Dual-Functional Phosphorene Nanocomposite Membranes for the Treatment of Perfluorinated Water: An Investigation of Perfluorooctanoic Acid Removal via Filtration Combined with Ultraviolet Irradiation or Oxygenation

Abstract

Nanomaterials with tunable properties show promise because of their size-dependent electronic structure and controllable physical properties. The purpose of this research was to develop and validate environmentally safe nanomaterial-based approach for treatment of drinking water including removal and degradation of per- and polyfluorinated chemicals (PFAS). PFAS are surfactant chemicals with broad uses that are now recognized as contaminants with a significant risk to human health. They are commonly used in household and industrial products. They are extremely persistent in the environment because they possess both hydrophobic fluorine-saturated carbon chains and hydrophilic functional groups, along with being oleophobic. Traditional drinking water treatment technologies are usually ineffective for the removal of PFAS from contaminated waters, because they are normally present in exiguous concentrations and have unique properties that make them persistent. Therefore, there is a critical need for safe and efficient remediation methods for PFAS, particularly in drinking water. The proposed novel approach has also a potential application for decreasing PFAS background levels in analytical systems. In this study, nanocomposite membranes composed of sulfonated poly ether ether ketone (SPEEK) and two-dimensional phosphorene were fabricated, and they obtained on average 99% rejection of perfluorooctanoic acid (PFOA) alongside with a 99% removal from the PFOA that accumulated on surface of the membrane. The removal of PFOA accumulated on the membrane surface achieved 99% after the membranes were treated with ultraviolet (UV) photolysis and liquid aerobic oxidation.

A Review on Removal and Destruction of Per- and Polyfluoroalkyl Substances (PFAS) by Novel Membranes

“…Several reported studies [80,113] addressed the removal efficiency of PFAS when treating a high feed concentration (100 ppm). A high concentration of PFAS in the feed may lead to micelle formation when concentrations reach the critical micelle concentration.…”

“…[ 135,139] Phosphorene Nanocomposite membrane Highly effective Destruction of fluorine compound after membrane treatment was removed by UV photolysis and liquid aerobic oxidation, which can also negatively affect the membrane surface (99%). [113] Electromagnetic (microwave) membrane Effective to some extent Further improvement needed (65.9% degraded).…”

“…The use of NF and RO membranes can efficiently remove PFAS from water but may be impacted by fouling or require high pressure/energy to achieve appropriate separation [ 114 ]. Various modifications have been suggested to improve the membrane’s performance and longevity, including the development of novel membranes and surface modification of commercial membranes, which play a critical role in PFAS rejection [ 113 ]. Novel membranes developed for PFAS removal and treatment are described below:…”

“…Eke et al [ 113 ] developed a dual-function phosphorene nanocomposite membrane for filtration combined with treatment by UV irradiation (365 nm, 200 min operation) or by oxygenation (at a flowrate of 3 L/min for 280 min) ( Figure 12 a,b). Perfluorooctanoic acid (PFOA, 100 ppm) was removed using a nanohybrid membrane made of sulfonated polyether ether ketone and phosphorene.…”

“…The small amount of PFOA accumulated at the membrane’s surface during the treatment process was destroyed by UV light (98.4%) and liquid oxygen (96.6%). This study highlights the removal and destruction of fluorinated compounds from wastewater, but the long-term impact of photocatalysis on membrane degradation and stability is not addressed [ 113 ].…”