Diffusion dialysis of sulfuric acid in spiral wound membrane modules: Effect of module number and connection mode

• Mass transfer of sulfuric acid in SWDD membrane modules was investigated.
• Acid recovery ratio increases with module number and decreases with flow rate.
• Acid recovery ratio does not apparently change with initial feed concentration.
• The treating capacity for multi modules is not a simple sum of the single module.
• The treating capacity for D-d or T is nearly 3 or 8 times as that for S, respectively.

The main goal of this work is to explore the transfer of sulfuric acid in spiral wound membrane modules. The effect of various parameters such as connection modes, number of membrane modules, flow rate and initial feed concentration are fully investigated. The results show that the acid recovery ratio increases with the number of membrane modules and decreases with the flow rate but does not apparently changes with the initial feed concentration. Meanwhile, both the recovered acid concentration and the dialysate acid concentration are directly proportional to the feed concentration for different number of SWDD modules. For double SWDD membrane module system, the mode D-d (series connection in both acid side and water sides) seems to be the best one from the integrated viewpoints of acid recovery ratio and recovered acid concentration. For multi-modules system, the treating capacity is much higher than the sum contributed from each single module.