Joule-Heated Layered Double Hydroxide Sponge for Rapid Removal of Silica from Water

Dissolved silica is a major concern for a variety of industrial processes owing to its tendency to form complex scales that severely deteriorate system performance. In this work, we present a pretreatment technology using a Joule-heated sponge to rapidly remove silica from saline waters through adso...

Full description

Saved in:
Bibliographic Details
Published in:Environmental science & technology 2021-12, Vol.55 (23), p.16130-16142
Main Authors: Ma, Wen, Lu, Xinglin, Guan, Yan-Fang, Elimelech, Menachem
Format: Article
Language:English
Subjects:
Adsorption
Anion exchanging
Anions
Boundary layers
Desalination
Diffusion layers
Electrostatic properties
Heating
Hydroxides
Kinetics
Membranes
Nanostructure
Pretreatment
Reaction kinetics
Regeneration
Reverse osmosis
Scaling
Silica
Silicon Dioxide
Stainless steels
Treatment and Resource Recovery
Water Pollutants, Chemical - analysis
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Dissolved silica is a major concern for a variety of industrial processes owing to its tendency to form complex scales that severely deteriorate system performance. In this work, we present a pretreatment technology using a Joule-heated sponge to rapidly remove silica from saline waters through adsorption, thereby effectively mitigating silica scaling in subsequent membrane desalination processes. The adsorbent sponge is fabricated by functionalizing two-dimensional layered double hydroxide (LDH) nanosheets on a porous, conductive stainless-steel sponge. With the application of an external voltage of 4 V, the Joule-heated sponge achieves 85% silica removal and 95% sponge regeneration within 15 min, which is much more efficient than its counterpart without Joule-heating (360 min for silica adsorption and 90 min for sponge regeneration). Material characterization and reaction kinetics analysis reveal that electrostatic interactions and “memory effect”-induced intercalation are the primary mechanisms for silica removal by the LDH nanosheets. Moreover, Joule-heating reduces the boundary layer resistance on nanosheets and facilitates intraparticle diffusion of dissolved silica, thereby increasing silica removal kinetics. Joule-heating also enhances the release of silicate ions during the regeneration stage through exchange with the surrounding anions (OH– or CO3 2–), resulting in a more efficient sponge regeneration. Pretreatment of silica-rich feedwaters by the Joule-heated sponge effectively reduces reverse osmosis membrane scaling by amorphous silica scale, demonstrating great potential for silica scaling control in a broad range of engineered processes.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.1c05497