The simultaneous adsorption and photocatalytic degradation of phenol using electrospun p(3HB)-TiO2 nanocomposite fibers

Photocatalytic degradation and adsorption of crude oil on poly-3-hydroxybutyrate P(3HB) electrospun nanofiber immobilized with nanosized titanium dioxide (TiO2) for phenol cleanup was evaluated in this study. The P(3HB) used in this study which is made from renewable sources is cost effective and biodegradable. It is hydrophobic and thus was proven to show simultaneous adsorption of phenol while TiO2
photocatalytically degrades the adsorbed phenol molecules. Objectives: This study aims to develop a nanocomposite fibrous material using the environmentally friendly PHA
and inert TiO2 to simultaneously adsorb and degrade phenol. Methodology: Palm oil based sources of palm olein (PO), crude palm kernel oil (CPKO), waste cooking oil
(WCO) had been used in this study to produce poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx) bioplastics from wild type Cupriavidus necator
and recombinant Cupriavidus necator Re2058/pCB113. Meanwhile, P(3HB) homopolymer was extracted from mice pellets (mice fed with lyophilized cells of C. necator H16 containing 39 wt% PHB). Kaneka Commercial P(3HB-co-3HHx) with 11.8% and 8.4% of 3HHx monomer composition were used as comparison. Different applied voltages, polymer concentrations and mixed solvent ratios were tested and
optimized for the fabrication of electrospun nanofiber. Electrospun P(3HB)-TiO2 films were successfully fabricated and were used in adsorption studies. Phenol was used as
crude oil model as it is organic and stable. The fabricated nanofibers were characterized by FESEM, EDX, DSC, GPC and TGA and used for degradation of phenol under different parameters of contact time, pH, initial concentration, temperature and light condition. Results: It is apparent that high electrospinning voltage of 25kV produced
homogenous strands and better fibrous networks of the nanocomposite films. The intrusion rate of electrospinning was found to be optimum at 40 µL/min, meanwhile the
concentration of polymer solution for electrospinning was set at 10 wt. % for all sample types. The maximum adsorption capacities was 59.047 mg/g. Langmuir and Freundlich
isotherm models had been generated to provide reasonable fittings for this sorption data of oil and the sorbent. The trend of adsorptions were in a good agreement with Freundlich which R2= 0.99. The optimal contact time was 270 minutes of nearly 99.9% phenol removal. The equilibrium time was 10 minutes. The effects of photocatalyst-TiO2
loading on the rates of photocatalytic degradation of phenol had increased in four different light conditions: solar>UV>fluorescent>dark. The experimental results
illustrate that the kinetics of degradation of phenol are pseudo-2nd order. Phenol was effectively removed at pH 4 and at 60 0C and higher. Conclusion: In view of the results,
the P(3HB)-TiO2 nanocomposite films were proven to act as an effective material to simultaneously adsorb and degrade phenol in aquatic environment.