A review on the effect of amination pretreatment for the selective separation of CO2

Ngila

Kim

et al. 2016

Aerosol Air Qual. Res.

Self Cite

Detailed assessments of adsorption properties (isotherm, thermodynamics and kinetics) were carried out on chemically modified activated carbon (AC). Some pretreatment methods prior amination have been used to improve the CO 2 selective capture of AC in our previous works. Here, the inter-relationships among the adsorption properties were further investigated and reported. It was found that CO 2 molecules bind onto the heterogeneous surfaces of AC in a monolayer pattern as experimental data fit Freundlich isotherm rather than Langmuir. However, Redlich-Peterson, a 3-parameter model provided the best fit. The highest degree of precision of Chi-square analysis professed it as the most efficient error function for the isotherm study. Values of standard entropy showed to be the most significant thermodynamic limiting parameter in the adsorption process, as physisorption was found predominant for CO 2 collection at the interface. This observation was corroborated with temperature programmed desorption (TPD) analysis where ca. 86% of adsorbed CO 2 were desorbed below 500°C. The kinetic study indicated that CO 2 -AC interaction follows pseudo-second order while the higher R 2 of intraparticle diffusion over Elovich equation confirmed the deduction made from the thermodynamic study. Conclusively, the study of adsorption properties in this work provides useful information for designing proper adsorption reactor and subsequent regeneration of CO 2 -laden adsorbents at environmental levels.

Section: Textural Characteristics Of Adsorbentsmentioning

confidence: 95%

Section: Co 2 Adsorptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Isotherm, Thermodynamic and Kinetic Studies of Selective CO2 Adsorption on Chemically Modified Carbon Surfaces

Ngila

Kim

et al. 2016

Aerosol Air Qual. Res.

Self Cite

Evaluation of CO₂ adsorption capacity of electrospun carbon fibers with thermal and chemical activation

Kim

Jung

J of Applied Polymer Sci

et al. 2017

The use of urea was investigated as an alternative to the poisonous and expensive NH3 gas, commonly used for amination of adsorbents. First, we fabricated activated carbon nanofibers (AnFs) by electrospinning of urea‐doped polyacrylonitrile solution (N‐AnF). By increasing the activation temperature, the average specific surface area (SBET) and micropore volume (Vmicro) of pristine nFs improved from 27.3 to 300 m2/g and 0.004 to 0.13 cm3/g, respectively. Upon urea doping, both properties were further enhanced to 542 m2/g and 0.22 cm3/g, respectively. However, with chemical investigation via X‐ray photoelectron spectroscopy, we observed that the urea‐doping incorporated more of less desired quaternary‐N, along with other more basic and desirable N‐functionalities (i.e., nitrile, pyridinic, pyrrolic N) tethered. Based on the eventual CO2 adsorption results, we realized that average pore diameter (davg) is a limiting factor with regard to CO2 adsorption by AnFs; the lower the davg, the better the adsorption. Further examination via adsorption isotherm model fitting showed that CO2 molecules were homogenously collected in a monolayer pattern. However, three‐parameter model Redlich–Peterson model best fits the experimental data, suggesting that the adsorption is concentration‐driven and that it tends toward Langmuir rather than Freundlich at elevated concentration of CO2. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45534.

Electrospun melamine‐blended activated carbon nanofibers for enhanced control of indoor CO₂

Jeong

Wang

J of Applied Polymer Sci

et al. 2019

Electrospun carbon nanofibers were activated with melamine-polyacrylonitrile [melamine-blended carbon nanofibers (MACNFs)] for use as a fibrous adsorbent for indoor CO 2 removal. Although, melamine doping was intended solely to incorporate basic nitrogen functionalities on the nanofibers, it also shortened fabrication time, conserving time, and energy cost. The specific surface area and microporosity of the fibers were enhanced from 412 m 2 g −1 and 0.1646 cm 3 g −1 to 547 m 2 g −1 and 0.220 cm 3 g −1 , respectively, upon final CO 2 activation of the nanofibers. With the chemical properties, we observed significant tethering of pyridine functionality. The sample, MACNF-7 (10 mL of polymer solution doped with 0.7 g of melamine), provided the optimum melamine doping condition to achieve the highest CO 2 adsorption capacity of 3.15 mmol g −1 . The adsorption performance was based on simultaneous improvement in microporosity (physical) and surface basicity (chemical) properties of the adsorbent. However, in a binary mixture with nitrogen, the selective adsorption of CO 2 showed the predominance of the improved surface basicity over microporosity. The highest CO 2 selective capture (1.22 mmol g −1 ) was occurred for a CO 2 :N 2 ratio of 0.15:0.85, with a selectivity of 58.19 at 273 K. In a regeneration test, stable and robust performance was achieved more than five cycles.