污泥-兰炭末基成型活性炭的制备及吸附性能研究

Study on Preparation of Pressed Active Carbon Based on Sewage Sludge and Fine Semi-coke and Properties of Adsorption

摘要:

采用H2SO4和ZnCl2复合活化法，以脱水污泥和兰炭末为原料制备了污泥-兰炭末基成型活性炭，研究了pH、固液比和吸附时间对其处理稀释10倍兰炭废水效果影响，并进行成型活性炭的再生。单因素和正交实验结果表明：影响成型活性炭碘吸附值的因素由大到小依次为：活化温度>活化时间>浸渍比。最佳制备工艺条件为：活化温度750 ℃、活化时间2 h、浸渍比1:2.5 g/mL。污泥-兰炭末混合物的活化炭化过程共分为4个阶段：第一阶段为室温到200 ℃吸附水逸出阶段；第二阶段为200～338 ℃污泥脱气释放出CH4、CO2和N2阶段；第三阶段为338～642 ℃污泥热解形成半焦阶段，640 ℃出现硫酸钙分解释放二氧化硫放热峰；第四阶段为642 ℃以后半焦形成焦炭和氯化锌挥发阶段。制备的成型活性炭平均孔直径约9 nm，比表面积约194 m2/g，且含有烷烃、芳烃、醇和酚等多种类型的烃类及含氧官能团。兰炭废水处理结果表明：当pH≈8、固液比1:30 g/mL、吸附时间32 h，氨氮去除率和色度去除率分别约为83 %、42 %，成型活性炭经5次再生后，碘吸附值和抗压强度分别降低了31 %和62 %。

Abstract:

A kind of pressed active carbon was prepared by H2SO4 and ZnCl2 complex activation method, using dehydrated sewage sludge and fine semi-coke as the raw materials. The following factors were considered such as pH, solid-to-liquid ratio and adsorption time in treating semi-coking wastewater which had been diluted 10 times. And then pressed active carbon was revived after adsorption. The single factor experiment and orthogonal experiments showed that the influencing factors of iodine sorption value by pressed active carbon were activation temperature, activation time and immersion ratio in turn. The optimum technological conditions were: the activation temperature was 750 ℃, the activation time was 2 h and the immersion ratio was 1:2.5 g/mL. The charring process of sewage sludge and fine semi-coke compound was made up of four steps, the first stage was adsorption water escape phase from room temperature to 200 ℃, while in the second stage between 200~338 ℃ sewage sludge released volatile matter such as CH4, CO2 and N2. Sewage sludge pyrolysized and formed semi-coke in the third stage from 338~642 ℃. Annaline decomposed and released sulfur dioxide exothermic peak at 640 ℃.The last stage semi-coke turned to coke and zinc chloride volatilized after 642 ℃. The pressed active carbon had the average hole diameter of 9 nm and specific area of 194 m2/g. Furthermore, the product contained alkane , arene, alcohol, hydroxybenzene and many other kinds of alkanes and oxygen containing functional groups.The results indicated that while in the condition of pH≈8, solid-to-liquid ratio was 1:30 g/mL and adsorption time was 32 h, the remove effect of ammonia nitrogen and chromaticity were best, which can reach to 83 % and 42 %.While after five times recondition，the iodine sorption value and compression strength of pressed active carbon reduced by 31 % and 62 % separately.