Preparation Of Four Wood-based Fiber Active Carbon And Its Adsorption Properties For Formaldehyde

In this paper,four kinds of wood,Salix psammophila,poplar,fruit wood and elm,which are cheap and widely available in Inner Mongolia,were selected to prepare Salix fiber active carbon by the best process in the early stage.The best activation temperature for formaldehyde adsorption by the other three kinds of wood was discussed.In the formaldehyde adsorption test,a self-modified environmental box was used to study the natural adsorption and forced adsorption properties of four kinds of wood fiber active carbon.The formaldehyde adsorption properties of four kinds of wood fiber active carbon were analyzed through the main chemical composition,absolute dry density and pore structure,and preliminary conclusions were obtained.Finally,the tree species conforming to the initial conclusions were selected for validation test.The results showed that:1.The main chemical compositions of Salix psammophila from different habitats are different.The cellulose content of Salix psammophila from Kuqi desert and Salix psammophila from Mu Us desert are 40.75%and 43.16%respectively,the lignin content is 25.85%and 26.05%respectively,and the hemicellulose content is 32.17%and 31.17%respectively.The cellulose content of Populus alba var.pyramidalis,Prunus armeniaca and Ulmus pumila are 45.2%,40.65%and 41.35%respectively,the lignin content is 22.82%,21.69%and 21.96%respectively,and the hemicellulose content is 31.85%,31%and 32.11%respectively.The absolute dry density of Salix psammophila in Kuqi desert and Salix psammophila in Mu Us desert are 0.562g/cm3 and 0.589g/cm3 respectively,the absolute dry density of Populus alba var.pyramidalis is the lowest 0.376g/cm3,the absolute dry density of Ulmus pumila is 0.469g/cm3,and the absolute dry density of Prunus armeniaca is the highest 0.764g/cm32.Activation temperature has great influence on the specific surface area and pore volume of FAC,and has little influence on the minimum pore diameter.The minimum pore size of FAC prepared by activation with Ammonium Phosphate as activator is about 0.7nm,and its nitrogen adsorption/desorption isotherms are all Class I isotherms,all of which are mainly micropores FAC,and the micropore pore size distribution of these samples is mainly 1?2 mesopores are mainly 2?4nm,and macropores are basically absent.3.In this paper,the order of tree species with good to bad formaldehyde adsorption performance is:apricot,elm,Salix psammophila and Populus alba var.pyramidalis.it is found that when the absolute dry density of wood is 0?0.80g/cm3,the optimal activation temperature for the adsorption of formaldehyde by fiber active carbon is 800? when the wood density is greater than 0.50g/cm3,and the optimal activation temperature for the adsorption of formaldehyde by fiber active carbon is 700?.Through the analysis of pore structure on adsorption performance,FAC adsorption performance for formaldehyde is jointly determined by the most probable pore diameter,micropore specific surface area and micropore volume.Natural adsorption performance is better than forced adsorption.