微生物絮凝剂M-C11处理高岭土悬浊液的响应曲面优化

采用响应曲面法对微生物絮凝剂M-C11处理高岭土悬浊液的过程参数进行优化,选取中心复合实验设计(CCD),以pH、M-C11投加量和CaCl2投加量等因素为自变量,以处理后的高岭土悬浊液絮凝率(Fr)为响应值,并借助扫描电镜对絮凝剂的作用机理进行初步探讨。结果表明,微生物絮凝剂M-C11可显著改善高岭土悬浊液的絮凝性能,且选取的3种单因素水平均可影响絮凝剂活性。经多元回归拟合分析,在M-C11投加量为2.56 mL,CaCl2 投加量为0.37 g/L的最优条件下,微生物絮凝活性实验值可达92.37%,接近模型预测值(92.30%)。CaCl2 投加量对絮凝效果的影响高于M-C11投加量(PCaCl2PM-C11)。Ca2+可中和高岭土颗粒表面负电荷,絮凝剂分子为悬浮颗粒提供吸附结合位点,促进絮体凝聚沉淀,M-C11絮凝机理是电中和、吸附架桥和网捕等联合作用的结果。

Optimization for kaolin suspension by bioflocculant M-C11 treatment using response surface methodology

The response surface methodology (RSM) and the central composite design were used for obtaining the parameters in kaolin suspension by bioflocculant M-C11 treatment. pH, M-C11 dosage and CaCl2 dosage were the interactive variables, and the flocculating rate (Fr) was the response value. The mechanism of the bioflocculation was deduced by the scanning electron microscope. The results showed that the bioflocculant could considerably improve the flocculating characteristics of the kaolin suspension, which was influenced by the above three variables. Multiple regression fitting indicated that the flocculating rate was as high as 92.37%, in close agreement with the predicted value (92.30%) under the optimized conditions: M-C11 dosage of 2.56 mL,CaCl2 dosage of 0.37 g/L. CaCl2 dosage influenced the flocculating effect more significantly than M-C11 dosage. Cationic ions neutralized the surface negative charges in the kaolin particels. And the bioflocculant promoted the coagulation by providing adsorption sites for the suspended particles. The M-C11 biofocculating mechanism was the combination of charge neutralization,absorption bridging and netting mechanism.