Nanoscale Zero-Valent Iron Groundwater Remediation

Injection

Injection rate 40 /s

Aquifer Transport

Groundwater flow velocity 0.35 m/d

Particle aggregate size 1.0×

Reaction Kinetics

Corrosion / passivation rate k_corr 0.05 /s

Live Readouts

Contaminant remaining

100%

Active (reactive) Fe⁰

Plume front distance

0.0 m

Fresh Fe⁰ nanoparticle (reactive core)

Passivated (Fe₂O₃ oxide shell)

Chlorinated contaminant (e.g. TCE)

How it works

Nanoscale zero-valent iron (nZVI) injected into a contaminated aquifer degrades chlorinated solvents like TCE by donating electrons from a Fe⁰ core (reductive dechlorination), while an oxide/hydroxide shell builds up on the surface and eventually shuts the reaction down. Three coupled processes are modeled per particle:

Shrinking core:   r_core(t) = r_core0 − k_corr · t
Reactivity:       η = r_core / r_core0  (0 = fully passivated)
Degradation:      dC/dt = −k_SA · a_s(η) · C     (pseudo-first-order)
Transport:        dx/dt = v_flow + √(2·D) · ξ(t),   D = D0 / n_agg

Shrinking core — the Fe⁰ core shrinks at a roughly constant rate as it corrodes into an Fe₂O₃/FeOOH shell; particles fade from orange to gray as η → 0 and stop reacting.
k_corr slider — how fast that shell forms. Higher k_corr means shorter reactive lifetime but faster initial degradation.
Aggregate size — nZVI particles clump in real aquifers. By Stokes–Einstein, effective dispersivity D scales as 1/n_agg, and clumping also buries reactive surface area, so bigger aggregates travel less and react slower per Fe⁰ atom — the central engineering trade-off in nZVI field deployment.
Flow velocity — the Darcy groundwater velocity advecting the injected plume downgradient from the well.
Yellow-green points are contaminant molecules; when an active nZVI particle's reaction shell overlaps one, it is stochastically reduced (removed) with probability set by k_SA·η·dt.

Fe⁰ (reactive) Passivated Contaminant

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