Abstract. The effect of flow rate of ozone-containing gas and pH on the mass transfer coefficient of ozone through water in a bubble column reactor has been studied. Ozone was generated from air using a corona discharge ozone generator. The flow rate of air was varied from 2 to 5 L min -1 , while pH was varied from 4 to 10. The gas containing ozone was bubbled to the reactor containing 1.5 L of 2% KI solution. The temperature was set at 281C. The concentration of ozone was determined using titrimetric method every 5 minutes. The results show that the concentration of ozone increases with time, and it reaches a steady-state concentration after 30 minutes of ozonation. The gas flow rate and pH apparently affect both the concentration and the kLa. The highest kLa of 2.1 10 -2 s -1 is obtained at pH 4 with a gas flow rate of 4 L min -1 .
This research was conducted to calculate the mass transfer coefficient value for ozonation reaction of κ-carrageenan solution in the bubble column reactor. Ozone gas was produced using ozone generator type corona discharge. In this study, operating conditions were regulated at ozone gas flow rate 2- 5 L min-1, pH 4-10, and temperature 29 ± 1 oC. Samples were tested every 5 minutes to determine the dissolved ozone concentration. The results showed that dissolved ozone concentrations increased with increasing ozonation time and ozone gas flow rate. However, a very high gas flow rate can increase turbulence so that the mass transfer coefficient (kLa) value decreased. In alkaline conditions, the formation of free radicals (HO*) increases so that the amount of dissolved ozone decreases. The kLa value of ozone gas in κ-carrageenan solution is slightly lower than the kLa value of the ozone gas in the water. The results of this study indicate that (kLa) ozone gas in water is 0.131 / minute while the value (kLa) in κ-carrageenan solution is 0.128 / minute.
According to WHO, preventable diseases, including infectious diseases, are the most common cause of death in children. Based on Indonesia's 2019 health profile data, the top five morbidity and mortality in children aged 1-4 years are acute respiratory tract infections (ARI) of (25.8%), pneumonia (21.7%), fever (14%), diarrhea and gastrointestinal disease (14.4%). Zinc has an important role in immunity especially for younger child
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