posted on 2023-09-29, 20:03authored byWeijian Ding, Kexin Ma, Amy E. Childress
Membranes play critical roles in
seawater desalination, wastewater
treatment, potable water reuse, and resource recovery. Their performance
can be adversely affected by compaction, which can limit their practical
use and durability. While previous studies have employed scanning
electron microscopy to measure thickness before and after compaction,
real-time compaction measurement has not been possible. This study
introduces a novel method to quantify the compaction of membranes
under low pressure (up to 12.5 psi) by combining electrical impedance
spectroscopy with dynamic mechanical analysis. Short- and long-term
mechanical tests were conducted to investigate instant compaction,
creep, recovery, and hysteresis. The method was validated using in
situ and ex situ measurements. Results indicate that the initial instant
compaction (98% of total compaction) contributes more to total compaction
than subsequent instant compaction (from 83 to 67% of total compaction).
The ratio of creep to instant compaction is introduced as a key indicator
of material resilience; its increase from 2.4 to 49% indicates that
as pressure increases, creep contributes more to total compaction.
While limited to low pressures and a dry testing environment, this
novel method shows promise for detecting and predicting performance
and fatigue of water treatment membranes in various applications.