Glucose Test of Reduced Sugar

Based on the glucose standard curve, this experiment proceeds the glucose test of reduced sugar. First, 0.5 ml reduced sugar and 0.5 ml DNS indicator were poured into a tube and placed in a water tank at a constant temperature of 100 °C for 5 min and then cooled in a cold water bath. To this was added 3 ml of distilled water, and a spectrophotometer measuring a wavelength of 540 nm was utilized to measure absorbency for comparison with the glucose standard curve. The glucose content of the reduced sugar was then calculated.

Mechanical and Biological Effects

This experiment investigated the mechanical and biological effects of ultrasound irradiation on hydrogen production (Figure 1). This included frequency, acoustic intensity, exposure time, and temperature. Natural frequencies at 0.5 and 1 MHz were calculated with the Rayleigh-Plesset equation and compared to the non-natural 0.25 MHz frequency of the transducer. Acoustic intensity was set at 25, 79, and 136 mW/cm2 to explore the effects on the growth and hydrogen production of the bacteria under irradiation. Exposure times were 10 sec, 5 min, and 15 min at a temperature of 37 °C, which is the most suitable for biological growth, and 30 °C for comparison. Bacterial concentrations of 10, 20, and 30% were used for determining the effects of bacterial concentration on hydrogen production. The pH was set at

6.5, 7.0, and 7.5 to explore the effects of acid or alkali growth media on bacterial growth and hydrogen production (Table 1). A full factorial experiment was not suitable because there are too many parameters in the Taguchi method. The latter can be a future reference for biohydrogen by irradiating the hydrogen producing bacteria with ultrasound.

Table 1. Six factors and two/three levels of the orthogonal array Ti2(21x35)


Level 1

Level 2

Level 3

A. Temperature (°C)



B. Ultrasound frequency (MHz)




C. Ultrasound intensity (mW/cm2)




D. Ultrasound exposure time


5 min

15 min

E. pH value




F. Bacterial concentration (%)




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