{
    "title": "Shock Electrodialysis Desalination",
    "inventor_name": "Martin Z. Bazant",
    "publication_year": 2015,
    "device_name": "Shock Electrodialysis",
    "goal": "Remove salt and contaminants from water to produce potable water.",
    "problem_addressed": "High energy and fouling issues of conventional desalination; need for portable, low-maintenance water purification, especially for fracking wastewater and remote locations.",
    "concept_summary": "An electrically driven shockwave is generated inside a porous medium (glass frit) through which salty water flows. The shock creates a sharp ion-concentration gradient, pushing fresh water to one side and brine to the other, allowing simple physical separation without traditional membranes.",
    "detailed_description": "Water flows through a porous glass frit sandwiched between electrodes (and optionally ion-selective membranes). When a voltage is applied, an over-limiting current drives electro-osmotic flow and surface conduction, producing a deionization shock that propagates against the flow. The shock divides the channel into a depleted (fresh water) region and an enriched (brine) region. The two streams are collected separately. Laboratory prototypes demonstrated continuous operation with >99 % ion removal and water recoveries up to 79 % due to electro-osmotic pumping.",
    "principles": [
        "Over-limiting current",
        "Electro-osmotic flow",
        "Deionization shock propagation",
        "Ion concentration polarization"
    ],
    "scientific_domains": [
        "Electrochemistry",
        "Chemical Engineering",
        "Fluid Mechanics"
    ],
    "mechanisms_of_action": [
        "Electric field induced ion migration",
        "Shockwave driven ion segregation",
        "Electro-osmotic pumping"
    ],
    "materials": [
        "Silica glass frit (porous medium)",
        "Nafion cation-selective membrane",
        "Metal electrodes (e.g., copper, silver)",
        "Aqueous electrolyte (e.g., NaCl solution)"
    ],
    "energy_sources": [
        "Electric power"
    ],
    "inputs": [
        "Salty water feed",
        "Applied voltage/current"
    ],
    "outputs": [
        "Fresh (desalinated) water",
        "Brine (concentrated salt) stream"
    ],
    "claimed_performance": "Removes >99 % (up to 99.99 %) of salt from 1-100 mM feeds; water recovery up to 79 % in laboratory prototype.",
    "experimental_evidence": "Laboratory demonstration of a continuous, scalable shock electrodialysis cell reported in *Environmental Science & Technology Letters* (2015) and *Langmuir* (2013); prototype achieved the ion removal and water recovery figures above.",
    "replication_status": "Only the MIT/Stanford research group has reported experimental results; no independent replication mentioned.",
    "keywords": [
        "shock electrodialysis",
        "deionization shock",
        "over-limiting current",
        "electro-osmotic flow",
        "water desalination",
        "porous media"
    ],
    "related_technologies": [
        "Reverse osmosis",
        "Electrodialysis",
        "Capacitive deionization",
        "Membrane filtration"
    ],
    "controversy_level": "low",
    "confidence_score": 0.86,
    "practicability_score": 0.71,
    "fringe_score": 0.18,
    "evidence_strength": 0.65,
    "risk_score": 0.12,
    "trl_estimate": 4,
    "source_urls": [
        "http://news.mit.edu/2015/shockwave-process-desalination-water-1112",
        "http://pubs.acs.org/doi/abs/10.1021/la4040547",
        "http://pubs.acs.org/doi/abs/10.1021/acs.estlett.5b00303",
        "https://www.youtube.com/watch?v=pyFdE6PsIk8",
        "http://web.mit.edu/bazant/www/papers/pdf/Deng_2014_Desalination.pdf"
    ],
    "organizations": [
        "MIT (Massachusetts Institute of Technology)",
        "Stanford University",
        "MIT Energy Initiative",
        "Weatherford International",
        "USA-Israel Binational Science Foundation",
        "SUTD-MIT Graduate Fellows Program"
    ],
    "applications": [
        "Desalination of seawater and brackish water",
        "Treatment of hydraulic fracturing (fracking) wastewater",
        "Portable emergency water purification",
        "Industrial process water recycling"
    ],
    "limitations": [
        "Not yet competitive with reverse osmosis for large-scale seawater desalination",
        "Requires electrical power and appropriate electrode/ membrane materials",
        "Scaling from laboratory cell to multi-thousand-cell stacks remains unproven"
    ],
    "open_questions": [
        "Long-term durability of porous glass frits under high current densities",
        "Energy efficiency and cost at commercial scale",
        "Effectiveness against a broad range of contaminants (e.g., heavy metals, pathogens)"
    ],
    "red_flags": [],
    "evidence_quotes": [
        "\"Our prototype continuously removes over 99 % (and up to 99.99 %) of salt from diverse electrolytes over a range of concentrations (1, 10, and 100 mM).\"",
        "\"Enhanced water recovery with increasing current (up to 79 %) is a fortuitous discovery, which we attribute to electro-osmotic pumping.\"",
        "\"The apparatus consists of a silica glass frit (1 mm thick with a 500 nm mean pore size) in an aqueous electrolyte (CuSO_4 or AgNO_3) passing ionic current from a reservoir to a cation-selective membrane (Nafion).\"",
        "\"Above the limiting current, deionized water (~=10^-^1/_4 M) can be continuously extracted from the frit, which implies the existence of a stable shock propagating against the flow.\"",
        "\"The breakthrough here is the engineering of a practical system, a continuous process using water flowing through cheap porous media, that should be relatively easy to scale up for desalination or water purification.\""
    ],
    "category": "Electromagnetism & Magnetism"
}