Reverse osmosis

=== Carbon Nanotubes (CNTs) ===
Carbon nanotubes are meant to potentially solve the typical tradeoff between the permeability and the selectivity of RO membranes. CNTs present many ideal characteristics including: mechanical strength, electron affinity, and also exhibiting flexibility during modification. By restructuring carbon nanotubes and coating or impregnating them with other chemical compounds, scientists can manufacture these membranes to have all of the most desirable traits. The hope with CNT membranes is to find a combination of high water permeability while also decreasing the amount of neutral solutes taken out of the water. This would help decrease energy costs and the cost of remineralization after purification through the membrane.<ref>{{Cite journal |last1=Ali |first1=Sharafat |last2=Rehman |first2=Syed Aziz Ur |last3=Luan |first3=Hong-Yan |last4=Farid |first4=Muhammad Usman |last5=Huang |first5=Haiou |date=2019-01-01 |title=Challenges and opportunities in functional carbon nanotubes for membrane-based water treatment and desalination |url=https://www.sciencedirect.com/science/article/pii/S0048969718328432 |journal=Science of the Total Environment |language=en |volume=646 |pages=1126–1139 |doi=10.1016/j.scitotenv.2018.07.348 |pmid=30235599 |bibcode=2019ScTEn.646.1126A |s2cid=52311560 |issn=0048-9697}}</ref>