Adsorption Of Cr Ions(Ⅵ) By Modified Activated Carbon

In this study, the effect of modified activated carbon on its adsorption performance of Cr(Ⅵ)in water was investigated. The phosphoric acid activated carbon(PAC) was used as the raw material, and the N-PAC was modified by 10% nitric acid 4h under 40℃ and the Fe-PAC was modified by impregnation method with 0.2mol/L FeSO4. The results of static adsorption showed that the adsorption rate of modified activated carbon absorbing Cr(Ⅵ) increased greatly. Under room temperate 50 mL concentration of 100mg/L Cr(Ⅵ) solution was disposed by 0.2g activated carbon. The adsorption rate of N-PAC and Fe-PAC absorbing Cr(Ⅵ) were 79.21% and 90.59%,respectively, while that of original PAC was only 49.58%. The rise of pH and temperature are conducive to activated carbon adsorption of Cr(Ⅵ). Regenerating activated carbon by 0.12 mol/L NaOH chemical method and 0.5 h 300 ℃ heating method can improve its secondary adsorption rate of Cr(Ⅵ)Through the specific surface area and pore volume of activated carbon, and from the point of view of thermodynamics, this article studied the adsorption of Cr(Ⅵ) by activated carbon.Test results showed that acid functional groups of modified activated carbon increases to a certain extent, the specific surface area and pore volume has a certain degree. The result of XPS showed that the O 1 s area of the activated carbon increased through the modification by nitric acid. This suggested the increase of oxygen containing functional groups of activated carbon. By the Fe 2p points peak showed the exist of divalent and trivalent iron oxide on the surface of Fe-PAC. Three kinds of activated carbon adsorption isotherm is in line with Langmuir model and in a certain concentration range, the process of adsorption could be well described by Lagergren pseudo second order model. Temperature rise is conducive to the adsorption reaction. Thermodynamic studies showed that activated carbon adsorption of Cr(Ⅵ) in water is a chemical adsorption. The process was spontaneous and endothermic.The breakthrough time and exhaustion time of modified activated carbon dynamic adsorption of water Cr(Ⅵ) was shortened as the initial concentration and the flow rate increases.The dynamic adsorption effect of Fe-PAC is the best. When the initial concentration of Cr(Ⅵ) is 100mg/L and the rate is 1mL/min, the breakthrough time and exhaustion time of 0.5g Fe-PAC was the longest. The breakthrough time of Fe-PAC was about 13 minutes and the exhaustion time was about 350 minutes. The adsorption effect of N-PAC was second, the PAC was the worst.