硝酸镁改性活性炭及吸附性能研究

Magnesium Nitrate Modified Activated Carbon and Adsorption Performance of Acid Red Dye

为了提高活性炭的吸附性能,以硝酸镁和活性炭为原料,采用等体积浸渍高温焙烧法制备了氧化镁改性活性炭材料(MgO-GAC)并采用扫描电镜对其形态结构进行分析,考察了p H、温度、吸附时间对复合材料吸附废水中低浓度活性红染料的影响.结果表明,硝酸镁3.5 mol·L^(-1)、焙烧温度600℃、焙烧时间2 h,MgO-GAC的碘吸附值为960.42 mg·g^(-1).扫描电镜(SEM)照片显示,未改性颗粒活性炭表面微孔直径约3μm,改性MgO-GAC复合材料表面的微孔大小均匀,孔径约6~7μm,其表面负载着大量的细小圆形颗粒,高温焙烧对颗粒活性炭有扩孔作用,且可以使硝酸镁转化为多孔氧化镁,并有效负载到颗粒活性炭表面.MgO-GAC复合材料吸附活性红X-3B染料的最佳条件为:投加量为0.1 g,温度为30℃,p H值为6,活性红染料的去除率可达92.5%.改性颗粒活性炭的制备方法是可行的,高温扩孔和负载的多孔氧化镁能够增大颗粒活性炭的表面积,从而提高了活性红染料的吸附效果.

In order to improve the adsorption performance of activated carbon,magnesium oxide modified activated carbon(MgO/GAC)was prepared by equal volume impregnation with magnesium nitrate and activated carbon,adopting high temperature roasting.The influence of temperature and adsorption time on the adsorption of low-concentration reactive red dye in wastewater was tested by the composite material.The results showed that the iodine adsorption value of Mg0-GAC was 960.42 mg·g^(-1) with 3.5 mol·L^(-1) magnesium nitrate impregnation,calcination temperature 600 ℃,calcination time 2 h.Scanning electron microscopy(SEM)photos showed that the surface of the unmodified granular activated carbon had the micropore diameter of about 3μm,and the surface of the modified Mg0-GAC composite had hte uniform micropore size,with the pore size of about 6-7μm.The surface was loaded with a large number of small round particles.High-temperature roasting had a pore expansion effect on granular activated carbon,and could convert magnesium nitrate into porous magnesium oxide,which could be effectively loaded on the surface of granular activated carbon.The optimal conditions for the adsorption of Reactive Red X-3B dye with the Mg0-GAC composite material were as follows:the dosage was 0.1 g,the temperature was 30℃,the pH value was 6,and the removal rate of reactive red dye reached 92.5%.The preparation method of modified activated carbon was feasible,high temperature expansion and porous magnesia increased the surface area of granular activated carbon,which improved the adsorption effect of the reactive red dye.