Probing molecular interaction mechanisms of organic fouling on polyamide membrane using a surface forces apparatus: Implication for wastewater treatment

Qingye Lu; Jun Huang; Omar Maan; Yang Liu; Hongbo Zeng

doi:10.1016/j.scitotenv.2017.12.022

Probing molecular interaction mechanisms of organic fouling on polyamide membrane using a surface forces apparatus: Implication for wastewater treatment

Sci Total Environ. 2018 May 1:622-623:644-654. doi: 10.1016/j.scitotenv.2017.12.022. Epub 2017 Dec 13.

Authors

Qingye Lu¹, Jun Huang², Omar Maan³, Yang Liu⁴, Hongbo Zeng⁵

Affiliations

¹ Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada. Electronic address: qingye.lu@ucalgary.ca.
² Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
³ Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada.
⁴ Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada. Electronic address: yang.liu@ualberta.ca.
⁵ Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada. Electronic address: hongbo.zeng@ualberta.ca.

PMID: 29223088
DOI: 10.1016/j.scitotenv.2017.12.022

Abstract

Surface fouling is the dominant fouling mechanism of thin-film composite (TFC) membranes used in reverse osmosis (RO) technology. Understanding the complex interactions between foulant-membrane which drive the attachment and growth of foulants on membrane surface is of both fundamental and practical importance. This work aims to understand the molecular interaction mechanisms of organic fouling on RO-TFC membranes. A surface forces apparatus (SFA) was employed to directly measure the interaction forces and time-dependent adsorption behaviors between model organic foulants: humic acid (HA), bovine serum albumin (BSA), and lipopolysaccharides (LPS) and a polyamide (PA) thin film. PA thin film was prepared by interfacial condensation polymerization on mica substrates using m-phenylenediamine and 1,3,5-benzenetricarbonyltrichloride. The interaction forces between PA films and different foulant (HA, BSA, LPS) were directly measured under controlled solution chemistries in an asymmetric configuration (foulant-deposited PA films vs. PA films). The adsorption behaviors of these foulants on PA films were directly monitored in a symmetric configuration (PA films vs. PA films). These interactions were examined as a function of both contact time and solution chemistry (ionic strength). In asymmetrical configuration, both HA and BSA show repulsion with PA surface during approach and adhesion during separation, but LPS demonstrates repulsion only. In symmetrical configuration, all the foulants show adsorption on PA surface and the initial adsorption rate of foulant to PA surface follows the order of BSA>LPS>HA. The interaction mechanisms between PA films and foulants were discussed based on the interaction forces and interaction dynamics measurement.

Keywords: Adhesion; Adsorption; Organic fouling; Polyamide; Surface forces; Wastewater treatment.