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The rapid global industrialization worsens the contamination of heavy metals in aquatic ecosystems on the earth. In this study, the green, ultrafine cellulose-based porous nanofibrous membranes for efficient heavy metal removal through incorporation of chitosan by the conventional and core-shell electrospinning ways were firstly obtained. The relations among parameters of electrospun solution, micro-morphology and porosity for nanofibers, the variation of chemical active sites and adsorption performance of biocomposite nanofibrous membranes for conventional and core-shell electrospinning as well as the adsorption effect factors of copper ions including initial concentration, pH of solution and interaction time were comprehensively investigated. The results show that the average diameter for conventional and core-shell ultrafine nanofibers at 50% chitosan and 30% chitosan loading can achieve 56.22 nm and 37.28 nm, respectively. The core-shell cellulose acetate/chitosan (CA/CS) biocomposite nanofibrous membranes induced the surface aggregation of copper ions to impede the further adsorption. The more uniform distribution for chemical adsorption sites can be obtained by the conventional single-nozzle electrospinning than by the core-shell one, which promotes the adsorption performance of copper ions and decreases the surface shrinkage of nanofibrous membranes during adsorption. The 30% CS conventional nanofibrous membranes at the pH=5 aqueous solution showed the optimum adsorption capacity of copper ions (86.4 mg/g). The smart combination of renewable biomass with effective chemical adsorptive sites, the electrospinning technology with interwoven porous structure and the adsorption method with low cost and facile operation shows a promising prospect for water treatment.