{
    "title": "Graphene Oxide Filter",
    "inventor_name": "Rahul Nair",
    "publication_year": 2014,
    "device_name": "Graphene Oxide Membrane Filter",
    "goal": "Provide ultrafast, highly selective water filtration and desalination by allowing only water and very small ions to pass through graphene-oxide nano-capillaries.",
    "problem_addressed": "Efficient removal of water from mixtures (seawater, industrial gases, liquids) and selective separation of salts and small ions for drinking water, dehydration, and concentration processes.",
    "concept_summary": "Multilayer graphene-oxide laminates form nano-capillaries that are impermeable to gases and most liquids but allow rapid permeation of water monolayers. The membranes exhibit size-exclusion (~=9 Angstrom cutoff) and ion-sponging, enabling ultrafast desalination and pervaporation without high pressure or temperature.",
    "detailed_description": "The invention uses a composite membrane consisting of a graphene-oxide layer deposited on a porous support (ceramic or polymeric). Water molecules are drawn through the sub-nanometer channels by capillary action, while larger ions and molecules are blocked. The membrane can be operated in pervaporation, gas-phase separation, or continuous flow modes, and may be used in detectors, gas drying, or concentration steps. The selective permeability arises from the low-friction graphitic structure of graphene oxide and the tunable pore size of the laminate.",
    "principles": [
        "Capillary action",
        "Size-exclusion (nanopore filtering)",
        "Selective permeability",
        "Pervaporation",
        "Ion sponging"
    ],
    "scientific_domains": [
        "Materials Science",
        "Chemical Engineering",
        "Nanotechnology",
        "Fluid Mechanics"
    ],
    "mechanisms_of_action": [
        "Water molecules permeate through sub-nanometer graphene-oxide channels",
        "Small ions are adsorbed and concentrated within the channels (ion sponging)",
        "Pressure or vacuum can enhance flow but is not required"
    ],
    "materials": [
        "Graphene oxide",
        "Porous ceramic support (alumina, zeolite, silica)",
        "Porous polymeric support (PTFE, PVDF, polycarbonate)",
        "Ceramic",
        "Polymer"
    ],
    "energy_sources": [
        "Pressure differential",
        "Vacuum (optional)"
    ],
    "inputs": [
        "Water-containing mixture (liquid or gas)",
        "Optional pressure or vacuum"
    ],
    "outputs": [
        "Filtered water",
        "Dehydrated product",
        "Concentrated solution"
    ],
    "claimed_performance": "Water flow rates up to 10 x faster than helium; ion exclusion for species >9 Angstrom; ion concentration inside membrane hundreds of times higher than external solution; ultrafast filtration comparable to a coffee filter but with atomic-scale selectivity.",
    "experimental_evidence": "The authors reported in Science (Feb 14 2014) that graphene-oxide laminates allow ultrafast flow of two water monolayers and block ions larger than 9 Angstrom. Earlier work (Science 2012) showed water permeation 10 x faster than helium through 1 um-thick GO membranes.",
    "replication_status": null,
    "keywords": [
        "Graphene oxide",
        "Nanofiltration",
        "Desalination",
        "Pervaporation",
        "Ion sponging",
        "Selective membrane"
    ],
    "related_technologies": [
        "Reverse osmosis",
        "Nanofiltration membranes",
        "Polymeric pervaporation membranes",
        "Graphene-based separation technologies"
    ],
    "controversy_level": "low",
    "confidence_score": 0.9,
    "practicability_score": 0.7,
    "fringe_score": 0.2,
    "evidence_strength": 0.6,
    "risk_score": 0.1,
    "trl_estimate": 6,
    "source_urls": [
        "https://www.rexresearch.com/graphene-water-filter",
        "https://patents.google.com/patent/US2015231577"
    ],
    "organizations": [
        "University of Manchester"
    ],
    "applications": [
        "Drinking-water desalination",
        "Industrial gas drying",
        "Food-industry concentration (juice, milk)",
        "Fuel system dehydration",
        "Laboratory detector systems"
    ],
    "limitations": [
        "Scalability of large-area GO membrane production",
        "Potential fouling and membrane degradation over time",
        "Need for precise control of pore size (<9 Angstrom)",
        "Performance with real seawater containing organics and bio-fouling agents"
    ],
    "open_questions": [
        "Long-term durability and reuse cycles of GO membranes",
        "Cost-effective manufacturing at commercial scale",
        "Effectiveness for complex mixtures (e.g., seawater with microbes)",
        "Optimal porous support material for maximum flux"
    ],
    "red_flags": [],
    "evidence_quotes": [
        "\"The thin membranes made from such laminates were impermeable to all gases and vapours, except for water.\"",
        "\"If immersed in water, the laminates become slightly swollen but still allow ultrafast flow of not one but two monolayers of water.\"",
        "\"Small salts with a size of less than nine Angstroms can flow along but larger ions or molecules are blocked.\"",
        "\"Those ions that can go through do so with such a speed as if the graphene membranes were an ordinary coffee filter.\"",
        "\"The graphene capillaries suck up small ions as powerful hoovers leading to internal concentrations that can be hundreds of times higher than in external salty solutions.\""
    ],
    "category": "Water Harvesting & Atmospheric Water"
}