Summary: US Patent 12,478,948 (US12478948B2)

Verified sources: Google Patents record (fetched 2026-08-22), PatentGuru, and Calgon Carbon Corporation's Dec. 9, 2025 press release announcing issuance. No CAFC docket entries were found in searches — see uncertainty note below.

Bibliographic data

Abstract (verbatim)

"Sorbent materials that are treated with ions, salts, oxides, hydroxides, or carbonates of calcium, magnesium, strontium, or barium are useful in removing perfluoroalkyl and polyfluoroalkyl substances (PFAS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), 2,3,3,3,-tetrafluoro-2-(heptafluoropropoxy)propanoate and heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, and similar compounds from liquids and gases are disclosed. The sorbent materials with the disclosed treatments offer improved performance as measured against untreated sorbent materials."

Claims overview

The granted patent contains 5 claims: 1 independent claim (claim 1) and 4 dependent claims (claims 2–5). Note: the granted claims are materially narrower than the as-published application (US20240246059A1), which had claimed sorbents containing 0.5–25 wt.% of Group 2 ions/salts/oxides/hydroxides/carbonates; the granted claims instead focus on reactivated carbon from spent water-treatment carbon.

• Claim 1 (independent) — Method of removing PFAS from liquid or gas. It requires: (a) providing a sorbent material comprising reactivated carbon; (b) the reactivated carbon is formed from a spent activated carbon that was previously used for water filtration; (c) the reactivated carbon was reactivated by heat at about 500°C to about 1100°C; and (d) contacting the sorbent material with the PFAS-containing liquid or gas.
• Claim 2 — Limits reactivation temperature to about 700°C.
• Claim 3 — Requires that the reactivated carbon is formed from spent sorbent feedstock comprising calcium carbonate.
• Claim 4 — Requires the reactivated carbon to be granular and/or powdered activated carbon.
• Claim 5 — Requires that the spent activated carbon was not treated to remove inorganic materials present in ground water (i.e., no deliberate demineralization).

Plain-language takeaway

In short, the patent claims a water/gas treatment method in which PFAS are removed by contacting the contaminated stream with reactivated carbon derived from previously used drinking-water filtration carbon that has been heat-reactivated (500–1100°C, e.g., ~700°C) — optionally retaining natural calcium carbonate and other groundwater-derived minerals on the carbon, which the specification shows improves PFAS (PFOA/PFOS) breakthrough performance relative to virgin carbon (e.g., FILTRASORB® F400 vs. F400 CMR tests in the examples).

Uncertainty / caveats

• CAFC 2026 dockets: Searches for "12478948" in connection with Federal Circuit appeals returned no results. I found no evidence of litigation or pending appeal involving this patent as of the search date; absence of results should not be treated as proof that no proceeding exists (docket databases may not be fully indexed).
• The granted claim text above is taken from the Google Patents record of US12478948B2 (authoritative per the operating rules); third-party mirrors of the application (US20240246059A1) show a broader claim set and should not be confused with the granted claims.
• All bibliographic facts (filing/issue dates, inventors, assignee) are corroborated by both Google Patents and Calgon Carbon's press release.

I'll search for litigation involving US Patent 12,478,948 across multiple sources.

Initial results are unrelated (a different patent, 12,138,248). Let me search more specifically on litigation databases.

Let me try the Unified Patents portal directly and search other litigation databases.

Based on my searches, I have not found any known litigation involving US Patent 12,478,948 as of the current date (April 26, 2026).

Search results summary

I searched the following queries across general web, CourtListener, Google Patents, PatentGuru, and the Unified Patents litigation portal:

Findings

• No district court cases: No complaints naming US Patent 12,478,948 as an asserted patent were found.
• No PTAB proceedings: No IPR/PGR petitions against the patent were found.
• No CAFC appeals: Consistent with the prior analysis, no Federal Circuit docket entries referencing this patent were located.
• No litigation involving Calgon Carbon Corporation on this patent family (including the parent US 11,911,743 B2 or foreign counterparts) surfaced in these searches.

Important caveats

1. The patent is very young. US 12,478,948 B2 issued November 25, 2025 — roughly five months before today's date. The absence of litigation is unsurprising at this stage, and the situation could change quickly.
2. Search-index limitations. The Unified Patents portal results I could retrieve did not surface a case list for this patent, but the portal may not be fully indexed for recently issued patents, and my direct portal access was limited. PACER would be the definitive source for district-court filings, and I could not confirm negative results there with certainty.
3. No evidence ≠ proof of absence. I found no affirmative evidence of litigation, but I cannot rule out that a case exists that is not yet indexed in the sources available to me.

Conclusion: As of April 26, 2026, there is no known litigation — no plaintiffs, defendants, case numbers, filing dates, or outcomes — involving US Patent 12,478,948 that I was able to identify. If litigation has been filed, it is not yet reflected in the publicly indexed sources I searched.

The initial searches surfaced trade-related litigation (antidumping at the Court of International Trade) but not the PGR docket itself. Let me dig deeper for the specific proceeding and any petition details.

Proceedings overview

One PGR is on file — all 5 claims are untested, nothing has been canceled or sustained, and the patent's first (and so far only) AIA challenge was filed yesterday. Per the canonical USPTO Open Data Portal block, there is exactly 1 proceeding: PGR2026-00071, filed 2026-08-21 by Norit Americas, Inc. against Calgon Carbon Corporation, status Pending. Breakdown: 1 pending / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denied. The defensive posture today is "watch this space," not "the patent is dead": the PGR is a serious, strategically timed competitor challenge, but it is one day old, no ground is yet public, and no claim has been canceled. The patent remains presumed valid and enforceable.

PGR2026-00071 — Norit Americas, Inc. v. Calgon Carbon Corporation

• Type: Post-Grant Review (PGR; AIA Chapter 32)
• Filed: 2026-08-21
• Status: Pending (verbatim from USPTO Open Data Portal; last modified 2026-08-21) — plain-English gloss: the petition was filed the day before this analysis; the docket is at its very first procedural step.
• Judge panel: Not yet public. No Administrative Patent Judge panel has been named in any source I could retrieve, and no docket documents for this proceeding surfaced in web searches as of 2026-08-22 (the PTAB E2E and commercial docket indexes do not yet appear to have captured a one-day-old proceeding).
• Petition grounds: Not publicly available as of today. I will not speculate on which claims or which art the petition asserts. Two things are knowable without the petition: (1) PGR is the broadest AIA vehicle — a petitioner may raise any invalidity ground under §§ 101, 102, 103, and 112 (including written-description and indefiniteness), unlike IPR which is limited to § 102/§ 103 prior-art grounds; and (2) the filing was 4 days before the statutory 9-month post-grant window closed — grant date 2025-11-25, PGR deadline 2026-08-25 under 35 U.S.C. § 321(c), filed 2026-08-21. Filing at the tail of the window strongly suggests Norit deliberately preserved access to § 101/§ 112 grounds, which would be foreclosed in an IPR.
• Institution decision: None yet — none is possible this early. The statutory sequence: Calgon's preliminary response is due within 3 months of the notice of filing date (≈2026-11-23, extendable for good cause under 37 C.F.R. § 42.207); the Director's institution decision is then due within 3 months after the preliminary response is filed or, if none, after its deadline (35 U.S.C. § 324(c)) — so expect a decision roughly 2027-02/2027-03 absent extensions.
• Final Written Decision: None. If the PGR is instituted, the FWD is statutorily due within 12 months of institution (35 U.S.C. § 326(a)(11)), extendable by up to 6 months for good cause — i.e., no earlier than roughly 2028 under the current schedule.
• Settlement / termination: None. The proceeding was filed 2026-08-21 and no settlement, termination, or stipulation exists. (Terms would in any event likely be confidential if they ever occur.)
• Appeal: None. No FWD exists, so there is nothing to appeal to the Federal Circuit.
• Defensive value: For a defendant facing assertion today, this proceeding is a live threat, not a completed victory — no claim of US 12,478,948 has been canceled, and you cannot yet cite any PTAB outcome. What it does tell you: a direct commercial competitor believed the patent worth a last-minute, full-scope (including § 112) PGR attack. Monitor institution; if the PTAB institutes, the odds of at least partial claim narrowing materially increase, and the FWD (if adverse to Calgon) would give you a citable disposition.

Strategic summary

Claims CANCELED vs. SUSTAINED vs. UNTESTED. No claims have been canceled and none have been sustained. All five claims (independent claim 1 and dependent claims 2–5) remain UNTESTED — the PGR petition is pending but its grounds are not yet public, and no institution decision has issued. The patent is exactly as it issued on 2025-11-25: claim 1 (reactivated carbon from spent water-filtration carbon, heat-reactivated at ~500–1100°C, contacted with PFAS-bearing liquid/gas), claim 2 (~700°C), claim 3 (calcium carbonate in the spent feedstock), claim 4 (granular and/or powdered form), claim 5 (no deliberate removal of groundwater-derived inorganics).

Estoppel landscape. Two distinct positions matter. For Norit and its privies: if the PGR reaches a FWD, 35 U.S.C. § 325(e)(2) estops them from raising in district court any ground that was raised or reasonably could have been raised in the PGR — meaning Norit itself (and any customer/defendant in privity with it) will be limited in parallel invalidity litigation once the FWD issues. For a defendant NOT in privity with Norit: PGR estoppel does not apply at all. Every § 102/§ 103 ground remains available to you in district court, and you may also file your own IPR in a narrow, currently open window: IPR becomes available to third parties on 2026-08-25 (9 months from grant, per 35 U.S.C. § 311(c)(1)) and stays available only until/unless the PGR is instituted — after institution, § 311(c)(2) bars third-party IPRs until the PGR terminates. If you have stronger art than whatever Norit pled, that window is your only independent PTAB shot for years.

Pattern signals. This is a competitor-versus-competitor challenge, not a defensive-aggregator play (no Unified Patents or similar entity in the chain). Norit Americas and Calgon Carbon are direct rivals in the activated carbon market — both appear together as US producers contesting the Commerce Department's antidumping reviews of Chinese activated carbon at the Court of International Trade (MLex reports, 2025-01-24 and 2026-05-26). That commercial rivalry frames the PGR as a market-share fight over PFAS-treatment carbon, which tends to mean well-resourced, serious advocacy on both sides. There is no pattern of multiple PTAB filings by Norit on this patent, no prior Calgon PTAB advocacy record I can identify, and — per the canonical USPTO block — no other AIA proceeding on US 12,478,948 or (in the data provided) its parent US 11,911,743 B2.

Recommended next steps

• Do not over-claim the PGR. There is no FWD to quote and no disposition to link. The only authoritative proceeding facts are: PGR2026-00071, Norit Americas, Inc. v. Calgon Carbon Corp., filed 2026-08-21, Pending (USPTO Open Data Portal). If a demand letter cites claims 1–5 of US 12,478,948, the correct response is not "the claims are canceled" (they are not) but "these claims are under active, timely post-grant challenge, and assertion is premature."
• Calendar the milestones (all approximate, subject to extension): preliminary response due ≈2026-11-23; institution decision due ≈2027-02/2027-03 under § 324(c); if instituted, FWD due within 12 months of institution (extendable 6 months), i.e., no earlier than ≈2028. Track the docket at USPTO PTAB E2E (search PGR2026-00071); the petition and grounds should become publicly retrievable within days.
• Act on the third-party IPR window now. From 2026-08-25 until PGR institution, a defendant not in privity with Norit can still file its own IPR on § 102/§ 103 grounds. If you have art not already committed to Norit's petition, this is the last independent PTAB opportunity for years — but it closes the moment the Director institutes the PGR.
• Preserve district-court invalidity arguments. Absent privity with Norit, you face no § 325(e)(2) estoppel: you can plead every § 102/§ 103 ground in district court regardless of the PGR's outcome, and you can adopt (and improve on) Norit's grounds once the petition is public.
• Caveat on sources: Web searches as of 2026-08-22 returned no docket documents for PGR2026-00071 — only unrelated proceedings with similar numbers (e.g., Samsung v. Netlist PGR2025-00071 / IPR2026-00071, on different patents) and CIT trade-litigation coverage of Calgon/Norit. All proceeding identity and status data above comes from the canonical USPTO Open Data Portal block in this prompt, which I treat as authoritative; the petition's claims and grounds are unknown to me and I have not fabricated them.

Ownership Chain Analysis — US Patent 12,478,948 (US12478948B2)

Data caveat up front: The USPTO Assignment Center is a JavaScript application not directly crawlable by the search tools available to me, and no reel/frame numbers for this patent's assignments appear in any indexed source I could retrieve (Google Patents legal events, PatentGuru, PubChem patent pages, USPTO.gov mirrors, press coverage). I therefore report the assignment events that are affirmatively documented and flag the reel/frame fields and correspondents as not retrievable from my sources rather than fabricating them. The substantive finding — that ownership never left the original operating assignee — is well-supported.

Inventors

Pattern check: No unusual pattern. Neither inventor departed the assignee after filing — both continue to appear on new Calgon Carbon applications into 2025–2026. There is no "inventors flee, portfolio fire-sale" signature. Both are career staff scientists/engineers at a large operating company (Richard A. Mimna additionally appears on Calgon Carbon sorbent-device patents going back years, e.g., US 11,697,095-family work with Greenbank, Vaughn, Gebhard, Evanovich, Tramposch et al.).

Original assignee

Calgon Carbon Corporation (Moon Township, PA).

• Line of business: Global manufacturer of activated carbon (coal-, wood-, and coconut-based), carbon reactivation services, and water/air treatment systems. The patent's subject matter — reactivated carbon for PFAS removal — is squarely its core commercial business (FILTRASORB® grades, "Custom Municipal React" reactivated carbon, and a proprietary reactivation process with >99.9% PFAS destruction removal efficiency per the company's Dec. 9, 2025 announcement).
• Product embodiment: Yes. Calgon Carbon's Dec. 9, 2025 press release announcing issuance of US 12,478,948 describes the claimed reactivated-carbon PFAS-removal technology as a marketed service: "capturing and destroying PFAS contamination and subsequently returning the recovered activated carbon to continued use," combined with its FILTRASORB® grades. The specification's own Examples test commercial products (F400, F400 CMR, CAL 12X40).
• Current status: Operating. Wholly owned subsidiary of Kuraray Co., Ltd. (TYO: 3405) since Kuraray's 2018 take-private of Calgon Carbon. No bankruptcy, no dissolution, no patent-focused acquisition.

Assignment timeline

The USPTO Assignment Center's underlying records, as reflected in the Google Patents legal-events block for US12478948B2, show exactly two recorded assignments — both routine inventor-to-employer assignments recorded the same day. No post-issuance transfer, security interest, merger, change of name, or license appears in the record. No reel/frame numbers or correspondent names were retrievable from my searchable sources; I have not fabricated them.

• 2024-05-26 (recorded) — Reel/frame not retrievable from available sources

  • Conveyance: Assignment (inventor to assignee)
  • Assignor: Richard A. Mimna (inventor)
  • Assignee: Calgon Carbon Corporation
  • Correspondent: not retrievable (prosecution firm of record on the family is DLA Piper LLP (US) per PatentGuru; whether DLA Piper also served as assignment correspondent is unverified)
  • Context: Standard inventor-assignment recorded ~3 months after the continuation application US 18/442,503 was filed (2024-02-15) — routine prosecution-chain hygiene, not a transfer of ownership.

• 2024-05-26 (recorded) — Reel/frame not retrievable from available sources

  • Conveyance: Assignment (inventor to assignee)
  • Assignor: Rebecca L. Distefano (inventor)
  • Assignee: Calgon Carbon Corporation
  • Correspondent: not retrievable
  • Context: Same-day companion recording for the second co-inventor; identical routine nature.

Net position: Ownership of US 12,478,948 has never left Calgon Carbon Corporation. There are no recorded assignments out of the company — no transfer to any LLC, holding company, patent-assertion entity, or lender. This is the expected profile of a patent still owned and practiced by its original operating assignee.

Timeline diagram

timeline
    title Ownership of US 12478948
    2019 : Priority filed by Calgon Carbon
    2020 : Utility and PCT filed by Calgon Carbon
    2024 : Continuation filed by Calgon Carbon
    2024 : Inventors assign rights to Calgon Carbon
    2025 : Patent issued to Calgon Carbon
    2026 : Norit files PGR challenge

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT. The patent moved only from inventors to their employer (Calgon Carbon Corporation, recorded 2024-05-26). No transfer to any "IP / Patents / Licensing / Holdings / Ventures" LLC appears in the record; the assignee is a 29-patent-grant operating company with manufacturing capacity, not a registered-agent shell.

2. Known asserter in the chain — NOT PRESENT. Neither current nor prior assignee matches any public NPE list (Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, or Spangenberg entities). The only adversarial actor touching this patent — Norit Americas, Inc., petitioner in PGR2026-00071 (filed 2026-08-21) — is a challenger, not a transferee, and is itself an operating company (a direct activated-carbon competitor of Calgon).

3. Repeat correspondent across the chain — NOT PRESENT (as a chain signal); correspondent data unverified. With only two same-day inventor assignments there is no multi-link chain in which a recurring correspondent could be identified. DLA Piper LLP (US) is the family's prosecution firm of record; a single appearance of a firm on routine prosecution work is not an NPE tell, and I found no evidence DLA Piper or any other firm recurs as correspondent across multiple NPE transfers involving this patent.

4. Cascading transfers — NOT PRESENT. Two assignments, one date, both inventor→employer. No chained LLCs, no <24-month cascade, no common-principal shell network.

5. Pre-litigation transfer — NOT PRESENT. The 2024-05-26 assignments predate grant (2025-11-25), not litigation. No infringement suit naming US 12,478,948 has been identified anywhere (see prior litigation analysis: no district-court cases, no PTAB petitions other than Norit's PGR, no CAFC appeals as of the search date).

6. Bankruptcy fire-sale — NOT PRESENT. Calgon Carbon has never been in Chapter 7/11; it was acquired in 2018 by Kuraray as a going concern and remains operating.

7. Privateering — NOT PRESENT. No transfer of the patent to any third-party NPE for assertion on Calgon's behalf. No SEC disclosures or EFF/Patent Progress coverage indicating privateering. Calgon's own press release positions the patent as part of its commercial PFAS-treatment portfolio, which it practices itself.

8. Defensive aggregator (anti-NPE) — NOT PRESENT. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN. The patent remains with its practicing operating owner — which is the opposite of an anti-NPE-neutralized asset.

Verdict

Operating-company assertion.

The assignment record contains only routine inventor-to-employer assignments (recorded 2024-05-26); ownership has remained continuously with Calgon Carbon Corporation, a large operating manufacturer that practices the claimed reactivated-carbon PFAS-removal technology in its commercial FILTRASORB®/reactivation business and announced the grant as a commercial portfolio event (Dec. 9, 2025 press release). No shell transfers, no known-asserter names, no cascades, no pre-litigation conveyances, no bankruptcy, and no privateering appear anywhere in the chain — every NPE signal is absent, and the only proceeding touching the patent is a competitor's PGR challenge (Norit Americas, PGR2026-00071), which is the classic posture of an operating company defending commercially valuable turf, not a troll. The one caveat: no infringement suit by Calgon Carbon against a competitor has been located as of this analysis, so "assertion" is evidenced by practice-plus-competitive-pressure rather than by a filed complaint.

Verify at the USPTO Assignment Center: https://assignmentcenter.uspto.gov/ (patent-number search for 12478948) or the patent index at https://assignment.uspto.gov/patent/index.html. If the full reel/frame and correspondent data are needed (e.g., for a due-diligence deliverable), the Assignment Center's direct query is the authoritative source; my search tooling could not retrieve those specific fields, and I have deliberately not supplied them from inference.

The provided patent text includes a truncated citations list (124 citations). Let me retrieve the full list of cited references.

The full citations list (124 refs) is truncated in the source. Let me retrieve the cited references from the parent patent and the Google Patents citation record.

Prior Art Analysis — US Patent 12,478,948 (US12478948B2)

1. USPTO database search — identifier verification

I searched for patent number 12478948 (application US 18/442,503; continuation of US 16/839,862, now US 11,911,743 B2). The number resolves unambiguously to US12478948B2, "Perfluoroalkyl and polyfluoroalkyl sorbent materials and methods of use" (Calgon Carbon Corporation; Distefano & Mimna; priority 2019-04-03; granted 2025-11-25). No similarly numbered patent (e.g., 12,478,248 or 11,911,743) was substituted — the identifier is confirmed as US 12,478,948, with 5 claims (1 independent). The patent's citation record lists 124 cited references per the Google Patents record.

2. Critical data caveat — the citation list is only partially retrievable

The authoritative Google Patents record supplied with this analysis contains the Citations (124) section, but the text I received is truncated after the fifth entry (cut off mid-title at "Hard granular activa…"). My web searches in this session did not return the remaining 119 citations — the USPTO/Google Patents citation tables are not fully crawlable through the available search tooling, and I reached the session's search-step limit. I will not fabricate the remaining 119 references. What follows is (a) full analysis of the five verified citations from the record, (b) a flagged, knowledge-based identification of the most relevant prior art categories for the granted claims, and (c) a per-claim § 102 assessment. For a complete deliverable, the full citation table must be pulled directly from the Google Patents page (URL: https://patents.google.com/patent/US12478948B2/en → "Citations") or USPTO PATFT/Patent Center.

3. Verified citations (from the patent record) and § 102 analysis

These are the five references affirmatively shown in the supplied patent text. For each: full citation, dates, description, and anticipation potential against granted claims 1–5 (recited in the "Claims" section of the record).

3.1 US 2,038,071 A — "Fluid treating device"

• Full citation: US2038071A — Patent Finance Corp — "Fluid treating device"
• Filing date: 1932-11-09 | Publication date: 1936-04-21
• Description: A pre-war fluid-treating device patent — an apparatus for contacting fluids with a treating medium (a filter/adsorber vessel configuration). It is a hardware/device disclosure, not a sorbent-chemistry or water-remediation method.
• § 102 anticipation potential: None — does not anticipate any claim. It discloses neither reactivated carbon formed from spent water-filtration carbon (claim 1), nor a ~700°C heat reactivation step (claim 2), nor calcium-carbonate-bearing spent feedstock (claim 3), nor PFAS/PFOA/PFOS as a target contaminant. At most it is background on fluid-contacting containers (relevant to the specification's "container/cartridge" passages, which are not claimed).

3.2 US 3,713,281 A — "Heat and moisture exchange packing"

• Full citation: US3713281A — G. Asker — "Heat and moisture exchange packing"
• Filing date: 1971-11-02 | Publication date: 1973-01-30
• Description: A packing medium for heat-and-moisture exchange (air-handling/evaporative media). Unrelated to carbon sorbents, PFAS, or water purification chemistry.
• § 102 anticipation potential: None. No reactivated carbon, no spent-water-filtration-carbon precursor, no PFAS. Not a sorbent-material or water-treatment disclosure relevant to any of claims 1–5.

3.3 US 3,757,488 A — "Gas removal method and composition"

• Full citation: US3757488A — ITT (International Telephone and Telegraph) — "Gas removal method and composition"
• Filing date: 1971-04-27 | Publication date: 1973-09-11
• Description: A gas-removal method and sorbent composition (mid-20th-century gas-purification art). The closest of the five to "sorbent" subject matter, but it concerns gas-phase contaminant removal with unspecified/legacy sorbent compositions — no PFAS, no reactivated carbon provenance, no thermal-reactivation step.
• § 102 anticipation potential: Low/none. Even construed most favorably to the challenger, it lacks (i) reactivated carbon from spent activated carbon previously used for water filtration (claim 1), (ii) the 500–1100°C heat-reactivation limitation (claims 1–2), and (iii) any PFAS (a class of compounds not commercially defined until decades later). Cannot anticipate claims 1–5.

3.4 GB 1,336,241 A — "Purification process"

• Full citation: GB1336241A — Osaka Soda Co., Ltd. — "Purification process"
• Filing date: 1970-02-05 | Publication date: 1973-11-07
• Description: A Japanese-assignee purification process patent — general purification technology (likely adsorption-based treatment of fluids). No PFAS teaching is possible given the era; no reactivated-carbon-from-spent-drinking-water-carbon teaching is evident from the title/record.
• § 102 anticipation potential: None substantiated. Anticipation would require every claim element in this single reference; nothing in the retrievable record indicates disclosure of the PFAS + reactivated-carbon-from-spent-water-filtration-carbon combination of claim 1.

3.5 WO 1981/000399 A1 — "Hard granular activated carbon"

• Full citation: WO1981000399A1 — The Carborundum Company — "Hard granular activated carbon"
• Filing date: 1979-08-01 | Publication date: 1981-02-19
• Description: A PCT application on hard granular activated carbon — i.e., GAC manufacture/hardness (binder/attrition properties). This is the single most topically relevant of the five verified citations because claim 4 of the granted patent requires granular and/or powdered activated carbon. However, granular activated carbon per se is decades-old commodity art; this reference would at most be combinable background for the form limitation (claim 4).
• § 102 anticipation potential: None against claim 1 standing alone; no single-reference anticipation of any claim. It does not disclose reactivation of spent water-filtration carbon, heat reactivation at 500–1100°C, PFAS/PFOA/PFOS as target analytes, or calcium-carbonate-bearing feedstock. It could only serve as a secondary reference (obviousness, § 103) for the granular form — not anticipation (§ 102).

Net on the verified five: none of the five references visible in the record anticipates any of claims 1–5 as a single reference. They are classic "background" citations (device, packing, gas-removal, purification, GAC-formation art) accumulated by the examiner or applicant during prosecution, not blocking art.

4. Most relevant prior art for the granted claims (flagged field knowledge)

The granted claims are narrow and specific: reactivated carbon from spent activated carbon previously used for water filtration, heat-reactivated at ~500–1100°C (e.g., ~700°C), optionally retaining calcium carbonate/groundwater minerals, contacted with PFAS-bearing liquid/gas. The genuinely threatening prior art — i.e., the art a § 102/§ 103 challenger (e.g., Norit Americas, PGR2026-00071) would deploy — falls into three categories. I flag these as from my training data, not verified against the patent's 124-citation list (I could not retrieve the full list this session):

1. GAC reactivation art (pre-2019): The reactivation of exhausted drinking-water-treatment GAC in steam/kilns above ~700–900°C is well-documented commodity practice going back decades (the patent's own specification concedes reactivated carbon is "manufactured by heating spent, exhausted activated carbon in furnaces… using steam as a selective oxidant"). Any pre-2019 patent or publication teaching reactivation of municipal-water spent carbon with heat in the 500–1100°C range would read on claim 1's reactivation element — the key question becomes whether it also discloses PFAS removal by the reactivated product.

2. PFAS adsorption on GAC (pre-2019): By 2019, granular activated carbon was already the "leading solution" for PFOA/PFOS removal (the specification admits this in Background). Pre-2019 disclosures of PFAS removal using GAC — including studies and patents using reactivated carbon — would be the primary § 102 candidates for claim 1's "contacting … with a liquid or gas containing the PFAS" element. EPA/UCMR-era literature and vendor technical literature on PFAS + GAC are the likely wellspring for such grounds.

3. Calcium/metal-bearing carbon sorbents: Pre-2019 disclosures of activated carbon containing calcium/magnesium oxides or carbonates (e.g., from hard-water service or deliberate impregnation) used for contaminant removal — relevant to claims 3 and 5 (calcium carbonate in feedstock; minerals retained from groundwater).

Honest bottom line: based on the record available to me, the most relevant single-reference anticipation candidates cannot be identified with confidence because the full 124-reference citation table was not retrievable in this session. The five verified citations do not anticipate. A complete § 102 mapping requires the full citation list, which is publicly available at the Google Patents page and in the PGR2026-00071 petition (once public — its grounds, filed 2026-08-21, are not yet available).

5. Per-claim § 102 anticipation summary (based on verified citations)

6. Recommended next steps for a complete prior-art deliverable

1. Pull the full citation table from https://patents.google.com/patent/US12478948B2/en (Citations section) — 124 entries, of which only 5 were retrievable here. Run each of the ~119 remaining references through the same per-claim § 102 grid.
2. Monitor PGR2026-00071 (Norit Americas v. Calgon Carbon, filed 2026-08-21): the petition's grounds, once public (PTAB E2E), will identify the challenger's own view of the best § 102/§ 103 art — the highest-value shortcut to the "most relevant prior art" list.
3. For any § 102 theory, require single-reference completeness: every element of claim 1 (reactivated carbon + spent-water-filtration provenance + 500–1100°C heat reactivation + PFAS contact) must appear in one reference; the old device/packing/purification citations in the record cannot carry that load.

Sources: Google Patents record for US12478948B2 (fetched 2026-08-22; authoritative for bibliographic data and the first five citations); PatentGuru inventor page (corroborating bibliographic data); Calgon Carbon Dec. 9, 2025 issuance press release (corroborating grant/assignee). The remaining citations and the PGR petition grounds are explicitly not in my possession, and I have not invented them.

Let me dig deeper into the actual cited references for this patent family and related PFAS/reactivated-carbon prior art.

§ 103 Obviousness Analysis — US 12,478,948 B2

1. Scope, ground rules, and source caveat

This analysis evaluates whether the granted claims (1–5) of US 12,478,948 B2 would have been obvious to a person of ordinary skill in the art (PHOSITA) as of the priority date (April 3, 2019) under 35 U.S.C. § 103, using the KSR framework (predictable variation, substitution of known elements, obvious-to-try).

Source caveat up front: The "Prior Art" section of the patent record ("Citations (124)") is truncated in the materials available to me; only the first five entries are fully visible (US2038071A, US3713281A, US3757488A, GB1336241A, WO1981000399A1). I therefore supplement the visible citation list with search-verified references from the family's prosecution record (e.g., US20210179449A1, cited by the Examiner against the parent application US20200316560A1) and with well-documented commercial prior art in carbon reactivation and PFAS adsorption. Where a reference's content is inferred rather than verified, I say so explicitly rather than fabricating details.

2. The claimed invention (recap — see Patent Summary for full text)

• Claim 1 (independent): Method of removing PFAS from liquid or gas by (a) providing a sorbent material comprising reactivated carbon, (b) the reactivated carbon being formed from a spent activated carbon previously used for water filtration, (c) the reactivated carbon being reactivated by heat at about 500°C to about 1100°C, and (d) contacting the sorbent with the PFAS-containing liquid or gas.
• Claim 2: ~700°C reactivation temperature.
• Claim 3: spent feedstock comprises calcium carbonate.
• Claim 4: granular and/or powdered activated carbon.
• Claim 5: the spent activated carbon was not treated to remove inorganic materials present in ground water.

The inventive contribution, in plain terms, is the recognition that reactivated carbon from spent drinking-water GAC — i.e., carbon that retains natural groundwater minerals (notably CaCO₃ → CaO on reactivation) and is not acid-washed — removes PFAS at least as well as, and per the Examples better than, virgin carbon.

3. The PHOSITA

A PHOSITA would be an engineer or chemist with a B.S./M.S. (or equivalent experience) in environmental/chemical engineering, with several years' experience in drinking-water and wastewater treatment using adsorption media — specifically granular and powdered activated carbon (GAC/PAC), carbon reactivation, and emerging-contaminant (PFAS) treatment. They would know standard test methods (e.g., ASTM D6586 RSSCT), standard reactivation practice, and the EPA's 2016 70-ppt PFOA/PFOS health advisory (referenced in the patent's own Examples).

4. Prior-art landscape (three reference groups)

Group A — PFAS removal with activated carbon (the "why use carbon" art)

• The patent's own Background (§ [0004]): "GAC has emerged as a leading solution" for PFAS removal — an admission that using GAC to remove PFAS was known.
• Mimna (inventor) publications, Feb. and Dec. 2018 (Calgon Carbon): peer-reviewed RSSCT studies of PFOA/PFOS and short-chain PFAS removal with GAC, confirming GAC as the standard PFAS adsorbent and RSSCT as the standard evaluation method before the priority date. (Note: the Dec. 2018 publication falls within the § 102(b)(1) grace period; the Feb. 2018 publication predates the 2019-04-03 effective filing date by >1 year and is potential § 102(a)(1) art, though it is best used as state-of-the-art evidence.)
• US20210179449A1 / EP3810549B1 (Evoqua Water Technologies, priority 2018-08-14) — "Modified Activated Carbon and Methods of Using Same": cited by the Examiner against the parent application US20200316560A1 (asterisked in the family's "Cited By" record). Given its title and the family prosecution context, it addresses modified activated carbons for PFAS removal. Caveat: I could not retrieve its full text in this session; I treat it as § 102(a)(2) art based on its 2018-08-14 priority and its Examiner citation, but I do not assert specific disclosures beyond the title.
• US20170297940A1 (Veolia, 2017): water treatment by adsorption on active carbon with clarification — representative of routine GAC water-treatment practice pre-2019.
• WO1981000399A1 (Carborundum Co., 1981), "Hard granular activated carbon …" — from the visible citation list; supports granular activated carbon as a mature, known sorbent form (relevant to claim 4).

Group B — Thermal reactivation of spent water-treatment carbon (the "how to make reactivated carbon" art)

Thermal reactivation of spent GAC was a mature commercial service decades before 2019. Representative art:

• US2933454A (Pittsburgh Coke & Chemical, 1960) — "Reactivation of spent adsorbent carbon."
• US3816338A (CPC International, 1974) — "Process for the reactivation of powdered carbon."
• US4957721A (1990) — "Process for regeneration of activated carbon."
• DE3344228A1 (Bergwerksverband, 1985) — regeneration of loaded carbon-based adsorption agents.
• General, textbook-level knowledge (confirmed by the patent's own specification and by Evoqua's later description of the known process in US20240417293A1/EP4440994A1): reactivation is "commonly performed by subjecting the carbon to elevated temperatures typically but not limited to temperatures of 700°C to 800°C in a controlled atmosphere including water vapor in a rotating kiln or multiple hearth furnace." The conversion CaCO₃(s) → CaO(s) + CO₂(g) at reactivation temperatures is elementary chemistry recited in the patent's own Detailed Description.

Group C — Mineral-accumulation on water-treatment carbon and mineral-modified carbons

• EP0379041A1 (Rheinbraun, 1990) — process for removing inorganic pollutants from liquids with carbonaceous materials.
• General knowledge: GAC beds treating groundwater/hard water accumulate CaCO₃ scale; the patent itself admits spent municipal-drinking-water carbon "frequently contain[s] significant amounts of inorganic minerals," including calcium carbonate. The idea that calcium/magnesium oxides on carbon surfaces affect adsorption of ionizable organic species is routine sorbent-chemistry knowledge (e.g., the extensive prior literature on CaO/MgO-impregnated and ash-containing carbons for anionic contaminant removal). Caveat: I did not verify a specific pre-2019 reference teaching CaO-modified carbon for PFAS; the Group C combination rests on general knowledge plus the reactivation art.

5. Obviousness of claim 1 — primary combination

Primary combination: Group A (PFAS removal with GAC) + Group B (thermal reactivation of spent water-treatment carbon).

Element-by-element mapping:

Motivation / reason to combine (KSR):

1. Design need and market pressure. Before 2019, PFAS in drinking water was a well-known regulatory and public-health problem (EPA 2016 health advisory; the patent's own Background recites the health concerns). Utilities using GAC for PFAS faced high operating costs because GAC beds exhaust quickly; reactivation was the established cost-reduction route for spent GAC. A PHOSITA designing a PFAS adsorption system would have had a direct economic incentive to select reactivated carbon over virgin carbon.
2. Substitution of a known equivalent. Reactivated carbon was a commercially standard substitute for virgin GAC in municipal water treatment, with restored (typically 90%+) adsorption capacity. Selecting it for PFAS — a contaminant known to be removable by GAC — is the substitution of one known element for another to obtain a predictable result (KSR, 550 U.S. at 416).
3. Obvious to try with a finite set of options. The sorbent universe for PFAS was small (virgin GAC, reactivated GAC, ion exchange, RO — per the patent's own Background). Testing the standard, cheaper, commercially available alternative (reactivated GAC) is squarely the "obvious to try" scenario with a limited number of identified, predictable solutions.
4. The temperature limitation is not inventive. 500–1100°C brackets the standard reactivation window (700–800°C); choosing any temperature in the claimed range is routine optimization of a known process parameter, not a new result.

Conclusion on claim 1: The combination of Group A + Group B renders claim 1 obvious. A PHOSITA would have been motivated to run a PFAS adsorption column with commercially reactivated GAC (from spent municipal carbon, heat-reactivated in the conventional range), and would have had a reasonable expectation of success because reactivated GAC was known to retain its adsorption function for organic contaminants generally and PFAS specifically was known to be GAC-removable.

6. Dependent claims

• Claim 2 (~700°C): 700°C is the textbook center of the conventional reactivation range (700–800°C). It is an obvious, even preferred, process parameter disclosed in the reactivation art itself.
• Claim 3 (feedstock comprising calcium carbonate): This describes the natural state of spent drinking-water GAC. The patent's own specification admits spent municipal carbon contains calcium carbonate scale (and Ca, Mg, Na, K, Zn ions/oxides/carbonates). A PHOSITA using spent municipal carbon as the Group B feedstock would inevitably encounter CaCO₃-laden material; the limitation adds no inventive step — it is an inherent property of the claimed feedstock.
• Claim 4 (granular and/or powdered): GAC and PAC are the two standard commercial forms of activated carbon (the patent's own definitions of GAC/PAC by 50-mesh/80-mesh sieves are industry-standard definitions). Selecting either form for the adsorption column is an obvious design choice, supported by WO1981000399A1 (granular carbon) and US3816338A (powdered carbon reactivation).
• Claim 5 (no treatment to remove groundwater inorganics): This is a negative limitation — it merely excludes an optional acid-wash step. Prior-art reactivation processes (Group B) do not require acid washing; skipping an optional purification step is the obvious default. Any benefit from retained minerals (CaO) would have been expected by a PHOSITA familiar with mineral-modified carbons (Group C), and is in any event an inherent result of reactivating unwashed spent carbon rather than a new discovery.

7. Secondary considerations — counter-analysis (why the patent owner would resist, and why it likely fails)

• Unexpected results. Calgon's strongest argument is the Examples: F400 CMR (0.36% Ca) and CMR High Ca (~2% Ca) delayed PFOA/PFOS breakthrough vs. virgin F400 (Figs. 1–7). Counter-arguments: (i) the granted claims do not require any elevated mineral content, any specific Ca level, or any performance improvement — they cover any reactivated carbon from spent water-treatment carbon, so the demonstrated improvement is narrower than the claim; (ii) the improvement tracks the known CaO content, and a PHOSITA would have expected mineral oxides on carbon to interact with anionic PFAS species (electrostatic/surface-complexation effects of CaO/MgO on carbon are known sorbent chemistry); (iii) the data are small-scale RSSCT runs at single inlet concentrations, not proof of genus-wide unexpected superiority. Also notable: in the patent's own Table 3/Fig. 7, the acid-washed CMR (0.65% Ca) performed worst, while the virgin carbon outperformed it — showing performance is not a simple function of the claimed structural features.
• Long-felt need / commercial success. PFAS removal was indeed a long-felt need, but the solution space was already occupied by GAC; the invention is a materials substitution within that known solution, not a new solution. Calgon's commercial success with reactivation services is tied to its business model and to regulatory pressure, not demonstrated to be causally attributable to the claimed method.
• Prosecution history. The claims were materially narrowed from the as-filed 0.5–25 wt.% Group 2 treatment claims to the reactivated-carbon-from-spent-water-carbon claims — consistent with the applicant conceding the broader treatment claims and resting on the commercial reactivation embodiment. Narrowing does not create non-obviousness; the surviving claims are the ones that most closely track the known commercial practice.

8. Realistic assessment of the obviousness case

Strongest obviousness theory: Claim 1 = Group A (GAC-for-PFAS, admitted to be the leading solution) + Group B (decades-old thermal reactivation of spent municipal GAC at conventional temperatures). This is a classic substitution-of-known-elements combination. Dependent claims 2, 4, and 5 are very weak under challenge — they recite a standard temperature, standard physical forms, and the mere omission of a washing step. Claim 3 describes an inherent property of the feedstock.

Most vulnerable point for the challenger: whether a PHOSITA would have had a reasonable expectation that reactivated carbon would remove PFAS adequately, given a general industry perception that reactivated carbon can be slightly inferior to virgin (e.g., 5–10% attrition/activity loss per the later Evoqua description of the known process). The answer for § 103 purposes is that the claim does not require equal-or-better performance — it requires only that reactivated carbon remove PFAS when contacted, and reactivated GAC was already in routine drinking-water service for organic contaminants. Adequacy, not superiority, is all the claim demands, and adequacy was predictable.

What I could not verify (and did not fabricate): the full 124-reference citation list (truncated), the complete disclosure of Evoqua's US20210179449A1, and any pre-2019 reference specifically teaching CaO-modified carbon for PFAS. The core combination above does not depend on those unverified items.

9. Relationship to the pending PGR

Norit Americas' PGR2026-00071 (filed 2026-08-21, four days before the statutory § 321(c) window closed) is pending; its grounds are not yet public, so I do not speculate on whether Norit's grounds mirror the combinations above. Notably, PGR permits § 112 (written description/indefiniteness) and § 101 grounds in addition to § 102/§ 103, and the late-window filing suggests the petitioner wanted access to the full-scope vehicle. A § 103 case of the type outlined above — using Group A + Group B and the "inherent CaCO₃/CaO in spent municipal carbon" rationale — is well-suited to PGR because it depends heavily on the patent's own admissions (Background, reactivation description, CaCO₃→CaO reaction, and Examples), which are available on the face of the specification.

10. Bottom line

Claims 1, 2, 4, and 5 of US 12,478,948 B2 present a strong § 103 case: the claimed method is the routine combination of (i) the known use of GAC for PFAS removal and (ii) the decades-old practice of thermally reactivating spent municipal drinking-water carbon at 500–1100°C (conventionally ~700–800°C), with claims 2/4/5 adding only conventional parameters, standard physical forms, and the omission of an optional acid-wash step. Claim 3 adds an inherent property of the feedstock. The patent's asserted improvement is real but is narrower than the claims and attributable to a known variable (retained CaO), which undercuts the "unexpected results" counterargument. The principal open question — whether the patent owner can show the reactivated-carbon-for-PFAS selection produced results the art would not have predicted — is the battleground, but on the current record the claims read as obvious to a PHOSITA.