黏结剂对污泥基颗粒炭性能的影响

Effect of binders on performance of granular carbons from sewage sludge

以城市污水处理厂剩余污泥为原料,可溶淀粉、羧甲基纤维素、硅酸钠和硫酸钙为黏结剂,采用两步炭化法制备污泥基颗粒炭,探讨了黏结剂种类对样品性能的影响.结果显示:可溶淀粉样品(SSGAC-T)具有最大的比表面积和孔容,SSGAC-T、羧甲基纤维素样品(SSGAC-C)和硅酸钠样品(SSGAC-Si)含有丰富的微孔和中孔,硫酸钙样品(SSGAC-S)为典型的中孔吸附剂;样品的抗压强度均随浸泡时间的延长而降低,但SSGAC-S的抗压强度下降程度最小;4种黏结剂都使样品表面生成新的官能团,且样品的表面均呈酸性,它们的p HPZC分别为6.37、6.16、5.85和5.53;相同条件下,SSGAC-S对亚甲基蓝的饱和吸附量最高,为71.94mg/g;根据对污泥炭的表征,初步推测硅酸钠和硫酸钙能与碳发生化学反应.

Two-step carbonization method was used to prepare granular carbons with sewage sludge as raw material and soluble starch, carboxymethylcellulose, sodium silicate and calcium sulfate as binders. And then, the effect of binders on sample proporties was discussed. The results showed that the specific surface area and pore volume of samples from soluble starch （SSGAC-T） were the greatest. SSGAC-T samples from carboxymethylcellulose （SSGAC-C） and sodium silicate （SSGAC-Si） had a lot of micropores and mesopores, while the sample from calcium sulfate （SSGAC-S） was the typical mesoporous adsorbent. The compressive strength of all samples decreased with soaking time, while the reduction degree in compressive strength of SSGAC-S was minimal. The new functional groups were formed due to the addition of binders. The surfaces of all samples were acidic, and the pHPZC of all samples were 6.37, 6.16, 5.85 and 5.53, respectively. Under the same conditions, the methylene blue adsorption capacity of SSGAC-S was the greatest with a value of 71.94mg/g. According to the characterization of sludge carbons, it was preliminarily conjectured that sodium silicate and calcium sulfate could react with carbons.