GO-based filtration membrane for removal of Endocrine Disrupting Compounds (EDCs) from water

A. Paneri, S. Moghaddam
University of Florida,
United States

Keywords: Water filteration, membrane technology, graphene oxide

Summary:

We live in a world where synthetic chemicals have become a part of our day-to-day life. As a result, some of these pollutants enter our water streams and food chain and interfere with the normal functions of a living body in different ways. Endocrine Disrupting Chemicals (EDCs) are one such class of micro-pollutants which affect the endocrine (hormonal) system by interfering with the developmental processes of humans and wildlife species. Many of the man-made and some of the naturally occurring chemicals are widely considered to be EDCs. The effects of EDCs depend on both the timing and level of exposure, being especially perilous when exposure occurs during a developmental stage. Many of the recent scientific reports and reviews published have concluded that EDCs have adverse effects on reproductive outcomes (infertility, malformations, and cancers). These chemicals are also shown to impact thyroid function, brain function, obesity and metabolism. Municipal waste water systems are a prominent pathway for EDCs to enter water bodies. Results have shown that conventional techniques such as coagulation, flocculation, and precipitation processes do not effectively remove EDCs from the water supply, especially the low molecular weight compounds ranging from 100 to 500 Da. Retention of organic contaminants by Nanofiltration (NF) and Reverse Osmosis (RO) membranes have been an area of active research since the late 1970’s, yet their applicability has remained limited due to the high energy consumption of the process. Graphene oxide (GO) has a skeleton of 2D sheet of sp2 hybridized carbon atoms in a honeycomb crystal lattice (graphene backbone) and is covalently decorated with oxygen-containing functional groups. The surface oxidative groups render GO electrically nonconductive, highly hydrophilic and a net negative surface charge under aqueous environments. These properties, along with its highly impermeable graphene backbone poses GO as a potentially viable material for filtration applications. In the present study, an attempt is made to utilize the superior water selective transport property of GO laminates and investigate their potential as filtration membranes with high permeate flux. A layer-by-layer (L-b-L) approach was utilized to prepare a thin film composite membrane with a polymer support and a few layers of GO interlinked via poly(allylamine hydrochloride) (PAH). The prepared membrane exhibited a fourfold increase in the permeate flux in comparison to the commercially available nanofiltration (NF) membranes. The rejection performance of the membrane was evaluated by studying permeation of ibuprofen and a rejection rate of higher than 75% was achieved.