Atulkumar N. Raut

The foremost aim of the present study was to enhance butanol production in an extractive fermentation study in presence of non-ionic surfactant using immobilized cells. Earlier studies had shown improved butanol production with non-ionic surfactant and immobilized cells independently. Therefore, in the present work, the combined effect of extractive fermentation and immobilized cells on butanol production was studied. Different matrices (brick, bamboo, cotton fiber, flannel cloth, and polyurethane foam) were tested for immobilization of Clostridium sporogenes. Immobilized biomass thus obtained was used in an extractive fermentation study with non-ionic surfactant L62. Biomass immobilized on polyurethane foam (PF) doubled the butanol production in presence of 6% (v/v) L62 with respect to control (free cells without surfactant). Further, the effect of different carbon sources was also studied to check the suitability of different industrial wastes containing different carbon sources. Glucose was found to be the best carbon source.

The present study was undertaken in order to investigate effect of diverse parameters such as fermentation media, pH, initial concentration of biomass, different surfactant concentrations, and immobilization on increasing butanol and total solvent production. Cheng’s fermentation media was successfully tested and perceived to increase final solvents concentration. Controlled pH at 12th and 24th hours had negative effect on butanol enhancement; however, it resulted in more butyric acid production which remained accumulated. Ten percent (v/v) biomass was evaluated to increase final solvents concentration and hence butanol yield compared to 20% and 30% (v/v) of initial biomass concentrations. Effect of surfactant concentration (3–20%) was studied on butanol production. Six percent (v/v) L62 resulted in 49% higher final butanol concentration compared to control. Simultaneous immobilization and fermentation showed higher butanol production (16.8 g/L with 6%) which was attributed to partial immobilization of biomass.

Extractive butanol fermentation with non-ionic surfactant, a recently explored area, has shown promising results with several advantages but is relatively less investigated. This work reports the extractive fermentation with selected non-ionic surfactants (L62 and L62D) to enhance butanol production using a high-butanol producing strain (Clostridium beijerinckii MCMB 581). Biocompatibility studies with both the surfactants showed growth. Higher concentrations of surfactant (>5%) affected the cell count. 15.3 g L⁻¹ of butanol and 21 g L⁻¹ of total solvents were obtained with 3% (v/v) L62 which was respectively, 43% (w/w) and 55% (w/w), higher than control. It was found that surfactant addition at 9th h doubled the productivity (from 0.13 to 0.31 g L⁻¹ h⁻¹ and 0.17 to 0.39 g L⁻¹ h⁻¹, respectively for butanol and total solvent). Butanol productivity obtained was 2–3 times higher than similar studies on extractive fermentation with non-ionic surfactants. Interestingly, mixing did not improve butanol production.

Highly monodispersed ruthenium nanoparticles were prepared wet impregnation technique using RuCl · HO as a precursor. Ru nanoparticles were supported on AlO to synthesize Ru nanocatalyst. The nanocatalyst was characterized by various techniques like XRD, SEM, TEM and BET analysis. The catalyst was used for hydrogenation of phenol under mild condition. The activity of the catalyst was checked by varying different parameters such as reaction temperature, time, H partial pressure, metal loading and catalyst amount. The catalyst was recovered from product and reused up to four times without significant loss in its catalytic activity. After a reaction time of 1 h, Ru/AlO nanocatalyst showed high reactivity (82% conversion) and selectivity to cyclohexanone (67%) at 80°C and 20 bar hydrogen pressure.