Abstract:

A novel technology of froth flotation coupled ultrafiltration has been developed for recovering nano-sized TiO₂ photocatalyst from its organic wastewater. First, the ultrafiltration efficiency for the recovery of nano-sized TiO₂ photocatalyst was evaluated according to the permeate flux and the rejecting ratio. Second, in order to reduce the concentration of the feeding solution, froth flotation was performed with cetyltrimethylammonium bromide (CTAB) as the collector. The effects of CTAB concentration, volumetric air flow rate and pore diameter of gas distributor on the performance of froth flotation were investigated. Finally, the suitable operation conditions of the proposed technology were determined. The experimental result showed that under the suitable operation conditions of pH 7.0, CTAB concentration 0.20g/L, volumetric air flow rate 15mL/min, and pore diameter of gas distributor 180μm, the enrichment ratio and the recovery percentage of nano-sized TiO₂ photocatalyst reached 22.52 and 99%, respectively. Meanwhile, the operating time of the membrane increased by 133% compared to that in ultrafiltration only operation.

Key words: foam, flotation, nanoparticles, surfactants, ultrafiltration

摘要：

本研究的目的是开发一种新型的泡沫浮选耦合超滤技术的方法，以实现从有机废液体系中经济、高效地回收纳米TiO₂光催化剂。首先，对超滤膜分离有机废液中纳米TiO₂光催化剂的使用效率，包括透过通量和截留率进行评价。随后，为了减少超滤操作进料液中纳米TiO₂光催化剂的浓度，在泡沫浮选阶段确定以阳离子表面活性剂——十六烷基三甲基溴化铵（CTAB）作为捕获剂，研究了CTAB浓度、气体体积流速、分布器孔径对泡沫浮选回收纳米TiO₂光催化剂富集效率的影响。最后，确定泡沫浮选耦合超滤耦合回收纳米TiO₂光催化剂的工艺条件。试验结果表明，采用耦合工艺，在pH 7.0、CTAB浓度0.20g/L、气体体积流速15mL/min以及分布器孔径180μm的条件下，纳米TiO₂光催化剂富集比和回收率分别为22.52和99%，同时膜的使用寿命较非耦合操作提高了133％。

关键词: 泡沫, 浮选, 纳米粒子, 表面活性剂, 超滤