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At least 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Process for purifying hydrogen gas for use in fuel cells

The invention generally relates to a process for purifying a hydrogen gas for use in a fuel cell. The process involves taking a hydrogen feed stream from a high-pressure tank and passing it through a purifier comprising an adsorbent to provide a purified hydrogen stream which is sent to a fuel cell. A particular adsorbent which can be used is a metal-organic framework composition. The adsorbent can be housed in a device such as a canister or cartridge having an inlet and outlet port.

Morris, William↗
DOE OSTI2013

Recent Approaches to Modeling Transport of Mercury in Surface Water and Groundwater - Case Study in Upper East Fork Poplar Creek, Oak Ridge, TN - 13349

In this case study, groundwater/surface water modeling was used to determine efficacy of stabilization in place with hydrologic isolation for remediation of mercury contaminated areas in the Upper East Fork Poplar Creek (UEFPC) Watershed in Oak Ridge, TN. The modeling simulates the potential for mercury in soil to contaminate groundwater above industrial use risk standards and to contribute to surface water contamination. The modeling approach is unique in that it couples watershed hydrology with the total mercury transport and provides a tool for analysis of changes in mercury load related to daily precipitation, evaporation, and runoff from storms. The model also allows for simulation of colloidal transport of total mercury in surface water. Previous models for the watershed only simulated average yearly conditions and dissolved concentrations that are not sufficient for predicting mercury flux under variable flow conditions that control colloidal transport of mercury in the watershed. The transport of mercury from groundwater to surface water from mercury sources identified from information in the Oak Ridge Environmental Information System was simulated using a watershed scale model calibrated to match observed daily creek flow, total suspended solids and mercury fluxes. Mercury sources at the former Building 81-10 area, where mercury was previously retorted, were modeled using a telescopic refined mesh with boundary conditions extracted from the watershed model. Modeling on a watershed scale indicated that only source excavation for soils/sediment in the vicinity of UEFPC had any effect on mercury flux in surface water. The simulations showed that colloidal transport contributed 85 percent of the total mercury flux leaving the UEFPC watershed under high flow conditions. Simulation of dissolved mercury transport from liquid elemental mercury and adsorbed sources in soil at former Building 81-10 indicated that dissolved concentrations are orders of magnitude below a target industrial groundwater concentration beneath the source and would not influence concentrations in surface water at Station 17. This analysis addressed only shallow concentrations in soil and the shallow groundwater flow path in soil and unconsolidated sediments to UEFPC. Other mercury sources may occur in bedrock and transport though bedrock to UEFPC may contribute to the mercury flux at Station 17. Generally mercury in the source areas adjacent to the stream and in sediment that is eroding can contribute to the flux of mercury in surface water. Because colloidally adsorbed mercury can be transported in surface water, actions that trap colloids and or hydrologically isolate surface water runoff from source areas would reduce the flux of mercury in surface water. Mercury in soil is highly adsorbed and transport in the groundwater system is very limited under porous media conditions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Adsorption of Ruthenium, Rhodium and Palladium from Simulated High-Level Liquid Waste by Highly Functional Xerogel - 13286

Fission products are generated by fission reactions in nuclear fuel. Platinum group (Pt-G) elements, such as palladium (Pd), rhodium (Rh) and ruthenium (Ru), are also produced. Generally, Pt-G elements play important roles in chemical and electrical industries. Highly functional xerogels have been developed for recovery of these useful Pt-G elements from high - level radioactive liquid waste (HLLW). An adsorption experiment from simulated HLLW was done by the column method to study the selective adsorption of Pt-G elements, and it was found that not only Pd, Rh and Ru, but also nickel, zirconium and tellurium were adsorbed. All other elements were not adsorbed. Adsorbed Pd was recovered by washing the xerogel-packed column with thiourea solution and thiourea - nitric acid mixed solution in an elution experiment. Thiourea can be a poison for automotive exhaust emission system catalysts, so it is necessary to consider its removal. Thermal decomposition and an acid digestion treatment were conducted to remove sulfur in the recovered Pd fraction. The relative content of sulfur to Pd was decreased from 858 to 0.02 after the treatment. These results will contribute to design of the Pt-G element separation system. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Evaluation of a low cost humate solution as an in situ amendment to enhance attenuation of uranium in an acidic plume - 15445

A single well injection test was conducted in the acidic portion of a groundwater contamination plume beneath the F-Area Seepage Basins on the U.S. Department of Energy's Savannah River Site to evaluate humate as a viable amendment to enhance attenuation of uranium and other radionuclides. Humate is typically used as an inexpensive organic fertilizer. A solution of humate was injected into a monitoring well in the heart of the F-Area Seepage Basins plume. The geochemical conceptual model suggests humate adsorbs to mineral surfaces creating a subsurface treatment zone in which uranium adsorption is enhanced. Following humate injection, groundwater was sampled from the injection well at regular intervals to determine the composition of groundwater and to evaluate the sorption of contaminants within the treatment zone. Attenuation of uranium, radioiodine and Strontium-90 was determined by comparing concentrations to analytes unaffected by the humate, specifically tritium, nitrate, and specific conductance. The post-injection monitoring data showed enhanced uranium attenuation in the treatment zone as uranium concentrations rebounded to only 68% of the pre-test concentrations. Radioiodine attenuation was complicated by changing speciation during the test. When pH was elevated by the humate injection, iodate dominated and enhanced attenuation was observed. As pH decreased, iodide dominated and enhanced attenuation decreased. Humate did not significantly attenuate Strontium-90. Results of the humate injection test demonstrate that humate strongly adsorbs to the aquifer sediments at acidic pH. Humate desorption curves suggest that a substantial fraction of humate will remain adsorbed to the sediments for long-periods of time. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Development of Treatment Process for Radioactive Wastewater Generated from Molybdenum-99 Study - 16415

Molybdenum-99 (Mo-99) high acidic waste solution was securely stored at INER for numerous years. Until 2004, the procedures of waste solution draw-out and pressure-release were accompanied, along with construction of treatment facilities. In 2009, after simulated solution and small volume Mo-99 waste solution tests, the treatment procedure was determined. Then batch-scale treatment facilities were set up. The waste solution was preserved using the instrument, along with modification of some facilities simultaneously. Ultimately all of 12 tanks of Mo-99 inorganic waste solution stored in Building 014 were finished on July, 2012. And residential 5 tanks of those solution served in Building 015B were also completed on September, 2014. A practicable process has been developed for treating radioactive waste generated from Mo-99 study, and it can effectively remove radionuclides from a nitric acid solution. At first, after the waste was sucked from the bucket, the pH value was adjusted to about 10.0 through acid-alkali neutralization. Then, an adsorbent of natural zeolite powder was added to adsorb nuclides, and two adsorption columns filled with Cs-treat and Sr-treat adsorbents were used for removing nuclear species of Cs-137 and Sr-90. In this step, the nuclear species of Cs-137 and Sr-90 contained in the liquid waste are significantly reduced to a degree for manual operation allowable. Then, nitrate ion and mercury ion were removed through another procedure. As a result, the operations were safer and more efficient than other conventional methods. Additionally, the hazard of accidental leakage caused by corrosion of the bucket after long period of storage can be effectively prevented and potential pollution threats are also eliminated. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Adsorptive Removal of Cs-137 and Sr-90 from Water in the Spent Fuel Pool of Taiwan Research Reactor - 18169

The cleanup of spent fuel pool in Taiwan Research Reactor (TRR) is a significant milestone in the decommissioning project of TRR. Due to the water was polluted by the ruptured spent nuclear fuel rods, the fission products and actinides were required to be removed from the water prior to transporting the water to the radioactive liquid wastes treatment plant. A granular aluminosilicate adsorbent (namely GWC) was loaded into a special designed water submersion adsorber to remove radionuclides from water in consideration of the subsequent retrieving after used. The unit is able to be placed underwater without heavy shield shroud, and easily to be assembled and disassembled. More than 95% of β-emitters had been removed from the 980 m{sup 3} of contaminated water in the SFP and generated about 1.5 m{sup 3} of spent GWC which adsorbed with 4*10{sup 12} Bq of radionuclides. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Conventional and Next Generation Treatment Technologies for PFAS - 20067

In 2016, the United States Environmental Protection Agency (USEPA) established a Health Advisory Limit (HAL) for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) (individually and the summation) of 70 nanograms per liter (ng/L) based on developing toxicological information. These two compounds are among several thousand per- and polyfluoroalkyl substances (PFAS). Due to a multitude of commercially beneficial physical and chemical properties, the availability of PFAS-relevant and practical water treatment technologies is limited. The use of conventional adsorbents, such as activated carbon (AC) and anion exchange (AIX) resins, have become a 'de facto' interim measure to immediately address drinking water above this criterion. However, these adsorbents can have marginal long-term efficiency and are relatively unproven against the diversity of polyfluorinated compounds. Additionally, geochemical and/or co-contaminant competition can significantly impede adsorption based PFAS removal. These challenges may be addressed using engineered filtration, such as reverse osmosis or nanofiltration (RO/NF); however, for larger flow systems RO/NF may have unacceptable reject ratios as high as 35% and the capital cost may preclude these technologies. Extending these technologies to natural waters, which have various degrees of geochemical and co-contaminant competition, often requires a treatment train, combining conventional adsorbents or engineered filtration with pretreatment and more innovative and emerging remediation solutions for PFAS. Conventional and Next Generation water treatment technologies for PFAS generally employ one of three mechanisms (adsorption, separation, or destruction). These mechanisms include many types of technologies for both municipal drinking water and extracted natural water applications. The previously mentioned AC, AIX, and RO/NF are commercially available technologies that are actively being deployed for PFAS treatment. Research and development around these technologies is focused on optimization, and ultimate destruction of PFAS is achieved through incineration. Next Generation water treatment technologies include PFAS-specific flocculants, foam fractionation, novel AIX resins, new engineered adsorptive media, electrochemical treatment, sonolysis, and photolysis, radiation, and plasma (forms of advanced reductive processes [ARP]). Research and development around these technologies is focused on proof of concept and assimilation to real world applications. As the PFAS-relevant destructive technologies (such as incineration, electrochemical treatment, sonolysis, and ARP) are energy intensive, the state of the practice for PFAS water treatment is to focus adsorption/separation based technologies on reducing and concentrating the volume of water requiring destructive treatment. This enables more flexibility with respect to circulation frequency, residence time, and more control over energy usage. Water treatment for PFAS presently requires multiple technologies (i.e. a treatment train) to protect human health in a cost-conscious manner. An investment in research and development to explore new technologies is part of a key initiative for efficient protection of human health. This presentation attempts to review PFAS-relevant water treatment technologies and provide perspective as to their status with respect to applicability and commercial relevance. (authors)

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

CO2 Capture Using Amines Bound to Silica

One of the main culprits of global warming is the increased amount of carbon dioxide, or CO2, in the atmosphere. NASA's global climate reports a 13% increase in atmospheric CO2 from 2000 to present. Adsorptive CO2 capture by nitrogen groups of amine-containing solvents is one of the most mature technologies deployed in petrochemical and natural gas processing plants to purify industrial gases. However, key challenges in widespread application include solvent induced reactor corrosion, amine degradation, and high regeneration energy for repeated cycling. An alternative approach is to immobilize amines on solid supports. Key performance metrics of solid amine-based CO2 adsorbents include the CO2 adsorption capacity and stability to degradation over hundreds of thousands of regeneration cycles. Our research aims to develop descriptors for CO2 capture capacity and stability against oxygen-induced degradation for amines bound to porous silica supports using experimental and computational techniques. We experimentally measure the change in CO2-uptake using solid amine adsorbents with varying chemical compositions and exposure to varying gas streams and use high-performance computers to simulate the nature and strength of CO2-adsorption and oxidative degradation reaction mechanisms. Insights from our work can facilitate the development of stable solid amine adsorbents for large-scale CO2 capture processes.

amines↗
DOE OSTI2018

Trends in the Catalytic Activity of Hydrogen Evolution during CO 2 Electroreduction on Transition Metals

During CO 2 electroreduction (CO 2 R), the hydrogen evolution reaction (HER) is a competing reaction. We present a combined experimental and theoretical investigation of the HER activity of transition metals under CO 2 R conditions. Experimental HER polarization curves were measured for six polycrystalline metal surfaces (Au, Ag, Cu, Ni, Pt, and Fe) in the presence of CO 2 gas. We found that the HER activity of the transition metals is significantly shifted, relative to the CO 2 -free case. Density functional theory (DFT) calculations suggest that this shift arises from adsorbate–adsorbate interactions between *CO and *H on intermediate and strong binding metals, which weakens the *H binding energy. Using a simple model for the effect of *CO on the *H binding energy, we construct an activity volcano for HER in the presence of CO 2 gas that is consistent with experimental trends. In conclusion, the significant changes in HER activity in the presence of CO 2 gas is an important consideration in catalyst design and could help develop catalysts that are more selective for CO 2 R than the HER.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Increasing Al-Pair Abundance in SSZ-13 Zeolite via Zeolite Synthesis in the Presence of Alkaline Earth Metal Hydroxide Produces Hydrothermally Stable Co-, Cu- and Pd-SSZ-13 Materials

Replacing alkaline for alkaline-earth metal hydroxide in the synthesis gel during the synthesis of siliceous SSZ-13 zeolite (Si/Al~10) yields SSZ-13 with novel, advantageous properties. Its NH 4 -form ion-exchanges higher amount of isolated divalent M(II) ions than the conventional one: this is the consequence of an increased number of Al pairs in the structure induced by the +2 charge of Sr(II) cations in the synthesis gel that force two charge-compensating AlO 4 – motives to reside closer together. We characterize the +2 state of Co(II) ions in these materials with infra-red spectroscopy and X-ray absorption spectroscopy measurements and show their utility for NOx pollutant adsorption from ambient air: the ones derived from SSZ-13 with higher Al pair content contain more isolated cobalt(II) and, thus, perform better as ambient-air NOx adsorbers. Notably, Co(II)/SSZ-13 with an increased number of Al pairs is significantly more hydrothermally stable than its NaOH-derived analogue. Loading Pd(II) into Co-SSZ-13(Sr) produces an active NOx adsorber (PNA) material that can be used for NOx adsorption from simulated diesel engine exhaust. The critical issue for these applications is hydrothermal stability of Pd-zeolites. Pd/SSZ-13 synthesized in the presence of Sr(OH) 2 does not lose its PNA capacity after extremely harsh aging at 850 and 900 °C (10 h in 10% H 2 O/air flow) and loses only ~55% capacity after hydrothermal aging at 930 °C. This can be extended to other divalent metals for catalytic applications, such as copper: we show that Cu/SSZ-13 catalyst can survive hydrothermal aging at 920 °C without losing its catalytic properties, metal dispersion and crystalline structure. Thus, we provide a new, simple, and scalable strategy for making remarkably (hydro)thermally stable metal-zeolite materials/catalysts with a number of useful applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Designer Metal–Organic Frameworks for Size–Exclusion–Based Hydrocarbon Separations: Progress and Challenges

The separation of hydrocarbons is of primary importance in the petrochemical industry but remains a challenging process. Hydrocarbon separations have traditionally relied predominantly on costly and energy intensive heat-driven procedures such as low temperature distillations. Adsorptive separation based on porous solids represents an alternative technology that is potentially more energy efficient for the separation of some hydrocarbons. Great efforts have been made recently not only on the development of adsorbents with optimal separation performance but also towards the subsequent implementation of adsorption-based separation technology. Emerging as a relatively new class of multifunctional porous materials, metal-organic frameworks hold substantial promise as adsorbents for highly efficient separation of hydrocarbons. This is because of their exceptional and intrinsic porosity tunability which enables size-exclusion based separations that render the highest possible separation selectivity. In this review, we highlight the recent advances in the development of MOFs for separation of selected groups of hydrocarbons, including methane/C2 hydrocarbons, normal alkanes, alkane isomers, alkane/alkene/alkyne, and C8 alkylaromatics, with a particular focus on separations based on size-exclusion mechanism. Insights into tailor-made structures, material design strategies, and structure-property relations will be elucidated. In addition, the existing challenges and possible future directions of this important research field will be discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Sulfonyl PIM–1: A diverse separation membrane with dilation resistance

A sulfone modified variant (soPIM–1) of the first polymer of intrinsic microporosity has been studied through molecular simulations to analyze its applicability for adsorption–based separations of diverse nonpolar, quadrupolar, and dipolar adsorbate species. Single component gas phase adsorption isotherms of each adsorbate are provided. Here, the adsorptive properties of soPIM–1 are reported from the application of two methods: (a) traditional grand canonical Monte Carlo (GCMC) simulations and (b) a combination of Monte Carlo and molecular dynamics (GCMC/MD) techniques, which accounts for sorption–induced polymer dynamics. The calculated isosteric heats of adsorption are compared to those from the parent PIM–1 structure and reveals increased CO2 affinity with relatively no change in hydrocarbon affinity. Moreover, to quantify soPIM–1's resistance to dilation the evolution of the microporous structure across the adsorption isotherm loading pressures has been evaluated. Relatedly, nonequilibrium MD simulations have been utilized to determine that soPIM–1 is approximately twice as stiff as PIM–1.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Condition-dependent NO x adsorption/desorption over Pd/BEA: A combined microreactor and in situ DRIFTS study

Pd/BEA is chosen as a model passive NO x adsorber (PNA) to elucidate the effect of the feed gas composition on the NO x adsorption/desorption behavior. The Brønsted acid and the partially hydrolyzed framework Al (P-HAl(OH)) sites in HBEA adsorb NO and NO 2 under dry conditions. Moreover, the performance of HBEA is not affected by CO, while CO inhibits nitrate formation and promotes NO adsorption via the Pd(NO)(CO) complexes formation over Pd/BEA. H 2 O inhibits NO adsorption over the Brønsted acid and P-HAl(OH) sites, and ionic Pd is the only active site for NO x adsorption under wet conditions. Furthermore, NO adsorption over hydrated Pd (Pd 2+ (OH)(NO)(H 2 O) 3 ) is weaker than NO adsorption over bare ionic Pd (Z 2 [Pd 2+ (NO)], Z[Pd 2+ (OH)(NO)]). Dehydration of Pd 2+ (OH)(NO)(H 2 O) 3 forms more stable Z[Pd 2+ (OH)(NO)] during desorption. Here, the NO adsorption capacity of Pd/BEA improves in the presence of CO under both dry and wet conditions by forming a stable carbonyl–nitrosyl complex.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Engineering Single-Atom Cobalt Catalysts toward Improved Electrocatalysis

In this paper, the development of cost-effective catalysts to replace noble metal is attracting increasing interests in many fields of catalysis and energy, and intensive efforts are focused on the integration of transition-metal sites in carbon as noble-metal-free candidates. Recently, the discovery of single-atom dispersed catalyst (SAC) provides a new frontier in heterogeneous catalysis. However, the electrocatalytic application of SAC is still subject to several theoretical and experimental limitations. Further advances depend on a better design of SAC through optimizing its interaction with adsorbates during catalysis. Here, distinctive from previous studies, favorable 3d electronic occupation and enhanced metal-adsorbates interactions in single-atom centers via the construction of nonplanar coordination is achieved, which is confirmed by advanced X-ray spectroscopic and electrochemical studies. The as-designed atomically dispersed cobalt sites within nonplanar coordination show significantly improved catalytic activity and selectivity toward the oxygen reduction reaction, approaching the benchmark Pt-based catalysts. More importantly, the illustration of the active sites in SAC indicates metal-natured catalytic sites and a media-dependent catalytic pathway. Achieving structural and electronic engineering on SAC that promotes its catalytic performances provides a paradigm to bridge the gap between single-atom catalysts design and electrocatalytic applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

In Situ Synthesized Hydroxyapatite—Cellulose Nanofibrils as Biosorbents for Heavy Metal Ions Removal

The synthesis of hydroxyapatite (HAp) in the presence of cellulose nanofibrils (CNF) or TEMPO-oxidized CNF (TCNF) was performed in situ by wet chemical precipitation process, using chemical precursors, to hybrid a low-cost biosorbents for removal of Co{sup 2+} as a model heavy metal ion. The removal is investigated by batch adsorption method depending on the pH value, the dosage of adsorbent, initial Co{sup 2+} concentration and the contact time of adsorption. The removal of Co{sup 2+} reached the maximum (87%) at pH 6 by using a dosage of 0.5 g L{sup −1}. The TCNFs is shown to increase the nucleation and growth of the HAp synthesized, providing higher surface area (138 m{sup 2} g{sup −1}) with lower pore diameter (11.89 nm), compared to the CNFs based hybrid (135 m{sup 2} g{sup −1}, 14.42 nm) or pure HAp (118 m{sup 2} g{sup −1}, 13.32 nm), however, both resulting to a higher adsorption capacity (25 mg g{sup −1}) of Co{sup 2+} compared to HAp or TCNF (20–22 mg g{sup −1}). The adsorption is follows primarily by pseudo-first and Elovic order kinetic models which is due to the physisorption of Co{sup 2+} and surface ionic interactions with available negative phosphate (from HAp) and/or carboxylic (from TCNF) groups, fitting well with the Freundlich adsorption isotherm, and secondly due to the ion-exchange mechanism of Co{sup 2+} with Ca{sup 2+} from HAp. Both hybrid adsorbents show good adsorption (≥40%) capacity even after third reusing cycle, and high temperature stability (weight loss of 14%) up to 1000 °C, however, the CNF-HAp hybrid represent a high-value alternative to relatively costly TCNF.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Reactive Dye Adsorption from Aqueous Solution on HPEI-Modified Fe{sub 3}O{sub 4} Nanoparticle as a Superadsorbent: Characterization, Modeling, and Optimization

In this work, the optimum condition for the adsorption of Reactive Blue 19 dye onto Fe{sub 3}O{sub 4} functionalized with hyperbranched polyethylenimine (Fe@HPEI) was determined using response surface methodology. The properties of synthesized magnetic Fe@HPEI nanoparticles were ascertained using FTIR, SEM, TEM, VSM and zeta potential measurement. The experimental adsorption data indicating the positive effect of adsorbent dose and contact time, and the negative effect of pH, initial dye concentration and ionic strength on dye adsorption. At optimal condition; pH 3.4, contact time 25 min, adsorbent dose 0.4 g/L and initial dye concentration 113 mg/L, Fe@HPEI nanoparticles removed dye up to 99.27%. The maximum experimental dye adsorption was near to the predicted value of 100%, which confirmed the reliability of the selected statistical model. The dye adsorption data were fitted well to Langmuir isotherm and pseudo-second-order kinetic, and the maximum adsorption capacity was 500 mg/g. Totally, Fe@HPEI as an effective superadsorbent can be repeatedly utilized for the adsorption of dye from the aqueous environment.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Chitosan–Gelatin @ Tin (IV) Tungstatophosphate Nanocomposite Ion Exchanger: Synthesis, Characterization and Applications in Environmental Remediation

The present study reported the synthesis of novel organic–inorganic hybrid nanocomposite by incorporating tin (IV) based ion exchanger into the hybrid polymer network of chitosan and gelatin prepared under vacuum for the efficient removal of heavy metal ions and toxic dyes from an aqueous fluid. The physicochemical studies such as ion exchange capacity (IEC), chemical stability, thermal stability, pH titration and distribution behaviour studies were also carried out to determine the cation exchange behaviour of the material. The surface morphology and structural properties were studied by the techniques such as FTIR, FESEM, EDS, TEM and XRD. Distribution studies confirmed the synthesized CG/STPNC had the highest selectivity for Pb{sup 2+} ions (85.3 mL/g). Maximum adsorption of methylene blue (82%) was achieved within 240 min at 500 mg of adsorbent dose, 10 mg/L of the initial concentration of dye, pH of 7 and 30 °C of temperature. Adsorption kinetic data fitted well with pseudo-second order rate model with R{sup 2} = 0.995. The correlation value 0.95 and favourable R{sub L} = 0.21 of adsorption data suggested better fit for Langmuir adsorption. Thus the synthesized nanocomposite ion exchanger was found to be a promising cation exchanger as well as an adsorbent for heavy metal ion and dye removal from textile industrial effluents. Graphical abstract: .

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

Gas sorption and non-Darcy flow in shale reservoirs

Gas sorption and non-Darcy flow are two important issues for shale gas reservoirs. The sorption consists of dissolution and adsorption. Dissolved gas and adsorbed gas are different. The former is dissolved in the shale matrix, while the latter is concentrated near the solid walls of pores. In this paper, the Langmuir equation is used to describe adsorption and Henry’s law is used to describe dissolution. The K coefficient in Henry’s law of 0.052 mmol/(MPa g TOC) is obtained by matching experimental data. The amount of dissolved gas increases linearly when pressure increases. Using only the Langmuir equation without considering dissolution can lead to a significant underestimation of the amount of sorbed gas in shales. For non-Darcy gas flow, the apparent permeability model for free gas is established by combining slip flow and Knudsen flow. For adsorbed gas, the surface diffusion effect is also considered in this model. Here, the surface diffusion coefficient is suggested to be of the same scale as the gas self-diffusion coefficient, and the corresponding effective permeability is derived. When

02 PETROLEUM↗