Membrane fouling is one of the most significant issues to overcome in membrane-based technologies as it causes a decrease in the membrane flux and increases operational costs. This study investigates the effect of common chemical cleaning agents on polymeric nanofibrous membranes (PNM) prepared by polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polyamide 6 (PA6) nanofibers. Common alkaline and acid membrane cleaners were selected as the chemical cleaning agents. Membrane surface morphology was investigated. The PAN PNM were selected and fouled by engine oil and then cleaned by the different chemical cleaning agents at various ratios. The SEM results indicated that the use of chemical agents had some effects on the surface of the nanofibrous membranes. Moreover, alkaline cleaning of the fouled membrane using the Triton X 100 surfactant showed a two to five times higher flux recovery than without using a surfactant. Among the tested chemical agents, the highest flux recovery rate was obtained by a binary solution of 5% sodium hydroxide + Triton for alkaline cleaning, and an individual solution of 1% citric acid for acidic cleaning. The results presented here provide one of the first investigations into the chemical cleaning of nanofiber membranes.

• Keywords
• PAN, chemical agents, cleaning, membrane, microfiltration, nanofiber,
• Publication type
• Journal Article MeSH

In order to protect the environment, it is important that oily industrial wastewater is degreased before discharging. Membrane filtration is generally preferred for separation of oily wastewater as it does not require any specialised chemical knowledge, and also for its ease of processing, energy efficiency and low maintenance costs. In the present work, hybrid polyacrylonitrile (PAN) nanofibrous membranes were developed for oily wastewater filtration. Membrane surface modification changed nitrile groups on the surface into carboxylic groups, which improve membrane wettability. Subsequently, TiO2 nanoparticles were grafted onto the modified membranes to increase flux and permeability. Following alkaline treatment (NaOH, KOH) of the hydrolysed PAN nanofibres, membrane water permeability increased two- to eight-fold, while TiO2 grafted membrane permeability increase two- to thirteen-fold, compared to unmodified membranes. TiO2 grafted membranes also displayed amphiphilic properties and a decrease in water contact angle from 78.86° to 0°. Our results indicate that modified PAN nanofibrous membranes represent a promising alternative for oily wastewater filtration.

• Keywords
• PAN, TiO2, membrane filtration, nanofibre, nanoparticle, oily wastewater, separation,
• Publication type
• Journal Article MeSH

Cleaning of wastewater for the environment is an emerging issue for the living organism. The separation of oily wastewater, especially emulsified mixtures, is quite challenged due to a large amount of wastewater produced in daily life. In this review, the membrane technology for oily wastewater treatment is presented. In the first part, the global membrane market, the oil spill accidents and their results are discussed. In the second and third parts, the source of oily wastewater and conventional treatment methods are represented. Among all methods, membrane technology is considered the most efficient method in terms of high separation performance and easy to operation process. In the fourth part, we provide an overview of membrane technology, fouling problem, and how to improve the self-cleaning surface using functional groups for effectively treating oily wastewater. The recent development of surface-modified membranes for oily wastewater separation is investigated. It is believed that this review will promote understanding of membrane technology and the development of surface modification strategies for anti-fouling membranes.

• Keywords
• membrane, nanomaterial, oil separation, self-cleaning, surface modification,
• Publication type
• Journal Article MeSH
• Review MeSH