粉状褐煤对水中草甘膦的动态吸附

采集内蒙霍林河煤矿褐煤样品,加工成粒径0.38~0.83 mm作为吸附剂,对模拟草甘膦废水进行动态吸附实验。考察了吸附柱高(3、5和10 cm)、草甘膦初始浓度(0.5%、0.75%和1.0%)、流速(1、2和3 mL/min)、pH(9、11和13)和离子强度(IS, 0.001、0.01和0.1 mol/L)对草甘膦的吸附穿透曲线和传质区长度的影响。实验结果表明,降低柱高、增大初始浓度、提高流速、增加离子强度均会使穿透时间提前,pH变化对穿透时间影响很小;柱高、初始浓度、流速、IS和pH引起的传质区长度的平均变化率绝对值分别为0.675、6.300、1.625、47.727和0.263,可见,与柱高、初始浓度和流速相比,IS对传质区长度的影响较大,pH影响较小。低浓度条件下,吸附穿透曲线的实验数据符合BDST模型拟合条件(R2 >0.99),在仅改变柱高或流速时,穿透时间理论值与实测值的最大误差均为5.71%,运用该模型能够准确地预测褐煤吸附柱的操作时间。

Dynamic adsorption of glyphosate in water by lignite

Lignite sample was collected from a coal mine in Huolinhe, Inner Mongolia Autonomous Region. The lignite was ground to particle for size from 0.38 mm to 0.83 mm. Columns with diameter 5 cm were packed with the lignite particles, which was used to perform experiments of dynamic adsorption of glyphosate. The effects of some factors on adsorption breakthrough curve and mass transfer zone lengths were investigated. These factors included the column heights (3, 5 and 10 cm), initial glyphosate concentrations (0.5%, 0.75% and 1.0% in weight), flow rates of solution (1, 2 and 3 mL/min), solution pH (9, 11 and 13) and ion strength (IS) (0.001, 0.01 and 0.1 mol/L). The results showed that the breakthrough time would be shortened with the column height reduced, initial concentration increased, the flow rate increased or ionic strength increased. But the pH (9, 11 and 13) had almost no effect on the breakthrough time. The average change rate of height of mass transfer zone caused by column height, initial concentration of glyphosate, flow rate, IS and pH were 0.675, 6.300, 1.625, 47.727 and 0.263, respectively. This result indicated that IS had effect on the height of mass transfer zone more heavily than those of column height, initial glyphosate concentration or flow rate, while pH had the least effect on the height of mass transfer zone. The data from the dynamic adsorption were well fitted with the BDST model (R2 >0.99) under the low concentration. When column heights or flow rates were changed only, the margin of error between the theoretical and experimental values of breakthrough time was less than 5.71%. This indicates that the operation time can be accurately predicted using the BDST model.