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本文报导了在表面活性剂存在时 ,阴离子聚丙烯酰胺 (PAM A)对高岭土悬浮液的絮凝和脱水试验结果。所研究的表面活性剂有SDS(十二烷基硫酸钠 )、CTAB(十六烷基三甲基胺溴化物 )和TX 10 0 (非离子型表面活性剂聚氧乙烯酯 )。物理吸附和化学吸附联合控制着PAM A在高岭土表面上的吸附量。PAM A在新鲜的高岭土和经表面活性剂预处理的高岭土表面上的最佳絮凝浓度约为表面复盖面积的 5 0 % (即Г最佳絮凝 ≈Г∝/ 2 )。高岭土悬浮液经三种表面活性剂预处理后 ,PAM A絮凝得到的絮团较大。用SDS预处理的高岭土经絮凝后 ,其沉降速度最大 ,SRF值最小 ,此时 ,约 40 %呈物理吸附 ,其它为化学吸附。此时形成的絮团适于过滤 ,可大幅度降低SRF值。在所有情况下 ,与SRF最小值对应的PAM A浓度要比最佳絮凝所要求的浓度低得多 ,此时 ,PAM A吸附密度约为最大吸附密度的 2 5 % (即Г最小SRF≈0 2 5Г∝)。表面活性剂与PAM A混合物的添加对高岭土悬浮液絮凝和脱水的影响决定于PAM A与表面活性剂相互作用的特性。PAM A与SDS混合物和PAM A与TX 10 0混合物的添加增大了沉降速度 ,而PAM A与CTAB混合物的添加降低了沉降速度。同时添加聚合物和表面活性剂时 ,聚合物对滤饼水分的控制要比表面活性剂控制程度大得多。
This paper reports the experimental results of anionic polyacrylamide (PAM A) flocculation and dehydration on kaolin suspensions in the presence of surfactants. The surfactants studied are SDS (Sodium Lauryl Sulfate), CTAB (Cetyltrimethylammonium Bromide) and TX10 (Nonionic Surfactant Polyoxyethylene Ester). Physical adsorption and chemisorption jointly control the amount of PAM A adsorbed on the kaolin surface. The optimum flocculation concentration of PAM A on the surface of fresh kaolin and surfactant pretreated kaolin is about 50% of the surface area (ie, Γ optimal flocculation ≈Γα / 2). After the kaolin suspension was pretreated with three surfactants, the flocculation by PAM A was larger. After flocculation with kaolin, the sedimentation speed of SDS-treated kaolin was the highest and the SRF value was the smallest. About 40% of the kaolins were physically adsorbed and others were chemisorbed. The flocs formed at this time are suitable for filtration, which can greatly reduce the SRF value. In all cases, the concentration of PAM A corresponding to the minimum SRF is much lower than that required for optimal flocculation, at which point the PAM A adsorption density is about 25% of the maximum adsorption density (ie Γ minimum SRF ≈0 2 5Γα). The effect of the addition of the surfactant and PAM A mixture on the flocculation and dehydration of the kaolin suspension depends on the nature of the PAMA interaction with the surfactant. The addition of PAM A to SDS mixture and PAM A to TX 10 0 mixture increased the settling velocity, whereas the addition of PAM A to CTAB mixture decreased the settling velocity. With the addition of both polymer and surfactant, the polymer controls the moisture content of the filter cake much more than the surfactant controls.