Defense Logistics Agency

Wastewater produced from hydraulic fracturing of unconventional oil and gas wells is a complex mixture of high levels of salts and variable levels of organics, naturally occurring radioactive material, and microbial life. Due to the increasing amount of produced water generated, wastewater management is a growing challenge. Beneficial reuse of produced water, following fit-for-purpose treatment, can address the need for wastewater management but requires a full understanding of its composition including organic constituents. Here, we identify a new set of chlorinated surfactant transformation products present in water produced from the Marcellus shale region. Produced water samples were analyzed using liquid chromatography-quadrupole-time-of-flight (LC-QTOF) mass spectrometry. Chlorinated surfactants were identified using tandem mass spectrometry (MS/MS), and ethoxylate oligomers were differentiated using Kendrick Mass Defect analysis. Proposed chemical structures of the newly identified chlorinated surfactants were confirmed by comparison with a synthetic reference standard. Mechanistic studies under simulated subsurface conditions were performed. Our results suggest that the chlorination of injected surfactants can occur at 60 °C in the presence of concentrated hydrochloric acid, which is commonly used during well stimulation processes. These findings illustrate the importance of identifying potential transformation products to ensure proper treatment and reuse of produced water.

2D nanosheets such as graphene oxide (GO) can be stacked to construct membranes with fine-tuned nanochannels to achieve molecular sieving ability. These membranes are often thin to achieve high water permeance, but their fabrication with consistent nanostructures on a large scale presents an enormous challenge. Herein, GO-based hollow fiber membranes (HFMs) are developed for dye desalination by synergistically combining chemical etching to form in-plane nanopores (10-30nm) to increase water permeance and polyamine functionalization to improve underwater stability and enable facile large-scale production using existing membrane manufacturing processes. HFM modules with areas of 88 cm2 and GO layer thicknesses of ≈500nm are fabricated, and they exhibited a stable dye water permeance of 75 L m-2 h-1 bar-1, rejection of >99.5% for Direct red and Congo red, and Na2SO4/dye separation factor of 300-500, superior to state-of-the-art commercial membranes. The versatility of this approach is also demonstrated using different short polyamines and porous substrates. This study reveals a scalable way of designing 2D materials into high-performance robust membranes for practical applications.

Modern power grids coordinate electricity production and consumption via multi-scale wholesale energy markets. Historically, levelized cost metrics were the de facto standard for techno-economic analyses of energy systems and comparison of technology options. However, these metrics neglect the complexity of energy infrastructure including the time-varying value of electricity. An emerging alternative is multi-period optimization, which considers the locational marginal price of electricity as input data (parameters). In this work, we present a general interface for multi-period optimization with time-varying energy prices to facilitate rapid analysis and comparison of potential energy systems models. The PriceTakerModel class is written in the IDAES�-PSE platform and allows users to generate a multi-period, price-taker model instance, as well as automatically generate common operational constraints for their model, such as start-up and shutdown. We show this interface successfully generates multi-period price-taker models, facilitates model discrimination, and aids in analyzing various technologies for deployment in unique energy markets.

Incorporating phenyl groups into ultrathin polyorganosilica membranes improves hydrothermal stability for H2/CO2 separation.

Produced water is the largest waste stream associated with hydraulic fracturing. The presence of unknown dissolved contaminants in produced water prevents its reuse. Many of these contaminants are transformation products─compounds that are generated during the fracturing process by chemical reactions between injected chemicals and reservoir components. Reactions among fracturing fluid additives, reservoir brine, and injected oxidants result in halogenation reactions that generate halogenated contaminants with high expected toxicity. Here, we investigate the role of subsurface iron in facilitating subsurface halogenation reactions. Experiments were performed using a model brine, cinnamaldehyde as a model fracturing fluid additive, two different oxidants used in hydraulic fracturing (ammonium persulfate and sodium hypochlorite), and three different iron species (iron(II) dichloride, iron(III) trichloride, and iron(II) dichloride chelated with citric acid). We observed that iron(II) dichloride increased iodination reactions in the presence of ammonium persulfate oxidant, while iron(III) trichloride increased bromination reactions in the presence of sodium hypochlorite oxidant. Although the absence of replicate analyses in this study precludes the ability to assess the reproducibility of the data, we believe that these results can serve as inspiration for future researchers to consider the potential involvement of iron in chemical reactions of fracturing fluid additives.

Carbon capture remains an integral technology to mitigate pollution from one of the most prevalent greenhouse gases. CO2 desorption/absorbent regeneration for both solid- and liquid-based systems is widely recognized as an energy-intensive and costly process operation. Consequently, tremendous work was devoted toward developing new absorbents and regeneration processes to promote their economic feasibility for extensive implementation. In this review, we broadly and deeply review more than 10,000 papers and extract the hidden trends of carbon capture and absorbent regeneration in the past few decades, using a novel data-mining analysis technique. We comprehensively analyzed an array of recent absorbent regeneration methods utilized in postcombustion, precombustion, carbon capture from industrial point sources, and direct air carbon capture, with an emphasis on sorbent and solvent-based techniques. Advanced regeneration methods using these techniques were illustrated and discussed, followed by recommendations for further research efforts.