Nitrogen oxide reduction through absorbent solutions containing nitric acid and hydrogen peroxide in hollow fiber membrane modules

Abstract

Emissions of nitrogen oxides such as NO and NO2, which are commonly known as NOx, are threats to human existence and cause environmental problems. Mainly, two techniques have been developed to drastically reduce these emissions, which are dry and wet processes. The wet process has several advantages, major identifiable advantages are the adaptability to the flue gas, low operating temperatures and no poisoning and inactivation catalyst. Also, a mixture of hydrogen peroxide and nitric acid are used as absorbents solution for NOx reduction in the wet process. The advantages of using this mixture include the ability to reduce the negative effect of NOx and does not contaminate the scrubbing solution. In addition, nitric acid has an economical advantage in the process considering the fact that it is produced in the process. Finally, it can be conducted at ambient temperature. This study furthermore used a mixture of hydrogen peroxide and nitric acid solutions as an absorbent to reduce NOx in hollow fiber membrane modules. The hydrogen peroxide oxidized HNO2 to nitric acid, while enhances the oxidation through an autocatalytic reaction. The effects of the feed gas flow rate, hydrogen peroxide concentrations and number of fibers on the NOx reduction, absorbed NOx and flux were varied to study. The experimental results showed that the increase in the feed gas flow rate from 100 to 200 mL/min decreased NOx reduction from about 98 to 94% but increased the absorbed NOx and flux from about 0.13 to 0.255 mmol/h and 0.85–1.63 mmol/m2.h, respectively The increase in proportion of NOx in the feed gas effect was dominant than the increase in absorbed NOx. An increase in hydrogen peroxide concentration from 0.5 to 10 wt.% in the absorbent solutions increased NOx reduction, absorbed NOx and flux from about 94 to 98%, 0.257–0.267 mmol/h and 1.09–1.13 mmol/m2.h, respectively. Additionally, the H2O2 plays an important role in enhancing HNO2 oxidation to HNO3. Furthermore, an increase in the number of fibers from 50 to 150 in the membrane module increased NOx reduction and absorbed NOx from 86 to 97% and 0.23–0.27 mmol/h. Flux decreased from 2.98 to 1.13 mmol/m2.h due to increment in the gas-liquid contact surface area.

Effects of Operating and Structural Parameters on Removal of Nitric Oxide by Oxidation in a Ceramic Hollow Fiber Membrane Contactor

“…It should be noted that a single ceramic fiber membrane was used in this study, so the overall reduction efficiencies are not as high as those reported by Kartohardjono et al [33]. The size of hollow fiber varies greatly, and the removal efficiency per fiber cannot be compared.…”

“…Denitration was performed in a ceramic HFMC with surface modification. Kartohardjono et al [33] conducted a similar study. They assessed NO reduction performance using 50-150 fibers in an HFMC module, but the provided values were insufficient to compare.…”

“…It helped to achieve nonwetting conditions and over atmospheric operating conditions in order to enhance the chemical absorption of gas [36]. The size of the hollow fiber is larger than that of Kartohardjono et al [33]. The gas mixture passes through the porous area of the membrane and comes into contact with the solution.…”

Hollow Fiber Membrane Modules for NOx Removal using a Mixture of NaClO3 and NaOH Solutions in the Shell Side as Absorbents

“…Various technologies have been developed to reduce the NOx concentration in the air. These technological developments include dry methods such as Selective Catalytic Reduction & Selective Non-catalytic Reduction (Brandenberger, Kröcher, Tissler, & Althoff, 2008;Cheng & Bi, 2014;Jug, Homann, & Bredow, 2004;Roy & Baiker, 2009), and wet methods such as absorption using absorbents (Fangyang, Jiali, Wei, Jiyun, & Jianfeng, 2020;Kartohardjono, Merry, Rizky, & Pratita, 2019). The SCR method uses NH3 as a reducing agent over catalysts based on V2O5-WO3/TiO2 or Cu-and Fe-zeolite, which is very efficient to reduce NOx but requires high temperatures around 300 to 400 °C (Grossale, Nova, & Tronconi, 2008;Mehring, Elsener, & Kröcher, 2012;.…”

The Effect of the Number of Fibers in Hollow Fiber Membrane Modules for NOx Absorption

“…Furthermore, 49% of NOx comes from motor vehicles, 27% comes from the activities of the electricity generation industry, and 19% comes from household activities. NOx has also been reported to have the ability to cause acid rain, form fog fumes, decrease water quality, destroy ecosystems, and contribute to global warming (Choi et al, 2014;Gao et al, 2018;Kartohardjono et al, 2019a;Sun et al, 2019). In addition, NOx is also having harmful effect on the human being (Kartohardjono et al, 2019b).…”