A novel cost-effective PAN/CNS nanofibrous membranes with rich carboxyl groups for high efficient adsorption of Lanthanum(III) ions

Nowadays, the functional carbonaceous nanospheres (CNS) originated from the simple one-pot hydrothermal carbonization reaction of the renewable biomass are getting much attention, attributing to the facile, low-cost and eco-friendly preparation method. However, the applications of the CNS suffer from many restrictions due to the difficulty of recovery from aqueous phase. Herein, we presented an easy, cost-effective and sustainable synthesis avenue to prepare a novel PAN/CNS nanofibrous membranes (NFMs) with plentiful carboxyl groups for effective adsorption of La 3+ ions through the fine combination of hydrothermal carbonization, electrospinning and alkaline activation treatment process. The resulting carboxylate rich PAN/CNS NFMs with ultrahigh CNS loading (up to 70 wt%) displayed good flexibility and excellent adsorption quantity towards La 3+ ions. The adsorption data preferred to follow the Langmuir isotherm and pseudo-second-order kinetic models, and the maximum adsorption amount of La 3+ ions calculated from the Langmuir isotherm model was up to 174.5 mg/g. Furthermore, the adsorption thermodynamics was also explored and the results revealed that the adsorption of La 3+ ions on the activated PAN/CNS-70 NFMs was a spontaneous and endothermic process. Meanwhile, the activated PAN/CNS-70 NFMs exhibited good reusability and the adsorption efficiency still maintained at about 90% after three recycling tests. Noticeably, this work may offer a new strategy to construct a cost-effective and environmentally friendly nanofibrous adsorbent for high efficient recovery of La 3+ ions.