Sustainable Recovery of Ionic Resources from Resin Regeneration Wastewater: Long-Term Evaluation, Membrane Fouling Analysis, and Cleaning

Abstract

Macroporous resins, being highly efficient and reusable, have been widely applied for the treatment of highsalinity organic wastewater. However, resin regeneration generates a large amount of organic wastewater, which causes serious environmental pollution. In this work, the continuous recovery of resin regeneration wastewater was achieved by using an electrodialysis (ED) process. The results showed that the recovered NaOH concentration approached 0.2 mol/L after 10 consecutive batch experiments. The anline in regeneration wastewater can be successfully rejected by ion exchange membranes, and the COD content in the concentrate stream was <100 mg/L. Energy consumption analysis indicated approximately 2.6−3.0 kWh/kg of NaOH was maintained during the batch experiments. Furthermore, different cleaning methods were proposed for investigation of the membrane fouling reversibility. Ultrasonic stimulation combined with 1% HCl can successfully restore ion exchange membrane performance (e.g., membrane surface resistance and ion exchange capacity). Membrane characterization showed ultrasonic treatment combined with 1% HCl cleaning can restore the membrane to its virgin state. The proposed ED process for the recovery of NaOH from regenerated resin wastewater not only showed long-term stability but also presented superior reusability of membranes, which offered great potential for industrial application.

Internally Cross-Linked Polysulfone-Based Anion Exchange Membranes with pH Stability for Carboxylate Separation

“…Among these techniques, ED stands out as a promising and sustainable technology, thanks to its high selectivity for ionic compounds, ease of operation, and low carbon footprint. − In ED, target carboxylates can be selectively separated from liquid streams based on electro-driven of ions that transport through ion-exchange membranes (IEMs). − An appropriate anion exchange membrane (AEM) for the desalination of carboxylate must exhibit a high organic ion transport capability and pH stability. − Due to its affordability, robust physical-chemical stability, and chemical reactivity, polysulfone (PSF) is commonly used for membrane fabrication. , Particularly, chlorinated PSF (CMPSF), which can be easily reacted with some functional monomers via a substitution reaction, has been explored to create polymers with ion exchange capacities (IECs) for IEMs. For example, based on the functionable sites of trimethylamine and triethylamine, Tang et al.…”