Water dynamics on bisphenol-covered silica as model for water purification filters

To optimize the efficiency of water filters, it is important to understand how the water interacts with the filter and how undesirable substances present in water impact the functionality of the filter. One of these undesirable substances is bisphenol A. This project will explore the potential of synthetic sand or clay filters in aiding in the removal of BPA from the water.

Water purification can be performed through a series of processes, one of them filtering. To optimize the efficiency of water filters, it is important to understand how the water interacts with the filter and how undesirable substances present in water impact the functionality of the filter. One of these undesirable substances is bisphenol A or BPA. BPA is used for the million ton production of plastics for water bottles, CDs and DVDs, and epoxy resins lining water pipes or food and beverage cans.

Since BPA has relatively high water solubility, it has been found in discharge water coming from municipal wastewater treatment plants. Its origin can be traced to irrigation pipes, plastic trash in the oceans, and from plastics in landfills and material recycling plants. The environmental risks are currently evaluated extensively given that bisphenols are now recognized as endocrine disrupter and toxic to many aquatic organisms.

About the project

This project will explore the potential of synthetic sand or clay filters in aiding in the removal of BPA from the water by investigating how the BPA interacts with sand and clay. Spectroscopy, as a technique to examine bond breaking and bond making, is a suitable technique to follow the fate of water and BPA in the sand or clay. Furthermore, spectroscopy can also give information of the strength of adsorption of the BPA on the sand or clay– the stronger the adsorption the higher the possibility to use sand/clay as means to remove BPA from water.

Since neutrons are very sensitive to hydrogen, neutron scattering is a very potent technique to look at hydrogen-rich components (BPA) in a bulk material (sand/clay). This makes it the preferred choice for our study over optical spectroscopy. We will use the chemistry laboratories of the European Spallation Source ESS ERIC to prepare our samples. We have applied and received time at the Neutron Vibrational Spectrometer VISION at the Spallation Neutron Source SNS in the United States to perform the first neutron scattering experiments.

This project is a collaboration between the European Spallation Source ERIC and the Swedish Water Research joining expertise in neutron scattering and chemical synthesis with our competence in development, innovation and implementation of new solutions for the water services industry.

This research benefits from the use of the VISION beamlines at ORNL’s Spallation Neutron Source, which is supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy under contract No. DE-AC0500OR22725 with UT Battelle, LLC.

Objective of the project

The removal of BPA from water is mainly done by filtration, using membranes or by adsorption, using different materials with varying porosity (clays, zeolites, chitosan etc…). The filtration has great advantages because BPA accumulates in natural sediments rather than in aqueous solution. Filtration is promoted by the presence of total organic carbon (TOC) in the aquatic environment. Recent studies on partition coefficients of BPA between sediments and water in river basins and lakes, with values around 3.8, show that the presence in sediments is predominant. Studies on filtration materials with low pore size, < 0.1 μm, are particularly interesting because they mimic natural sediment pore size values. Future materials for BPA filtration or adsorption can take advantage of a better understanding of the adsorption process and the partition coefficient between water and the porous material.

Project members from Sweden Water Research and and its owners

Partners in this project