Sustainable production of flocculant-containing bacterial cellulose composite for removal of PET nano-plastics

Polyethylene terephthalate (PET) nano-plastics (PNP) is a major source of water pollution which in turn causes health issues in humans. There is no effective method to completely remove PNP from wastewater. In this study, bacterial cellulose (BC)/bacterial flocculant (BF) composite was produced from PNP ammonia hydrolysate through the co-cultivation of Taonella mepensis WT-6 and Diaphorobacter nitroreducens R9. The structural characterization of the BC/BF composite through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermal and mechanical analyses demonstrated that the amino-group-rich flocculant produced by the D. nitroreducens R9 was incorporated into the BC network without interfering the self-aggregation of cellulose fibrils. Fast PEP removal was observed in pure and tap water with maximum sorption capacity (Qmax) of 124.65 mg/g and 115.60 mg/g, respectively, whereas least removal was observed for campus lake water with a Qmax value of 84.78 mg/g. A 10 mM SO42− significantly decreased the adsorption capacity to 44.52 mg/g, while 2 mM Ca2+ contributed to the adsorption of PNP with a maximum adsorption capacity of 144.78 mg/g at pH 6.0. The potential adsorption mechanism was investigated through adsorption kinetic studies, isothermal models, and thermodynamics studies. The adsorbed BC/BF was recycled by desorbing PNP with ammonia water, and the eluent could be utilized as a medium for sustainable production of BC/BF. The reusable BC/BF adsorbent produced through the co-culture technique can effectively control PNP pollution.