Concentration of high boiling point organic solvents by osmotically assisted reverse osmosis

High boiling point organic solvents (HBOS) are integral to various industrial applications due to their versatile properties. However, the disposal of these solvents raises significant environmental concerns and incurs substantial costs. In this research, an osmotically assisted reverse osmosis (OARO) strategy was utilized to effectively concentrate and treat HBOS (N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP)) wastewater for recycling of the solvents. The influence of several operational parameters, comprising flow rate, applied pressure, number of membrane modules, and their connection mode, was systematically investigated. Specifically, enhancing the operating pressure and reducing flow rates will both lead to higher concentrations of DMF. Furthermore, we developed a simulation model that can reproduce and predict the OARO process well. Investigating long-term operational stability revealed that the OARO process can sustain stable operations for approximately 18 months. Finally, real DMF wastewater containing 1.0 wt.% DMF from an RO membrane company was treated using the OARO technique, resulting in a successful concentration of approximately 42 times. The findings of this research underscore the significant practical applicability of the OARO strategy for HBOS wastewater recovery, recycling, and reuse.