Adsorption Of Surface-modified Bamboo Charcoal To The Organic Pollutions In Micro-pollutted Water

In this paper, three kinds of methods were used on the surface modification of bamboo charcoal, nitric acid modification, ammonia modification and microwave modification. The adsorption effects of these modified bamboo charcoals on four organic pollutions were also studied in this paper. Through the modification of the basic adsorption parameters before and after the charcoal and the analysis of its microstructure, exploration on the causes in changes on adsorption effect of surface-modified charcoal was made. The result of the study reveals that:(1)Among the three kinds of surface modification bamboo charcoal, the nitric acid modification is benefit for the absorption of UV254 and UV410 in the best adsorption conditions. Bamboo charcoal 34% nitric acid modified carbon (O-2) makes the two indicators of carbon removal rates increased by 28.18% and 32.86%, but nitrate modified wasn't conducive to the CODMn and 2, 4-DCP adsorption, high concentrations of nitric acid modification conditions on the adsorption of each index were negatively; low concentration of ammonia modification could increase the adsorption of each index but not obviously. High concentrations of nitric acid makes the modified lower; microwave modified to make bamboo charcoal for the removal of all indexes were improved, and larger than ammonia modification, microwave modification on the 2,4-DCP removal efficiency of the most excellent, compared to unmodified carbon, the removal rate increased 16.25%.(2)The adsorption capacity for organic results of the bamboo charcoal before and after the modification show that, the adsorption process for CODMn, UV254, UV410 both before and after modification can be illustrated by Freundlich-type adsorption isotherm. The adsorption process for 2,4-DCP of unmodified charcoal, ammonia modified charcoal, and microwave modified charcoal is similar to the single-layer adsorption, can be illustrated by Langmuir-type adsorption isotherm.(3)Modification of nitric acid and ammonia led their iodine adsorption value, ash and moisture content decreased. The iodine values of micro-wave modification charcoal tend to slightly increase combined with a little decrease. Along with the degree of deepening, the ash, moisture content reduced. The contents of surface functional groups in bamboo charcoal significant change in three kinds of modified conditions: The nitric acid modified carbon surface oxygen groups increased significantly with the total alkalinity decreased; The total acidity of the ammonia surface modification carbon decreased and total alkalinity significantly increased, with the contents of the nitrogen functional group become higher; microwave carbons reduced the total content of surface functional groups, and make the total acidity and total alkalinity increased slightly.(4)SEM-EDS analysis, XRD, infrared spectroscopy, Raman spectroscopy, TG-DSC analysis were used in the study of modified charcoal microstructure analysis results .The results showed that the oxide content in the nitric modified carbon was increased remarkably, the crystal structure became regular, orderly, and the degree of graphitization increased that make its removal rate of large molecules conducive to UV254, UV410 significantly increased. While the carbon structure of the surface oxygen functional groups increased, so that bamboo charcoal can improve its hydrophilic and acidity increased, resulting the removal efficiency of CODMn and 2,4-DCP decreased. Total alkalinity of ammonia surface modified carbon increased, along with the nitrogen-containing functional groups and the hydrophobic increased. It is beneficial for the adsorption of the organic pollution indicators, but signs of corrosion in the surface of the ammonia surface modified carbon were observed, making the micro-porous volume decrease and resulting in the removal of the index. Micro-wave modification makes the charcoal micro-pore volume increases, thus facilitating the absorption of various indicators.Surface modification of bamboo charcoal improves the adsorption selection to organic pollutions. The adsorption effect of bamboo charcoal before and after modification was combined with the bamboo charcoal pore structure, surface properties and adsorptive interaction. The most important factors determine the final adsorption effect of the bamboo charcoal.