Plant phenolic extraction and anti-microbial testing for membrane antifouling

Abstract

Membranes are industrially used as effective technologies for separating particles from water streams. However, fouling is a prominent issue with their cost effectiveness in many applications. Biofouling, the fouling caused by biofilm growth on the membrane surface, is an issue in many applications that provide an environment favorable for microbial growth. This thesis explores the viability of using ethanol and pure water plant extracts, made from Scots pine needles and willow branches, as an antimicrobial treatment for RC70PP (commercial regenerated cellulose acetate) membranes. The efficacy is tested against 24 hour old E. coli ATCC 8739 bacteria with 0.1 OD at 600 nm.

Based on disc diffusion testing and Petrifilm testing, extracts made from pure water and 80% ethanol with Scots pine needles did not show antimicrobial activity for E. coli, neither as the pure extract, three times concentrated pure extract, nor after adsorption to the surface of the RC70PP membrane. 80% and 50% ethanol extracts of willow branch also did not show antimicrobial activity for E. coli as pure extracts nor as three times concentrated pure extracts. FTIR showed consistent modification of membrane surface for 80% ethanol extracts of Scots pine needles, in extracts at 70C for 18 hours after the RC70PP membrane being immersed for 4 hours at room temperature. No other extracts showed consistent modification of RC70PP surfaces in this way. Therefore, the conclusion is that the Scots pine and willow extracts tested are not found to be suitable for transferring E. coli antimicrobial properties to membrane surfaces.