Work

Do membrane transport properties vary under dynamic and cyclic RO? Evidence for constant permeability and hysteresis from channel history

Year: 2025

Type: article

Abstract: Dynamic and cyclic operation of reverse osmosis (RO) systems is increasingly investigated for integration with renewable energy sources. Pilot-scale data from the National Renewable Energy Laboratory (NREL) are re-examined using a steady-state correlation framework derived from the solution–diffusion model under steady, ramped, and sinusoidal operating conditions. Results show that a constant permeability coefficient accurately describes all operating regimes when feed salinity is properly accounted for. Ramped experiments align with steady-state correlations, with the only deviation explained by a lower feed conductivity (approximately 10% lower EC). Under sinusoidal operation, the cycle-averaged water flux matches steady-state predictions, while the observed hysteresis originates not from pressure-dependent transport but from finite-rate salt redistribution within the feed channel, reflecting the transient coupling between pressure variation and concentration dynamics. These findings simplify the modeling of wave- and renewable-driven desalination systems, confirming that intrinsic membrane permeability can be treated as constant and that transient deviations result primarily from feed-salinity variation and feed-channel history, supporting constant-parameter frameworks for system control and design optimization. • Constant membrane permeability captures both steady and dynamic RO behavior. • Flux–pressure hysteresis arises from finite-rate salt redistribution in the feed channel. • Spatiotemporal modeling confirms hydrodynamic, not intrinsic, permeability effects. • Results validate constant-parameter models for renewable-driven desalination systems.

Source: Desalination

DOI: 10.1016/j.desal.2025.119644

Author: Mingheng Li

Institution: California State Polytechnic University

Language: English

Topic: Membrane Separation Technologies

Subfield: Water Science and Technology

Field: Environmental Science

Domain: Physical Sciences

SDG: Affordable and clean energy

Open Access status: hybrid

Estimated APC paid: $4,580