BET theory

About: BET theory is a research topic. Over the lifetime, 9046 publications have been published within this topic receiving 286142 citations.

Surface texture, chemistry and adsorption properties of acid blue 9 of hemp (Cannabis sativa L.) bast-based activated carbon fibers prepared by phosphoric acid activation

Abstract: Hemp ( Cannabis sativa L) bast was used to prepare activated carbon fibers by phosphoric acid activation at 400–600 °C The pyrolysis process, textural and chemical properties for the samples were investigated by means of TG/DTA, SEM, cryogenic N 2 adsorption, FTIR and XPS Dye adsorption on the resultant sample was also measured The textural properties of the activated carbon fibers were found to be strongly dependent on the activation temperature Activated carbon fibers exhibited narrow pore size distributions with maxima in the micropore and small mesopore regions BET surface area, total pore volume, micropore volume and mesopore volume increased with the increase of activation temperature up to 450 °C and then decreased with further heating, and a sample with maximum surface area of 1142 m 2 g −1 and total pore volume of 067 cm 3 g −1 was obtained Phosphoric acid facilitated the conservation of porous structure, led to the creation of tremendous porosity, and resulted in various P-containing functional structures on the surface and in the bulk phase of the resultant samples The adsorption of acid blue 9 on the sample could be favorably described by Langmuir isotherm, and the adsorption kinetics was found to be well fitted by the intraparticle diffusion model

Activated carbons for the removal of heavy metal ions: A systematic review of recent literature focused on lead and arsenic ions

Abstract: This work is a systematic review of the literature over the past decade of the application of activated carbon (microporous or mesoporous) as adsorbents for the removal of heavy metals, focusing especially on lead (Pb) and arsenic (As) ions from the aqueous phase. Classical examples from our lab are also given. Activated carbon is known to provide a high surface area for adsorption. Generally, surface modification is typically required, such as oxidation, treatment with ammonia or even impregnation with ferric ion, etc. and the adsorbent material may originate from various sources. The pristine materials, after modification and those after batch-wise adsorption, were characterized by available techniques (BET analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, thermal analyses, X-ray photoelectron spectroscopy). Adsorption isotherms, thermodynamics and kinetics of the process are also discussed. Selected studies from the literature are examined in comparison with other adsorbents. The role of chemistry in the metals adsorption/removal was investigated.

Production and characterization of Lemna minor bio-char and its catalytic application for biogas reforming

Abstract: Pyrolysis of fast-growing aquatic biomass - Lemna minor (commonly known as duckweed) with the emphasis on production, characterization and catalytic application of bio-char is reported in this paper. The yield of bio-char was determined as a function of L. minor pyrolysis temperature and sweep gas flow rate. It was found that the pore development during L. minor pyrolysis was not significant and the changes in the reaction conditions (temperature and sweep gas flow rate) did not alter markedly the textural characteristics and BET surface area of the bio-char produced. Thermogravimetric/differential thermogravimetric (TG/DTG) analyses of L. minor and different bio-char samples in inert (helium) and oxidative (air) media showed substantial differences in their TG/DTG patterns. A comparison of scanning electron micrographs (SEM) of L. minor, bio-char and ash indicated that the basic structural features of L. minor remained intact and were not affected by thermolysis. The inorganic ash content of L. minor derived bio-char is significantly higher than that of typical terrestrial (plant) biomass. The energy dispersive spectroscopic (EDS) analysis of L. minor ash showed that it mostly consisted of silica, and small quantities of Na, K and Ca compounds. The treatment of bio-char with CO2 at 800 °C increased its BET surface area. It was found that CO2-treated bio-char exhibited appreciable initial catalytic activity in biogas reforming.

Photocatalytic activity of structured mesoporous TiO2 materials.

Abstract: Starting from colloidal TiO2 nanoparticles in combination with tetraethyl orthosilicate using neutral Pluronic or cationic cetyltrimethylammonium as templates, a series of structured mesoporous silicas has been obtained. The structure of the mesoporous titania was confirmed by isothermal gas adsorption, transmission electron microscopy, and X-ray diffraction. The pore diameter ranged between 3.8 and 10.9 nm, and the BET surface area varied from 99 to 584 m2 g-1. The photocatalytic activity of these samples for the degradation of phenol in aqueous solution has been compared with that of standard P-25 TiO2. Even though the activity of these new mesostructured materials is lower that those found for P-25 TiO2, the turnover frequency of the photocatalytic activity (moles of phenol degraded per Ti atom present at initial reaction time) is much higher for the mesoporous titania, particularly with low titanium contents for those materials (mpTiO2-5 and TiO2SBA15-5).

Porous Siloxane–Organic Hybrid with Ultrahigh Surface Area through Simultaneous Polymerization–Destruction of Functionalized Cubic Siloxane Cages

Abstract: A novel hierarchically porous, hyper-cross-linked siloxane–organic hybrid (PSN-5) has been synthesized by Friedel–Crafts self-condensation of benzyl chloride-terminated double-four-ring cubic siloxane cages as a singular molecular precursor. Simultaneous polymerization of the organic functional groups and destruction of the siloxane cages during synthesis yielded PSN-5, which has an ultrahigh BET surface area (∼2500 m2 g–1) and large pore volume (∼3.3 cm3 g–1) that to our knowledge are the highest values reported for siloxane-based materials. PSN-5 also shows a high H2 uptake of 1.25 wt % at 77 K and 760 Torr.