Decoupling the electrochemical behavior of associated manganese oxide (MnO2) and the capacitive property of microporous carbonaceous support allows one to have deep insight in a capacitive deionization (CDI) process. A series of electrodes with different MnO2/carbon weight ratios were thus fabricated in this study and their CDI performances were evaluated by operating at different applied potentials in three consecutive charging/discharging circles. Interestingly, it was noted that the capacitance of the electrodes decreased proportionally with increasing MnO2/carbon weight ratio. However, high CDI performances were often observed at electrodes associated with certain amount of MnO2, which was of particularly significant when applied potential exceeded -1.2 VRHE. It is therefore proposed that salt removal at low operation potential is mainly attributed to the electric double layer (EDL) capacitance arisen by microporous carbonaceous materials. By contrary, operation under high applied potential led high CDI performance, presumably through faradaic or electrochemical charge induced by established electric field. Our results furthermore suggested that CDI efficiency enhancement can be achieved by increasing either the capacitance when operated under low applied potential or the faradaic or electrochemical charge if high potential is applied.

Interplay between manganese oxide and microporous carbonaceous support in capacitive deionization

Hydrogen generation from water splitting by photoelectrochemical cell (PEC) is a potential approaches for the generation of hydrogen which can fulfill the global energy requirement. In the process of developing economical and efficient photo-catalysts for water oxidation, n-type monoclinic BiVO4 has been widely explored due to its efficient solar to hydrogen (STH) absorption efficiency and band gap. But the photo conversion efficiency of BiVO4 catalyst is relatively low due to poor charge transport, fast surface charge recombination and sluggish water oxidation kinetics. In current report, BiVO4 photocatalyst composite with graphitic carbon nitride (C3N4) was prepared by dip coating technique to overcome poor charge transport. With the addition of C3N4 in BiVO4 photo current for water oxidation was increased ~22 times (0.95 mA/cm2 at 1.23 V RHE) with regard to pristine BiVO4 (0.046 mA/cm2 at 1.23 V RHE) under simulated one sunlight illumination in K2HPO4 electrolyte. The electrochemical measurements shows improvement in charge carrier density, charge mobility, electrochemical surface area and reduction in bulk and surface resistance with C3N4 addition in BiVO4. The phenomena of surface states formation was used to further confirm the observation. The detailed physical and chemical characterization of samples carried out. Further PEC performance was corroborated with changes in band gap, crystal lattice, surface grain morphology occurred due to C3N4 addition in BiVO4.

Electrochemical investigation of the effect of graphitic carbon nitride addition in BiVO4 to improve photoelectrochemical water oxidation performance

The Renewable Energy status report stated that 48% of total energy is being consumed in Heating and Cooling sector. The energy in this sector is mostly provided by using fossil fuel and it is generating about 39% of carbon dioxide green house gas. It is necessity of time to develop new energy storage materials integrated system to utilize abundant renewable energy such as solar energy to fulfill energy requirement in this particular sector. In current study, newly designed combining solar thermal water and space heating system with phase change material (PCM) has been presented. The new integrated configuration of solar thermal water and space heating system consist of solar thermal collector, insulated energy storage tank, solar energy operated pump, space heating chambers and logic based integrated circuit for efficient operation of system. This is the first time we have integrated PCM storage tank in parallel to water storage tank and space heating chamber for long term efficient use of Solar energy. The heat energy storage and releasing characteristic of synthesized PCM Stearic acid/Palmitic acid and commercial available PCM such as wax, Puretemp68 were tested in new fabricated solar thermal water heating system. The experiments for charging and discharging of PCM were conducted in Mesa, Arizona (33.4152° N, 111.8315° W) summer and winter weather condition. The heat storage, heat releasing, stability of compound and efficiency of different phase change materials with respect to water and space heating were studied. It was observed that synthesized PCM Stearic acid/Palmitic acid has shown efficient charging and discharging behavior. The current solar thermal water heating setup integrated with PCM has shown efficient performance in cold climate, low heat losses during night and efficient solar harvesting capability.

Development, integration and real environment investigation of off-grid solar thermal water and space heating system using phase-change materials

Iodine is the major halogen, and it is a fission product or a decay product of its precursors, for example, Te. Iodine will form some iodide with other fission products (e.g. CsI) which can dissolve into the primary salt. Therefore, nearly all iodine isotopes remain in the salt in the form of I- instead of validation. 131I and 133I were found in MSRE exiting gas which came as a result of volatilization of Te precursors. Since element iodine is a vaporized material, it is one of the major radioactive source term concerns for other types of reactor such as Na-cooled reactor. However, iodine is in the form iodides that can remain in the salt for MSRs, therefore, the salt has a high retention capability of iodine. The iodides in the salt may have some impacts on the salt properties including physical and thermochemical properties. However, such data are very scarce and impacts on the salt properties are not well understood. The iodide in the salt may also lead to corrosion. The present study investigated iodide electrochemical behaviors in molten fluoride salts and iodine ion separation from the salt. The study tested two type of working electrode: Tungsten and graphite. Based on the thermodynamic calculations experimental measurments, the oxidation potential of W is more negative than that of iodine ion, therefore, W electrode cannot be applied as the anode for iodine separation, and then graphite electrode was selected. The electrochemical measurements using graphite working electrode indicates that there is a passive layer which complicates the behaviors of iodide ion by the blocking effect of the layer at the graphite working electrode. The blocking effects made the redox potential shift to a sufficiently positive value. In this case, the oxidation current actually decreases as the potential moves positive, and the process of the iodide ions penetrating through this film becomes rate-limiting. An increase in the concentration of iodide relieved the ‘blocking effect’ and yielded a higher current. The reason for this might be the little amount of replacement of passivation layer by the addition of sodium iodide. Moreover, both cyclic voltammetry and chronoamperometry test were employed to identify the characteristic of the separation of iodide ions. Finally, two pathways, the formation of either I2 gas or KI3 gas, were proposed for the separation mechanism of iodide ions from the system from both thermodynamic calculations and experimental demonstrations.

Iodide in fluoride salts: Its behaviors and iodine ion separation

Fungi are ubiquitous in the environment and are capable of producing highly deleterious chemical species as part their metabolic and respiratory pathways. These chemicals are potentially degrading to fabrics and organically coated metals used in the defense industry. The chemical structures and physical features of fabrics affect their propensity for microbiological decomposition. Aluminum alloys are predominantly used in aircraft for their low weight and comparatively high strength and toughness. These alloys are organically coated for corrosion protection. Defense aircraft operate around the world most frequently in hot, humid environments. In interior regions of the aircraft where sunlight cannot penetrate, fungal spores attach and proliferate leading to microbiologically influenced corrosion (MIC). This type of growth is unsightly, produces objectionable odors, and ultimately can compromise aircraft structural integrity. The presence of organic materials such as hydraulic fluid (HF), corrosion preventative compounds (CPCs) and the organic coatings themselves act as a feedstock for the fungi. Digesting the organic content, the fungi leave by-products such as organic acids, esterases, and lipases which are corrosive and destructive to protective coatings and structural metals, in addition to fabrics. A combination of field and laboratory exposures were used to challenge defense materials and assets to fungal growth.  Fabrics and organically coated metal coupons were exposed to deep tropical jungles in Panama and Suriname for up to 24 months. Coated aluminum panels, with and without HF and CPCs, were also exposed in a controlled elevated temperature and humidity chamber for 84 days with intentional inoculation with select fungal spores.  All samples were examined with environmental scanning microscopy. Additional analytical techniques were performed for the different materials including molecular microbial analysis, weight loss, mechanical property degradation and glucosamine concentration (a measure of biomass). The effectiveness of cleaning procedures were examined.

Fungal degradation of defense materials and assets

The catalytic materials were developed from metal-organic frameworks (MOFs) that contain transition metal ions such as Ce, Cu, Zr, V, Cr, Mn, Fe, Co, and Ni ions. The preparation conditions (e.g., temperature, atmosphere and duration) were well-defined to obtain metal oxide catalysts with controllable morphologies. The methodology avoided the aggregation of nanoparticles and kept the porous structure. The MOF-derived catalysts exhibited high reactivity in the low-temperature catalytic decomposition of volatile organic compounds (VOCs). The light-off temperatures were all lower than 200 °C for MnOx, Co3O4, CuO, and CeO2 derived from Mn-BDC, ZIF-67, CuBDC, and CeBDC, respectively. Ceria catalyst with a unique hierarchical structure developed from parallelepiped Ce-MOF material degraded VOCs (e.g., toluene, cyclohexane, o-xylene, methanol and acetone) at temperatures lower than 150 °C. The extraordinary catalytic performance is due to the high specific surface area, large number of surface defects and oxygen vacancies, as well as good reducibility. The activity and selectivity are comparable to the working noble metal supported catalysts, providing a new perspective for developing efficient low-cost catalysts for VOCs abatement.

Catalytic materials derived from MOFs for low-temperature VOC remediation

Mixtures of alkali and alkaline-earth fluoride and chloride melts are ideal candidates as heat-transfer and storage media in molten-salt reactors (MSRs) and in concentrated solar power (CSP) applications due to their low melting points and relatively high thermochemical stability. However, their utilization at elevated temperatures (500 – 800 °C) is currently limited due to impurity-driven corrosion of salt-facing structural alloys such as stainless steels. For this work, several analytical techniques were used to quantify trace impurities such as water, hydroxides, oxides and alloying elements in chloride salts, to better understand their chemistry and their effects on corrosion of salt-facing materials. Elemental analysis by ICP-OES and combustion were done to quantify alloying element, water and oxide impurities. Synchrotron X-ray diffraction was performed to quantify crystalline phases at varying purities of salts. This talk reports new insights into the chemistry of impurities in molten chloride salts and how they might affect the corrosion experiments.

Impurity analysis in chloride salts using various analytical techniques

Advanced oxidation processes (AOPs) are considered efficient tools for the elimination effluents containing recalcitrant compounds. Therefore, AOPs can be used as a tertiary treatment to remove those compounds not eliminated during conventional wastewater treatment plants (WWTPs). AOPs can also be used as a pre-treatment step to degrade the initial persistent contaminants and further coupled to a secondary biological treatment for a more efficient biodegradation. During these combined processes, the transformation products generated may actually be more toxic or persistent that the initial ones. Therefore, monitoring the presence of these substances along the treatments is necessary. Among the pharmaceuticals from the group of β-blockers, metoprolol has been detected in wastewater in the range 160-2000 ng/l. Moreover, its main human metabolite, metoprolol acid, has been found at much higher concentration and shown to be a recalcitrant in certain biological treatment processes, which highlights its potential environmental relevance. In this study, a comprehensive overview of the elimination of metoprolol and metoprolol acid was performed coupling fungal (FG) and activated sludge (CAS) treatments with UV/H2O2 processes. Two different combinations were tested including UV/H2O2 as pre-treatment and post-treatment step of hospital wastewater. The extent on compound transformation was evaluated via a suspect screening methodology using a liquid chromatography system coupled to a high resolution mass spectrometer (LC-LTQ-Orbitrap-MS/MS). While the different combinations attained high elimination rates of target pollutants, the extent on compound transformation differed in large proportion depending on the set-up and the matrix: higher abundance of persistent intermediates was found at the end of the experiments when CAS+AOP, FG+AOP and AOP+FG combinations were performed compared to AOP + CAS. Results reveal how combined treatments may represent a feasible solution to improve total pollutant removal when treating complex wastewater matrices. Comprehensive studies of the transformation products generated are highly recommended when evaluation of combined treatments, since the target analysis of parent compound did not provide complete information to draw conclusions of the best treatment performance to use.

Coupling of UV/H2O2 and biological treatment for the removal of the pharmaceuticals metoprolol and metoprolol acid from hospital wastewater

An activity-tunable biocatalyst was prepared to disrupt algal cell walls for lipid extraction. It was synthesized by co-immobilization of cellulase and lysozyme on the surface of amino-functionalized magnetic nanoparticles (MNPs) employing glutaraldehyde. The competition between cellulase and lysozyme during immobilization was caused by the limited active sites of the MNPs. The maximum recovery of activities (cellulase: 78.9% and lysozyme: 69.6%) were achieved due to synergistic effects during dual-enzyme co-immobilization. The co-immobilized enzymes showed greater thermal stability and wider pH tolerance than free enzymes under harsh conditions. They have higher catalytic efficiency for the hydrolysis of algal cell walls. More importantly, 60% of co-immobilized enzyme activities were retained after six successive cycles.

Activity-tunable biocatalyst for algal cell wall degradation and lipids extraction

Drugging large protein pockets is a challenge due to the need for higher molecular weight ligands which generally possess undesirable physicochemical properties. In this communication, we highlight a strategy utilizing dimeric small molecule binding to inhibit the STING protein, which contains a large symmetric binding site. By taking advantage of the 2:1 binding stoichiometry, maximal buried interaction with STING protein can be achieved while maintaining the ligand physicochemical properties necessary for oral exposure. This mode of binding requires unique considerations for potency optimization including simultaneous optimization of protein-ligand as well as ligand-ligand interactions. Successful implementation of this strategy led to the identification of a lead compound, which exhibits good oral exposure, slow binding kinetics, and functional inhibition of STING mediated cytokine release.

Discovery of small molecule STING antagonists: Novel use of small molecule dimers to drug large protein pockets

In this presentation we will discuss how to write a great paper and get it accepted by a good journal with a broad aims and scope like Science of the Total Environment (STOTEN) from Elsevier. General outline of this presentation will consists on four bullet points : i) before you begin, ii) select your audience, iii) the article structure and iv) the review and editorial process.  Few aspects related to the submisison of your paper will be highlighted: graphical abstract, article transfer service, social media and article-based publishing. Plagiarism is very relevant and needs to be checked by the authors before submission. As we know publishing is one of the necesssary steps embedded in the scientific research process. Different types of papers can be submitted such as new and original research results, critical review papers and discussions and letters to the editor . In summary as researcher you need a strong manuscript to present your contributions to the scientific community with a novel, clear, useful and exciting message. In addition it should be presented and constructed in a logical manner. Finally few examples of recently published papers in STOTEN will be presented and discussed among the participants.

How to write a great paper and get it accepted by a good environmental journal like Science of the Total Environment (Elsevier): Guide and recommendations

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.