Adsorption of CO₂ on Activated Carbons Prepared by Chemical Activation with Cupric Nitrate

Abstract

Activated carbons were prepared from a lignocellulosic material, African palm shells (Elaeis guineensis), by chemical impregnation of the precursor with solutions of 1–7% w/v Cu­(NO3)2 at five different concentrations. These were carbonized in a carbon dioxide atmosphere at 1073 K to obtain different carbons. Their textural properties were characterized by nitrogen and carbon dioxide adsorption isotherms in order to evaluate the pore-size distribution. The immersion enthalpies of the activated carbons in benzene, dichloromethane, and water were determined. The CO2 adsorption capacities of the materials at 273 K under low-pressure conditions were also determined. Chemical characterization was performed by mass spectrometry, Fourier transform infrared spectroscopy, and temperature-programmed reduction. With this method of preparation under the concentrations described, activated micro–mesoporous carbons were obtained, with the formation of highly mesoporous solids that favored the process of diffusion of molecules of CO2 into the material. Here, we show that activated carbons were obtained with different textural characteristics: surface Brunauer–Emmett–Teller areas varied between 473 and 1361 m2 g–1 and micropore volume between 0.18 and 0.51 cm3 g–1. The activated carbon with the highest values of textural parameters was ACCu5-1073. Micro–mesoporous solids were obtained with the methodology used. This is important as it may help the entry of CO2 molecules into the pores. The adsorption of CO2 in the materials prepared presented values between 103 and 217 mg CO2 g–1; the values of volume of narrow microporosity obtained were between 0.16 and 0.45 cm3 g–1. The solid with the greatest capacity for adsorption of CO2 and volume of narrow microporosity was ACCu3-1073. The use of these solids is of importance for future practical and industrial applications. The adsorption kinetic of CO2 in the activated carbons prepared with metallic salt of copper is in good accordance with the intraparticle diffusion model, for which diffusion is the rate-limiting step. The adsorption of CO2 in the prepared activated carbons is favorable from the energy and kinetic point of view, as these accompanied by the presence of wide micro–mesoporosity favor the entry of CO2 into the micropores.

Valorization of spent disposable wooden chopstick as the CO2 adsorbent for a CO2/H2 mixed gas purification

“…Table 4 tabulates each experimental condition in terms of coded variables and response values. It can be seen that case 1 exhibited the highest production yield, but the lowest CO 2 adsorption, whilst case 5 showed the maximum adsorption capacity with an extremely low production yield but still in the acceptable range of the dry biomass-derived ACs, of 5–40 wt% 52 , while the lowest production yield was obtained at case 6 . Table 5 illustrates the ANOVA analysis of these two response variables.…”

“…Figure 2 shows the FTIR spectra of the parental biochar and all ACs prepared by steam activation at 700–900 °C for 1–2 h. The FTIR spectrum of the biochar that appeared at a wavenumber lower than 920 cm −1 indicated the presence of aromatic C–H out-of-plane bending 51 . Bands of intensity between wavenumbers of 920–1300 cm −1 are the overlapping C–O stretchings of various surface groups, including the C–O vibration of ethers (942–1300 cm −1 ), esters (1100–1250 cm −1 ), cyclic ethers (1140 cm −1 ), lactonic groups (1160–1370 cm −1 ), phenolic groups (1180–1220 cm −1 ), and also carboxylic acids and cyclic anhydrides (1180–1300 cm −1 ) 52 . The bands at 1480–1650 cm −1 indicated the presence of polyaromatic C=C stretching vibration of sp 2 hybridized carbons 52 .…”

“…Bands of intensity between wavenumbers of 920–1300 cm −1 are the overlapping C–O stretchings of various surface groups, including the C–O vibration of ethers (942–1300 cm −1 ), esters (1100–1250 cm −1 ), cyclic ethers (1140 cm −1 ), lactonic groups (1160–1370 cm −1 ), phenolic groups (1180–1220 cm −1 ), and also carboxylic acids and cyclic anhydrides (1180–1300 cm −1 ) 52 . The bands at 1480–1650 cm −1 indicated the presence of polyaromatic C=C stretching vibration of sp 2 hybridized carbons 52 . The peaks found at a wavenumber of 1650–1800 cm −1 were attributed to the presence of the C=O stretching vibration of carboxylic and lactones.…”

Enhancement of carbon dioxide adsorption performances by hydrazinolysis of poly(n-vinylformamide) grafted fibrous adsorbent

“…As a result, solid adsorbent has been widely studied and recommended to be an alternative technology due to its simplicity, low operational requirements, low cost, ease of control, and high adsorption efficiency. Generally, various types of solid adsorbent have been explored to have a suitable candidate for CO2 capture, including mesoporous silicon [3][4][5][6], activated carbon [7], carbon nanotube [8], metal-organic framework [9], zeolite [10], aerogel [11,12], polymers [13] and many others. Porous organic polymers are broadly exploited and have been classified into various forms such as hyper-cross-linked polymers, conjugated microporous polymers and grafted fibrous sheets.…”

Synthesis of exopolysaccharide-based organo-montmorillonite with improved affinity towards carbon dioxide and hydrophilic character

“…Other CO 2 capture attempts were performed with materials such metal-inorganic-organic core-shell material [9], chemically modified activated carbon with nitric acid and ammonium aqueous solutions [10], cupric nitrate [11] or polyacrylonitrile [12], functionalized carbonaceous and silica-based materials [13], zeolites and layered double hydroxides [14][15][16], metal-organic frameworks (MOFs), mesoporous silica, clay, porous carbons, porous organic polymers (POP), and metal oxides (MO) [16]. Most of these materials involve costly/sophisticated synthesis procedures but low surface affinity as reported to their specific surface area as defined earlier [17].…”