STUDY ON THE PROPERTIES OF DIFFERENT ACTIVATED CARBON FIBERS AND THEIR ADSORPTION CHARACTERISTICS FOR FORMALDEHYDE

Porous structure and surface chemistry of activated carbon fibers obtained by differ-ent precursors and activation methods were investigated. Adsorption isotherms werecharacterized by nitrogen adsorption at 77K over a relative pressure range from 10 6to 1. The regularization method according to Density Functional Theory (DFT) wasemployed to calculate the pore size distribution in the samples. Their specific surfaceareas were calculated by BET method, micropore volume and microporous specificsurface area calculated by t-plot method and MPD by Horvath-Kawazoe equation. Mi-cropore volume of rayon-based ACF was higher than that of other samples. The staticand dynamic adsorption capacity for formaldehyde on different ACFs was determined.The results show that steam activated Rayon-based A CFs had higher adsorption capac-ity than that of steam and KOH activated PAN-A CFs. Breakthrough curves illustratedthat Rayon-ACFs had longer breakthrough time, thus they possessed higher adsorp-tion capacity for formaldehyde than that of PAN-ACFs. The entire sample had smalladsorption capacity and short breakthrough time for water. Rayon-A CFs had exccl-lent adsorption selectivity for formaldehyde than PAN-ACFs. And the samples withhigh surface areas had relatively high adsorption capacity for formaldehyde. Elementaicontent of different A CFs were performed. Rayon-based A CFs contained more oxygenthan PAN-ACFs, which may be attributed to their excellent adsorption capacity forformaldehyde.

Study on the Adsorption Characteristics of Inorganic Activated Charcoal Gel on Formaldehyde

In this paper, the powdered activated carbon is taken as the main raw material to develop a new material of inorganic activated charcoal gel by using silicate cement as the gelling agent. The micro-structure of this material is characterized by XRD, BET, SEM, EDS and so on; and the adsorption and cyclic regeneration characteristics of formaldehyde on the material are primarily studied. The experimental results show that this material is an adsorbent on the basis of micropores distributed between 0.60-1.12 nm, with specific surface area of 452.86 m2/g, average pore size of 2.62 nm and total pore space of 0.30 m3/g. The samples have excellent formaldehyde adsorption ability with saturation adsorption of 268.00 mg/g; after 20 times of cyclic adsorption and desorption, the formaldehyde adsorption rate of the samples can remain 49% of the original value, showing good cyclic regeneration of the samples.

Study on Adsorption of Formaldehyde by Modified Activated Carbon

By using potassium permanganate impregnation method,common activated carbon was processed in 0. 079 mol/L KMnO4 solution at 650℃ to obtain modified activated carbon loaded with manganese oxide,and then different quantities of common activated carbon and modified activated carbon were used to adsorb 0. 3 mg/m^3 formaldehyde. The results showed that carbon and manganese atoms on the surface of modified activated carbon could adsorb formaldehyde,and the removal rate of 0. 3 mg/m^3 formaldehyde by 30 g of modified activated carbon reached 80%,increased one time compared with that by common activated carbon. Different amounts of activated carbon had various effects on the adsorption of formaldehyde,and the best usage of common activated carbon and modified activated carbon was 100 and 30 g respectively.

DFT study on the interaction of HCHO molecule with S-doped TiO_(2) (001) surface without and with water and oxygen molecules

The interactions of formaldehyde(HCHO)molecule with S-doped anatase TiO_(2)(001)surface without and with water and oxygen were studied by density functional theory(DFT).The adsorption energy of HCHO adsorption on S-doped TiO_(2) surface with water and oxygen(-709.62 kJ/mol)is much larger than that without water and oxygen(-312.14 kJ/mol).For HCHO adsorption system without water and oxygen,one CeH bond of HCHO molecule is broken.The oxygen and carbon atoms of HCHO are bonded to the titanium and sulfur atoms of SeTiO_(2) surface,respectively,and form a CH_(2)OS structure.For the system with water and oxygen,H_(2)O and HCHO molecules are both dissociated.HCHO molecule not only interacts with TiO_(2) surface,but also combines with O_(2) molecule.Two CeH bonds of HCHO are broken,one hydrogen atom(H1)is bonded to the sulfur atom(S)of TiO_(2) surface doping,while another hydrogen atom(H_(2))is bonded to the O atom(O_(2))of O_(2) molecule.The remaining CeO bond can be oxidized to form CO_(2) in subsequent action by oxygen from the atmosphere.The surface doping of sulfur have significant impact on the degradation of HCHO molecule on anatase TiO_(2)(001)surface with H_(2)O and O_(2).