No abstract

A multistep and high-cost biodiesel production could be simplified using the direct transesterification (DT) method.

Utilization of waste spent coffee grounds (SCG) remains limited and requires pre-treatment before being discarded to avoid pollution to the environment. Lipids contained in SCG could be converted to biodiesel through an in situ transesterification method. Current in situ transesterification of wet SCG biomass, conducted at high reaction temperature to reduce the water effect and reduce reaction time, is energy intensive. A new approach, which combines simultaneous extraction-transesterification in a single step using soxhlet apparatus, was developed to produce biodiesel directly from wet SCG biomass. A homogeneous base catalyst at a concentration of 0.75 M showed better catalytic activity than acid, with hexane as a co-solvent on fatty acid (FA) extraction efficiency and FA to fatty acid methyl ester (FAME) conversion efficiency. Studying the factorial effect of ratio of methanol to hexane and reaction time led to the highest FA to FAME conversion efficiency of 97% at a ratio of 1 : 2 and 30 min reaction time. In addition, the catalyst could be used five times without losing its activity. In term of energy consumption, the reactive extraction soxhlet (RES) method could save 38-99% of energy compared to existing methods.

Electrospun nanofibers are unique one-dimensional materials with high surface area to volume ratio which can be used in various applications including in antibacterial application. In this study, we demonstrated a simple fabrication of polyethylene oxide-polypyrrole (PEO-PPy) composite nanofibers with antibacterial properties. The polymerization of pyrrole was conducted using ammonium persulfate (APS) initiator at ambient temperature for 24 h. The resulting PEO-PPy nanofibers were then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared (FTIR), and tensile tests. The morphology of nanofibers observed by SEM revealed that the minimum concentration of PEO was 8 wt % to obtain the bead-free nanofibers. Meanwhile, variation of pyrrole concentration does not alter the morphology of nanofibers significantly. The crystallinity of the nanofibers increased with increasing the PEO amount indicated by two typical peaks located at 2θ = 19°and 23°, respectively. On the other hand, polypyrrole contributed the antibacterial properties significantly to the nanofibers and as a result, the antibacterial activity determined by UV-Vis spectrophotometer increased dramatically with increasing pyrrole concentration from 0.1 to 0.2, 0.3, 0.4, and 0.5 mM. The electrospun nanofiber mats exhibited good antibacterial properties on E. coli and biocompatibility properties on L929 fibroblasts cell.