{ "schema": "auturnal.deep-research-review.v2", "slug": "water-harvesting-sorption", "title": "Harvesting Water from Dry Air: Sorption Thermodynamics, Cycling and Delivered Yield", "category": "Materials and resources", "dek": "An atmospheric water harvester must adsorb, release, condense and collect water repeatedly.", "english": "An atmospheric water harvester must adsorb, release, condense and collect water repeatedly. Equilibrium sorption capacity describes only one part of that cycle. This review connects metal-organic-framework demonstrations to working capacity, cycle kinetics and heat rejection, establishing a consistent boundary for comparing delivered water rather than isolated material uptake.", "abstract": "An atmospheric water harvester must adsorb, release, condense and collect water repeatedly. Equilibrium sorption capacity describes only one part of that cycle. This review connects metal-organic-framework demonstrations to working capacity, cycle kinetics and heat rejection, establishing a consistent boundary for comparing delivered water rather than isolated material uptake.", "refs": [ "ef-16-1", "ef-16-2", "ef-16-3" ], "sections": [ [ "A material does not deliver a glass of water", "Water captured inside a sorbent is not yet collected liquid. It must be released under practical thermal conditions, transported to a condenser and recovered without excessive loss. A high equilibrium uptake can coexist with low daily production when desorption is slow or condensation is inefficient. The correct system metric is delivered water under declared environmental and energy conditions.", [] ], [ "Demonstrations at different boundaries", "Kim and colleagues demonstrated solar-driven water harvesting with a metal-organic framework under low-humidity conditions. Fathieh and colleagues tested practical atmospheric harvesting in desert air. Hanikel and colleagues studied rapid cycling with a metal-organic framework. These papers address material capability, field operation and cycling productivity. Projected capacity, collected water per cycle and daily yield are different metrics and should remain distinct.", [ "ef-16-1", "ef-16-2", "ef-16-3" ] ], [ "Working capacity is a difference", "Useful uptake is the difference between loading at adsorption conditions and residual loading after regeneration. A material that binds water strongly can have high maximum capacity but retain much of it during practical release. The full adsorption-desorption cycle therefore matters more than the highest point on one isotherm. Hysteresis and structural changes can further alter the available working window.", [] ], [ "Kinetics competes with equilibrium", "Reaching equilibrium may take longer than the available nighttime adsorption period. Thin sorbent layers can improve transport but reduce material per device volume. Faster cycling can increase daily output even when each cycle collects less water. An optimization that maximizes uptake per kilogram alone can therefore miss a more productive device architecture.", [] ], [ "Regeneration has a heat budget", "Heating the sorbent and its support, desorbing water and compensating thermal losses all require energy. Solar heat is an input even when it carries no electricity bill. Reporting water yield without the collector area, irradiation history and auxiliary power obscures the system boundary. Heat recovery can improve performance, but its benefit must be measured at the device level.", [] ], [ "The condenser can become the bottleneck", "Released vapor must encounter conditions that permit condensation. Ambient temperature, condenser area and heat rejection determine the recoverable fraction. A sorbent can release water successfully while much of it escapes uncollected. Measuring both desorbed vapor and collected liquid identifies this loss and prevents material improvements from being credited with a system benefit they did not produce.", [] ], [ "Climate averages can mislead", "Relative humidity changes with temperature, and an average daily humidity does not reproduce the actual adsorption window. A device may perform well during brief favorable periods but poorly across the full season. Field evaluation should preserve hourly conditions, downtime and unsuccessful cycles. Comparing devices at the same nominal humidity but different temperatures can also conceal different vapor pressures.", [] ], [ "Water quality and durability complete the metric", "Repeated cycling can alter sorbent structure, support materials and collected-water composition. A useful deployment assessment includes durability, contamination control and maintenance, alongside yield. The analysis here concerns transport and accounting, not a claim that any constructed system produces drinking water. Independent quality measurements are necessary before assigning that use.", [] ], [ "A daily yield combines several incompatible maxima", "Maximum equilibrium uptake, maximum cycle count and maximum collection efficiency may occur under different operating conditions. Multiplying their separate best values creates a device that may never exist. A proposed test would measure them jointly over complete cycles, including heating, cooling and condensation. Water collected should be weighed at the outlet, while energy accounting includes regeneration and any fans or pumps. The comparison should specify ambient temperature and humidity trajectories rather than one favorable point. The linear cycle-count figure intentionally holds uptake swing fixed; it illustrates bookkeeping, not an engineering promise that more cycles preserve the same swing.", [] ], [ "The correct denominator depends on the use case", "Yield per sorbent mass is informative for material comparison but can favor a heavy or energy-intensive device when used as a system metric. A portable collector may be constrained by total mass; a stationary installation by area, energy supply or maintenance. A proposed operating map would report delivered water per total device mass, per collection area and per supplied energy under the same cycle. These are not interchangeable rankings. Water quality and long-term material stability are separate requirements, and a high initial yield does not establish either. A credible comparison keeps those endpoints visible instead of compressing them into one headline capacity.", [] ], [ "A model that can be challenged", "The four equations below are a compact analytical model, not a joint fit to all the cited papers. Their interpretation is as follows. A Langmuir isotherm is used only as an illustrative equilibrium relation; cooperative water adsorption in real frameworks can differ substantially. Working capacity is the loading change between actual adsorption and desorption conditions. A first-order uptake approximation exposes finite-time losses; transport-limited devices can require distributed models. Delivered water Y depends on sorbent mass, working capacity, completed cycles n and collection fraction eta_c.\nThe observational target is collected liquid water per device area and declared energy input. The model deliberately isolates a tractable mechanism; its purpose is to reveal which measurements would distinguish that mechanism from an alternative. Parameter values in the figures are declared illustrative inputs. A curve produced by those values is a mathematical consequence, not an estimate of an unmeasured biological or physical quantity.", [] ], [ "A discriminating validation design", "The primary comparison should test delivered yield at matched environmental and energy boundaries. The unit of independent replication is independently operated device cycle; repeated readings from the same unit improve precision but do not create independent replication. A strong validation would hold out different climates and seasonal operating windows before choosing thresholds or fitting nuisance corrections. In particular, finite cycling time and condenser losses must be measured, constrained or varied in a sensitivity analysis. Report both the principal estimate and how it changes when that assumption is relaxed. A model that succeeds only after choosing the most favorable exclusion rule has answered a different question from one evaluated with a locked rule.", [] ], [ "Worked numerical analysis", "For a constructed device with one kilogram of sorbent, working capacity 0.2 kilograms of water per kilogram, two completed cycles and collection fraction 0.7, daily delivered water is 0.28 kilograms. Doubling cycles only doubles yield if working capacity and collection remain unchanged. In the kinetic model, kt = 1 reaches 63.2% of equilibrium uptake, while kt = 3 reaches 95.0%. The plots separate equilibrium loading from finite-time productivity.\nThese calculations can be reconstructed from the companion Python file and its parameter table. Axis labels retain the model's units, and the caption distinguishes the quantities varied from those held fixed. The numerical examples were selected to expose a dependency, not to reproduce the appearance of a published figure. A useful independent check is to evaluate a limiting case and then recompute an intermediate point without the plotting code. Agreement validates the arithmetic within the declared model; it does not establish that nature follows that model.", [] ], [ "Evidence, transfer and next steps", "The scope of the conclusion is limited by finite cycling time and condenser losses. Transfer to different climates and seasonal operating windows requires evidence beyond fitting the original observations. A future replication should preserve raw measurements, calibration records, exclusions and a machine-readable link between each result and the corresponding analysis. The evidence table below identifies what each selected primary study contributes. The comparison is a focused narrative synthesis, not a systematic review or a claim that all subsequent evidence has been surveyed. The proposed study has not been performed here. Its value is that a negative result would constrain an explicit explanation rather than merely lower a benchmark score.", [] ] ], "equations": [ { "tex": "q(p)=q_m\\frac{bp}{1+bp}", "explanation": "A Langmuir isotherm is used only as an illustrative equilibrium relation; cooperative water adsorption in real frameworks can differ substantially." }, { "tex": "\\Delta q=q_{ads}-q_{des}", "explanation": "Working capacity is the loading change between actual adsorption and desorption conditions." }, { "tex": "q(t)=q_{eq}(1-e^{-kt})", "explanation": "A first-order uptake approximation exposes finite-time losses; transport-limited devices can require distributed models." }, { "tex": "Y=m_s\\Delta q\\,n\\eta_c", "explanation": "Delivered water Y depends on sorbent mass, working capacity, completed cycles n and collection fraction eta_c." } ], "table": { "headers": [ "Evidence or design choice", "What it identifies", "What remains unresolved" ], "rows": [ [ "Source 1", "A MOF-based device demonstrated solar-driven low-humidity water harvesting.", "Material uptake and projected output are not identical to field yield." ], [ "Source 2", "Desert testing examined practical collection from atmospheric moisture.", "Weather, device geometry and cycle conditions constrain comparison." ], [ "Source 3", "Rapid cycling increased the relevance of kinetic performance.", "Cycle speed alone does not establish full-system energy or water quality." ], [ "Primary observable", "collected liquid water per device area and declared energy input", "finite cycling time and condenser losses" ], [ "Independent test", "delivered yield at matched environmental and energy boundaries", "Requires new measurements" ], [ "Transfer set", "different climates and seasonal operating windows", "Not validated by the constructed numerical example" ] ] }, "protocol": [ "Specify collected liquid water per device area and declared energy input before fitting.", "Retain independent identifiers for each independently operated device cycle.", "Separate different climates and seasonal operating windows from model development.", "Measure or bound finite cycling time and condenser losses.", "Record units, calibration and the observation operator.", "Compare the primary model with a named rival explanation.", "Prespecify the test: delivered yield at matched environmental and energy boundaries.", "Archive raw data, exclusions, parameter files and executable analysis." ], "limitations": [ "Material uptake and projected output are not identical to field yield.", "Weather, device geometry and cycle conditions constrain comparison.", "Cycle speed alone does not establish full-system energy or water quality.", "Companion figures are constructed analytical examples, not new experimental results.", "Transfer to different climates and seasonal operating windows has not been demonstrated by this review." ], "evidence": [ { "source": "ef-16-1", "result": "A MOF-based device demonstrated solar-driven low-humidity water harvesting.", "boundary": "Material uptake and projected output are not identical to field yield.", "locator": "Abstract / selected primary-source sections; see linked bibliographic record." }, { "source": "ef-16-2", "result": "Desert testing examined practical collection from atmospheric moisture.", "boundary": "Weather, device geometry and cycle conditions constrain comparison.", "locator": "Abstract / selected primary-source sections; see linked bibliographic record." }, { "source": "ef-16-3", "result": "Rapid cycling increased the relevance of kinetic performance.", "boundary": "Cycle speed alone does not establish full-system energy or water quality.", "locator": "Abstract / selected primary-source sections; see linked bibliographic record." } ], "research_questions": [ "Which loss dominates between sorption and collected liquid?", "How does the optimal cycle change with hourly climate?", "Can long-term cycling preserve both yield and water quality?" ], "diagram": [ "Ambient vapor", "Working sorption window", "Regeneration and condensation", "Collected water" ], "keywords": [ "Materials and resources", "water-harvesting-sorption", "measurement", "identifiability" ], "kind": "ai_assisted_research_guide", "author": "Codex (AI)", "original_language": "en", "created_date": "2026-10-22", "published_date": "2026-10-22T13:02:56+00:00", "publication_status": "published_commissioned_review", "version": 5, "previous_version": "/guides/water-harvesting-sorption/v4/", "analytic": "water-harvesting-sorption", "peer_reviewed": false, "journal_publication": false, "disclosure": { "authorship": "Source-based research review and original mathematical analysis written by Codex (AI). Cited experiments belong to the cited research teams.", "figures": "Concept cover created with the built-in ImageGen tool. Quantitative figures are explicit constructed analyses, with code and numerical data; they are not measurements from the cited papers.", "review": "This local draft has no independent peer-review or journal-acceptance record." }, "revision_note": "First English local draft; upload and publication deferred at the owner's request.", "review_scope": "A focused narrative analysis of the named primary studies, not a systematic literature search or a claim to comprehensive coverage through 2026.", "section_kinds": [ "author_analysis_or_verification_proposal", "source_based_review", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal", "author_analysis_or_verification_proposal" ], "source_slug": "water-harvesting-sorption", "source_revision": "41dc5ea7bf1db9868e2ee5b121f7021c823cc018", "source_article_sha256": "8057be5763ce1d14d7ef00eb2528c3c3e78740921712644627dd1291f8ce4e27", "sources": [ { "id": "ef-16-1", "doi": "10.1126/science.aam8743", "url": "https://doi.org/10.1126/science.aam8743", "title": "Water harvesting from air with metal-organic frameworks powered by natural sunlight", "authors": [ { "given": "Hyunho", "family": "Kim" }, { "given": "Sungwoo", "family": "Yang" }, { "given": "Sameer R.", "family": "Rao" }, { "given": "Shankar", "family": "Narayanan" }, { "given": "Eugene A.", "family": "Kapustin" }, { "given": "Hiroyasu", "family": "Furukawa" }, { "given": "Ari S.", "family": "Umans" }, { "given": "Omar M.", "family": "Yaghi" }, { "given": "Evelyn N.", "family": "Wang" } ], "journal": "Science", "year": 2017, "article_slug": "water-harvesting-sorption", "verified_date": "2026-10-22", "verification": "DOI/title/authors/journal metadata checked against Crossref. Narrative claims were scoped to accessible primary publisher or author records, abstracts and selected text; full-text and supplementary-methods coverage is not exhaustive.", "source_article_slug": "water-harvesting-sorption" }, { "id": "ef-16-2", "doi": "10.1126/sciadv.aat3198", "url": "https://doi.org/10.1126/sciadv.aat3198", "title": "Practical water production from desert air", "authors": [ { "given": "Farhad", "family": "Fathieh" }, { "given": "Markus J.", "family": "Kalmutzki" }, { "given": "Eugene A.", "family": "Kapustin" }, { "given": "Peter J.", "family": "Waller" }, { "given": "Jingjing", "family": "Yang" }, { "given": "Omar M.", "family": "Yaghi" } ], "journal": "Science Advances", "year": 2018, "article_slug": "water-harvesting-sorption", "verified_date": "2026-10-22", "verification": "DOI/title/authors/journal metadata checked against Crossref. Narrative claims were scoped to accessible primary publisher or author records, abstracts and selected text; full-text and supplementary-methods coverage is not exhaustive.", "source_article_slug": "water-harvesting-sorption" }, { "id": "ef-16-3", "doi": "10.1021/acscentsci.9b00745", "url": "https://doi.org/10.1021/acscentsci.9b00745", "title": "Rapid Cycling and Exceptional Yield in a Metal-Organic Framework Water Harvester", "authors": [ { "given": "Nikita", "family": "Hanikel" }, { "given": "Mathieu S.", "family": "Prévot" }, { "given": "Farhad", "family": "Fathieh" }, { "given": "Eugene A.", "family": "Kapustin" }, { "given": "Hao", "family": "Lyu" }, { "given": "Haoze", "family": "Wang" }, { "given": "Nicolas J.", "family": "Diercks" }, { "given": "T. Grant", "family": "Glover" }, { "given": "Omar M.", "family": "Yaghi" } ], "journal": "ACS Central Science", "year": 2019, "article_slug": "water-harvesting-sorption", "verified_date": "2026-10-22", "verification": "DOI/title/authors/journal metadata checked against Crossref. Narrative claims were scoped to accessible primary publisher or author records, abstracts and selected text; full-text and supplementary-methods coverage is not exhaustive.", "source_article_slug": "water-harvesting-sorption" } ], "original_source_url": "/guides/assets/v9-english-frontiers-articles-water-harvesting-sorption-json-8057be5763ce1d14.json", "pdf": { "document_id": "fd11bf15-16c3-54d0-bdfe-8c0eabbfe174", "version_id": "7913d189-6864-5c2f-9547-c7bc3343ee1f", "media_type": "application/pdf", "authentication_required": true, "download_audited": true }, "presentation_change": "Complete version-bound translated reading views and selectable authenticated original/translated PDFs; original scientific text and evidence retained.", "source_locale": "en", "source_version_id": "45b70cad-848e-5c85-b307-906573f9fcc3", "translations": [ { "locale": "zh", "translation_id": "7820d19b-1f7e-56b0-ab15-dc537865e0d1", "translated_content_sha256": "e66205056afd5c36fe64e56daf782d43232ea450a10f0f59ffd9c1bd890079fd", "sha256": "cb7dc5c7f04df947e3f997bdaec5b6b282251cb3359d9ae246b5572db6d4244a", "byte_length": 948398 }, { "locale": "es", "translation_id": "50e1283d-0ae0-583e-9fbe-b3049681767c", "translated_content_sha256": "c9ee7cae56661fec1c7ac66ebd1f7bda67f90a2f218bc718d4b2863c51cf3afe", "sha256": "f9766f87e3193c2f2a7d088459b034b66203a1d6f79bbb1304f57b7a75f9b888", "byte_length": 712860 }, { "locale": "ja", "translation_id": "93e7e34b-7019-5c57-96e0-2f723436a6b4", "translated_content_sha256": "24f58748a8cd276c37b5dbc0d52b3ad1009b3943dafa0bb31f9bf92393861a7f", "sha256": "2fbc9a739bde783dc20e9e8be082c49656e15c22a1d490c9d8a4d9b3e8ed41a6", "byte_length": 912756 }, { "locale": "ar", "translation_id": "15475fdb-0b17-59b4-91d5-6f324437b14a", "translated_content_sha256": "57f6370e523197587bfec9971c966bbd5882161fecaf6a3a9cb69531184af237", "sha256": "5c1b5f52014433e6778ac8ea107936d7f129040d4483d2ddb71de2041e0c99c4", "byte_length": 697067 } ] }