Mass Transport and Wetting Resistance in Membranes for Advanced Water Treatment

1 in 4 people on Earth face a lack of clean and safe water sources for drinking, irrigation, sanitation, and economic development. The urgent need for water motivates the use of unconventional water resources, such as seawater and wastewater. Advanced water treatment technologies that allow us to access these unconventional resources are drawing increasing attention. Membrane processes including reverse osmosis (RO) and nanofiltration (NF) have been rapidly growing as advanced water treatment technologies for desalination and water reuse due to high productivity, costeffectiveness, and scalability. The objective of this dissertation research is to further understand mass transport of water and solutes across membranes and increase the effectiveness of innovative distillation-based membrane technologies.&nbsp; Numerous potentially harmful compounds exist in feed streams entering advanced water treatment facilities, and thus, understanding membrane rejection in reverse osmosis and nanofiltration for hundreds of compounds is critical for securing high quality product water. A large rejection dataset was compiled, and machine learning techniques enhanced by molecular fingerprints were used to predict membrane rejection of organic compounds. These techniques allowed us to interpret the relationship between the molecular structure of the solute and its rejection in membrane processes. The machine learning models showed high prediction accuracy (Spearman and Pearson coefficients of 0.86-0.99) both with training and test sets. Then, the trained models were analyzed using Shapley values to study the effects of sub-structures of organic compounds on membrane rejection.&nbsp; The second study in this dissertation focused on addressing the low water flux of the osmotic distillation (OD) process. We found that the high membrane thickness (typically 30-100 m) of current membranes was the main cause of low water fluxes. An optimal membrane thickness of 0.073 m was derived with element-scale simulations, and it was able to achieve water fluxes exceeding those of current commercial forward osmosis (FO) membranes. In addition, comparison of module-scale performance with OD and FO membranes found that optimized OD membranes can outcompete high-performance FO membranes in maximum achievable water flux (25.3 vs. 18.6 kg m-2h-1 for OD and FO membranes, respectively) and water recovery (0.28 vs. 0.18).&nbsp; The third study in this dissertation focused on the transport of volatile compounds in membrane distillation (MD). Rejection of volatile compounds in MD is highly varied and poorly understood. This study analyzed a variety of volatile and semi-volatile organic compounds to yield a comprehensive understanding of transport in MD. The effects of different molecular properties on transport were studied first, and we found the Henry&rsquo;s constant and diffusion coefficient were important in determining solute flux. Then, the transport resistances across MD membranes were quantified and two distinct transport regimes (membrane resistance regime and boundary layer resistance regime) were defined. Hydrophobic membranes are susceptible to membrane pore wetting, which results in failure of the system. To overcome this issue in pressure-driven distillation treating low surface tension liquids, the final study in the dissertation focused on fabricating omniphobic, wetting resistant membranes. Nanoporous membranes were modified with re-entrant structures and low surface energy. The results showed the liquid entry pressure values of the modified membranes were much higher than those of conventional membranes with cylindrical pores, allowing for the desalination at 16 bar with a 15% water-ethanol mixture. This low surface tension feed solution wetted the membrane with cylindrical pores.&nbsp;</p

Reliability Improvement for Booster Reciprocating Compressor In CCR Reformer

Case Stud

Analysis and on-stream countermeasures of High Thrust Bearing Temperature of A Centrifugal Compressor

Case StudyThe problem of high bearing temperature is a frequent concern for most rotating machinery. In case of critical equipment such as critical compressors or turbines, its consequences could lead to total plant shut down and huge losses. Furthermore it is very hard to find its cause, and solutions. On-stream remedies are very limited because the machines aren’t stopped. For the investigation and analysis of high thrust bearing problem of centrifugal compressor, it is required to understand the mechanism of bearing temperature increase as well as thrust load balance. In addition, it is also needed to review the quality and quantity of lube oil supply, and maintenance and operation history in various aspects. Based on actual experience of high thrust bearing temperature rise in recycle gas compressor of Residue Hydrogen Desulfied (RHDS) plant, this case study will show how to analyze it and take on-stream countermeasures, as well as lessons-learned for maintenance and design

Reliability Improvement for Booster Reciprocating Compressor In CCR Reformer

Case Stud

COVID-19 Molecular Pathophysiology::Acetylation of Repurposing Drugs

Abstract: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces immune-mediated type 1 interferon (IFN-1) production, the pathophysiology of which involves sterile alpha motif and histidine-aspartate domain-containing protein 1 (SAMHD1) tetramerization and the cytosolic DNA sensor cyclic-GMP-AMP synthase (cGAS)–stimulator of interferon genes (STING) signaling pathway. As a result, type I interferonopathies are exacerbated. Aspirin inhibits cGAS-mediated signaling through cGAS acetylation. Acetylation contributes to cGAS activity control and activates IFN-1production and nuclear factor-κB (NF-κB) signaling via STING. Aspirin and dapsone inhibit the activation of both IFN-1 and NF-κB by targeting cGAS. We define these as anticatalytic mechanisms. It is necessary to alleviate the pathologic course and take the lag time of the odds of achieving viral clearance by day 7 to coordinate innate or adaptive immune cell reactions

SAE TECHNICAL PAPER SERIES Spray Targeting to Minimize Soot and CO Formation in Premixed Charge Compression Ignition (PCCI) Combustion with a HSDI Diesel Engine Spray Targeting to Minimize Soot and CO Formation in Premixed Charge Compression Ignition (PCC

ABSTRACT The effect of spray targeting on exhaust emissions, especially soot and carbon monoxide (CO) formation, were investigated in a single-cylinder, high-speed, direct-injection (HSDI) diesel engine. The spray targeting was examined by sweeping the start-ofinjection (SOI) timing with several nozzles which had different spray angles ranging from 50 o to 154 o . The tests were organized to monitor the emissions in Premixed Charge Compression Ignition (PCCI) combustion by introducing high levels of EGR (55%) with a relatively low compression ratio (16.0) and an open-crater type piston bowl. The study showed that there were optimum targeting spots on the piston bowl with respect to soot and CO formation, while nitric oxide (NOx) formation was not affected by the targeting. The soot and CO production were minimized when the spray was targeted at the edge of the piston bowl near the squish zone, regardless of the spray angle. Targeting this spot is believed to enhance the pre-ignition mixing of air and the spray effectively with the help of the squish flow. The results from the narrow angle nozzles (50 o and 85 o ) indicated that soot could be optimized when the spray was targeted at the bottom of the piston bowl which provided the longest spray travel distance. However, CO emission increased but was significantly reduced when the spray was targeted at the inner surface of the bowl with a corresponding increase in soot emission. In the standard diesel combustion regime, the soot and CO increased as SOI was retarded, and the minimum soot was achieved with SOI of about -20 degree ATDC. This SOI timing provides a rough boundary between conventional diesel and PCCI combustion as seen from the heat release rate data

SAE TECHNICAL PAPER SERIES Stoichiometric Combustion in a HSDI Diesel Engine to Allow Use of a Three-way Exhaust Catalyst

ABSTRACT The objectives of this study were 1) to evaluate the characteristics of rich diesel combustion near the stoichiometric operating condition, 2) to explore the possibility of stoichiometric operation of a diesel engine in order to allow use of a three-way exhaust after-treatment catalyst, and 3) to achieve practical operation ranges with acceptable fuel economy impacts. Boost pressure, EGR rate, intake air temperature, fuel mass injected, and injection timing variations were investigated to evaluate diesel stoichiometric combustion characteristics in a singlecylinder high-speed direct injection (HSDI) diesel engine. Stoichiometric operation in the Premixed Charge Compression Ignition (PCCI) combustion regime and standard diesel combustion were examined to investigate the characteristics of rich combustion. The results indicate that diesel stoichiometric operation can be achieved with minor fuel economy and soot impact. The fuel consumption at stoichiometric operation increases about 7% compared to the best fuel economy case of standard diesel combustion. However, NOx emissions decrease to around 0.1 g/kW-hr due to oxygen deficiency at stoichiometric condition. Variations of injection timing, intake air temperature, EGR, and boost pressure did not affect the fuel consumption significantly. In general, emissions and fuel consumption were dependent strongly on the equivalence ratio under high EGR and rich operating conditions. Extending the operating range will be the subject of future studies

4,4′-Diaminodiphenyl Sulfone (DDS) as an Inflammasome Competitor.pdf

The aim of this study was to examine the use of an inflammasome competitor as a preventative agent. Coronaviruses have zoonotic potential due to the adaptability of their S protein to bind receptors of other species, most notably demonstrated by SARS-CoV. The binding of SARS-CoV-2 to TLR causes the release of pro-IL-1β, which is cleaved by caspase-1, followed by formation and activation of the inflammasome, which is a mediator of lung inflammation, fever, and fibrosis. The NLRP3 inflammasome is implicated in a variety of human diseases including Alzheimer’s disease (AD), prion diseases, type 2 diabetes, and numerous infectious diseases. By examining the use of 4,4′-diaminodiphenyl sulfone (DDS) in the treatment of patients with Hansen’s disease, also diagnosed as Alzheimer’s disease, this study demonstrates the diverse mechanisms involved in the activation of inflammasomes. TLRs, due to genetic polymorphisms, can alter the immune response to a wide variety of microbial ligands, including viruses. In particular, TLR-Arg677Trp was reported to be exclusively present in Korean patients with lepromatous leprosy (LL). Previously, mutation of the intracellular domain of TLR2 has demonstrated its role in determining the susceptibility to LL, though LL was successfully treated using a combination of DDS with rifampicin and clofazimine. Of the three tested antibiotics, DDS was effective in the molecular regulation of NLRP3 inflammasome activators that are important in mild cognitive impairment (MCI), Parkinson’s disease (PD), and AD. The specific targeting of NLRP3 itself or up-/downstream factors of the NLRP3 inflammasome by DDS may be responsible for its observed preventive effects, functioning as a competitor

Water Desalination via Pressure-Driven Distillation with Chlorine-Resistant and Large-Area Polymeric Membranes

Pressure-driven distillation is a separation process in which hydraulic pressure is used to drive water vapor transport across an air-trapping porous hydrophobic membrane. Current development of pressure-driven distillation is limited by a lack of robust, large-area membranes. Here, we report desalination using pressure-driven vapor transport through scalable polymeric polytetrafluorethylene membranes. The membranes showed pressure-driven water flow with near-complete rejection of sodium chloride (greater than 99%) under hydraulic pressures of up to 10.3 bar. Membrane structure, surface chemistry, and desalination performance were found to be unaffected by doses of sodium hypochlorite up to 3000 ppm h. Flux decline due to biofouling from Pseudomonas aeruginosa bacterium was effectively mitigated using chlorine. Membranes also exhibited high temperature resilience with operation up to 60 °C. Overall, this work demonstrates the use of large-area polymeric materials in pressure-driven distillation and highlights key advantages in chlorine and heat tolerance