Complex organic fouling and effect of silver nanoparticles on aquaporin forward osmosis membranes

Abstract

Despite the negligible pressure used in forward osmosis (FO), the process still suffers from fouling. Recent studies demonstrated that this issue is common among all FO membrane types, including aquaporin-based filters. To address this problem, various approaches have been proposed. However, despite the biocidal effects of silver, no attempt has been made to apply silver for fouling mitigation in aquaporin FO membranes. Consequently, the present work focuses on the investigation of controlled combined organic fouling of aquaporin FO membranes and the effects of silver nanoparticles on the membrane performance and its properties. The obtained data show that in contrast with unaltered membranes, the membranes doped with silver nanoparticles are much more resistant to fouling. After the first filtration run, pristine membranes exhibited a flux decline of 50%, while the flux decline of the modified membranes was limited to 10%. Physical cleaning restored the flux of both membranes to 100%. Analysis of the membranes showed that the membrane water flux was not affected by the covalent binding of the silver nanoparticles. Further, the membranes' chemistry, zeta potential, contact angle, roughness, and antimicrobial resistance were altered.

The Journey of Water Remediation through Biomimetic Strategies: A Mechanistic Insight

“…The effect of modifying aquaporin FO membranes with silver nanoparticles (NFs) was investigated by Balkenov et al. [ 40 ] On modifying aquaporin membranes, it is usual to observe a sharp decline in water flux due to aquaporin closure. However, in this case, a mere reduction of about 10% was observed.…”

Organic Fouling in Forward Osmosis: A Comprehensive Review

“…Experiments demonstrated that tannic acid plays a significant role in flux decline and fouling compared to alginate, and the presence of divalent calcium ions had a favourable effect on flux decline by combined foulants. Another study by Balkenov et al [112] showed that, when two model foulants (alginate + BSA or tannic acid) were added to a feed solution, there was a 12% loss in permeate flux. However, when three foulants were added to the feed side, the flux declined by 27%.…”

Behaviour of Aquaporin Forward Osmosis Flat Sheet Membranes during the Concentration of Calcium-Containing Liquids

“…The FO setup used in this study was described earlier and included two variable-speed peristaltic pumps (Cole-Parmer, Vernon Hills, IL, USA), membrane holder (Sterlitech, Kent, WA, USA), electronic balance (OHAUS, Parsippany, NJ, USA), and stirrer plate [29]. The membrane holder was aligned horizontally, the draw solution was placed on the balance, and the feed on the stirrer plate.…”