An Autopsy Study of a Fouled Reverse Osmosis Membrane Used for Ultrapure Water Production

Hojung Rho,Kangmin Chon,Jaeweon Cho

doi:10.3390/w11061116

Hojung Rho, Kangmin Chon + Show 1 more

Open Access

https://doi.org/10.3390/w11061116

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Abstract

This study investigated the fouling and cleaning behaviors of reverse osmosis (RO) membranes in a lab–scale ultrapure water (UPW) production system via membrane autopsies and characterization of dissolved organic matter (DOM) and membrane foulants. Most of DOM were effectively removed by the MFC filter, with the exception of the peak at 150 Da. The RO membranes were effective in reducing conductivity, DOM, total nitrogen (TN), and ultraviolet A (UVA254nm) concentration; the polishing stage using IER filter resulted in ultra-trace levels of all these parameters required for semiconductor manufacturing (> 18.2 ΩM). The quantity of the desorbed RO membrane foulants, in terms of dissolved organic carbon (DOC), varied considerably depending on the type of desorbing agents: 0.1 N NaCl (65.12 mgC m−2) > 0.1 N NaOH (46.14 mgC m−2) > deionized water (25.39 mgC m−2) > 0.1 N HCl (15.95 mgC m−2). The high cleaning efficiency of the salt solution (0.1 N NaCl) was attributed to the efficient desorption of hydrophilic DOM foulants from the RO membrane surfaces. These results demonstrate that the salt cleaning may provide a promising option to recover the performance of the RO membranes fouled primarily by hydrophilic DOM fractions.

Highlights

During recent decades, the demand for ultrapure water (UPW) has risen continuously in a variety of industrial applications, such as power generation, pharmaceutical formulations, and semiconductor manufacturing [1]
The reverse osmosis (RO) membranes were effective in reducing conductivity and dissolved organic carbon (DOC), total nitrogen (TN), and UV absorbance at 254 nm (UVA254) concentrations; the polishing stage using ion-exchange resin (IER) filters resulted in ultra-trace levels of all these parameters
The achieved purity degree of UPW satisfied the electrical resistivity of the IER permeate (> 18.2 ΩM) at room temperature (~ 20 ◦ C) that is required for semiconductor manufacturing [1]

Summary

Introduction

The demand for ultrapure water (UPW) has risen continuously in a variety of industrial applications, such as power generation, pharmaceutical formulations, and semiconductor manufacturing [1]. UPW is considered a key determinant of the quality and performance of high value-added industrial products, including pharmaceuticals and semiconductors, which require a high degree of accuracy in manufacturing processes [4]. UPW production has received considerable attention as an emerging water market throughout the world. The production of UPW aims to remove all types of contaminants, including suspended solids, salt ions, organic and inorganic materials, particulate and colloidal matters, bacteria, dissolved gases (i.e., CO2 and O2 ), and trace ions, leaving only water molecules [1]. The required degree of purity of UPW varies considerably depending on its specific uses. For UPW used as cooling water, it is important to eliminate potentially corrosive substances and scale–forming materials from source water, as deposits via chemical precipitation promote corrosion and/or scaling on the surfaces of

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