Iranian Journal of Chemical Engineering (IJChE)

Abstract Ultrasonic distillation has been implemented as a green technology for desalination of saltwater due to its low energy consumption. It has also been proposed as an alternative to conventional distillation for separating water-ethanol mixtures, offering easy operating conditions and significant reduction in energy consumption (up to 80%). The Response Surface Methodology (RSM) was employed to optimize key parameters that influence ethanol enrichment, which includes initial ethanol concentration, solution height, and the quantity of ultrasonic modules. A central composite design (CCD) was utilized to reduce the number of experimental trials while formulating a predictive mathematical model. The findings suggest that elevated initial ethanol concentrations and an augmented number of modules significantly improved the ethanol concentration in the collected mist. Under optimal conditions—65% ethanol concentration, 2.5 cm solution height, and three modules—the purity of ethanol attained was akin to that achieved through conventional distillation techniques, accompanied by markedly diminished energy consumption. This research illustrates the potential of ultrasonic distillation for ethanol separation, offering operational efficiency and reduced energy demands.

Abstract Humidification-dehumidification (HD) desalination has been identified as a sustainable, reliable, and energy-efficient technology for producing freshwater on a small scale. VP-HD systems operated at one-stage, multi-stage, and multi-feeding vacuum humidification-over atmospheric pressure dehumidification arrangements can be the recent modifications of an HD system. The present study offers a theoretical investigation and experimental verification of two VP-HD systems, encompassing both sub-atmospheric pressure humidification and over-atmospheric dehumidification. Two designs are evaluated, one comprising a three-stage humidification setup and the other featuring a three-feeding one-stage humidification apparatus. The results show which design has better performance than previous conventional and variable pressure HD systems. The parametric analysis reveals that an upsurge in freshwater generation is observed with an increase in air temperature, feed salinity, and a decrease in humidifier pressure. Additionally, an optimal water-to-air ratio is identified. The study further highlights that multi-stage humidification yields better results concerning freshwater productivity and specific power consumption. Three-stage humidification is found to be the most efficient in terms of freshwater production and specific power consumption, achieving the highest values of 1.93 L h^-1 m^-2 and 0.21 kWh L^-1, respectively. The agreement between theoretical and experimental outcomes is deemed satisfactory.

Abstract Sorghum bicolor L., a plant of Gramineae family is a perenial grass which is grown in many parts of tropical and warm temperates of the world. Sorghum seeds are rich in carbohydrates and can be used as fermentation medium providing it is produced through proper extraction and sacharification processes. In this study, the fermentation capacity of an aqueous or ethanolic extract from sorghum seed was investigated in Lab-scale bioreactors by using three selected Lactobacillus species including L. delbrueckii, L. acidophilus and a new isolated strain identified as a Lactobacillus sp.
Among the selected bacterial species, Lactobacillus delbrueckii was found to have unique characteristics as it could tolerate different physico-chemical conditions. Compared to other species, L. delbrueckii could remain metabolically active in high concentration of NaCl and lactic acid, which is particular to the fermentation of sorghum seed extract neutrilized by NaOH. L.delbrueckii could also tolerate high temperature and, additionally, was able to produce more lactic acid in high concentration of carbohydrate during fermentation process (Yield 85-90%). In conclusion, the results of this study demonstrated that hydrolysed sorghum seed extract has enough nutrients to support the efficient growth of lactic acid bacteria and production of lactic acid under favorable conditions (37°C, 100 g/L initial carbohydrate concentration).

Abstract Spray dryer was used to produce potato powder from potato juice. Turning potatoes into powder will increase its substance durability, ease of transportation and the storage. The important factors affecting the powder produced by spray dryer include inlet air temperature, volumetric flow rates of feed and air. Experiments were conducted according to Taguchi’s method by considering 3 levels for each one of the mentioned parameters and 2 levels for atomizer’s nozzle diameter. The objective was to obtain the optimized process conditions for producing potato powder with desirable color. By analyzing the experimental results, the optimized conditions for producing potato powder by spray dryer were determined. It was also revealed that by adding 1 percent maltodextrin (dry mass basis) to the feed, the product’s adhesion will decrease significantly and the amount of product will be increased.

Abstract Drying behavior of sugar beet was investigated in a bench scale fluidized bed dryer with an energy carrier (3 mm glass beads) and a freeze dryer. The effect of the type of dryer (fluidized bed dryer & freeze dryer) on the rate of drying and properties of dried sugar beet were studied. It was found that drying could be useful for the storage of sugar beet for a long time before processing, but the removal of more than 90% of its initial water content is necessary for the dried sugar beet to conserve its sugar content and other properties during storage. The results of experiments in two different dryers
showed that drying time in a fluidized bed dryer with energy carriers is much less than that of a freeze dryer, but the dried matter obtained by the freeze dryer has a better appearance in comparison to fluidized bed dryer. Also, the shrinkage of drying material with a change of moisture content was investigated and it was seen that a linear relation with reasonable error between these two variables was evaluated. The results are useful for mathematical modeling of the
process.