Evaluation of solid phase extraction efficiency of functionalized biochar for polyphenols from Punica granatum

The biochars functionalized with polyethylimine (BPE), orthosilicate and polyaniline were evaluated for solid phase extraction of pomegranate phenolics, namely gallic acid, rutin, ellagic acid, naringin, quercetin, apigenin and kaempferol. Characterization of composites of biochar for morphology, functional group and elemental composition has been done. Solid phase extraction cartridges packed with these composites were used for extraction. Most of these biochar composites attained nano‐sized porous structure. Functional group analysis suggests that oxygenated groups of biochar were interacted with electrophilic primary amines and polysilane chain of polyethylimine and orthosilicate, respectively. The formation of biochar‐polyaniline composite occurred through emeraldine base. All composites exhibited good retention capacity for all phenolics except kaempferol. BPE composites were found suitable for recovery of ellagic acid at present solvent system (aqueous methanol). The process was optimized by a quadratic model suggesting the pre‐concentration (60–95%) of ellagic acid (quadratic polynomial relationship, r2 = 1.00). Breakthrough curves were derived for the ellagic acid, which provide the information of retention equilibrium volume, column capacity and recovery of ellagic acid for the BPE packed solid phase extraction cartridges.