木糖脱色用活性炭的成型工艺

Research on molding process of activated carbon for xylose decoloring

针对木糖脱色用粉状炭环境污染严重、废炭回收困难、再生处理不易等缺点,选择合适的粉状活性炭和黏结剂,研究其成型工艺。通过试验得到木糖脱色用成型活性炭的最佳工艺条件为:m(炭粉)∶m(复合黏结剂)∶m(水)=1∶0.4∶2.5,复合黏结剂中含有A和B两组分,m(A)∶m(B)=1∶4。混合成型后在150℃下干燥,强度在87%以上;温度在80℃左右,对木糖液脱色效果最佳,脱色率为75.36%;常温酸碱浸泡几乎对试样没有破坏,用酸碱煮沸5 min,颗粒表层略微有脱落,但对整体结构没有破坏。成型后活性炭的相关性能为:碘吸附值985mg/g,亚甲基蓝吸附值225 mg/g,焦糖脱色率60%,比表面积1 438.56 m^2/g。吸附饱和后的成型活性炭经酸洗后,再生性能较好。

Activated carbon is a kind of important functional porous material with large specific surface area and pore structure. Activated carbon is widely used on industrial scale as an adsorbent mainly for the purification/separation of liquids and gases or as catalyst and catalyst support. Activated carbon is commonly prepared by the well-known methods of physical activation or chemical activation. In the chemical method, H3PO4 is the most widely used impregnation agent. There are some advantages of powder activated carbon, such as large surface area and adsorption efficiency, quick response filter and so on. But the application of activated carbon in the sugar industry exists some drawbacks, such as serious environmental pollution, difficult to recycle and regeneration. So the application of molded activated carbon has obtained wide attention. In this study, activated carbon was molded for xylose bleaching. The optimum molding process was achieved when the ratio of toner to composite binder to water was 1：0. 4：2. 5 ; the mass ratio of component A to component B in the adhesive was 1：4; the molded product was dried at 150 ℃ with the measured intensity of 87%. The optimum bleaching performance was obtained at 80 ℃ , and the decoloration rate was 75.36%. At room temperature, the samples immersed in acid or alkali were barely damaged. When boiled in acid for 5 min, the surface of the particle surface came off slightly, but the overall structure was not destroyed, indicating their strong acid and alkali resistance. Other relevant properties of the molded activated carbon were ： the iodine adsorption value was 985 mg/g ; the methylene blue adsorption value was 225 mg/g; the caramel decoloration rate was 60% ; the specific surface area of the molded activated carbon was 1 438.56 m2/g. After adsorption saturation, it was better to regenerate it with diluted hydrochloric acid.