Title: Solar-thermal membrane for dewatering aqueous organic-acid solutions

Abstract

A thermally conductive porous membrane has been developed to directly absorb solar energy and conduct heat that can effectively evaporate liquid water at the interface between the membrane and the bulk feed solution. Here, black, porous, thermally conductive graphite foam support is employed as an effective photothermal-energy absorber and heat conductor that heats up an aqueous feed solution to produce vapor. Graphite nanoparticle-slurry coating is applied onto the foam surface to reduce the pore size and generate a microporous membrane. Then, application of a dense graphene oxide membrane coating as an active separation layer on the microporous nanoparticle surface of internal foam channels allows vapor permeation of volatile molecules. Acetic acid/water solution was studied as a model feed system to experimentally demonstrate effective separation. This model vapor permeation system demonstrates excellent acetic acid separation, with a separation factor of 8.3, under simulated 0.7 sun irradiation. The membrane hydrophobicity and nanostructure, including pore size and surface chemistry, played a significant role in enabling high permselectivity of water vapor over acetic acid molecules, as well as liquid solution. Pore size reduction from open pores to a nonporous dense layer in the membrane enables effective separation of water vapor from the organic vapor,more » while it reduces the permeation flux. Also, the hydrophilicity of the membrane surface shows ~3 times higher permeation flux with higher permselectivity, compared with the hydrophobic membrane surface. This work introduces a process of directly using renewable energy instead of conventional heating to drive selective separation of water from organic acids.« less

Authors:

Jang, Gyoung G.  ^[1];

• Search DOE PAGES for author "Jang, Gyoung G."
• Search DOE PAGES for ORCID "0000-0003-4305-8723"

Tsouris, Costas  ^[1];

• Search DOE PAGES for author "Tsouris, Costas"
• Search DOE PAGES for ORCID "0000-0002-0522-1027"

Hu, Michael Z.  ^[1]

• Search DOE PAGES for author "Hu, Michael Z."
• Search DOE PAGES for ORCID "0000-0001-8461-9684"

---

+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Manufacturing Science Division

Publication Date:

Thu Dec 24 00:00:00 EST 2020

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:

1777794

Alternate Identifier(s):

OSTI ID: 1809755

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Separation and Purification Technology

Additional Journal Information:

Journal Volume: 267; Journal Issue: 267; Journal ID: ISSN 1383-5866

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

14 SOLAR ENERGY; solar membrane; dewatering; concentrating organic acids; hydrophobic membranes; hydrophilic membranes