Development of novel biopolymer membranes by electrospinning as potential adsorbents for toxic metal ions removal from aqueous solution

This work aims to develop novel biomembranes based on PLA, PBS, or their blend and composites, with the Cloisite (R) 20A nanoclay, as adsorptive materials for metal ions removal. To obtain a membrane with good morphology and thinner diameter of the fibers, a series of nonwoven mats were prepared by electrospinning. To improve the adsorption performance of the electrospun membranes, thermal and acid modifications were carried out in the nanoclay before the electrospinning process, and the final electrospun membranes were applied in the removal of Cr(VI), Cu(II), Cd(II), Zn(II), Ni(II), and Mn(II) ions present in a multi-metal solution. The PBS/PLA/C20A (80/10/10) membrane obtained with an injection flow rate of 3 mL/h, needle tip-to-collector distance of 15 cm, and voltage of 20 kV were selected for the synthesis of the adsorptive membranes, which has the best morphology due to the small average diameter of the fiber and bead-free structures. The characterization techniques (TGA, BET, helium pycnometry, RMN, and DMA) results proved that the addition of PLA and nanoclay resulted in the formation of a material more resistant and with high porosity and specific surface area than the neat PBS. It can be seen that the membranes prepared with the nanoclay after thermal modification showed high metal removal efficiency than the mats designed with the raw nanoclay and after acid modification. It was also possible to conclude that PBS and PLA present the capacity to gradually release organic carbon compounds, which can be used directly as electron donors for Cr(VI) reduction.