Thermal-driven osmosis utilizing hollow fiber membranes: Sustainable dye water treatment and electricity extraction

• Published in: Desalination 2024-06, Vol.579, p.117485, Article 117485
• Main Authors: Luo, Qizhao, Huang, Lu, Yun, Panfeng, Qiu, Tenghui, Tang, Bin, Huang, Kaiming, Hu, Xuejiao, Jiang, Haifeng
• Format: Article
• Language: English
• Subjects: Desalination; Dye water treatment; Electricity generation; Hollow fiber membrane; Low-grade heat energy; Thermo-osmotic energy conversion technology
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2024.117485

Excessive discharges of chemical dyes have led to severe contamination of seawater, resulting in significant ecological damage. Thermo-osmotic energy conversion technology, which purifies wastewater and generates electricity under temperature gradients, has garnered considerable interest from researchers. However, the operational efficiency of thermo-osmotic energy conversion is inherently limited by the effective membrane area, and conventional systems typically employ flat membranes as separators, resulting in suboptimal performance for the same floorage. In this study, we introduce a novel system that combines thermo-osmotic energy conversion technology with hollow fiber membranes that possess a high effective membrane area, thereby achieving optimized performance. Driven by the temperature gradient, the water in the dye solution condenses outside the membrane and converted from vapor to liquid. The continuous accumulation of condensed water generates pressure and drives a water turbine for sustainable power generation. Our results demonstrate that at temperature gradient of 40 °C, the system can achieve the power output of 16.75 Wm−3 and the freshwater production rate of 70.29 kg m−3 h−1 under ideal conditions. This study presents a novel water-electricity co-production system based on low-grade waste heat recovery for dye solution treatment, which extends the applicability of thermo-osmotic energy conversion technology and improves its practicality. •Hollow fiber membrane combined thermal-osmosis hybrid system was proposed.•Simultaneous generation of freshwater and electricity was achieved under dye solution.•Optimal operating conditions for the system are discussed.•A theoretical model was developed to optimize water and electricity output of the system.