多层光源内置式气-液-固循环流化床光催化降解双酚A

Photocatalytic degradation of bisphenol A in a gas-liquid-solid circulating fluidized bed photoreactor with internal multi-layered lamps using Gd-doped TiO_2 particles

悬浮浆态光催化反应体系具有固-液接触面积大、过程效率高和处理量较大的优点,但存在浆态体系中纳米催化剂难于分离回收的问题,为解决这一难题,提出了在废水污染物光催化降解过程中使用易于沉降分离的微米级颗粒光催化剂,并与新设计的多层光源内置式气-液-固循环流化床相结合组成的光催化反应体系.以微米级颗粒Gd-TiO2为光催化剂,环境内分泌干扰物双酚A(BPA)为模型物,考察和评价了该反应器体系的性能.结果表明,在光催化降解BPA的过程中,催化剂浓度、表观气速和表观液速均存在相应的最佳值.以Gd-TiO2为催化剂时,最优反应条件为:催化剂浓度为6.gL-1,表观气速为8.34×10-3m.s-1,表观液速为1.11×10-2m.s-1.在最佳操作条件下,Gd-TiO2催化体系在催化降解性能和沉降分离性能方面都优于P25-TiO2浆态体系.因此,以易于沉降分离的微米级颗粒催化剂与多层光源内置气-液-固循环流化床技术相结合组成的光催化体系,在废水污染物光催化降解处理方面具有较大应用前景.

A new photocatalytic degradation process combining particle and gas-liquid-solid circulating fluidized bed photoreactor（GLSCFBPR） technologies is proposed,in order to take the advantage of suspended slurry photocatalytic systems that can maximize the efficiency of photon utilization,oxidation rates and reactor throughput,and to solve the separation problem of nanophotocatalysts from the slurry system.The performance of the proposed process was evaluated using Gd doped TiO2 microparticles as photocatalyst and bisphenol A as model pollutant.Photocatalyst concentration,superficial gas velocity and superficial liquid velocity all have a corresponding optimum value in the new reactor system.When the micrometer Gd-TiO2 was used,the optimum operation conditions were photocatalyst concentration 6 g·L-1,superficial gas velocity 8.34×10-3m·s-1 and superficial liquid velocity 1.11×10-2 m·s-1.Under the optimized operation conditions,the Gd-TiO2 fluidized system exhibited superior photocatalytic degradation and sedimentation separation performance to that of the P25-TiO2 slurry system.Therefore,the new photocatalytic reactor system combining easily separable microparticles and a gas-liquid-solid circulating fluidized bed reactor is highly suitable for large-scale industrial applications of photocatalysis for water treatment and purification.