Study On Modification And Adsorption Properties On Salix Fibrous Activated Carbon

Salix fibrous activated carbon?FAC?and its modified materials were characterized by physical property,surface morphology,pore structure,infrared spectroscopy and XRD in the paper.During the experiment,the modifier and the ideal modification process were selected in order to prepare the ideal modified Salix fibrous activated carbon.In addition,the magnesium ion from water and formaldehyde was adsorbed by FAC and its modified materials and the influence of five conditions which is temperature,pH,adsorption time,dosing quantity,and concentration on removal rate for magnesium ion were investigated.Finally,the adsorption models were used to analyze the mechanism of adsorption between magnesium ions and FAC and its modified materials.The results show that:1.The FAC has great adsorption capacity for iodine and methylene blue,the iodine adsorption value is 1281.00 mg·g^-1,methylene blue adsorption value is 132.50 mg·g^-1.Besides,it has good fiber morphology,larger length diameter ratio,rich pore structure,the specific surface area was 1162.00 m²·g^-1,micropores were the primary pore and the main pore diameter distribution is from 1 nm to 3 nm on the adsorbent surface.At last,it consists of graphite microcrystals and containing some oxygen-containing functional groups,such as hydroxyl groups,ketones,aldehydes,lactones and carboxyl groups,on the surface.The structural characteristics of aromatic or phosphorous compounds are more obvious.2.Within a certain range,the adsorption effects of FAC on magnesium ion can be improved by increasing temperature,prolonging adsorption time,increasing the amount of FAC and improving the solution pH and initial concentration.The adsorption capacity,and removal rate were 68.67 mg·g^-1,and 27.47%,respectively.Here,the temperature,adsorption time,dosage of FAC,pH,and concentration were room temperature,3 h,2.00g·L^-1,initial pH,and 500 mg·L^-1,respectively.The adsorption mechanism of magnesium ions through FAC can be explained preferably by the kinetic model of particle diffusion and the Temkin isotherm model.3.The modification by nitric acid is more beneficial to the adsorption of magnesium ions on FAC,the modified process is as follows:the mass ratio of solid to liquid,modification timeis were 1:30,and two days,respectively.In this process,that fibers whole morphology of modified adsorbent has not been changed,compared with initial adsorbent,the relative content of the oxygen element and the nitrogen element on the surface were increased,the specific surface area,and pore volume were reduced,the average pore size were increased.Infrared spectra showed that the peak intensity of oxygen containing functional groups such as aldehydes and ketones were enhanced,the content of carboxyl,phenolic hydroxyl and lactone was improved by Boehm titration.4.The FAC by nitric acid modification on the adsorption properties of magnesium ions was improved,the adsorption capacity,and removal rate were 98 mg·g^-1,and 38%,respectively.Here,the temperature,adsorption time,dosage of modification FAC,pH,and concentration were room temperature,3.5 h,2.00 g·L^-1,initial pH,and 500 mg·L^-1,respectively.Chemisorption is the main adsorption method in the adsorption process,the phenomenon that loss of magnesium ions from the surface of adsorbents not be observed evidently during the test.The adsorption of modified activated carbon to magnesium ions was a chemical adsorption process from fast to slow,which is in accordance with the Langmuir isothermal adsorption model.5.The fibrous activated carbon of Salix and its ideal modified material all have certain adsorption properties to formaldehyde,but the adsorption amount of formaldehyde is 1.02 mg g^-1 of modified activated carbon,which is increased by108.16%.It is mainly due to the increase of oxygen functional groups on the surface of modified activated carbon,and the enhancement of surface polarity leads to the improvement of the adsorption performance of polar formaldehyde.