Biomass is considered as the largest renewable energy source in the world. However, some of its inherent properties such as hygroscopicity, lower energy content, low mass density and bio-degradation on storage hinder its extensive application in energy generation processes. Torrefaction, a thermochemical process carried out at 200-300°C in a non-oxidative environment, can address these inherent problems of the biomass. In this work, torrefaction of bagasse was performed in a bench-scale tubular reactor at 250°C and 275°C with residence times of 30, 60 and 90 mins. The effects of torrefaction conditions on the elemental composition, mass yield, energy yield, oxygen/carbon (O/C) and hydrogen/carbon (H/C) ratios, higher heating values and structural composition were investigated and compared with the commercially available 'Thar 6' and 'Tunnel C' coal. Based on the targeted mass and energy yields of 80% and 90% respectively, the optimal process conditions turned out to be 250°C and 30 mins. Torrefaction of the bagasse conducted at 275°C and 90 min raised the carbon content in bagasse to 58.14% and resulted in a high heating value of 23.84 MJ/kg. The structural and thermal analysis of the torrefied bagasse indicates that the moisture, non-structural carbohydrates and hemicellulose were reduced, which induced the hydrophobicity in the bagasse and enhanced its energy value. These findings showed that torrefaction can be a sustainable pre-treatment process to improve the fuel and structural properties of biomass as a feedstock for energy generation processes.
The present study proposed the isolation of arsenic resistant bacteria from wastewater. Only three bacterial isolates (MNZ1, MNZ4 and MNZ6) were able to grow in high concentrations of arsenic. The minimum inhibitory concentrations of arsenic against MNZ1, MNZ4 and MNZ6 were 300 mg/L, 300 mg/L and 370 mg/L respectively. The isolated strains showed maximum growth at 37 °C and at 7.0 pH in control but in arsenite stress Luria Bertani broth the bacterial growth is lower than control. All strains were arsenite oxidizing. All strains were biochemically characterized and ribotyping (16S rRNA) was done for the purpose of identification which confirmed that MNZ1 was homologous to Enterobacter sp. while MNZ4 and MNZ6 showed their maximum homology with Klebsiella pneumoniae. The protein profiling of these strains showed in arsenic stressed and non stressed conditions, so no bands of induced proteins appeared in stressed conditions. The bacterial isolates can be exploited for bioremediation of arsenic containing wastes, since they seem to have the potential to oxidize the arsenite (more toxic) into arsenate (less toxic) form.
The energy demand of the world is skyrocketing due to the exponential economic growth and population expansion. To meet the energy requirement, the use of fossil fuels is not a good decision, causing environmental pollution such as CO2 emissions. Therefore, the use of renewable energy sources like biofuels can meet the energy crisis especially for countries facing oil shortages such as Pakistan. This review describes the comparative study of biodiesel synthesis for various edible oils, non-edible oils, and wastes such as waste plastic oil, biomass pyrolysis oil, and tyre pyrolysis oil in terms of their oil content and extraction, cetane number, and energy content. The present study also described the importance of biodiesel synthesis via catalytic transesterification and its implementation in Pakistan. Pakistan is importing an extensive quantity of cooking oil that is used in the food processing industries, and as a result, a huge quantity of waste cooking oil (WCO) is generated. The potential waste oils for biodiesel synthesis are chicken fat, dairy scum, WCO, and tallow oil that can be used as potential substrates of biodiesel. The implementation of a biodiesel program as a replacement of conventional diesel will help to minimize the oil imports and uplift the country's economy. Biodiesel production via homogeneous and heterogeneous catalyzed transesterification is more feasible among all transesterification processes due to a lesser energy requirement and low cost. Therefore, biodiesel synthesis and implementation could minimize the imports of diesel by significantly contributing to the overall Gross Domestic Product (GDP). Although, waste oil can meet the energy needs, more available cultivation land should be used for substrate cultivation. In addition, research is still needed to explore innovative solvents and catalysts so that overall biodiesel production cost can be minimized. This would result in successful biodiesel implementation in Pakistan.
The aim of present research aims to fabricate a system of enteric coating of hydrogel beads with pH-sensitive polymer, which shows solubility at pH > 7, and explore their potential to target the colon for drug delivery. Hydrogel beads were fabricated through the extrusion-dripping technique followed by ion gelation crosslinking. Moreover, freeze-thaw cycle was implemented for crosslinking of polyvinyl alcohol (PVA)/Ca-alginate blend beads. The oil-in-oil solvent evaporation method was adopted for the Eudragit coating of hydrogel beads using different coat: core ratios (4:1 or 8:1). Coated and uncoated hydrogel beads were evaluated by in vitro physicochemical properties, swelling and drug release behaviours, and in vivo pharmacokinetics, swelling, and toxicity evaluation. Diclofenac sodium was loaded as an experimental drug. Drug entrapment efficiency for the PVA/Ca-alginate beads was calculated as 98%, and for Ca-alginate beads, it came out to a maximum of 74%. Drug release study at various pH suggested that, unlike uncoated hydrogel beads, the coated beads delay the release of diclofenac sodium in low pH of the gastric and intestinal environment, thus targeting the colon for the drug release. It was concluded that Eudragit S-100-coated hydrogel beads could serve as a more promising and reliable way to target the colon for drug delivery.Graphical abstract.