ARTICLE pubs.acs.org/IECR
Antimicrobial m-Aramid Nanofibrous Membrane for Nonpressure Driven Filtration Sam Soo Kim,† Daun Jung,† Uk Han Choi,‡ and Jaewoong Lee*,§ †
School of Textiles, Yeungnam University, Gyeongsan 712-749, South Korea Department of Applied Microbiology and Biotechnology, Yeungnam University, Gyeongsan 712-749, South Korea § Korean Intellectual Property Office, Daejeon, 302-701, South Korea ‡
ABSTRACT: An antimicrobial nanofibrous membrane for nonpressure driven filtration is reported. m-Aramid as an N-halamine precursor was dissolved in N,N-dimethylacetamide (DMAc), and the m-aramid nanofibrous membrane was formed using an electro-spinning process. The morphology of the m-aramid membrane was analyzed by scanning electron microscopy (SEM), and the mean pore size, pore size distribution and liquid permeability of the m-aramid membrane were determined using a capillary flow porometer. The antimicrobial efficacy of the m-aramid membrane was performed by nonpressure driven filtration. The chlorinated m-aramid membrane showed excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus. The chlorine lost after filtration could be regained upon rechlorination.
1. INTRODUCTION Antimicrobial materials have attracted considerable attention due to the enhanced interest in hygiene. To date, many antimicrobials including aldehydes, cationic agents, alcohols, peroxygens, phenols and chlorination phenols, metal ions, and halogens (in a variety of functional groups including N-halamines) have been studied.16 In particular, N-halamine has been widely recognized over the past 2 decades owing to its impressive antimicrobial efficacy against bacteria.7,8 In N-halamine structures, a covalent bond exists between the nitrogen and halogen. Generally, chlorine has been used and is connected to amine, amide, or imide groups. In addition, a heterocyclic structure is preferred because dehydrohalogenation can occur with R-hydrogen under UV light or heat.9,10 N-halamines with heterocyclic structure have been studied extensively for water disinfection,1114 fibers,8,15 and polymers.9,16 Aromatic amide, aramid as one of N-halamine precursors, can be defined as a synthetic polymer possessing over 85% polyamide, which contains an amide (CONH) group between two aromatic rings. Aramid is also divided into p- and m-aramid, and the dehydrohalogenation-free structure of aramid has attracted considerable attention as an N-halamine precursor due to no R-hydrogen.9,17,18 On the other hand, p-aramid is decomposed easily during chlorination in bleach. Akdag et al.19 suggested the decomposition mechanism of p-aramid during bleaching. Unlike p-aramid, m-aramid is stable under bleaching, and Lee et al.9 suggested the stability of chlorine after becoming an N-halamine structure. Regarding water disinfection, filtration using a membrane could be a significant method to inactivate bacteria. In the case of a pressure driven membrane process, microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) have been used and the pore sizes of the membranes for each process are 10010 000 nm, 2100 nm, 0.52 nm, and
