This dataset tracks 239 patent families published between 2015 and mid-2026 that match a search combining electrodialysis, electrodialysis reversal, and ED-stack terminology with heavy metal removal, selective electrodialysis, ion separation, or metal recovery language. That count reflects families rather than raw document publications, which is the fairer unit because it neutralises duplicate filings across jurisdictions and continuation applications. The true figure for 2025-2026 will be somewhat higher once pending applications finish publishing, since publication typically lags filing by around 18 months.

The assignee ranking spans academic institutions such as MIT and Ghent University, water-treatment specialists, and industrial conglomerates, without a single filer holding a dominant share. Notably, every tracked leading assignee shows zero filings in the most recent full year, several down 100% year-on-year, which means the field currently lacks an active incumbent leader. That makes this a good moment for a new entrant to establish a strong position, provided they clear the historical foundational claims first.

The filing trend is flat to declining rather than growing: activity sat around 10-12 families per year through the first half of the tracked period, peaked at 21 in 2024, and has since dropped sharply into 2026 — though that final year is still partial due to publication lag. This pattern is more consistent with a maturing field that had one recent wave of interest than with a fast-growing emerging technology. Anyone evaluating this space for R&D investment should weigh the flat historical trend against the possibility of a delayed 2025-2026 rebound once more filings publish.

US4246092A, granted to Research Products Rehovot Ltd. in 1981, claims a method and apparatus for selective electrodialytic separation using a thin, dense, non-porous charged membrane made of water-insoluble hydrophobic polymer with covalently bound ionizable groups, separating diluting and concentrating compartments. Its claim language around membrane composition and ionizable-group chemistry recurs across later selective-electrodialysis filings in this corpus, making it a foundational reference point rather than a currently enforceable barrier given its age. Anyone designing a selective-ED system should still map their membrane chemistry against its claim scope as part of a broader prior-art review, since its structural language shaped much of what followed.

The secondary IPC subclasses in this dataset — C08J for polymer processing, C25B for electrolytic production, and C22B for metal extraction — show meaningful but comparatively low filing volume relative to the dominant C02F and B01D clusters. That gap suggests under-claimed territory in metal-selective membrane chemistry, energy-recovery integration for ED stacks, and acid/alkali co-production from waste-metal streams. None of these branches show a dominant claim holder in the current ranking, which is the clearest signal of open filing space in this landscape.