Physicochemical characteristics of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) electrospun nanofibres for the adsorption of phenol

Abstract

In this study, adsorption treatment of phenol pollutant using electrospun poly(3-hydroxybutyrate) [P(3HB)] and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] is highlighted for the first time. Both P(3HB) and P(3HB-co-3HHx) were extracted from bacterial cells and nanofibres were fabricated through electrospinning technique for the adsorption of phenol. The electrospun nanofibres were optimised after preliminary study of the electrospinning parameters (i.e. applying different voltages, polymer concentrations and mixed solvent ratios). The effects of adsorption under different variables such as contact of time, pH, initial concentration and temperature were studied. The raw polymers were characterised with gas chromatography (GC), gas permeation chromatography (GPC) while the electrospun fibres were investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and viewed under field emission scanning electron microscope (FESEM). P(3HB) had higher molecular weight as well as higher crystallinity and thermal stability than P(3HB-co-3HHx). The maximum phenol adsorption capacity of optimised nanofibre with weight of 0.14 g was 35.7 mg/g. The adsorption trend of the isotherm followed the Freundlich (R 2 = 0.99) and adsorption kinetics of pseudo-second-order. The equilibrium contact time was 10 min with 99.8% of the phenol removed and attained 99.9% removal after optimal contact time of 270 min for all samples. This innocuous product has strong affinity towards organic pollutants and zero by-products were produced after the adsorption.