Chemical Cycles Research Articles

Design rules for reciprocal coupling in chemically fueled assembly.

Biology regulates the function and assembly of proteins through non-equilibrium reaction cycles. Reciprocally, the assembly of proteins can influence the reaction rates of these cycles. Such reciprocal coupling between assembly and reaction cycle is a prerequisite for behavior like dynamic instabilities, treadmilling, pattern formation, and oscillations between morphologies. While assemblies regulated by chemical reaction cycles gained traction, the concept of reciprocal coupling is under-explored. In this work, we provide two molecular design strategies to tweak the degree of reciprocal coupling between the assembly and reaction cycle. The strategies involve spacing the chemically active site away from the assembly or burying it into the assembly. We envision that design strategies facilitate the creation of reciprocally coupled and, by extension, dynamic supramolecular materials in the future.

Solvation rules: aromatic interactions outcompete cation-π interactions in synthetic host-guest complexes in water.

Chemical double mutant cycles were used to measure the interaction of a N-methyl pyridinium cation with a π-box in a calix[4]pyrrole receptor. Although the cation-π interaction is attractive (-11 kJ mol-1), it is 7 kJ mol-1 less favourable than the corresponding aromatic interaction with the isosteric but uncharged tolyl group.

Simultaneous detection of thirteen exons of dystrophin gene by optimized multiplex PCR assay to screen Duchenne/Becker muscular dystrophy

Advancements in Polymerase Chain Reaction (PCR) technology and other techniques like Deoxyribonucleic acid (DNA)signal and target amplification have become key procedures in molecular diagnostics. PCR enables the synthesis of nucleic acids in vitro through which a DNA segment can be specifically replicated in a semiconservative way that sets forth deletion and mutation analysis. Multiplex PCR (M-PCR) is beneficial over standard and long PCR as this can amplify more than one locus using the respective primer sets. In harmony with this, the present study aimed to optimize M-PCR followed by its chemistry and condition to screen Duchenne Muscular Dystrophy (DMD) [OMIM #310200] and Becker Muscular Dystrophy (BMD) [OMIM #300376]. Muscular Dystrophies (MDs) are a broad group of hereditary, progressive, and degenerative disorders of muscles. X-linked recessive D/BMD are caused by mutation/s in the dystrophin gene [OMIM #300377] that encodes for dystrophin protein [UniProt#P11532]. As dystrophin is the human metagene with 79 exons, mutational analysis is very challenging. Chamberlain set (10 plex), Beggs set (9 Plex), and Kunkel set (7 Plex) is used for many years to diagnose this condition. However, in this study, Beggs set is customized with 13 exons to screen DMD gene mutation in a single reaction. Optimization of M-PCR was designed with many physicochemical parameters. According to the literature and after many appraisals the present study demonstrated the most sufficient concentration of various chemical components and optimal cycling conditions to optimize the modified Beggs set (13 Plex). 50 µL PCR reaction includes primer(s) (0.3–0.5 µM each), dNTP mixture (160 µM each), Dream Taq buffer (1X), Taq DNA polymerase (6U/50 µL), DNA template (250 ng/50 µL), BSA (0.4 µg/µL), and MgCl2 (1.4 mM). To get the most effective results cyclic conditions obtained were 10 min initial denaturation at 94°C, 62°C annealing temperature, and 35 PCR cycles at 72°C extending temperature. Consequently, the study successfully formulated a less expensive and simple approach for >3000 bp that was used to screen D/BMD. Finally, a developed M-PCR mix with a unique combination of specificity and sensitivity coupled with great flexibility has led to a true revolution in molecular diagnostics.

Aromatic interactions with heterocycles in water.

Conformationally well-defined supramolecular complexes that can be studied in different solvents provide a platform for separating and quantifying free energy contributions due to functional group interactions and desolvation. Here 1:1 complexes formed between four different calix[4]pyrrole receptors and eleven different pyridine N-oxide guests have been used to dissect the factors that govern aromatic interactions with heterocycles in water and in chloroform solution. 1H NMR spectroscopy shows that the three-dimensional structures of the complexes are fixed by four H-bonding interactions between the pyrrole donors at the bottom of the receptor and the N-oxide acceptor on the guest, locking the geometrical arrangement of interacting functional groups in the binding pocket at the other end of the receptor. An aromatic heterocycle on the guest makes two stacking interactions and two edge-to-face interactions with the side walls of the receptor. Chemical double mutant cycles were used to measure the free energy contribution of these four aromatic interactions to the overall stability of the complex. In chloroform, the aromatic interactions measured with pyridine, pyrimidine, furan, thiophene and thiazole are similar to the interactions with a phenyl group, but the effect of introducing a heteroatom depends on where it sits with respect to the aromatic side-walls of the cavity. A nitrogen lone pair directed into a π-face of the side-walls of the binding site leads to repulsive interactions of up to 8 kJ mol-1. In water, the heterocycle aromatic interactions are all significantly more favourable (by up to 12 kJ mol-1). For the non-polar heterocycles, furan and thiophene, the increase in interaction energy correlates directly with hydrophobicity, as measured by the free energy of transfer of the heterocycle from n-hexadecane into water (ΔG°(water-hex)). For the heterocycles with polar nitrogen H-bond acceptors, water can access cracks in the walls of the receptor binding site to solvate the edges of the heterocycles without significantly affecting the geometry of the aromatic interactions, and these nitrogen-water H-bonds stabilise the complexes by about 15 kJ mol-1. The results highlight the complexity of the solvation processes that govern molecular recognition in water.

Reaction-driven assembly: controlling changes in membrane topology by reaction cycles.

Chemical reaction cycles are prototypical examples how to drive systems out of equilibrium and introduce novel, life-like properties into soft-matter systems. We report simulations of amphiphilic molecules in aqueous solution. The molecule's head group is permanently hydrophilic, whereas the reaction cycle switches the molecule's tail from hydrophilic (precursor) to hydrophobic (amphiphile) and vice versa. The reaction cycle leads to an arrest in coalescence and results in uniform vesicle sizes that can be controlled by the reaction rate. Using a continuum description and particle-based simulation, we study the scaling of the vesicle size with the reaction rate. The chemically active vesicles are inflated by precursor, imparting tension onto the membrane and, for specific parameters, stabilize pores.

Substituent effects on aromatic interactions in water.

Molecular recognition in water involves contributions due to polar functional group interactions, partial desolvation of polar and non-polar surfaces and changes in conformational flexibility, presenting a challenge for rational design and interpretation of supramolecular behaviour. Conformationally well-defined supramolecular complexes that can be studied in both water and non-polar solvents provide a platform for disentangling these contributions. Here 1 : 1 complexes formed between four different calix[4]pyrrole receptors and thirteen different pyridine N-oxide guests have been used to dissect the factors that govern substituent effects on aromatic interactions in water. H-bonding interactions between the receptor pyrrole donors and the guest N-oxide acceptor at one end of the complex lock the geometrical arrangement of a cluster of aromatic interactions at the other end of the complex, so that a phenyl group on the guest makes two edge-to-face and two stacking interactions with the four aromatic side-walls of the receptor. The thermodynamic contribution of these aromatic interactions to the overall stability of the complex was quantified by chemical double mutant cycles using isothermal titration calorimetry and 1H NMR competition experiments. Aromatic interactions between the receptor and a phenyl group on the guest stabilise the complex by a factor of 1000, and addition of substituents to the guest phenyl group further stabilises the complex by an additional factor of up to 1000. When a nitro substituent is present on the guest phenyl group, the complex has a sub-picomolar dissociation constant (370 fM). The remarkable substituent effects observed in water for these complexes can be rationalised by comparison with the magnitude of the corresponding substituent effects measured in chloroform. In chloroform, the double mutant cycle free energy measurements of the aromatic interactions correlate well with the substituent Hammett parameters. Electron-withdrawing substituents increase the strength of the interactions by a factor of up to 20, highlighting the role of electrostatics in stabilising both the edge-to-face and stacking interactions. The enhanced substituent effects observed in water are due to entropic contributions associated with the desolvation of hydrophobic surfaces on the substituents. The flexible alkyl chains that line the open end of the binding site assist the desolvation of the non-polar π-surfaces of polar substituents, like nitro, but at the same time allow water to interact with the polar H-bond acceptor sites on the substituent. This flexibility allows polar substituents to maximise non-polar interactions with the receptor and polar interactions with the solvent, leading to remarkably high binding affinities.

Adsorption of CO32-/HCO3- on a quartz surface: cluster formation, pH effects, and mechanistic aspects.

Soluble inorganic carbon is an important component of a soil carbon pool, and its fate in soils, sediments, and underground water environments has great effects on many physiochemical and geological processes. However, the dynamical processes, behaviors and mechanism of their adsorption by soil active components, such as quartz, are still unclear. The aim of this work is to systematically address the anchoring mechanism of CO32- and HCO3- on a quartz surface at different pH values. Three pH values (pH 7.5, pH 9.5 and pH 11) and three carbonate salt concentrations (0.07, 0.14 and 0.28 M) are considered, and molecular dynamics methods are used. The results indicate that the pH value regulates the adsorption behavior of CO32- and HCO3- on the quartz surface by affecting the CO32-/HCO3- ratio and the surface charge of quartz. In general, both HCO3- and CO32- ions were able to adsorb on the quartz surface and the adsorption capacity of CO32- is higher than that of HCO3-. HCO3- ions tended to uniformly distribute in an aqueous solution and contact the quartz surface in the form of single molecules instead of clusters. In contrast, CO32- ions were mainly adsorbed as clusters which became larger as the concentration increased. Na+ ions were essential for the adsorption of HCO3- and CO32-, because some of the Na+ and CO32- ions spontaneously associated together to form clusters, promoting the clusters to be adsorbed on the quartz surface through cationic bridges. The local structures and dynamics trajectory of CO32- and HCO3- showed that the anchoring mechanism of carbonate solvates on quartz involved H-bonds and cationic bridges, which changed in relation to the concentration and pH values. However, the HCO3- ions mainly adsorbed on the quartz surface via H-bonds while the CO32- ions tended to be adsorbed through cationic bridges. These results may help in understanding the geochemical behavior of soil inorganic carbon and further the processes of the Earth's carbon chemical cycle.

Modeling Analysis of a Polygeneration Plant Using a CeO2/Ce2O3 Chemical Looping.

In the current context of complexity between climate change, environmental sustainability, resource scarcity, and geopolitical aspects of energy resources, a polygenerative system with a circular approach is considered to generate energy (thermal, electrical, and fuel), contributing to the control of CO2 emissions. A plant for the multiple productions of electrical energy, thermal heat, DME, syngas, and methanol is discussed and analyzed, integrating a chemical cycle for CO2/H2O splitting driven using concentrated solar energy and biomethane. Two-stage chemical looping is the central part of the plant, operating with the CeO2/Ce2O3 redox couple and operating at 1.2 bar and 900 °C. The system is coupled to biomethane reforming. The chemical loop generates fuel for the plant's secondary units: a DME synthesis and distillation unit and a solid oxide fuel cell (SOFC). The DME synthesis and distillation unit are integrated with a biomethane reforming reactor powered by concentrated solar energy to produce syngas at 800 °C. The technical feasibility in terms of performance is presented in this paper, both with and without solar irradiation, with the following results, respectively: overall efficiencies of 62.56% and 59.08%, electricity production of 6.17 MWe and 28.96 MWe, and heat production of 111.97 MWt and 35.82 MWt. The fuel production, which occurs only at high irradiance, is 0.71 kg/s methanol, 6.18 kg/s DME, and 19.68 kg/s for the syngas. The increase in plant productivity is studied by decoupling the operation of the chemical looping with a biomethane reformer from intermittent solar energy using the heat from the SOFC unit.

Stratospheric aerosol injection may impact global systems and human health outcomes

Solar radiation management (SRM) is a climate engineering strategy to reduce temperature increases due to global climate change. The most well-researched SRM methodology is stratospheric aerosol injection (SAI), which involves increasing the concentration of aerosol particles in the stratosphere to reduce the amount of solar radiation reaching Earth’s surface. The most considered and heavily researched aerosol for SAI is sulfate. SAI has been extensively modeled using various climate scenarios and investigated using data from previous volcanic eruptions, which provide an analog of the climate effects of SAI. Prior research has determined that SAI will not only decrease global temperatures but is likely to have direct impacts on ecosystem and public health. This review seeks to investigate the various ways by which SAI may impact global public health outcomes related to hydrologic cycling, atmospheric chemical cycling, frequency of natural disasters, food system disruptions, and ecological health through the pathways of water, air, soil, and biota. SAI has the potential to decrease negative health outcomes associated with rising temperatures but may have a myriad of impacts on global environmental systems. Anthropogenically altering the global climate, through both the release of greenhouse gases or through climatic engineering, has unknown consequences, many of which will likely impact global health and quality of life. A more holistic approach is necessary to understand the relative benefits and harms in using SAI as compared to the implication of global climate change.

Comparative exergoeconomic analysis of atmosphere and pressurized CLC power plants coupled with supercritical CO2 cycle

Recently, the incorporation of chemical looping combustion (CLC) and sCO2 Brayton cycle has been regarded as a promising technology for clean and efficient power generation. The intrinsic characteristics of the CLC reactors (interconnected circulating fluidized bed or fixed bed) allow them to operate at different pressures, leading to different technological directions. Therefore, a pair of “CLC coupled sCO2 cycle” systems was proposed, namely the atmosphere CLC (A-CLC-sCO2) and pressurized CLC (P-CLC-sCO2). The purpose of this paper is to determine which configuration holds more benefits from a combined exergetic and economic perspective. The operational boundary conditions for thermodynamic advantage of P-CLC-sCO2 over the optimized A-CLC-sCO2 was firstly investigated. Under respective optimal conditions, the exergy efficiency of P-CLC-sCO2 (51.09%) was found to be 1.16% higher than that of A-CLC-sCO2 (49.91%). Besides, the P-CLC-sCO2 exhibited a lower levelized cost of electricity (79.59 $/MWh) than A-CLC-sCO2 (81.31 $/MWh) when using a nickel-based oxygen carrier (OC), but the A-CLC-sCO2 could further reduce LCOE to 78.93 $/MWh by adopting ilmenite-based OC. In addition, the exergy and exergoeconomic analysis of the main components was carried out to find the system improvement strategies.

Thiosulfate enhanced Cu(II)-catalyzed Fenton-like reaction at neutral condition: Critical role of sulfidation in copper cycle and Cu(III) production

Thiosulfate (S2O32-) has been proven to be an effective promoter of Fenton-like reactions by accelerating the metal ions cycle. However, up to now, little is known about the role of sulfur transformation and intermediate sulfur in the regulation of metal chemical cycle and reactive species production. Herein, free Cu(II) was selected as catalyst for the activation of H2O2. The introduction of S2O32- significantly enhanced the degradation of benzoic acid, and the degradation rate (kobs) was 5.8 times that of Cu(II)/H2O2 system. The kinetic model revealed the transformation of sulfur species and demonstrated that sulfides (i.e., HS-/S2-, S2O32-) and S0 were the dominant electron donor for the reduction of Cu(II) into Cu(I). Consequently, the reduction and complexation roles of S2O32- significantly resolve the rate-limiting step and broaden the pH range of in Fenton-like reactions. Evidence for the critical role of high-valent copper (Cu(III)) and HO• on BA degradation was obtained by scavengers experiments, electron paramagnetic resonance and fluorescent probes. Meanwhile, the Cu(II)/H2O2/S2O32- system also exhibited satisfactory anti-interference ability of the various matrix. Overall, this study offers mechanistic insight into sulfidation in Cu chemical cycle and Cu(III) generation, and highlights the potential of S2O32- for Fenton-like reactions to control pollutants.

Preparation and thermal characterization of capric-myristic acid binary eutectic mixture with silver–antimony tin oxide and silver-graphane nanoplatelets hybrid-nanoparticles as phase change material for building applications

• Capric–Myristic acid (CA-MA) binary mixture is proposed for building applications. • Silver- Graphene nanoplatelets (Ag-GNP) (1% wt) was used as hybrid nanocomposites. • Melting and freezing temperature of CA-MA/ Ag-GNP (1% wt) are 18.7 °C and 15.7 °C. • The thermal conductivity of CA-MA/ Ag-GNP (1% wt) was enhanced by 18.52 %. • The prepared CA–MA/Ag-GNP (1% wt) mixture are suitable for building applications. The capric-myristic acid binary eutectic mixture (CA-MA) was prepared as phase change material (PCM) for building applications; later, novel hybrid-nanocomposites of silver–antimony tin oxide (Ag-ATO) and silver-graphane nanoplatelets (Ag-GNP) were added with CA-MA with a weight percentage of 1 and 2 respectively to form a hybrid-nanocomposite PCMs (HNCPCMs). The chemical and thermal characterization of pure CA-MA and HNCPCMs showed that their stability is significant for building applications. The melting temperature (T m ) and freezing temperature (T f ) of pure CA-MA synthesised are 18.15 °C and 16.00 °C, respectively, with melting latent heat (H m ) and freezing latent heat (H f ) of 158.75 J/g and 158.07 J/g, respectively. An HNCPCM of CA-MA/Ag-GNP (1 % wt) shows an improved melting thermal conductivity of 18.52 %, with negligible deviation in melting-freezing temperature and latent heat. The proposed CA-MA/Ag-GNP (1% wt) has significant thermal, chemical, and long-term cycling reliability, making it a promising material for building applications.

Energy and exergy analysis of combined power, methanol, and light olefin generation system fed with shale gas

Environmental problems and limitations of fossil fuel resources, especially crude oil, have intensified the importance of using cleaner and cheaper fuels besides enhancing energy conversion processes. Therefore, a novel power, methanol, and light olefin multi-generation system is designed and modeled in this paper. Chemical looping reforming, chemical looping combustion cycles, and Rankine power system are combined with methanol and light olefin production processes. The input fuel of the system is shale gas. The mass, energy, and exergy balance equations are applied for each system unit as a steady-state control volume to assess its thermodynamic operation. Then, the effects on the system performance of critical parameters are studied comprehensively. The results show that the necessary syngas can be supplied when 71.5% of the inlet shale gas is used in the steam reforming reactor of the chemical looping reforming cycle, and the steam to fuel ratio and carbon dioxide to fuel ratio are 0.61. Furthermore, if 31% of the produced methanol is consumed in the olefin production unit, the system energy and exergy efficiencies are achieved at 67.3% and 71.5%, respectively. In this case, the carbon dioxide flow rate is 800 kmol/hr, separated and stored in the chemical looping combustion cycle, leading to a clean thermodynamic system.

Synthesis of Methanol From a Chemical Looping Syngas for the Decarbonization of the Power Sector

Abstract One promising pathway for carbon capture and utilization is represented by the coupling of chemical looping cycles with liquid fuel synthesis processes. Methanol is an interesting fuel for gas turbines engines, due to its potential reduction of NOX and particulate emissions along with the absence of SO2 emissions. In this work, methanol production from the syngas generated by a three-reactors chemical looping process is investigated by mass and energy balances. The cycle is composed by a reducer reactor, where Fe2O3 is reduced to FeO by the injection of a reducing agent; an oxidizer reactor, where FeO reacts with CO2 and H2O to produce a syngas; an air reactor, where Fe3O4 is regenerated to Fe2O3 by ambient air. The produced syngas is then sent to a methanol synthesis plant. Several syngas compositions deriving from different CO2/(H2O+ CO2) molar fractions (1–3) at the oxidizer inlet are taken into account. The resulting methanol flow rates are almost equal in all investigated configurations (about 0.35 t/h). From an energy standpoint, the required electric power is greater for higher hydrogen mole fractions in the syngas. However, the case with 75% H2 content is characterized by the greatest methanol yield (12.6%), carbon efficiency (23%) and a high feed/recirculation ratio (0.80), thus representing the most indicated configuration among the investigated ones. Finally, by burning methanol in a gas turbine, the total CO2 emissions are halved with respect to the case without the system (if the CO2 associated with biogenic carbon in the reducer reactor is considered as net-zero).

Regulating DNA-Hybridization Using a Chemically Fueled Reaction Cycle.

Molecular machines, such as ATPases or motor proteins, couple the catalysis of a chemical reaction, most commonly hydrolysis of nucleotide triphosphates, to their conformational change. In essence, they continuously convert a chemical fuel to drive their motion. An outstanding goal of nanotechnology remains to synthesize a nanomachine with similar functions, precision, and speed. The field of DNA nanotechnology has given rise to the engineering precision required for such a device. Simultaneously, the field of systems chemistry developed fast chemical reaction cycles that convert fuel to change the function of molecules. In this work, we thus combined a chemical reaction cycle with the precision of DNA nanotechnology to yield kinetic control over the conformational state of a DNA hairpin. Future work on such systems will result in out-of-equilibrium DNA nanodevices with precise functions.

Evaluation of isoprene nitrate chemistry in detailed chemical mechanisms

Abstract. Isoprene nitrates are important chemical species in the atmosphere which contribute to the chemical cycles that form ozone and secondary organic aerosol (SOA) with implications for climate and air quality. Accurate chemical mechanisms are important for the prediction of the atmospheric chemistry of species such as isoprene nitrates in chemical models. In recent years, studies into the chemistry of isoprene nitrates have resulted in the development of a range of mechanisms available for use in the simulation of atmospheric isoprene oxidation. This work uses a 0-D chemical box model to assess the ability of three chemically detailed mechanisms to predict the observed diurnal profiles of four groups of isoprene-derived nitrates in the summertime in the Chinese megacity of Beijing. An analysis of modelled C5H9NO5 isomers, including isoprene hydroperoxy nitrate (IPN) species, highlights the significant contribution of non-IPN species to the C5H9NO5 measurement, including the potentially large contribution of nitrooxy hydroxyepoxide (INHE). The changing isomer distribution of isoprene hydroxy nitrates (IHNs) derived from OH-initiated and NO3-initiated chemistry is discussed, as is the importance of up-to-date alkoxy radical chemistry for the accurate prediction of isoprene carbonyl nitrate (ICN) formation. All mechanisms under-predicted C4H7NO5 as predominately formed from the major isoprene oxidation products, methyl vinyl ketone (MVK) and methacrolein (MACR). This work explores the current capability of existing chemical mechanisms to accurately represent isoprene nitrate chemistry in urban areas significantly impacted by anthropogenic and biogenic chemical interactions. It suggests considerations to be taken when investigating isoprene nitrates in ambient scenarios, investigates the potential impact of varying isomer distributions on iodide chemical ionisation mass spectrometry (I−-CIMS) calibrations, and makes some proposals for the future development of isoprene mechanisms.

Removing Cost Barriers to Template Carbon Synthesis for High-Performance Supercapacitors by Establishing a Zero-Emission Chemical Cycle from CO2

Template carbon (TC) is one of the most promising electrode materials for clean-energy devices (e.g., supercapacitors), but its application is hampered by the high cost of templates and carbon sources. Here, we report a green MgO template recycling technology that converts CO2 to high specific-surface-area TC by establishing a zero-emission chemical cycle at one-third the cost of nonrecycling methods. Up to 10 cycles of recycling demonstrate that the template’s dissolution and regeneration, as well as TC’s pore structure and physical properties, are extremely repeatable. Supercapacitors using symmetric TC electrodes deliver high-capacitance and -rate performances either in aqueous (KOH/H2O, >154 F g–1) or organic (Et4NBF4/AN, >140 F g–1) and ionic liquid (EMIMBF4, >178 F g–1) electrolytes, and ≈100% Coulomb efficiency, outperforming traditional commercial supercapacitors. This progress greatly reduces the cost of large-scale use of TC in supercapacitors and creates a sustainable link between CO2 reduction and clean-energy development.

Sr, Mg co-doped LaGaO3-δ supported Fe2O3 improved the water gas shift reaction with chemical looping

Fe2O3 is prospective for the chemical looping redox cycles but must contain a significant amount of inert supports to ensure high stability. The traditional inert supports (Al2O3, MgAl2O4, etc.) have a dilution effect on Fe2O3, which results in a compromised reactivity. In this work, we propose several Sr, Mg co-doped LaGaO3-δ to support Fe2O3 for chemical looping water splitting and investigated the synergy for the enhanced performance. Mechanistic study manifests that doping Sr increases the amount of oxygen vacancies, promoting the oxygen release and uptake during the redox reaction. Doping Mg mitigated the interaction between Fe2O3 and the supports, leading to much enhanced stability. Therefore, Fe2O3/La0.6Sr0.4Mg0.4Ga0.6O3-δ shows both high hydrogen yield (9.75 mmol.g−1) and peak hydrogen production rate (3.7 mmol.g−1.min−1). The performance shows only a slight decrease even after 100 cycles. The observed results can also inspire the selection and development of advanced supports to improve both the reactivity and stability of oxygen carriers.

Effect of chemical cleaning on nanofiltration process in treating surface water

Nanofiltration (NF) has been increasingly used in drinking water treatment plants; however, the severe membrane fouling caused by organic matter poses great challenges to the application of NF technology. This study investigated the mitigation of NF membrane fouling by different chemical cleaning reagents (e.g., citric acid, NaOH, Na4-EDTA, and Na-SDS), Na4-EDTA and Na-SDS performed better to achieve NF permeability recovery of up to 90.5–94.2 % just in a single chemical cleaning cycle. The hydraulic irreversible membrane fouling could be reduced by 44.9–53.8 % in the multi-cycle operation of chemical cleaning. Na4-EDTA-based cleaning was beneficial to the removal performance of sulfamethazine (SM2) and conferred higher removal efficiency than Na-SDS-based cleaning efficiency. The impact of chemical cleaning on energy consumption was evaluated and indicated that Na4-EDTA-based cleaning could reduce the proportion of unfavorable energy consumption by 4.54 %. The operation stability of the NF process could be effectively improved by chemical cleaning, and the organic pollutants accumulated on the membrane surface can be removed, especially the chemical cleaning using Na4-EDTA and Na-SDS. These findings could improve the operational efficiency of the NF process with low energy consumption, low chemical consumption, and less adverse environmental impact.

Phase Transitions in Chemically Fueled, Multiphase Complex Coacervate Droplets

AbstractMembraneless organelles are droplets in the cytosol that are regulated by chemical reactions. Increasing studies suggest that they are internally organized. However, how these subcompartments are regulated remains elusive. Herein, we describe a complex coacervate‐based model composed of two polyanions and a short peptide. With a chemical reaction cycle, we control the affinity of the peptide for the polyelectrolytes leading to distinct regimes inside the phase diagram. We study the transitions from one regime to another and identify new transitions that can only occur under kinetic control. Finally, we show that the chemical reaction cycle controls the liquidity of the droplets offering insights into how active processes inside cells play an important role in tuning the liquid state of membraneless organelles. Our work demonstrates that not only thermodynamic properties but also kinetics should be considered in the organization of multiple phases in droplets.