Laccase from Aspergillus niger: A novel tool to graft multifunctional materials of interests and their characterization

In the present study, we propose a green route to prepare poly(3-hydroxybutyrate) [(P(3HB)] grafted ethyl cellulose (EC) based green composites with novel characteristics through laccase-assisted grafting. P(3HB) was used as a side chain whereas, EC as a backbone material under an ambient processing conditions. A novel laccase obtained from Aspergillus niger through its heterologous expression in Saccharomyces cerevisiae was used as a green catalyst for grafting purposes without the use of additional initiator and/or cross-linking agents. Subsequently, the resulting P(3HB)-g-EC composites were characterized using a range of analytical and imagining techniques. Fourier transform infrared spectroscopy (FT-IR) spectra showed an increase in the hydrogen-bonding type interactions between the side chains of P(3HB) and backbone material of EC. Evidently, X-ray diffraction (XRD) analysis revealed a decrease in the crystallinity of the P(3HB)-g-EC composites as compared to the pristine individual polymers. A homogeneous P(3HB) distribution was also achieved in case of the graft composite prepared in the presence of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) as a mediator along with laccase as compared to the composite prepared using pure laccase alone. A substantial improvement in the thermal and mechanical characteristics was observed for grafted composites up to the different extent as compared to the pristine counterparts. The hydrophobic/hydrophilic properties of the grafted composites were better than those of the pristine counterparts.

Logistics and the waste sector: a London case study

London has traditionally exported most of its waste to former mineral workings in surrounding counties for landfill. Many of these sites are being filled and opportunities for new sites are limited. Virtually all waste reprocessing and recycling facilities, with the exception of textile sorting and some facilities for glass and organic waste composting, are outside London. The Mayor of London's Vision for Waste in London is that by 2020, municipal waste should not compromise London’s future as a sustainable city. This will involve managing waste better, so that its impact on the local and global environment and on London communities, economy and health is minimised. The majority of waste and recyclable materials in London are currently collected and transported for recovery, disposal or reprocessing by road in large vehicles. Environmental costs include, adding to congestion, noise, energy usage, air pollution, and accidents. The Mayor is keen to increase recycling and reuse of waste materials in London, and to ensure that as more of London's waste is diverted away from landfill sites to recycling facilities. Several projects and initiatives have been established and these are reviewed in the paper.