Extraction of shikimic acid from water hyacinth (Eichhornia crassipes) using sonication: An approach towards waste valorization

Shikimic acid (SA) is a valuable compound found in water hyacinth and is a precursor for synthesis of antiviral drug oseltamivir phosphate (Tamiflu®) which is used to treat H5N1 avian influenza. In the present work, the acid was extracted from different morphological parts (stem, leaves, and roots) of water hyacinth (a notorious aquatic weed) using sonication. The parametric study has been conducted by varying sonication time (10-50 min), solvent composition (methanol + water), solvent volume (20-50 mL), amplitude of sonication (30-60%), and pulse ratio (20-50%) for improving the recovery of shikimic acid (SA), antioxidant activity (AA) and total phenolic content (TPC) of water hyacinth extract. Also, the acid was extracted conventionally as a benchmark study. The highest yield of 2.4% at 40 min and 3.1% at 30 min was observed in case of conventional and ultrasound assisted extraction (UAE), respectively for stem. Leaves showed a higher TPC value of 7.4 mg GAE/g biomass and a higher AA was observed 83.21% at 20 min for stem in case of conventional method. The highest TPC value of 11.11 mg GAE/g biomass has been observed for leaves while stem has shown the highest AA of 87.72% at 10 min of sonication time for UAE. It was possible to recover the valuable chemicals with better processing conditions in the case of UAE.

Optimization and Reaction Kinetics Studies on Copper-Cobalt Catalyzed Liquid Phase Hydrogenation of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran

In the present work, hydrogenation of biomass derived 5-hydroxymethylfurfural (HMF) into fuel additive 2,5-dimethylfuran (DMF) is studied over Cu-Co/Al2O3 catalyst. The influence of various operating parameters such as temperature, pressure, catalyst amount, time and HMF concentration on the conversion HMF to DMF was optimized using well known Taguchi method as statistical tool. According to Taguchi method, under optimum reaction conditions viz. temperature 220 °C, pressure 30 bar, reaction time 6 h, catalyst loading 0.5 g, and HMF concentration of 0.2 wt%, maximum DMF yield (87 %) was recorded. Analysis of variance suggested that temperature and pressure are the most influencing factor. Mechanistic study suggested that DMF can be obtained via C = O hydrogenation over Cu metal due to preferential adsorption of HMF on Cu metal which further undergoes acid catalyzed hydrogenolysis and resulted DMF. The initial rates of reaction HMF to BHMF varied linearly with hydrogen pressure at different temperatures, catalysts loading, and reactant substrate concentration. These observations indicate first order kinetics for HMF disappearance. According to power-law model, the order with respect to HMF was found to be 0.9. The experimental data could also be explained using Langmuir-Hinshelwood kinetics. A competitive hydrogen with dissociative adsorption on catalysts surface and surface reaction as the rate-controlling step provided the best fit of the experimental data.

A versatile bi-metallic copper–cobalt catalyst for liquid phase hydrogenation of furfural to 2-methylfuran

This work presents the application of bi-metallic copper–cobalt catalysts towards one step hydrogenation of furfural to 2-methylfuran in liquid phase.