# Ideal Donnan Multivalent Membrane Partition & Electroneutrality Calculator

> Ideal Donnan Multivalent Membrane Partition & Electroneutrality Calculator is a paid API for AI agents from detect.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-11-01).

Computes the ideal ionic partition coefficients and Donnan potential for a charged membrane in equilibrium with a multi-ion solution, enforcing electroneutrality.

## Facts

- Endpoint: POST https://detect.halowerk.com/v1/F-TD2000-GEO-INDUSTRY-B007/ideal-donnan-multivalent-membrane-partition-electroneutrality?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ideal-donnan-multivalent-membrane-partition-electroneutrality-ec5661f9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yLqy-14N288-IL4tX3hy-

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability ideal-donnan-multivalent-membrane-partition-electroneutrality-ec5661f9 -d '<json body>'
```

Example prompt: Calculate the ideal Donnan equilibrium for a negatively charged membrane with a fixed charge density of -500 mM at 298 K, with Na+ (charge +1, bulk 100 mM) and Cl- (charge -1, bulk 100 mM) as the ion species.

## When to prefer this

Choose this endpoint when you need a rigorous, physics-based ideal Donnan equilibrium calculation for charged membranes with multivalent ion mixtures (charges -2 to +2), particularly for ion exchange membranes, nanofiltration modeling, or electrochemical systems. Prefer this over simplified monovalent-only models when your solution contains divalent or asymmetric electrolytes. It enforces electroneutrality explicitly, making it suitable for precise membrane science workflows.

## Known failure modes

- Electroneutrality cannot be satisfied for the given ion set — solver fails to converge
- Ion charge out of range (must be integer between -2 and +2)
- Fewer than 2 ion species provided (minimum required)
- More than 8 ion species provided (maximum exceeded)
- Temperature out of valid range (200–1000 K)
- Fixed charge density magnitude exceeds 10000 mM limit
- Bulk molar density below minimum threshold (0.000001 mM)
- Invalid or missing claim field in artifact payload

## How this service works

Compute ideal ionic partition and Donnan potential for an explicit membrane equilibrium.

## Output

Returns the computed Donnan potential (in volts or millivolts) and the ideal partition coefficients for each ion species between the bulk solution and the membrane phase, satisfying electroneutrality within the membrane, given the specified fixed charge density, temperature, and ion compositions.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "artifact": {
   "type": "object",
   "required": [
    "donnan"
   ],
   "properties": {
    "donnan": {
     "type": "object",
     "required": [
      "data",
      "claim"
     ],
     "properties": {
      "data": {
       "type": "object",
       "required": [
        "temperature_kelvin",
        "fixed_charge_molar_density",
        "ions"
       ],
       "properties": {
        "ions": {
         "type": "array",
         "items": {
          "type": "object",
          "required": [
           "charge",
           "bulk_molar_density"
          ],
          "properties": {
           "charge": {
            "type": "integer",
            "maximum": 2,
            "minimum": -2
           },
           "bulk_molar_density": {
            "type": "number",
            "maximum": 10000,
            "minimum": 0.000001
           }
          },
          "additionalProperties": false
         },
         "maxItems": 8,
         "minItems": 2
        },
        "temperature_kelvin": {
         "type": "number",
         "maximum": 1000,
         "minimum": 200
        },
        "fixed_charge_molar_density": {
         "type": "number",
         "maximum": 10000,
         "minimum": -10000
        }
       },
       "additionalProperties": false
      },
      "claim": {}
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ideal-donnan-multivalent-membrane-partition-electroneutrality-ec5661f9/health.json
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