Formic acid electrospun composite fibers based on polyhydroxybutyrate/polyamide 6 loaded with protonated montmorillonite as promising disposable heavy metal removal sorbent

The use of electrospinable biodegradable polyhydroxyalkanoate derived from microbial sources and their combination with naturally abundant layered aluminosilicates meet the requirements for the development of new sustainable and biodegradable heavy metal ions removal fibrous sorbent materials. In the present study, novel formic acid electrospun composite biodegradable polymeric fibers based on poly β-hydroxybutyrate/polyamide 6 (PHB/PA6), loaded with protonated montmorillonite (MMT-H) at 10 and 20 wt.% were prepared for the first time by electrospinning technique. The morphology, structure and thermal stability of electrospun composite fibers were investigated by SEM, ATR FT-IR, TGA and WAXD analysis. The as obtained composite fibrous mats were evaluated for their sorption capacity towards Cu²⁺ and Pb²⁺ heavy metal ions in aqueous solution through inductively coupled plasma (ICP) analytical technique. The finding of the optimum fibers showed effective removal of both metals. However the adsorption of Pb ions is higher than Cu cations. The maximum adsorption capacities (Qmax) were 17.30 and 55.55 mg/g for Cu and Pb ions, respectively, after 60 min. The adsorption of Pb (II) ions was described by Langmuir model whereas the adsorption of Cu ions was more fitted with Freundlich model.