(A) comparative study on $H_2S$ removal by absorbents for impeller-based scrubber

Abstract

furthermore, the dominant products from HOCl, $H_2O_2$, $S_2O_8^{2-}$, NaOH, and $CO_3^{2-}$ oxidation processes are sulfate ($SO_4^{2-}$), unknown substances, $SO_4^{2-}$, sulfide ($S^{2-}$), and $S^{2-}$, respectively. However, $S^{2-}$ is an unstable substance that can easily reverse back to $H_2S$ when pH is decreased. Precipitants were observed during the $H_2O_2$ and $S_2O_8^{2-}$ oxidation experiments. X-ray photoelectron spectroscopy (XPS) analysis has confirmed that they were sulfur elements ($S^0$). But precipitant would clog the impeller's mesh. As a result, HOCl was the best oxidant to use as absorbents in this study. The optimal impeller scrubber conditions were investigated, and it was discovered that L/G 6 with a 5 mM HOCl concentration and L/G 3 with a 7 mM HOCl concentration provided the best $H_2S$ removal performance (99.4% and 99.2% of the average removal efficiency in 1 hour with a gas flow rate of 0.5 L/min, respectively). However, L/G 3 with a 7 mM HOCl concentration produced more sulfate than L/G 6 with a 5 mM HOCl concentration. Therefore, L/G 3 with a 7 mM HOCl concentration is more suitable than L/G 6 with a 5 mM HOCl concentration because of lower energy consumption for pumping and higher sulfate production. The influence of rotation speed was investigated, and it was found that when the rotation speed of the impeller increased, the removal efficiency also improved. Because the higher the rotation speed, the smaller the droplets, the more surface area, and the more oxidation.

Since public complaints and human health problem effects from odors, especially hydrogen sulfide, has been considerably increased, many technologies have been raised and developed to handle and remove it. In this work, hypochlorous acid (HOCl), hydrogen peroxide ($H_2O_2$), persulfate ($S_2O_8^{2-}$), sodium hydroxide (NaOH), and carbonate ($CO_3^{2-}$) were compared as absorbents for the removal of hydrogen sulfide in order to be used in impeller-based scrubbers

moreover, the proportion of products from oxidation processes was investigated. In addition, the suitable absorbent was used in impeller-based scrubbers to evaluate the optimal condition for upscaling in long-term use and future studies. The results showed that the removal rates of 2 mM NaOH, 10 mM HOCl, 10 mM NaOH, and 10 mM $Na_2CO_3$ (all at 100%) were higher than those of 2 mM $Na_2CO_3$ (from 100% to 78.3%), 10 mM $H_2O_2$ (from 52.3 to 51.7%), and 10 mM $S_2O_8^{2-}$ (from 51.3 to 47.3%) in 1 hour