光热膜蒸馏过程去除高盐有机废水中苯酚的性能研究

Removal of phenol from highly salty organic wastewater using photothermal membrane distillation process

膜蒸馏技术对于非挥发性物质具有100%的理论截留率,但对于挥发性物质的截留效果不佳。本研究使用光热膜蒸馏技术,利用光能对膜表面进行原位加热,改善温差极化问题,提高水通量,降低苯酚/水透过比值.本工作通过喷涂法在聚四氟乙烯(PTFE)基膜上制备了碳纳米管(CNTs)复合膜.膜表面CNTs层赋予了复合膜优异的光吸收和光热转换性能,在全光谱范围内光吸收率可达90.64%.在1个太阳光强度下,膜表面温度可上升至(61±1)℃.在使用200 mg/L苯酚、3.5%(质量分数)NaCl溶液在35℃下作为进料液并施加1个太阳光辐射的光热膜蒸馏系统中,膜通量提高了34.4%,太阳能利用率为33.1%,同时盐的截留率始终大于99.9%.光热膜蒸馏对于高盐苯酚溶液中苯酚的分离效果相比传统膜蒸馏有明显提高:在进料液苯酚浓度为200 mg/L的条件下,施加1个太阳光强度后苯酚/水的透过比降低了35.2%.

Membrane distillation has a theoretical retention rate of 100% for nonvolatile substances.However,its ability of removing volatile substances is not satisfactory.In this work,photothermal membrane distillation was used to in-situ heat membrane surface by solar energy,which improved temperature polarization,increased flux and decreased the phenol-water permeation ratio.CNTs was sprayed on PTFE substrate to prepare the composite membrane which has excellent photothermal conversion performance.The light absorption of the composite membrane was 90.64% within the full spectrum range,and the surface temperature of it increased to(61±1)℃ underanirradianceof1sun.The results of photothermal membrane distillation using 200 mg/L phenol and 3.5%NaCl solution as the feed solution(35℃)show that a 34.4% increasing of water flux compared to the dark condition and solar energy utilization efficiency of 33.1%,while the salt rejection remained above 99.9%.The phenol separation was significantly improved compared photothermal membrane distillation to traditional membrane distilation under various conditions.The phenol-water permeation ratio decreased by 35.2% under 1 sun.