Robust KOH-thiourea-graphene oxide cross-linked membranes for desalination

Due to the well-defined two-dimensional nanochannel nanostructures, graphene oxide (GO) membranes hold huge possibilities for sustainable brackish water desalination and wastewater purification. However, achieving effective nanofiltration performance and sufficient structural stability of GO membranes in aqueous environments remains a major obstacle. Herein, the TU-GO-KOH membrane - the GO membrane cross-linked by thiourea (TU) after KOH treatment, was prepared for achieving relatively high water permeance (∼14.2 L m−2 h−1) and high rejection (∼86.3 %) for NaCl rejection. These performances exceeded the nanofiltration performances of most GO-based membranes and commercial membranes reported in the literature. More importantly, the TU-GO-KOH membrane exhibited excellent separation stability over long-term (for 168 h) and under high pressures (up to 9 bar). Furthermore, even under ultra-sonication treatment and after long-term immersion in solutions with harsh pH values, the TU-GO-KOH membrane still maintained its own stability, which holds considerable promise for sustainable water treatment under harsh conditions. Additionally, the TU-GO-KOH membrane also showed enhanced mechanical properties. Overall, the superior desalination performance and notable stability of the TU-GO-KOH membrane make it a highly promising candidate for practical desalination and wastewater treatment.