Addressing PFAS Contamination in Blood Bank Supplies with Hydrogel Nanocomposite Sorbents

Environmental pollutants continue to be a threat to global human health. Persistent contaminants, such as perfluoroalkyl substances (PFAS), have been linked to a multitude of adverse health effects such as cancerous tumors, increased blood cholesterol levels and liver damage. The dominant source of exposure to PFAS is through contaminated drinking water, and accumulation has been found to occur significantly in human blood serum. Thus, high-risk groups who are receiving frequent blood transfusions are exposed to these harmful chemicals in a dual fashion, which could prove detrimental. Traditional sorbents that display an affinity for PFAS include powdered activated carbon and clay. Recently, a protein found in plasma, albumin, has been identified as the major carrier protein for PFAS in human blood. The two most widely detected PFAS in human serum are perfluorooctanesulfonic acid, PFOS, and perfluorooctanoic acid, PFOA. As such, this work aims to develop hydrogel nanocomposites that have the capability to remove PFOA and PFOS from human blood serum. Crosslinked acrylamide polymers were synthesized with varied crosslinking densities of 0.1 mol%, 1 mol%, and 10 mol% to evaluate potential exclusion of serum proteins. In order to incorporate physiochemical properties of sorbents known to bind PFOA and PFOS, varied amounts of dried particulates were integrated into the synthesized hydrogels. Powdered activated carbon, sodium montmorillonite clay, and bovine serum albumin were studied at loadings of 1 wt% and 5 wt% respective to total reactant weight. The synthesized hydrogels were characterized via FTIR and TGA analysis. Competitive binding to evaluate PFOA and PFOS affinity was completed in a binding matrix of pH 7.4, similar to that of blood serum

Capture and Recycle of Industrial CO\u3csub\u3e2\u3c/sub\u3e Emissions Using Mircoalgae

A novel cyclic flow photobioreactor (PBR) for the capture and recycle of CO2 using microalgae was designed and deployed at a coal-fired power plant (Duke Energy’s East Bend Station). The PBR was operated continuously during the period May–September 2015, during which algae productivity of typically 0.1–0.2 g/(L day) was obtained. Maximum CO2 capture efficiency was achieved during peak sunlight hours, the largest recorded CO2 emission reduction corresponding to a value of 81 % (using a sparge time of 5 s/min). On average, CO2 capture efficiency during daylight hours was 44 %. The PBR at East Bend Station also served as a secondary scrubber for NOx and SOx, removing on average 41.5 % of the NOx and 100 % of the SOx from the flue gas. The effect of solar availability and self-shading on a rudimentary digital model of the cyclic flow PBR was examined using Autodesk Ecotect Analysis software. Initial results suggest that this is a promising tool for the optimization of PBR layout with respect to the utilization of available solar radiation

Capture and Recycle of Industrial CO\u3csub\u3e2\u3c/sub\u3e Emissions Using Mircoalgae

A novel cyclic flow photobioreactor (PBR) for the capture and recycle of CO2 using microalgae was designed and deployed at a coal-fired power plant (Duke Energy’s East Bend Station). The PBR was operated continuously during the period May–September 2015, during which algae productivity of typically 0.1–0.2 g/(L day) was obtained. Maximum CO2 capture efficiency was achieved during peak sunlight hours, the largest recorded CO2 emission reduction corresponding to a value of 81 % (using a sparge time of 5 s/min). On average, CO2 capture efficiency during daylight hours was 44 %. The PBR at East Bend Station also served as a secondary scrubber for NOx and SOx, removing on average 41.5 % of the NOx and 100 % of the SOx from the flue gas. The effect of solar availability and self-shading on a rudimentary digital model of the cyclic flow PBR was examined using Autodesk Ecotect Analysis software. Initial results suggest that this is a promising tool for the optimization of PBR layout with respect to the utilization of available solar radiation

DEVELOPMENT OF POLYMERIC SORBENTS AS REUSABLE FILTRATION SYSTEMS FOR REMEDIATION OF PFAS CONTAMINATED WATER

Decades of use of per- and polyfluoroalkyl substances (PFAS) in a multitude of consumer and industry-based products have led to a devastating amount of soil and water contamination. Although these chemicals and compounds possess advantageous qualities – such as that of PFAS in the role of fire-fighting foams that have no doubt saved countless lives and homes, we must take responsibility for the anthropogenic hazards that threaten our global health. This entails being able to cost-effectively remediate problems created in the past from overuse of toxic substances that could negatively impact our future, and in this case, the future of clean water availability. The chemical and thermal stability of PFAS have proved them to be an especially daunting challenge from an environmental remediation standpoint. Presently, the only full-scale water treatment separates via sorption and uses non-selective materials such as activated carbon (AC) or mineral media which are extremely difficult and/or costly to regenerate. Research focused on selective adsorption is becoming a more practical route for capture and removal from contaminated water systems. The work presented here investigates the development and effectiveness of polymer-based sorbents that have affinity toward PFAS through incorporation of various monomers that possess cationic and/or fluorinated functionalities. In some instances, composite systems were created with the inclusion iron oxide nanoparticles during the synthesis process. Although the main route of PFAS sorption occurs via ionic and hydrophobic interactions, several approaches were explored: (1) Thermoresponsive hydrogel expansion and contraction to drive contaminant into gel for sorption on functionalized sites; (2) Magnetic polymer composites allow for contaminant binding via sorption to cationic sites of quaternary amine functionalized polymers and removal via magnetic decantation; (3) Linear, non-crosslinked systems drive contaminant binding through flocculation with functionalized thermoresponsive polymers. The affinity of the synthesized materials for PFAS was evaluated at equilibrium conditions using a liquid chromatography coupled to mass spectrometer detection (LCMS) for quantification purposes, and the data was used to determine removal efficiency in both spiked and real-world environmental samples. Binding studies were conducted by subjecting 2.5 mg/mL of each sorbent to 500 ppb of aqueous PFAS for up to 24 h at room temperature for crosslinked systems and 1 h at 50 ºC for linear systems. Cationic crosslinked polymers showed high affinity for PFOA (\u3e80%) and PFOS (\u3e90%) across a range of aqueous pH (4 – 10). Linear polymers that included both cationic and fluorinated monomers showed improved flocculation and contaminant removal as compared to those systems with isolated functionality. Furthermore, upon exposure of the magnetic composites to an alternating magnetic field (AMF) for a period of 30 minutes, release of bound PFAS is realized in minor amounts depending on regeneration solvent selection. Overall, we have provided strong evidence that the materials presented here have a promising application as sorbents for PFAS contaminants in polluted water sources providing high binding affinities, a low-cost regeneration technique and are capable of withstanding use under environmental conditions offering a cost-effective alternative to current remediation approaches

Thermoresponsive Cationic Polymers: PFAS Binding Performance under Variable pH, Temperature and Comonomer Composition

The versatility and unique qualities of thermoresponsive polymeric systems have led to the application of these materials in a multitude of fields. One such field that can significantly benefit from the use of innovative, smart materials is environmental remediation. Of particular significance, multifunctional poly(N-isopropylacrylamide) (PNIPAAm) systems based on PNIPAAm copolymerized with various cationic comonomers have the opportunity to target and attract negatively charged pollutants such as perfluorooctanoic acid (PFOA). The thermoresponsive cationic PNIPAAm systems developed in this work were functionalized with cationic monomers N-[3-(dimethylamino)propyl]acrylamide (DMAPA) and (3-acrylamidopropyl)trimethylammonium chloride (DMAPAQ). The polymers were examined for swelling capacity behavior and PFOA binding potential when exposed to aqueous environments with varying pH and temperature. Comonomer loading percentages had the most significant effect on polymer swelling behavior and temperature responsiveness as compared to aqueous pH. PFOA removal efficiency was greatly improved with the addition of DMAPA and DMAPAQ monomers. Aqueous pH and buffer selection were important factors when examining binding potential of the polymers, as buffered aqueous environments altered polymer PFOA removal quite drastically. The role of temperature on binding potential was not as expected and had no discernible effect on the ability of DMAPAQ polymers to remove PFOA. Overall, the cationic systems show interesting swelling behavior and significant PFOA removal results that can be explored further for potential environmental remediation applications