Experimental Study on Preparation and Metal Ions Removal Capability of Expanded Graphite
|Keywords||Expanded graphite Metal Adsorption Modified|
Expanded graphite is a porous material, a wide range of pore size, total pore volume, there is great potential in the adsorption. The purpose of this article is to study the expanded graphite for several representative metal ion adsorption performance, optimize adsorption conditions, and on the basis of experimental data to mathematical analysis and mechanism, to further improve the adsorption capacity and range of applications of the expanded graphite The theoretical basis and direction. In addition, the article also prepared a modified expanded graphite to improve the adsorption properties of expanded graphite. Expanded graphite in order to the Qingdao Hongda later can raw materials used in the microwave expansion prepared expanded graphite, to calculate the ratio of the surface area by the BET equation and the BJH method, a pore volume and pore size distribution; using the scanning electron microscope (SEM), and FT-IR infrared The Analyzer observed morphology structure of the expanded graphite, and expanded graphite contains a functional group. Expanded graphite adsorption of lead, chromium, tin ion adsorption experimental results show that: the pH of the solution is to control the important factors of the three metal ion adsorption process; when the solution was made neutral or acidic, the initial concentration of lead solution of 300mg / L, adsorption time 300min, expanded graphite, the amount of adsorption on leaded ions reached 63mg / g; Preferably, the adsorption effect of graphite on the chromium ion when the solution was at pH = 3, the expansion; When the solution was acidic, the initial concentration of the tin solution 300mg / L, adsorption time 120min, expansion of graphite on the tin ion adsorption amount reached 343 mg / g. In addition, the Langmuir adsorption isotherm equation, Freundlich adsorption isotherm equation and Temkin adsorption isotherm equation expanded graphite adsorption experimental data for the three metals were used to fit the results show that the Langmuir isotherm equation can describe the three metal ions adsorption on expanded graphite balance, expanded graphite Langmuir model of adsorption of three metal ions the limit adsorption capacity were 70.42mg / g, 2.77mg / g, 378.78mg / g. Using a prospective, quasi-two, Elovich and Ritchie's-second-order adsorption kinetics model analysis of the experimental data and found that the quasi-second-order kinetic model to better describe the adsorption process. Nano-magnesium hydroxide modified expanded graphite lead ion adsorption experimental results show that: the expanded graphite compared with the original, modified expanded graphite can be found effective adsorption of lead ion adsorption from 70mg / g to 105mg / g. When the initial pH of 4-6, Pb (II) wastewater initial concentration of 100 mg / L, modified expanded graphite dosage of 0.035 g adsorption time of 120min, under the conditions of 25 ° C, leaded wastewater to The addition rate was about 98%. Langmuir, Freundlich, and Temkin adsorption isotherm model fit the data, the Langmuir model has a better linear correlation. Were used quasi-order kinetic model, pseudo-second Elovich Ritchie's-second-order kinetic model analysis of the experimental data and found that the modified expandable graphite adsorption of lead ions in the whole process to better meet the quasi-second-order kinetic model.