磷酸法木质活性炭除灰新工艺研究

Novel Demineralization Technology of Phosphate-activated Carbon

研究了磷酸在不同加热温度下生成聚合磷酸的水溶性和酸溶性。结果表明:随着加热温度的升高,磷酸形成的聚合磷酸的溶解性下降,水溶解度和酸溶解度分别从98.71%和98.93%降低至73.12%和74.80%。以商品磷酸法木质活性炭为样品,以常规水洗除灰为对照,研究了酸洗、加热洗涤、添加氧化剂次氯酸、离心脱水方式等对活性炭灰分及其吸附性能的影响,并对洗涤后的活性炭样品进行比表面积及孔结构测定,确定了适宜的洗涤条件:洗涤温度为80℃,使用5%HCl并添加次氯酸洗2次,水洗3次,洗涤过程均用离心脱水方式。洗涤过后,活性炭样品的灰分从常规水洗除灰的6.24%降低至1.49%;此时活性炭的比表面积1503 m^2/g、孔径3.656 nm、孔容积1.361 cm^3/g、碘吸附值975 mg/g、亚甲基蓝吸附值277.5 mg/g、焦糖脱色率110%,相比水洗除灰均有所增大。因此,活化过程在较低温度下进行并使用上述组合除灰工艺可制备出低灰分磷酸法木质活性炭。

The solubilities in acid and water of the polyphosphate obtained from phosphate at different temperatures were determined.The results showed that the solubility of polymeric phosphate decreased with the temperature increase;as the preparation temperature increased from 350℃to 650℃,the water solubility and acid solubility decreased from 98.71%and 98.93%to 73.12%and 74.80%,respectively.Compared with the conventional water elution process,the effects of acid pickling,heating,oxidant HClO and centrifugal process on the ash content and the adsorption capacity of commercial phosphate-activated carbon were studied.The specific surface area of activated carbon were determined.The results showed that the ash content of activated carbon reduced from 6.24%to 1.49%when the samples were washed twice by HCl and oxidant HClO and then washed three times by water in 80℃with centrifugal dehydration process compared the sample of water washing.And the specific surface area,pore diameter,pore volume,iodine adsorption value,methylene blue adsorption value and caramel decolorization were 1503 m^2/g,3.656 nm,1.361 cm^3/g,975 mg/g,277.5 mg/g,110%,which were larger than those of the water washed sample.Therefore,low-ash phosphate-activated carbon could be prepared at low temperature and by using the above demineralization process.