Solid-liquid extraction of sorrel calyces with ethanol

  Ethanol extraction of three particle size distributions of sorrel (Hibiscus sabdariffa) calyces was investigated.  Extraction rate was found to increase with reduced particle size, increased temperature and solvent mass (solvent-feed ratio).  At 30oC, maximum yield or concentration was achieved with 50:1 solvent-feed ratio but no substantial increment occurred in these parameters beyond 20:1 ratio.  No degradation of the extract’s components occurred between 27oC and 70oC since linear relation between extraction yield and temperature was sustained.  Peleg equation and a variant of it gave the best fit for extraction kinetics.  The smallest calyx particles

Thin layer drying models for sweet potato in tray dryer

Sweet potato is increasingly becoming important and popular as food stuff all over the world.  Therefore investigation of thin layer drying of sweet potato slices in three different dimensions was carried out between 50oC and 80oC in tray dryer using hot air at a flow rate of 2.5 m/s and 10% relative humidity.  Eight thin-layer drying kinetic models were assessed on blanched and unblanched sweet potato slices presented in three different dimensions.  The drying rate was observed to decrease with thickness and mass at a constant drying temperature.  Also, the drying rate was found to increase with temperature and the blanched slices dried faster than unblanched slices.  The eight models investigated fitted the experimental data of the six sweet potato samples between 50oC and 80oC adequately.  However, Page model was found to be the best for all the samples.  The results obtained are comparable to some of the reported works. Keywords: sweet potato, thin-layer drying models, page model, tray dryer, diffusion mechanis

Theoretical Study of Sand Entrainment and Deposits in Horizontal Oil Transport

Sand deposition in horizontal pipes transporting crude oil and sand affects oil recovery and causes loss of pipe integrity. One way of avoiding sand deposition in lines is by identifying potential sand deposit points for mounting boosters to help boost the inertia force of the flowing stream. This paper investigates a model approach to the problem. Results from simulation give potential sand deposit points in a 12 km pipeline. The Reynolds numbers estimated, show significant variations between the 6 and 8km points where viscous forces prevailed over inertia forces. Thus, the 6 km point is an ideal point for mounting a booster. Sand velocities remained constant at 0 km at different times down to the 8 km point although, the values differ axially per hour. Variations were incipient at the 10 km point through to the exit owing to hindered settling caused by inherent collisions of particles resting on the pipe wall. However, this also suggests that the 8 km point is a crucial point at or beyond which a booster pump is required to make up for the lost kinetic energy for a reliable and safe flow. Transport flow regimes were also investigated via parametric assessment on hourly basis

Preparation of phosphoric acid activated carbons from Canarium Schweinfurthii Nutshell and its role in methylene blue adsorption

Activated carbons were prepared by phosphoric acid activation of Canarium Schweinfurthii spent nutshell. The activation conditions for particles with average diameter of 2.36 mm, conducted in nitrogen chamber, were evaluated at 40 and 60% acid concentration, substrate/activating agent (impregnation) ratio of 1:1 to 1:4, activation time of 20 to 60 min and temperatures of 200 and 400°C. The results showed that the yield, BET surface area and adsorption capacities of activated carbon produced increased with impregnation ratio, activation time and temperatures. The activated carbon obtained using 1:4 impregnation ratios at 60 min with 40 wt% acid solution have BET surface area and adsorption capacity of 741 m2/g and 8.5 gMB/g Carbon while those for 60wt% acid solution were determined as 779 m2/g and 9.2 gMB/g Carbon, respectively

Solid-liquid extraction of oils of African elemi’s fruit

African elemi (Canarium schweinfurthii) contains oil in its fruit’s pulp and kernel. Solvent extraction of these oils using n-hexane has been investigated in this work to obtain some process parameters. This was done at different temperature over a period of time with varying solvent to feed (solid) mass ratios. Oil yield and extraction efficiency were observed to increase with time, temperature and materials ratio but in different fashions. The kinetics of the oils’ extraction was found to be adequately described by Peleg equation and a variant of it. At 30oC, kernel oil recorded the highest saturated extraction yield (Cs) with 7.5g solvent/g solid while no peak was observed for pulp oil extraction using 1 to 10g solvent/g solid. Kernel oil gave the highest saturated (maximum) yield (45.93g/100g solid) but pulp oil gave the highest initial extraction rate (Bo=3.5868 g/L.min) and fastest time constant (τo=9.84 min). Free fatty acid content of the extracted oils was observed to increase with leaching temperature while iodine value reduced with it. This phenomenon was more pronounced with kernel oil