Volatile organic compound adsorption in a gas-solid fluidized bed

2004 ◽  
Vol 50 (4) ◽  
pp. 233-240 ◽  
Author(s):  
Y.L. Ng ◽  
R. Yan ◽  
L.T.S. Tsen ◽  
L.C. Yong ◽  
M. Liu ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Activated Carbon ◽  
Adsorption Capacity ◽  
Fluidized Bed ◽  
Residence Time ◽  
Fixed Bed ◽  
Gas Concentration ◽  
Adsorption Characteristics ◽  
Bubbling Bed ◽  
Intraparticle Mass Transfer

Fluidization finds many process applications in the areas of catalytic reactions, drying, coating, combustion, gasification and microbial culturing. This work aims to compare the dynamic adsorption characteristics and adsorption rates in a bubbling fluidized bed and a fixed bed at the same gas flow-rate, gas residence time and bed height. Adsorption with 520 ppm methanol and 489 ppm isobutane by the ZSM-5 zeolite of different particle size in the two beds enabled the differentiation of the adsorption characteristics and rates due to bed type, intraparticle mass transfer and adsorbate-adsorbent interaction. Adsorption of isobutane by the more commonly used activated carbon provided the comparison of adsorption between the two adsorbent types. With the same gas residence time of 0.79 seconds in both the bubbling bed and fixed bed of the same bed size of 40 mm diameter and 48 mm height, the experimental results showed a higher rate of adsorption in the bubbling bed as compared to the fixed bed. Intraparticle mass transfer and adsorbent-adsorbate interaction played significant roles in affecting the rate of adsorption, with intraparticle mass transfer being more dominant. The bubbling bed was observed to have a steeper decline in adsorption rate with respect to increasing outlet concentration compared to the fixed bed. The adsorption capacities of zeolite for the adsorbates studied were comparatively similar in both beds; fluidizing, and using smaller particles in the bubbling bed did not increase the adsorption capacity of the ZSM-5 zeolite. The adsorption capacity of activated carbon for isobutane was much higher than the ZSM-5 zeolite for isobutane, although at a lower adsorption rate. Fourier transform infra-red (FTIR) spectroscopy was used as an analytical tool for the quantification of gas concentration. Calibration was done using a series of standards prepared by in situ dilution with nitrogen gas, based on the ideal gas law and relating partial pressure to gas concentration. Concentrations up to 220 ppm for methanol and 75 ppm for isobutane were prepared using this method.

Effect of ozonation on preloading of background organic matter in granular activated carbon filters

1997 ◽  
Vol 35 (7) ◽  
pp. 295-302 ◽  
Author(s):  
Ervin Orlandini ◽  
Tsegaye G. Gebereselassie ◽  
Joop C. Kruithof ◽  
Jan C. Schippers
Keyword(s):  
Mass Transfer ◽  
Organic Matter ◽  
Activated Carbon ◽  
Adsorption Capacity ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Fixed Bed ◽  
Granular Activated Carbon ◽  
River Rhine ◽  
Homogeneous Surface

Background Organic Matter (BOM) preloading is adsorption of BOM onto Granular Activated Carbon (GAC) prior to the adsorption of target compounds, such as pesticides and other organic micropollutants (e.g. atrazine). BOM preloading is commonly found to speed up the breakthrough of target compounds during GAC filtration. Ozonation of GAC filter influent may be expected to lower BOM preloading, because it results in less adsorbable and more biodegradable BOM compounds. Short Fixed Bed (SFB) tests with virgin and preloaded GAC, performed within this study, confirmed that preloading of BOM present in pretreated river Rhine water speeds up the breakthrough of atrazine in GAC filters. BOM preloading was found to lower equilibrium adsorption capacity of GAC for atrazine, and to slow down both external and internal mass transfer rate of atrazine on/into GAC. Adsorption capacity of (crushed) GAC was determined from atrazine adsorption isotherms, while mass transfer rate coefficients were determined by fitting the Homogeneous Surface Diffusion model to the breakthrough of atrazine in the SFB tests. More pronounced BOM preloading was found in the GAC filter receiving non-ozonated influent than in its ozonated counterpart. Biodegradation of ozonated BOM was shown to lower BOM preloading in GAC filters.

scholarly journals Process Optimization for Ethyl Ester Production in Fixed Bed Reactor Using Calcium Oxide Impregnated Palm Shell Activated Carbon (CaO/PSAC)

2012 ◽  
Vol 1 (3) ◽  
pp. 81 ◽  
Author(s):  
A Buasri ◽  
B Ksapabutr ◽  
M Panapoy ◽  
N Chaiyut
Keyword(s):  
Activated Carbon ◽  
Ethyl Ester ◽  
Calcium Oxide ◽  
Residence Time ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
Palm Shell ◽  
Bed Height

: The continuous production of ethyl ester was studied by using a steady-state fixed bed reactor (FBR). Transesterification of palm stearin (PS) and waste cooking palm oil (WCPO) with ethanol in the presence of calcium oxide impregnated palm shell activated carbon (CaO/PSAC) solid catalyst was investigated. This work was determined the optimum conditions for the production of ethyl ester from PS and WCPO in order to obtain fatty acid ethyl ester (FAEE) with the highest yield. The effects of reaction variables such as residence time, ethanol/oil molar ratio, reaction temperature, catalyst bed height and reusability of catalyst in a reactor system on the yield of biodiesel were considered. The optimum conditions were the residence time 2-3 h, ethanol/oil molar ratio 16-20, reaction temperature at 800C, and catalyst bed height 300 mm which yielded 89.46% and 83.32% of the PS and WCPO conversion, respectively. CaO/PSAC could be used repeatedly for 4 times without any activation treatment and no obvious activity loss was observed. It has potential for industrial application in the transesterification of triglyceride (TG). The fuel properties of biodiesel were determined. Keywords: biodiesel, calcium oxide, ethyl ester, fixed bed reactor, palm shell activated carbon

Adsorption Kinetics of Oxytetracycline onto Activated Carbon in a Closed-Loop Fixed Bed Reactor

2013 ◽  
Vol 11 (1) ◽  
pp. 569-576 ◽  
Author(s):  
Djamila Djedouani ◽  
Malika Chabani ◽  
Abdeltif Amrane ◽  
Aicha Bensmaili
Keyword(s):  
Mass Transfer ◽  
Activated Carbon ◽  
Closed Loop ◽  
Solid Phase ◽  
Positive Impact ◽  
Fixed Bed ◽  
Sorption Process ◽  
Fixed Bed Reactor ◽  
Dynamic Interactions ◽  
Initial Concentration

Abstract Batch experiments were carried out for the adsorption of oxytetracycline (OTC) onto powdered activated carbon (PAC). The operating variables examined were the initial concentration (20–150 mg L−1) and the adsorbent concentration (0.75–1.75 g L−1). As observed increasing the initial concentration, while decreasing the adsorbent dosage, had a positive impact on the amount of OTC uptake (mg g−1). The kinetics was examined in a closed-loop fixed bed adsorber to propose an adsorption mechanism, to understand the dynamic interactions of OTC with ECA08 activated carbon and to predict its fate with time. The sorption results were analyzed using chemical and physical kinetics models. For concentrations lower than 70 mg L−1, the sorption process was found to be controlled by both surface reactions and mass transfer. The average external mass transfer coefficient and intraparticle diffusion coefficient were found to be 0.0051 min−1 and 1.97 mg g−1 min−0.5, respectively. For concentrations higher than 70 mg L−1, mass transfer became rapid and the chemical reaction at the surface of the solid phase was the rate-limiting step. The results showed that the adsorption reaction was accurately described by the pseudo-second-order model.

Effect of Fractal Dimension of Powder Activated Carbon on SO2 Adsorption

2014 ◽  
Vol 955-959 ◽  
pp. 2169-2172 ◽  
Author(s):  
Bing Li ◽  
Jian Ming Xue ◽  
Yue Yang Xu ◽  
Hong Liang Wang ◽  
Chun Yuan Ma ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Activated Carbon ◽  
Adsorption Capacity ◽  
Activated Carbons ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Removal Capacity ◽  
Powder Activated Carbon

Five kinds of powder activatedcarbons were studied to investigate the removal of SO2 from flue gasin a fixed bed reactor. The fractal dimension of activated carbon was determined by N2 adsorption isothermat 77Kand SO2 adsorptioncapacity was correlated with thefractal dimension. The results show thatthe activated carbons prepared from different precursors by differentactivation methods have different fractal dimension. Big differences in SO2 adsorption capacity are found between fivekinds of activated carbons. SO2 adsorption capacity increases with the fractaldimension increasing. The results indicate that the fractal dimension could be used as a indicator of SO2removal capacity on powder activated carbon.

scholarly journals Modelling of NO adsorption in fixed bed on activated carbon

2011 ◽  
Vol 32 (4) ◽  
pp. 367-377 ◽  
Author(s):  
Lenka Kuboňová ◽  
Lucie Obalová ◽  
Oldřich Vlach ◽  
Ivana Troppová ◽  
Jaroslav Kalousek
Keyword(s):  
Nitric Oxide ◽  
Mass Transfer ◽  
Activated Carbon ◽  
Fixed Bed ◽  
Breakthrough Curves ◽  
Force Model ◽  
Transfer Coefficients ◽  
No Adsorption ◽  
Response Curves ◽  
Mass Transfer Mechanism

Modelling of NO adsorption in fixed bed on activated carbon Adsorption experiments of nitric oxide in nitrogen carrier gas were held on activated carbon in a fixed bed flow system. Breakthrough curves describing the dependence of exit concentrations of nitric oxide on time were matched with theoretical response curves calculated from the linear driving force model (LDF). The model assumes Langmuir adsorption isotherm for the description of non-linear equilibrium and overall mass transfer coefficient for mass transfer mechanism. Overall mass transfer coefficients were obtained by the method of least squares for fitting numerically modelled breakthrough curves with experimental breakthrough curves. It was found that LDF model fits all the breakthrough curves and it is a useful tool for modelling purposes.

Adsorption Characteristics of Uranyl Ions on Carboxymethylated Polyethyleneimine (CM-PEI) / Activated Carbon Composites

2007 ◽  
Vol 124-126 ◽  
pp. 1257-1260 ◽  
Author(s):  
Ke Chon Choi ◽  
Yongju Jung ◽  
Seok Kim ◽  
Soo Jin Park ◽  
Hyung Ik Lee ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Adsorption Capacity ◽  
Great Influence ◽  
Isotherm Models ◽  
Carbon Composites ◽  
Uranyl Ions ◽  
Adsorption Characteristics ◽  
Adsorption Data ◽  
Langmuir Isotherm Model ◽  
Adsorption Phenomena

We present the adsorption characteristics of uranyl ions on a new and innovative composite which was composed of a carboxymethylated polyethyleneimine (CM-PEI) and an activated carbon (F400) with a nanopore less than 2 nm in diameter. In this study, we examined the adsorption phenomena of uranyl ions on the CM-PEI/F400 composite and evaluated the adsorption data using various isotherm models. It was found that the adsorption of uranyl ions on the CM-PEI/F400 composite obeys the Langmuir isotherm model. In addition, it was observed that pH of solutions had great influence on the adsorption capacity of uranyl ions on the CM-PEI/F400 composite. Specially, the adsorption capacity of uranyl ions was linearly increased with an increase of pH at pH > 3.0.

scholarly journals Study on the Effect of Soft and Hard Coal Pore Structure on Gas Adsorption Characteristics

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xun Zhao ◽  
Tao Feng ◽  
Ping Wang ◽  
Ze Liao
Keyword(s):  
Pore Structure ◽  
Adsorption Capacity ◽  
Residence Time ◽  
Coalbed Methane ◽  
Gas Adsorption ◽  
Nitrogen Adsorption ◽  
Hard Coal ◽  
Research Results ◽  
Adsorption Characteristics ◽  
Soft Coal

In order to grasp the effect of soft and hard coal pore structure on gas adsorption characteristics, based on fractal geometry theory, low-temperature nitrogen adsorption and constant temperature adsorption test methods are used to test the pore structure characteristics of soft coal and its influence on gas adsorption characteristics. We used box dimension algorithm to measure the fractal dimension and distribution of coal sample microstructure. The research results show that the initial nitrogen adsorption capacity of soft coal is greater than that of hard coal, and the adsorption hysteresis loop of soft coal is more obvious than that of hard coal. And the adsorption curve rises faster in the high relative pressure section. The specific surface area and pore volume of soft coal are larger than those of hard coal. The number of pores is much larger than that of hard coal. In particular, the superposition of the adsorption force field in the micropores and the diffusion in the mesopores enhance the adsorption potential of soft coal. Introducing the concept of adsorption residence time, it is concluded that more adsorption sites on the surface of soft coal make the adsorption and residence time of gas on the surface of soft coal longer. Fractal characteristics of the soft coal surface are more obvious. The saturated adsorption capacity of soft coal and the rate of reaching saturation adsorption are both greater than those of hard coal. The research results of this manuscript will provide a theoretical basis for in-depth analysis of the adsorption/desorption mechanism of coalbed methane in soft coal seams and the formulation of practical coalbed methane control measures.

scholarly journals Comparative Study of CO2 Capture by Adsorption in Sustainable Date Pits-Derived Porous Activated Carbon and Molecular Sieve

2021 ◽  
Vol 18 (16) ◽  
pp. 8497
Author(s):  
Mohd Danish ◽  
Vijay Parthasarthy ◽  
Mohammed K. Al Mesfer
Keyword(s):  
Mass Transfer ◽  
Activated Carbon ◽  
Molecular Sieve ◽  
Fixed Bed ◽  
Utilization Factor ◽  
Adsorption Performance ◽  
Mass Transfer Zone ◽  
Date Pits ◽  
Porous Activated Carbon ◽  
Transfer Zone

The rising CO2 concentration has prompted the quest of innovative tools to reduce its effect on the environment. A comparative adsorption study using sustainable low-cost date pits-derived activated carbon and molecular sieve has been carried out for CO2 separation. The adsorb ents were characterized for surface area and morphological properties. The outcomes of flow rate, temperature and initial adsorbate concentration on adsorption performance were examined. The process effectiveness was investigated by breakthrough time, adsorbate loading, efficiency, utilized bed height, mass transfer zone and utilization factor. The immensely steep adsorption response curves demonstrate acceptable utilization of adsorbent capability under breakthrough condition. The adsorbate loading 73.08 mg/g is achieved with an 0.938 column efficiency for developed porous activated carbon at 298 K. The reduced 1.20 cm length of mass transfer zone with enhanced capacity utilization factor equal 0.97 at 298 K with Cin = 5% signifies better adsorption performance for date pits-derived adsorbent. The findings recommend that produced activated carbon is greatly promising to adsorb CO2 in fixed bed column under continuous mode.

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