Increasing oxygen functional groups of activated carbon with non-thermal plasma to enhance mercury removal efficiency for flue gases

2015 ◽  
Vol 263 ◽  
pp. 1-8 ◽  
Author(s):  
Bi Zhang ◽  
Ping Xu ◽  
Yong Qiu ◽  
Qiao Yu ◽  
Jingjing Ma ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Functional Groups ◽  
Removal Efficiency ◽  
Thermal Plasma ◽  
Flue Gases ◽  
Mercury Removal ◽  
Oxygen Functional Groups ◽  
Non Thermal Plasma

scholarly journals Role of Activated Carbon Precursor for Mercury Oxidation and Removal: Oxidized Surface and Carbene Site Interaction

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1190
Author(s):  
Regina Rodriguez ◽  
Domenic Contrino ◽  
David Mazyck
Keyword(s):  
Activated Carbon ◽  
Nitric Acid ◽  
Gas Phase ◽  
Functional Groups ◽  
Bituminous Coal ◽  
Activated Carbons ◽  
Elemental Mercury ◽  
Coconut Shell ◽  
Mercury Removal ◽  
Oxygen Functional Groups

Activated carbon (AC) is widely accepted for the removal of inorganic contaminants like mercury; however, the raw material used in the production of activated carbon is not always taken into consideration when evaluating its efficacy. Mercury oxidation and adsorption mechanisms governed by carbene sites are more likely to occur when graphitic-like activated carbons (such as those produced from high-ranking coals) are employed versus lignocellulosic-based ACs; this is likely due to the differences in carbon structures where lignocellulosic materials are less aromatic. In this research, the team studied bituminous coal-based ACs in comparison to coconut shell and wood-based (both less aromatic) ACs for elemental mercury removal. Nitric acid of 0.5 M, 1 M, and 5 M concentrations along with 10 M hydrogen peroxide were used to oxidize the surface of the ACs. Boehm titrations and FTIR analysis were used to quantify the addition of functional groups on the activated carbons. A trend was observed herein, resulting in increasing nitric acid molarity and an increased quantity of oxygen-containing functional groups. Gas-phase mercury removal mechanisms including physisorption, oxygen functional groups, and carbene sites were evaluated. The results showed significantly better elemental mercury removal in the gas phase with a bituminous coal-based AC embodying similar physical and chemical characteristics to that of its coconut shell-based counterpart. The ACs treated with various oxidizing agents to populate oxygen functional groups on the surface showed increased mercury removal. It is hypothesized that nitric acid treatment creates oxygen functional groups and carbene sites, with carbene sites being more responsible for mercury removal. Heat treatments post-oxidation with nitric acid showed remarkable results in mercury removal. This process created free carbene sites on the surface and shows that carbene sites are more reactive to mercury adsorption than oxygen. Overall, physisorption and oxygen functional groups were also dismissed as mercury removal mechanisms, leaving carbene-free sites as the most compelling mechanism.

Gas-Phase Mercury Removal by Modified Activated Carbons Treated with Ar-O2 Non-Thermal Plasma under Different O2 Concentrations

2018 ◽  
Vol 17 (3) ◽  
Author(s):  
Long Wu ◽  
Zhongsheng Shang ◽  
Hailu Zhu ◽  
Zhanyong Li ◽  
Guangqian Luo ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Thermal Plasma ◽  
Volume Fraction ◽  
Activated Carbons ◽  
Mercury Removal ◽  
Plasma Modification ◽  
Carbon Surface ◽  
Mercury Adsorption ◽  
Modified Activated Carbon ◽  
Non Thermal Plasma

Abstract During the plasma modification process on activated carbon surface, reactive gas of O2 in the plasma field dominates the formation of oxygen-containing groups on activated carbon surface, which is a key factor that affects the mercury adsorption. Previous studies showed that change the O2 concentration would influence the generation of oxygen-containing groups and thus affect the mercury adsorption. It is important to investigate the effects of O2 concentration in the non-thermal plasma field on the mercury adsorption characteristic of modified activated carbon. This work presents the results of the novel use of non-thermal plasma in Ar-O2 gas to increase surface oxygen functionality on the surface of a commercially available biomass carbon. The volume fraction of O2 in the Ar-O2 mixture was varied from 10 % to 100 %. The surface physical and chemistry properties of modified activated carbon were analyzed by using BET, FT-IR and XPS techniques. Results showed that activated carbon modified by Ar-O2 non-thermal plasma showed significantly better mercury removal performance compared with the original activated carbon. Moreover, increase O2 concentration in the plasma field can further increase the mercury removal efficiency of modified activated carbon. Higher O2 concentration can produce more O radicals during plasma system and facilitated the formation of carbonyl and ester groups on activated carbon surface and thus enhanced the mercury removal. Temperature programmed desorption (TPD) results indicated that mercury reacted with ester groups were prior to carbonyl groups. When O2 concentration increased to 100 %, the ester groups of modified activated carbon dominated the mercury adsorption process.

scholarly journals Indoor air quality improvement and purification by atmospheric pressure Non-Thermal Plasma (NTP)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Prince Junior Asilevi ◽  
Patrick Boakye ◽  
Sampson Oduro-Kwarteng ◽  
Bernard Fei-Baffoe ◽  
Yen Adams Sokama-Neuyam
Keyword(s):  
Air Quality ◽  
Built Environment ◽  
Indoor Air Quality ◽  
Removal Efficiency ◽  
Indoor Air ◽  
Thermal Plasma ◽  
Processing Parameters ◽  
Optimum Conditions ◽  
Non Thermal Plasma ◽  
The Impact

AbstractNon-thermal plasma (NTP) is a promising technology for the improvement of indoor air quality (IAQ) by removing volatile organic compounds (VOCs) through advanced oxidation process (AOP). In this paper, authors developed a laboratory scale dielectric barrier discharge (DBD) reactor which generates atmospheric NTP to study the removal of low-concentration formaldehyde (HCHO), a typical indoor air VOC in the built environment associated with cancer and leukemia, under different processing conditions. Strong ionization NTP was generated between the DBD electrodes by a pulse power zero-voltage switching flyback transformer (ZVS-FBT), which caused ionization of air molecules leading to active species formation to convert HCHO into carbon dioxide (CO2) and water vapor (H2O). The impact of key electrical and physical processing parameters i.e. discharge power (P), initial concentration (Cin), flow rate (F), and relative humidity (RH) which affect the formaldehyde removal efficiency (ɳ) were studied to determine optimum conditions. Results show that, the correlation coefficient (R2) of removal efficiency dependence on the processing parameters follow the order R2 (F) = 0.99 > R2 (RH) = 0.96, > R2 (Cin) = 0.94 > R2 (P) = 0.93. The removal efficiency reached 99% under the optimum conditions of P = 0.6 W, Cin = 0.1 ppm, F = 0.2 m3/h, and RH = 65% with no secondary pollution. The study provided a theoretical and experimental basis for the application of DBD plasma for air purification in the built environment.

Effect of the oxygen functional groups of activated carbon on its electrochemical performance for supercapacitors

Carbon ◽  
2021 ◽  
Vol 171 ◽  
pp. 980-981
Author(s):  
Xi-ran Li ◽  
Yang-hui Jiang ◽  
Pei-zhi Wang ◽  
Yan Mo ◽  
Wen-de Lai ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Electrochemical Performance ◽  
Functional Groups ◽  
Oxygen Functional Groups
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