14 research outputs found
Electrochemical Deammonification of Synthetic Swine Wastewater
The ammonia electrolysis process, which presents as only
products
nitrogen and hydrogen fuel, was evaluated for the deammonification
of wastewater. The effects of cell voltage, pH, and flow rate were
analyzed for single pass ammonia electro-oxidation of synthetic swine
wastewater. A surface response analysis was performed to obtain quadratic
models that predict the NH<sub>3</sub> conversion and hydrogen (H<sub>2</sub>) production where pH was identified as the variable with
the most statistic significance to explain changes in ammonia conversion
with hydrogen production. NH<sub>3</sub> conversions above 80% and
specific energy consumption under 3 kW·h kg<sup>–1</sup> of NH<sub>3,</sub> without considering the energy that can be obtained
from the H<sub>2</sub> produced, show that the ammonia electrolysis
technology has promising potential for the deammonification of wastewater
with less energy consumption than the conventional nitrification/denitrification
process
Dermatological Journals Indexed in MEDLINE/PubMed
<p>Dermatological Journals Indexed in MEDLINE/PubMed</p
Optimization of the Electrochemical Extraction and Recovery of Metals from Electronic Waste Using Response Surface Methodology
The rapid growth of electronic waste
can be viewed as both an environmental
threat and an attractive source of minerals that can reduce the mining
of natural resources. In this work, response surface methodology was
used to optimize an electrochemical process for the extraction and
recovery of base metals from electronic waste using a mild oxidant
(Fe<sup>3+</sup>). Through this process, the effective extraction
of base metals can be achieved, enriching the concentration of precious
metals and significantly reducing environmental impacts and operating
costs associated with waste generation and chemical consumption. The
optimization was performed using a bench-scale system specifically
designed for this process. Operating parameters such as flow rate,
applied current density, and iron concentration were optimized to
reduce the specific energy consumption of the electrochemical recovery
process to 1.94 kWh per kilogram of metal recovered
Anion Exchange Membrane Electrolyzers as Alternative for Upgrading of Biomass-Derived Molecules
Upgrading of biomass-derived
platform molecules to fuels or chemicals
provides a unique alternative for the substitution of fossil sources
with renewables. Electrochemical reduction (ECR) is one of the upgrading
technologies, alternative to catalytic reduction, which only requires
electricity as the energy input and can be powered by carbon free
energy sources. Moreover, ECR does not require external addition of
hydrogen, as this can be generated <i>in situ</i>. In this
work, an anion exchange membrane (AEM) membrane electrode assembly
(MEA) has been tested for the efficient reduction of biomass-derived
molecules and compared with a cation exchange membrane (CEM) MEA.
The cathode electrocatalyst has been modified with the addition of
hydrophobicity and anion exchange ionomers and incorporated onto an
anion exchange membrane. Electrochemical experiments were performed
with a metal free electrocatalyst in the presence and absence of surrogate
compounds. The results showed that changes in the catalyst formulation
can increase the overpotential for the competing hydrogen evolution
reaction (HER), while significantly enhancing the reduction of the
organic molecules. Bulk electrolysis experiments demonstrated higher
efficiencies for furfural ECR in AEM-MEA vs CEM-MEA, reaching conversions
up to 94% at 50 mA cm<sup>–2</sup> and in the absence of a
supporting electrolyte. Moreover, AEM-MEA was able to facilitate water
management during the reduction process and contribute to the separation
of small carboxylic acids
Facile Room-Temperature Electrodeposition of Rare Earth Metals in a Fluorine-Free Task-Specific Electrolyte
Electrochemical deposition of rare
earth metals at room temperature
has attracted increasing interest due to its advantage in energy efficiency
over traditional hydrometallurgical and pyrometallurgical processes.
Recent progress has been made with fluorinated electrolyte systems;
however, the formation of an electrode-passivating fluoride layer
by electrolyte decomposition is often overlooked. Such a passivation
layer causes significant and rapid decay of the deposition current
and significantly hinders practical application. To address this issue,
we demonstrate a fluorine (F)-free task-specific electrolyte utilizing
the borohydride anion for the efficient electrodeposition of rare
earth metals. By eliminating the passivation effect, the deposition
process exhibits a stable current and accumulates a thick neodymium
deposit on the electrode. Raman spectroscopy of the electrolyte reveals
a synergetic effect between rare earth borohydride and lithium borohydride
which promotes the dissociation of both borohydride salts, resulting
in significantly increased ionic conductivity and electrochemical
performance. Cyclic voltammetry and in-depth X-ray photoelectron spectroscopy
of the deposits suggest that the electrodeposition of rare earth metals
could undergo a Li-mediated reduction process. Quantitative analysis
of the deposits reveals that the overall concentration of the rare
earth elements reaches 75% which contains 40–48% metallic phase
Low-Temperature Electrochemical Upgrading of Bio-oils Using Polymer Electrolyte Membranes
While bio-oil-derived
fuels hold much promise as a replacement
for petroleum, transformation of the highly oxygenated mixture has
proven challenging. In particular, bio-oils are reactive and difficult
to upgrade through catalytic pyrolysis. To reach a stabilized product
capable of deep deoxygenation at elevated pressure and temperature,
conversion or separation of reactive groups is required. This paper
describes an electrochemical process for stabilization and upgrading
of bio-oils prior to hydrotreating at high pressure and temperature.
This electrolytic process uses a three-compartment cell designed to
hydrogenate reactive carbonyl components while separating small acid
molecules, such as acetic and formic acids, which act as catalysts
for condensation reactions and consume hydrogen gas to produce low-value
gases in hydrotreating. To avoid conductivity issues, electrodes are
appended to anion- and cation-exchange membranes. The cell was tested
using a mixed acetic acid and formic acid surrogate fed to the cathode
compartment, where the decrease in the concentration followed the
applied charge to the cell. Experiments performed using pine pyrolysis
oil demonstrated a significant reduction in the total acid number
(TAN), an increase in pH from 2.6 to over 4, and a modest reduction
of the carbonyl concentration. Analysis showed the reduction in TAN
was primarily due to removal of carboxylic compounds. Experiments
observed a decrease in the reactive carbonyl (aldehydes and ketones)
concentration that followed applied charge. The results with the newly
devised reactor show promise for the electrochemical route for upgrading
bio-oils, but significant improvements in TAN removal and carbonyl
conversion are needed. Given the distributed nature of biomass, an
electrochemical process paired with pyrolysis could be used to densify
and stabilize an oil product near the source. The densified liquid
could then be shipped to centralized refineries for final upgrading
to fuel and/or chemical products
Exploring Genomic, Geographic and Virulence Interactions among Epidemic and Non-Epidemic St. Louis Encephalitis Virus (Flavivirus) Strains
<div><p><i>St</i>. <i>Louis encephalitis virus</i> (SLEV) is a re-emerging arbovirus in South America. In 2005, an encephalitis outbreak caused by SLEV was reported in Argentina. The reason for the outbreak remains unknown, but may have been related to virological factors, changes in vectors populations, avian amplifying hosts, and/or environmental conditions. The main goal of this study was to characterize the complete genome of epidemic and non-epidemic SLEV strains from Argentina. Seventeen amino acid changes were detected; ten were non-conservative and located in proteins E, NS1, NS3 and NS5. Phylogenetic analysis showed two major clades based on geography: the North America and northern Central America (NAnCA) clade and the South America and southern Central America (SAsCA) clade. Interestingly, the presence of SAsCA genotype V SLEV strains in the NAnCA clade was reported in California, Florida and Texas, overlapping with known bird migration flyways. This work represents the first step in understanding the molecular mechanisms underlying virulence and biological variation among SLEV strains.</p></div
Correspondence analysis exploring the distribution of 200 non-conservative mutations in 14 SLEV strains through biological features.
<p>Axes CA1 and CA2 account for 84.8% of the total variation observed. HP: high pathogenicity, LP: low pathogenicity, HV: high viremia, LV: low viremia. Source of isolation: Mqt: mosquitoes, Mml: mammals, Brd: birds. Colored dots represent each mutation analyzed distributed by protein.</p
Phylogenetic analyses performed using the SLEV sequences listed in Table 1. (A): Maximum Likelihood analysis. (B): Bayesian inference analysis. (C) Geographic distribution of analyzed St. Louis encephalitis virus strains and migratory bird flyway.
<p>West Nile virus (Acc. Number: DQ211652), Murray Valley Encephalitis virus (Acc. Number: AF161266) and Japanese Encephalitis virus (Acc. Number: M18370.1) were used as outgroups. Abbreviations for the different geographic origin of strains were used as follow: USA (United States); MEX (Mexico); GTM (Guatemala); ARG (Argentina); BRA (Brazil); PERU (Peru); TRN (Trinidad); PAN (Panamá).</p
Spearman’s correlation indices and confidence intervals obtained comparing source of isolation (Mml: mammals, Brd: birds, Mqt: mosquito) and biological behavior (viremia in birds and pathogenicity in mice)in 14 SLEV strains.
<p>Gradient scale colors indicate strength of correlation (positive or negative). *: statistically significant differences.</p