Back extraction combined with magnetic solid phase extraction based on bubble column for separation and purification of juglone from Juglans mandshurica Maxim. coproducts

Juglone was first preliminary purified by back extraction (BE) which also completed the sustainability of microemulsion as a solvent for extraction of juglone in J. mandshurica Maxim. branches. Then, magnetic solid phase extraction (MSPE) based on bubble column (BC) was proposed to further purify the juglone, GO/ND/Fe 3 O 4 as adsorbent, which broke through the limitation that MSPE is only suitable for trace enrichment. Thus, a BE combined with MSPE based on BC (BE-MSPE/BC) technology to separate and purify juglone from J. mandshurica Maxim. was developed. Under the optimal conditions (optimal adsorption conditions: 0.5 h of adsorption time, 30 mg/mL of solid-liquid ratio, 5.5 of pH, 60 L/min of air flow; optimal desorption conditions: 0.4 h of desorption time, methanol of desorption agent, 100% of desorbent volume fraction, 8 of pH, 40 mg/mL of solid-liquid ratio, 80 L/min of air flow rate), the recovery yield and purity of juglone obtained by BE-MSPE/BC were 80.57% and 72.38%, respectively. BE-MSPE/BC, as a green separation and purification technology that can easily achieve large-scale and sustainable production, is expected to be an alternative method to separate and purify active components in biomass materials and products.