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Environmental Applications of Boron‐Doped Diamond Electrodes: 2. Soil Remediation and Sensing Applications
No full textThe chemical stability and electrocatalytic properties of borondoped diamond (BDD) electrodes give rise to various applications. While wastewater treatment is the most widely studied
field, the use of BDD for soil remediation and environmental
sensing is currently investigated more and more. With regards
to soil remediation, promising results have been reported for
the treatment of soil washing solutions. Anodic oxidation using
BDD at high current density allows high mineralization rates of
biorefractory soil pollutants and extracting agents to be
reached. At low current density, selective degradation of target
pollutants has been achieved, thus allowing the reuse of
extracting agents for further soil washing steps. BDD-based
electrochemical sensors have been studied for chemical oxygen
demand determination, pesticide/pharmaceutical detection as
well as other applications such as pH, O2 and analysis of various
organic and inorganic compounds. Low detection limits, wide
linear ranges and low standard deviations have been achieved.
The main reasons behind the superiority of BDD sensors are the
chemical stability, wide applicability and resistance of BDD
towards biofouling. The beauty of BDD sensing is that it can
work for a variety of organic and inorganic compounds under
many physicochemical parameter
Biodegradation of methylene blue dye in a batch and continuous mode using biochar as packing media
No full textBacterial species for metabolizing dye molecules were isolated from dye rich water bodies. The best microbial
species for such an application was selected amongst the isolated bacterial populations by conducting methylene
blue (MB) batch degradation studies with the bacterial strains using NaCl-yeast as a nutrient medium. The most
suitable bacterial species was Alcaligenes faecalis (A. faecalis) according to 16S rDNA sequencing. Process
parameters were optimized and under the optimum conditions (e.g., inoculum size of 3 mL, temperature of 30 °C,
150 ppm, and time of 5 days), 96.2% of MB was removed. Furthermore, the effectiveness for the separation of
MB combining bio-film with biochar was measured by a bio-sorption method in a packed bed bioreactor (PBBR)
in which microbes was immobilized. The maximum MB removal efficiencies, when tested with 50 ppm dye using
batch reactors containing free A. faecalis cells and the same cells immobilized on the biochar surface, were found
to be 81.5% and 89.1%, respectively. The PBBR operated in continuous recycle mode at high dye concentration
of 500 ppm provided 87.0% removal of MB through second-order kinetics over 10 days. The % removal was
found in the order of PBBR>Immobilized batch>Free cell. The standalone biochar batch adsorption of MB can
be described well by the pseudo-second order kinetics (R2 ≥0.978), indicating the major contribution of
electron exchange-based valence forces in the sorption of MB onto the biochar surface. The Langmuir isotherm
suggested a maximum monolayer adsorption capacity of 4.69 mg g−1 at 40 °C which was very close to experimentally
calculated value (4.97 mg g−1). Moreover, the Casuarina seed biochar was reusable 5 times
Genome Sequencing and Analysis of Strains Bacillus sp. AKBS9 and Acinetobacter sp. AKBS16 for Biosurfactant Production and Bioremediation
No full textMicrobial genomics facilitates the analysis of microbial attributes, which can be
applied in bioremediation of pollutants and oil recovery process. The biosurfactants derived from
microbes can replace the chemical surfactants, which are ecologically detrimental. The aim of this
work was to study the genetic organization responsible for biodegradation of aromatics and
biosurfactant production in potential microbes isolated from polluted soil. Bacterial isolates were
tested for biosurfactant production, wherein Bacillus sp. AKBS9 and Acinetobacter sp. AKBS16
exhibited highest biosurfactant production potential. Whole genome sequencing and annotations
revealed the occurrence of sfp and NPRS gene in the Bacillibactin biosynthetic gene cluster in
AKBS9 strain and emulsan biosynthetic gene cluster in AKBS16 strain for biosurfactant
production. Various aromatic compound ring cleaving oxygenases scavenging organic molecules
could be annotated for strain AKBS16 using RAST annotations
Adsorption of an emerging contaminant (primidone) onto activated carbon: kinetic, equilibrium, thermodynamic, and optimization studies
No full textThe current study addresses the removal of an
emerging environmental contaminant (primidone) in
batch adsorption experiments using commercial-grade
powdered activated charcoal (PAC). The experiments
for the removal of primidone were performed to identify
the effect of various adsorption parameters. The secondorder
rate expression best represented the adsorption
kinetics data. The Freundlich isotherm equation was
best fitted to the experimental adsorption data at equilibriumfor
removal of primidone using PAC. The values
for change in entropy (ΔSo) were positive, which indicates
that the degree of freedomof the process increases.
The negative values of change in enthalpy (ΔHo) and
change in Gibb’s free energy (ΔGo) indicate that the
physical adsorption is a dominant phenomenon, and the
process is feasible and spontaneous. The negative value
of ΔHo also represented the exothermicity of the adsorption
process. The Taguchi optimization technique
calculated the influence of variation of different process
parameters, viz., initial pH (pH0), PAC dosage (m),
initial adsorbate concentration (C0), solution temperature
(T), and process contact time (t), on the removal of
primidone by adsorption from aqueous solution. Each of
the above parameters was examined at three levels to
study their effects on the adsorptive uptake of primidone
using PAC (qe, mg g−1), and the optimum value necessary
to maximize qe was determined. The findings from
the ANOVA indicate that the PAC dose (m) is the most
notable parameter contributing 62.16% to qe and a
71.96% to the signal to noise (S/N) ratio data, respectively.
The confirmation experiments performed at the
optimum parameter condition validated the applicability
of the Taguchi design of experiments. The percent removal
and adsorptive uptake at the optimal condition
were 86.11% and 0.258 mg g−1, respectively
Pharmaceuticals and personal care products mediated antimicrobial resistance: future challenges
No full textHighly improved photoreduction of carbon dioxide to methanol using cobalt phthalocyanine grafted to graphitic carbon nitride as photocatalyst under visible light irradiation
No full textA substantially improved methanol yield was achieved from the photoreduction of carbon dioxide under
visible light by using a hybrid photocatalyst consisting of molecular cobalt phthalocyanine tetracarboxylic
acid (CoPc-COOH) complex immobilized to the organic semiconductor graphitic carbon nitride
(g-C3N4) and triethylamine as sacrificial electron donor. The structural and morphological features of
the hybrid photocatalyst determined by various techniques like FTIR, UV–Vis, Raman, XPS, TGA, BET
etc. After 24 h of light irradiation, the methanol yield by using g-C3N4/CoPc-COOH photocatalyst
(50 mg) was found to be 646.5 mmol g�1cat or 12.9 mmol g�1cat with conversion rate 538.75 mmol h�1 -
g�1cat. However, the use of homogeneous CoPc-COOH (6.5 mmol Co, equivalent to g-C3N4/CoPc-COOH)
and g-C3N4 (50 mg) provided 88.5 lmol (1770 lmol g�1cat) and 59.2 lmol (1184 lmol g�1cat) yield of
methanol, respectively under identical conditions. The improved photocatalytic efficiency of the hybrid
was attributed to the binding ability of CoPc-COOH to CO2 that provided the higher CO2 concentration
on the support. Further, the semiconductor support provided better electron mobility and charge separation
with the integrated benefit of facile recovery and recycling of the material at the end of the reduction
process
Enhanced biosorption and electrochemical performance of sugarcane bagasse derived a polylactic acid-graphene oxide-CeO2 composite
No full textIn view of the methyl orange (MO) dye on everyday applications in the textile, food, leather, paper, printing, and
pharmaceuticals industry, in addition to its toxic behaviour on human health, we have developed a biodegradable
polylactic acid (PLA)-based cerium dioxide (CeO2)-graphene oxide (GO) composite by means of a solgel
technique and tested its efficacy. For the study, the PLA polymer obtained is of renewable agriculture waste
origin (sugarcane bagasse) and was isolated by means of fermentation of the feedstock followed by the polymerization
of lactic acid. The instrumental techniques such as the powdered x-ray diffraction, scanning electron
microscopy etc. were employed for the physical characterization of the material. The various parameters such as
the kinetics, desorption, regeneration, pH, isotherm theories, and ionic strength were tested towards the adsorption
of MO dye onto the surface of GO-PLA-CeO2 composite. The outcome of the study exhibited that the GOPLA-
CeO2 composite revealed promising behaviour for the dye removal, which was allocated to the efficacy of
GO, PLA, and CeO2 properties. Also, the adsorption process of GO-PLA-CeO2 is completely dependent on the
initial concentration of MO and the adsorption equilibrium fitted well with the Langmuir isotherm. In addition,
the electrochemical characterization of the composite was studied by means of CV and impedance measurements.
Based on the outcome of the results, it can be said that the GO-PLA-CeO2 composite may be applied as a
suitable electrode material along with its efficient adsorption properties for the removal of MO dye from wastewater
Fate of the persistent organic pollutant (POP)Hexachlorocyclohexane (HCH) and remediation challenges
No full textPersistent Organic Pollutants (POPs) are hazards to human health and exhibit harmful effects to the environment,
owing to their typically lipophilic and bio-accumulative nature. Chlorinated compounds are most relevant
within the classical POPs, which are both toxic and hazardous. Lindane, ‘γ’ isomer of hexachlorocyclohexane (γ-
HCH), is one such organochlorine compound primarily used as a fumigant and an insecticide in agriculture. Due
to its continuous use in the past decade throughout the world and severe environmental impacts in terms of
toxicity and threats, there is an urgent need to develop cleaning up and remediation strategies for the lindanecontaminated
sites. Being electron deficient due to its highly chlorinated nature, the degradation pathway of γ-
HCH is previously thought to be generally under anaerobic condition via reductive dechlorination. But both
aerobic and anaerobic degradation pathways are suggested for HCH isomers and biodegradation pathway of
lindane has been completely elucidated in Sphingomonas paucimobilis UT26. Many bioremediation technologies
viz. biostimulation, bioaugmentation, bioreactor systems have been employed so far for the treatment of HCH
contaminated soil. However, the potential of these strategies has been tested at the laboratory scale and should
be implemented for field-scale treatment of soil and aquatic systems contaminated with lindane and other HCH
isomers. This review focuses on the fundamentals about the biodegradation and also various technologies utilized
for full-scale remediation of HCH contamination in sediment and soils
Treatment methods for removal of pharmaceuticals and personal care products from domestic wastewater
No full textEvaluation of Lead and chromium tolerance and accumulation level in Gomphrena celosoides: A novel metal accumulator from lead acid battery waste contaminated site in Nigeria
No full textBiology, tolerance, and metal (Pb and Cr) accumulating ability of Gomphrena celosoides were studied under hydroponic conditions. The seedlings were raised in Hoagland’s solution containing different concentrations of Pb (0, 500, 1000, 1500, 2000, 3000, 4000, and 5000mg l�1) and Cr (0, 50, 100, 150, 200, 300, and 400mg l�1). Biomass and metal accumulation in different plant
parts were determined at seven (7) and fourteen (14) days after stress. Antioxidant enzyme activities, protein, and proline contents were estimated in stressed and unstressed plants. Gomphrena celosoides was able to tolerate Pb and Cr concentrations up to 4000 and 100mg l�1, respectively in hydroponic solution. Metal accumulation was concentration and duration dependent with the highest Pb (21,127.90 and 117,985.29mg kg�1) and Cr (3130.85 and 2428.90mg kg�1) in shoot and root, respectively found in the plants exposed to 5000mg l�1 Pb and 400mg l�1 Cr for 14 days. Proline, antioxidant enzyme activities, and protein contents were the highest in plant exposed to higher Pb and Cr concentrations for 7 and 14 days. Gomphrena celosoides could be considered as Pb and Cr accumulator with proline and increase in antioxidant enzyme activities being the tolerance mechanisms