【作者】 李娜；

【导师】 吴兆亮；

【作者基本信息】 河北工业大学 ， 生物化工， 2019， 硕士

【摘要】 泡沫分离技术是一项新兴的绿色富集浓缩技术,其中泡沫排液过程吸引了越来越多研究者的关注。卢珂等人研究了塔壁对泡沫排液的影响,实验结果表明,外通道(两个泡沫液膜与管壁交汇处的Plateau边界区域)的排液速率大于内通道(三个气泡液膜交汇处的Plateau边界区域)的排液速率,由此提出“壁效应”。为了进一步强化泡沫排液,实现高效富集目标溶质,本文在“壁效应”的基础上,提出了与之相对应的“角效应”。首先研究泡沫分离过程中角效应强化泡沫排液的机理。随后,将井字形构件泡沫分离塔分别应用于从缫丝废水中提取丝胶蛋白和从缫丝下脚料中提取丝素蛋白的分离过程中。从固液接触面积的角度分析,在泡沫分离过程中,形成的泡沫排液通道中的液体与壁面接触面积越大,排液效果越好,实验结果表明存在角效应的构件跟仅有壁效应的圆套筒构件(具有相同的壁面积)相比,泡沫持液量明显降低。理论分析与实验结果相符。以牛血清白蛋白(BSA)为模拟体系,分析了角的个数、BSA浓度、气体体积流率对泡沫表观液体流速的影响,表明角效应通过降低间隙液的表观液体流速来降低泡沫持液率。确定了构件的结构参数,角度为90°,长度为400 mm的构件安装于距离塔顶40 mm处,能够显著促进泡沫排液。将井字形构件应用于泡沫分离缫丝废水提取丝胶蛋白的工艺中,实验结果表明,p H和温度对泡沫分离效率有很大影响,在p H 4.0,温度40°C,分布器孔径0.180 mm,气体体积流率150 m L/min的最佳操作条件下,丝胶蛋白的富集比和回收率分别为6.77和80.29%。根据十二烷基硫酸钠-聚丙酰胺凝胶电泳可知实验所得丝胶蛋白分子量为16 k Da。将井字形构件应用于泡沫分离缫丝下脚料提取丝素蛋白的工艺研究中,实验结果表明,井字形构件可以有效强化高粘度溶液的泡沫排液,丝素蛋白提取的最佳条件为氯化钙浓度40%,水浴搅拌加热至90°C,溶解一个小时。泡沫分离丝素蛋白的最佳操作条件为p H 5.0,温度25°C、气体体积速300 m L/min和分布器孔径0.180 mm。此时获得的丝素蛋白富集比和回收率分别为5.41和82.30%。综上所述,角效应能有效强化泡沫排液和提高泡沫分离性能,将井字形构件应用到缫丝废水和废弃物的处理中也获得较好的实验结果,促进泡沫分离的工业化应用。更多还原

【Abstract】 Foam fractionation is a promising green concentration method,and its foam drainage process has attracted increasing interest of researchers in recent years.Lu et al.had studied the “wall effect” on foam drainage and the experimental results indicated that the drainage rate of the interstitial liquid in the exterior channel(Plateau borders constructed by two intersecting films and the column wall)was higher than that in the interior channel(Plateau borders constructed by three intersecting films).In order to further strengthen the foam drainage and achieve the high enrichment of the desired material,the exterior channels could be further divided into wall channel and corner channel.Thus,“corner effect” was presented in the current work based on the “wall effect”.Firstly,the mechanism of foam drainage enhanced by “corner effect” during foam fractionation was investigated.Then,a novel column with groined internal component(GIC)was developed and used to separate silk sericin from the filature wastewater and silk fibroin from the waste silk.Considering the perspective of solid-liquid contact area,it is found that during foam fractionation,the more the liquid contact area in the formed foam drainage channels with the wall surface was,the better the drainage effect should get.The experimental results showed that the liquid holdup of the foam in the component with the corners effect was significantly lower than that in the inner sleeve component with only wall effect(have the same wall area).The theoretical analysis was consistent with the experimental results.Using bovine serum albumin as the desired material,the effects of corner numbers,the concentration of BSA and volume air flow rate on the superficial liquid velocity were investigated,respectively.Experimental results suggested that the “corner effect” could be used to reduce the liquid holdup of the foam by decreasing the superficial liquid velocity of entrained liquid inside the foam.The internal component with a suitable length of 400 mm,and a corner dimension of 90° could significantly strengthen foam drainage when it was mounted at the location of 40 mm from the top of the column.The novel foam fractionation column with groined internal component was applied to recover silk sericin from the filature wastewater.Experimental results indicated that p H and temperature had played a critical role in determining the performance of foam fractionation.Under the suitable operation conditions of p H 4.0,temperature 40°C,volumetric air flow rate 150 m L/min,and pore diameter of gas distributor 0.180 mm,the enrichment ratio and the recovery percentage of silk sericin reached 6.77 and 80.29%,respectively.The molecular weight of sericin was 16 k Da by sodium dodecyl sulfate polyacrylamide gel electrophoresis.In order to recover silk fibroin from the scraps of silk-reeling industry,GIC was applied to strengthen foam drainage.The experimental results showed that the GIC could effectively strengthen foam drainage of the solution with high viscosity,the suitable condition for extracting silk fibroin from the scraps of silk-reeling industry was calcium chloride concentration of 40%,temperature 90°C,dissolving in an hour.Under the suitable operation conditions of p H 5.0,temperature 25°C,volumetric air flow rate 300 m L/min,and pore diameter of gas distributor 0.180 mm,the enrichment ratio and the recovery percentage of silk fibroin reached 5.41 and 82.30%,respectively.Sum up,corner effect could effectively strengthen the foam drainage and improve the performance of foam fractionation.This work is expected to provide a cost-effective technique by using GIC to recover silk sericin from the filature wastewater and silk fibroin from the scraps of silk-reeling industry,and to promote the industrialization of foam fractionation in wastewater treatment.更多还原