•MgO@g-C3N4 nanocomposite was ultrasonically fabricated using the precursors MgO and g-C3N4.•The anchoring of MgO and g-C3N4 was verified by XPS, XRD and EDX techniques.•The nanocomposite has ...proficiently degraded the indigo carmine dye during a visible light driven process.•A Z-scheme model was suggested for the enhanced as confirmed through the *O2−, h+ and *OH involvement.
Herewith, a direct MgO@g-C3N4 photocatalyst lacking an electron mediator was synthesized via a facile calcination route exploiting MgO and g-C3N4 as precursors. The XRD, SEM, and XPS analysis confirmed the composite formation while the UV–Vis and N2 adsorption connoted a bangap 2.84 eV for the composite compared to 3.75 eV for MgO and larger surface area of 84 m2 g−1 than the 37 m2 g−1 the pure MgO. The Photocatalytic action of the as-prepared samples was assisted by the degradation of the indigo carmine (IC) dye in an aqueous solution under visible light illumination. The reaction was found to comply with the pseudo-first-order kinetics and the rate constant using MgO@g-C3N4 was 14 times that using g-C3N4. The superior photocatalytic performance could be credited to the formation of a MgO@g-C3N4 Z-scheme photocatalyst, which results in the efficient charge carriers separation. In view of the simple and efficient preparation protocol, this study will offer insights into the excellent performance of the Z-scheme for dye photocatalytic degradation.
Electrochemical Sizing of Organic Nanoparticles Cheng, Wei; Zhou, Xiao-Fei; Compton, Richard G.
Angewandte Chemie (International ed.),
December 2, 2013, Letnik:
52, Številka:
49
Journal Article
Recenzirano
The size of organic nanoparticles (NPs) can be electrochemically determined by Faradaic charge transfer when nanoparticles strike an electrode. Indigo NPs were used as a model (see distribution of ...the NP diameter). This strategy could be used for monitoring the size of a wide range of organic nanoparticles.
We report a new class of crystallization-induced red-emitting luminogen based on a synthetic biodegradable indigo derivative, Indigoid-B. This compound, upon an ultrasonic treatment, formed ...well-defined microcrystals that showed striking crystallization-induced emission (CIE) in mixed solvents of tetrahydrofuran-water.
Hemithioindigo (HTI) photoswitches have a tremendous potential for biological and supramolecular applications due to their absorptions in the visible‐light region in conjunction with ultrafast ...photoisomerization and high thermal bistability. Rational tailoring of the photophysical properties for a specific application is the key to exploit the full potential of HTIs as photoswitching tools. Herein we use time‐resolved absorption spectroscopy and Hammett analysis to discover an unexpected principal limit to the photoisomerization rate for donor‐substituted HTIs. By using stationary absorption and fluorescence measurements in combination with theoretical investigations, we offer a detailed mechanistic explanation for the observed rate limit. An alternative way of approaching and possibly even exceeding the maximum rate by multiple donor substitution is demonstrated, which give access to the fastest HTI photoswitch reported to date.
An unexpected principal limit to the photoisomerization rate for donor‐substituted hemithioindigos (HTIs; see figure) has been discovered; this provides a quantitative estimate for the highest possible photoisomerization rate. A mechanistic explanation for the observed limit is offered together with an alternative way of approaching the maximum rate by multiple donor substitution. This approach gave access to the fastest HTI photoswitch reported to date.
The present work describes the successful synthesize of spinel magnetic ferrite Mn1-xNixFe2O4 (x=0.0, 0.1, 0.2, 0.3, 0.4 & 0.5) nanoparticles via a simple microwave combustion method which was then ...evaluated for its photocatalytic activity in the degradation of indigo carmine (IC) synthetic dye, a major water pollutant. Our results reveal that the synthesized of Ni2+ doped MnFe2O4 nanoparticles possess well-crystalline pure cubic spinel phase, exhibit excellent optical and magnetic properties. Further, the photocatalytic performance of the synthesized nanoparticles at different concentration ratios of Ni2+ ions was monitored by photocatalytic degradation of indigo carmine synthetic dye under UV (λ=365nm) light irradiation. In order to get maximum photocatalytic degradation (PCD) efficiency, we have optimized various parameters, which include catalyst dosage, initial dye concentration, pH and Ni2+ dopant content. It was found that the reaction was facilitated with optimum catalyst dose of 50mg/100mL, high dye concentrations of 150mg/L and acidic pH and among all the synthesized samples, Mn0·5Ni0.5Fe2O4 exhibit superior performance of photocatalytic activity on the degradation of indigo carmine synthetic dye. These results highlighted the potential use of effective, low-cost and easily available photocatalysts for the promotion of wastewater treatment and environmental remediation. In addition, the antibacterial activity of spinel magnetic Mn1–xNixFe2O4 nanoparticles against two Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram negative bacteria (Pseudomonas aeruginosa and Escherichia coli) was also examined. Our antibacterial activity results are comparable with the results obtained using the antibiotic, streptomycin.
•Mn1–xNixFe2O4 nanoparticles are synthesized via simple microwave combustion method.•The photocatalytic degradation of indigo carmine synthetic dye was examined.•Mn0.5Ni0.5Fe2O4 shows superior photocatalytic activity and antibacterial activity.•Mn1–xNixFe2O4 nanoparticles show dual performance.
The present study was designed to produce novel cross-linked Chitosan and Chitosan/β-Cyclodextrin beads and study the adsorption of Indigo Carmine. Both adsorbents were characterized by SEM and FTIR ...techniques. Batch experiments were conducted in order to evaluate the effect of initial adsorbent's concentration, dye's initial concentration, initial pH and temperature. In all cases Chitosan/β-Cyclodextrin crosslinked beads exhibited higher removal efficiency of Indigo Carmine. Higher removal rates of Indigo Carmine were observed at low values of dye's initial concentration, pH and temperature, and high concentrations of adsorbent. The equilibrium adsorption data were a good fit for both Langmuir and Freundlich models and maximum adsorption capacity was 500.0 and 1000.0 mgIC/gadsorbent for Chitosan and Chitosan/β-Cyclodextrin crosslinked beads, respectively. Adsorption of Indigo Carmine was found to follow the pseudo-second order. The negative values of ΔGo, ΔHo and ΔSo indicate that the adsorption process is exothermic, spontaneous and favorable at low temperatures.
•Crosslinked chitosan and β-cyclodextrin/chitosan beads were produced.•Study of Indigo Carmine's adsorption on the produced beads.•Maximum adsorption capacity of IC on chitosan beads was 500.0 mg/g.•Maximum adsorption capacity of IC on β-cyclodextrin/chitosan beads was 1000.0 mg/g.•Adsorption of Indigo Carmine was found to follow the pseudo-second order.
Previous works conducted in our laboratory, reveled that Bacillus aryabhattai DC100 produce ligninolytic enzymes such as laccases and/or peroxidases, opening new applications in different ...bioprocesses, including the treatment of disposal residues such as dyestuffs from textile processing industries. This work described the degradation of three commercial model dyes Coomassie Brilliant Blue G-250 (CBB), Indigo Carmine (IC) and Remazol Brilliant Blue R (RBBR) under different culture media and operational conditions. The process was optimized using a Central Composite Rotatable Design, and the desirability predicted complete decolorization of 150 mg/L CBB at 37 °C, 304.09 rpm and salt concentration of 19.204 g/L. The model was validated with concentrations up to 180 mg/L CBB and IC, not being able to remove high amount of RBBR. The procedure here developed also allowed Chemical Oxygen Demands (COD) reductions in CBB of about 42%, meanwhile tests on real effluents from a local textile industry involved COD reductions of 50% in a liquid wastewater and 14% in semi-liquid sludge. Thus, allow the authorized discharge of wastewater into the corresponding treatment plant. Decolorization efficiencies and COD reductions open on the potential application of B. aryabhattai DC100 on the bioremediation of real effluents from textile industries.
•Bacillus aryabhattai shows ligninolytic enzymes such as laccases and/or peroxidases.•B. aryabhattai efficiently decolorizes some model dyestuffs.•B. aryabhattai reduces Chemical Oxygen Demands on real effluents.•B. aryabhattai shows potential application on the bioremediation of real effluents.
Present study explored the adsorptive characteristics of Indigo Carmine (IC) dye from aqueous solution onto rice husk ash (RHA). Batch experiments were carried out to determine the influence of ...parameters like initial pH (pH
0), contact time (
t), adsorbent dose (
m) and initial concentration (
C
0) on the removal of IC. The optimum conditions were found to be: pH
0
=
5.4,
t
=
8
h and
m
=
10.0
g/l. The pseudo-second-order kinetic model represented the adsorption kinetics of IC on to RHA. Equilibrium isotherms were analyzed by Freundlich, Langmuir, Temkin and Redlich–Peterson models using a non-linear regression technique. Adsorption of IC on RHA was favorably influenced by an increase in the temperature of the operation. The positive values of the change in entropy (Δ
S
0) and heat of adsorption (Δ
H
0); and the negative value of change in Gibbs free energy (Δ
G
0) indicate feasible and spontaneous adsorption of IC on to RHA.
A green adsorbent was evaluated to remove the carmine dye. Chitin nanowhiskers were synthesized via acid hydrolyzed method. The diameter of the synthesized chitin whiskers was about 20 nm and had 200 ...to 400 nm length. The morphology and chemical structure of the synthesized adsorbent were investigated by Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FT-IR), X- Ray Diffraction (XRD). The adsorption process parameters of the carmine dye removal were optimized as follow: adsorption time (3 h), initial carmine dye solution concentration (100 ppm), mass loaded of the chitin whiskers suspension 1% weight of chitin nanowhiskers, as an adsorbent (1.4 g). The removal efficiency of the carmine dye adsorption was about 85% which is modified 15% better than the previous researches. The results indicated that carmine dye molecules were absorbed by hydrogen bonding mechanism due to the N-H bond in the chitin nanowhiskers structure.
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•The invasion of false carmine cochineal (Dactylopius opuntiae) threatens cactus pear in the Mediterranean.•Introducing Hyperaspis trifurcata reduced cochineal populations in Israel, ...but often too late to prevent major damage.•Accelerated establishment of H. trifurcata in new hotspots and a “predator-prey dual introduction” approach helped protect cactus pear.•Cochineal’s rapid spread in the West Mediterranean vs. limited spread in the East highlights the need for similar biological control steps.•Bird phoresy likely accelerates cochineal spread; similar controls in Tunisia could prevent acclimatization in Sicily and further north along bird migration routes.
The invasion of false carmine cochineal Dactylopius opuntiae (Cockerell) (Hemiptera; Dactylopiidae) in the Mediterranean region presents a serious threat to cactus pear cultivation. The cochineal was first identified in Israel in 2013, and it soon became clear that biological control is the only long-term solution to protect the cactus pear Opuntia ficus-indica. Releases of the introduced predatory beetle Hyperaspis trifurcata Schaeffer (Coleoptera; Coccinellidae) began in 2016, demonstrating high efficacy and leading to a decline in cochineal populations and plant survival. While H. trifurcata can autonomously reach new cochineal hotspots, it often arrives too late to prevent substantial damage to cactus pear. Human intervention is therefore necessary to expedite the predator’s establishment in new infested sites. To facilitate the spread of the beetle, we consider two approaches: transferring beetle seeding stocks from northern locations through a volunteer network organized by the research team, and applying the ’predator – prey dual introduction’ concept to preemptively mitigate new hotspots expected to emerge as the cochineal spreads southward via winds or birds. These activities have led to a major decrease in the rate of spread of the cochineal population in the East Mediterranean, and in the damage that it inflicts to cactus pear hedgerows. Implementing a similar approach in North Africa can prevent or slow the spread of the cochineal to the northern coast of the central Mediterranean and avoid the heavy damage experienced in Morocco.
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