Antimonite Photocatalysis: Reaction-Diffusion Field

Reaction Conditions

UV intensity 70%

Catalyst loading 90 sites

Solution pH 6.5

Initial Sb(III) load 220 ions

Stirring rate (mixing) 50%

Live Water Chemistry

Sb(III) antimonite (toxic, mobile)

Sb(V) antimonate (adsorbs, removed)

Sb(III) 100%Sb(V) 0%

Sb(III) remaining

220

Sb(V) formed

Fitted k_obs (regression)

0.000 s⁻¹

Elapsed time

0.0 s

How it works

Antimonite ≠ antimonide. Antimonide nanocrystals (InSb, GaSb) are III–V semiconductors where Sb³⁻ bonds to a metal cation. Antimonite is the opposite chemistry: the oxoanion of trivalent antimony, Sb(OH)₃ / SbO₂⁻, the dominant dissolved form of the toxic pollutant Sb(III) in near-neutral water.

Instead of tracking individual ions colliding with catalyst spheres, this view solves the same chemistry as a reaction-diffusion field: two concentration maps, [Sb(III)] and [Sb(V)], diffuse across a 2D membrane by finite-difference Fick's-law diffusion, while a fixed catalyst-density map (teal dots) sets where the photocatalytic sink term is active:

∂C₃/∂t = D∇²C₃ − k(x,y)·C₃
∂C₅/∂t = D∇²C₅ + k(x,y)·C₃
k(x,y) = k₀ · (UV intensity) · f(pH) · catalyst_density(x,y)

Diffusion uses a 5-point Laplacian stencil with reflecting (zero-flux) walls, so C₃+C₅ is conserved exactly except for the local conversion term — the field never loses or gains mass, it only moves and converts.

UV intensity — scales the •OH generation rate everywhere the catalyst density is nonzero.
Catalyst loading — number of catalyst sites seeded into the density map; more sites raise the area with nonzero k(x,y).
Solution pH — antimonite adsorption peaks near pH ≈ 6.5 and falls off on either side, plotted live in the pH-response panel.
Stirring rate — sets the diffusion coefficient D; faster stirring replenishes Sb(III) near catalyst sites faster, raising the observed rate.
Reseed — refills the Sb(III) field to a fresh uniform concentration without resetting the catalyst map, and clears the kinetics trace.

The kinetics panel fits a least-squares line through ln(mean[Sb(III)]) vs. time over a sliding window — a statistically steadier k_obs estimate than reading off two points — and the small panel on the right shows the pH bell curve with today's operating point marked. Drag the main field to pan, and scroll/pinch to zoom.

1.0×

Photocatalyst density Sb(III) antimonite Sb(V) antimonate

Pseudo-first-order decay — ln[Sb(III)] vs t

pH response f(pH)

Antimonite Photocatalysis — Reaction-Diffusion Field