This research aims to produce activated carbon from molasses via a chemical activation process with potassium hydroxide (KOH) and a microwave heating process which consumes less energy and provides more rapid and uniform heat distribution than a conventional heating. The obtained activated carbon was then characterized with BET SEM and FTIR. It exhibited a large specific surface area of 1631 m2/g and a total pore volume of 1.124 cm3/g consisting of mesopore and micropore. In addition the active functional groups were also found on the surface of the activated carbon. Thus it was brought for the adsorption test with methylene blue. It was found that the adsorption capacity of the activated carbon increased with time and reached the equilibrium within 8 hours. The adsorption data of the activated carbon were corresponded to Langmuir isotherm with the highest adsorption capacity of 370.37 mg/g. The adsorption kinetic of the activated carbon exhibited pseudo-second order reaction suggesting to the chemisorption phenomenon. From the thermodynamic study it revealed that the adsorption process were endothermic and spontaneous reactions.

This research is the study of microwave distribution in the drying chamber to develop the belt-conveyor microwave dryer. The dimensions of the drying chamber are 90 cm width 3 cm length and 30 cm height. Two 800 W magnetrons were installed at the top of the chamber. It was found that the uniform of microwave distribution was observed at the center area of drying chamber. The uniform microwave distribution in the drying chamber at 400 W is achieved. A microwave leakage from the prototype is within the microwave oven safety standard of the US Department of Health and Human Services. This study can be used as a guideline for an industrial design for belt-conveyor microwave dryer.

Drying an agricultural product with hot air (HA) method causes a long drying time and results in high specific drying energy consumption (SEC). The dried product has high shrinkage percentage and low rehydration. Therefore this research aims to develop dried shiitake mushroom using belt-conveyor combined microwave-hot air drying method (MHB). The shiitake mushroom was dried by MHB at microwave power of 300 W 400 W 500 W and 600 W and air temperature of 65 oC with air velocity of 0.3 m/s and recycled air of 80% and by the HA drying method at air temperature of 65 oC. The samples were dried until their final moisture content less than 11.1% dry basis. The drying kinetics SEC of drying process and quality of dried shiitake mushroom were evaluated. The quality of dried product was considered in terms of color shrinkage rehydration texture water activity and microstructure. The results showed that the shiitake mushroom drying using MHB gave higher drying rate than that of HA drying method leading to short drying time and resulting in low SEC. The drying rate of un-blanched shiitake mushroom was higher than that of blanched shiitake mushroom. Dried shiitake mushroom from MHB drying gave lower values in shrinkage percentages and hardness but higher rehydration and larger pore size than that dried by HA drying. However the color values (L* +a* and +b*) of dried shiitake mushroom in all cases were not significantly different. Meanwhile dried shiitake mushroom from un-blanched case gave lower values in shrinkage percentage and hardness but higher values in all colors and rehydration and larger pore size than those of blanched case.

The aim of this work was to validate the sample preparation using a microwave digestion for determination of total arsenic in a spiked soil. Graphite fernace atomic absorbtion spectrophotometer (GFAAS) technique was used to determine the total arsenic using palladium nitrate Pd(NO3)3 as a modifier agent. The instrumental detection was performed under the condition steps of drying ashing atomizing and cleaning to be 100 1200 2250 and 2600 C. The external calibration curve was constructed using the automatic program based on the master standard of arsenic with 20 ppb. It was found that linearity range was in the range of 1 to 20 ppb with R2>0.999. Based on microwave digestion condition the sample preparation with and without HF was also compared the total arsenic in the spiked soil with a 10 ppb. The result shoewd that the arsenic content obtained fron the prearation with and without HF did not significantly diferent at the 95% confidence limit. The recovery was 80.3 and 82.3% for the spiked sample with 2.5 and 10 ppb respectively. The relative standard deviation was 2.15% (n=11). The results of this work can also confirmed that the preparation method using microwave digestion provided the more advantages such as rapid a little volume of reagents completely digestion.

The objectives of this research were to determine the suitable times of pork slices drying using microwave followed by hot air and to find specific energy consumption during drying. The physical characteristic (color and hardness) and the sensory test of dried pork slices were also investigated. Pork slices with the sizes of 50x50x1.3 and 50x50x2.2 millimeters were dried using the microwave at the powers of 160 320 480 640 and 800 watts until the samples did not burn during drying. Then the samples were dried using hot air at a temperature of 110oC until the moistures of the samples were lower than 20% dry basis. Based on the experimental results it was found that the suitable times of the samples drying using microwave were 50-600 seconds which depended on the microwave powers and the pork thicknesses. In hot air drying period drying times of the samples with thicknesses of 1.3 and 2.2 millimeters were 30 and 45 minutes respectively. The microwave powers had no significant effect on the redness (a value) and yellowness (b value) of dried pork the hardness of dried pork and the specific energy consumption (P<0.05). The pork thicknesses had the significant effect on the lightness (L value) and yellowness (b value) of dried pork the hardness of dried pork and the specific energy consumption (P<0.05). Moreover sensory scores of the dried pork obtained from this research were close to those obtained from the local market.