte and remove ADN are very costly in terms of both energy consumption and equipment cost. In the current work, a novel heterogeneous extraction method was proposed to separate ADN from the electrolyte using benzene or carbon tetrachloride (CTC) as the solvent. In addition, the nondominated sorting genetic algorithm (NSGA-III) was employed to optimize process parameters with respect to economy, environment, and safety. Results indicate that compared to traditional distillation separation, heterogeneous extraction using benzene and carbon tetrachloride decreased by 9.59 and 27.19% in terms of the total annual cost (TAC), respectively, while CO2 emission was reduced by 82.82 and 83.55%, and exergy efficiency was enhanced by 13.94 and 26.94%, while the safety index closely correlates with the selected solvents. This new heterogeneous extraction method opens possibilities for an efficient and sustainable design for recycling diverse electrolytes.