Vortex based hydrodynamic cavitation and anaerobic digestion based sugarcane bagasse biorefineries for revitalising the sugar industry.

Alternative renewable energy must emerge to sustainably meet the energy demands of the present and future. Current alternatives to fossil fuels are electricity from solar, wind and tidal energies and biofuels. Biofuels, especially bioethanol could be produced from lignocellulosic feedstock via pre-treatment and fermentation. The cellulose I content of most lignocellulosic feedstock is significant, yet its highly crystalline amphiphilic structure interlinked with the lignin network makes it difficult to process for bioethanol production. Processing lignocellulosic biomass via a range of physico-chemical, mechanical and biological pre-treatment methods have been well established, however a relatively new area on the use of cellulose II (a polymorph of native cellulose obtained via mercerisation or regeneration) for the production of bioethanol is still in its early stages. Hence, this review discusses in detail the advantages of using cellulose II over cellulose I as feedstock for bioethanol production. Furthermore, current green and sustainable methods for cellulose II production and the advantages and disadvantages of each method are discussed. In addition, examples from literature reporting higher fermentable sugar and bioethanol yields using cellulose II as feedstock are reviewed, thereby highlighting its importance in the field of bioethanol production. The conclusion from this review suggests that, in all the cases studied, fermentable sugar and/or bioethanol production was found to be higher when cellulose II was used as feedstock instead of native cellulose/lignocellulosic biomass. This higher yield could be attributed to the modified structural and lattice arrangement of cellulose II, its porous volume and degree of polymerisation.Engineering and Physical Sciences Research Council (Project no. EP/K036769/1) ; Queen's University Belfast's Ph.D. studentship

This work was supported by the Engineering and Physical Sciences Research Council (Project number EP/K036769/1), Robert Gordon University’s IDEAS PhD studentship and Queen’s University Belfast’s PhD studentship.A simple method for determining hydroxyl radical yields on semiconductor photocatalysts is highly desirable, especially when comparing different photocatalyst materials. This paper reports the screening of a selection of visible light active photocatalysts such as Pt-C3N4, 5% LaCr doped SrTiO3, Sr0.95Cr0.05TiO3 and Yellow TiO2 and compares them against WO3 and ultra violet (UV) light activated TiO2 P25 (standard commercial catalysts) based on their oxidative strengths (OH radical producing capability) using a well-studied chemical probe − coumarin. 7-hydroxycoumarin, the only fluorescent hydroxylation product of this reaction can then be measured to indirectly quantify the OH radicals produced. P25 under UV light produced the highest concentration of OH radicals (16.9 μM), followed by WO3 (0.56 μM) and Pt-C3N4 (0.25 μM). The maximum OH radical production rate for P25, WO3 and Pt-C3N4 were also determined and found to be 35.6 μM/hr, 0.28 μM/hr and 0.88 μM/hr respectively. The other visible light activated photocatalysts did not produce any OH radicals primarily as a result of their electronic structure. Furthermore, it was concluded that, if any visible light absorbing photocatalysts are to be fabricated in future for the purpose of photocatalytic oxidation, their OH radical producing rates (and quantities) should be determined and compared to P25.PostprintPeer reviewe

• Vortex based hydrodynamic cavitation devices degrade complex pollutants in water. • It is essential to use per-pass degradation model for evaluating efficacy of cavitation devices. • For the first time, experimental data for nearly 200 times scale-up is presented. • Degradation performance first decreases with increase in scale and then plateaus.