Tetracycline Removal Enhancement With Fe-Saturated Nanoporous Montmorillonite in a Tripartite Adsorption/Desorption/Photo-Fenton Degradation Process

2021 ◽  
Author(s):  
Shiva Chahardahmasoumi ◽  
Seyed Amir Hossein Jalali ◽  
Mehdi Nasiri Sarvi
Keyword(s):  
Antimicrobial Activity ◽  
Visible Light ◽  
Fenton Reaction ◽  
Degradation Process ◽  
Oh Radicals ◽  
Desorption Process ◽  
High Tc ◽  
Modified Montmorillonite ◽  
Adsorption Desorption ◽  
First Time

Abstract The adsorption and photo-Fenton degradation of tetracycline (TC) over Fe saturated nanoporous montmorillonite was analyzed. The synthesized samples were characterized using XRD, FTIR, SEM, and XRF analysis, and the adsorption and desorption of TC onto these samples as well as the antimicrobial activity of TC during these processes were analyzed at different pH. The results indicated that the montmorillonite is a great adsorbent for the separation of the TC from aqueous solutions, however, after increasing the amount of TC adsorbed, the desorption process started, and up to 50% of TC adsorbed onto non-modified montmorillonite was released back to the solution with almost no changes in its antimicrobial activity. After acid treatment (for creation of nanoporous layers) and Fe saturation of the montmorillonite, almost similar great separation was achieved compared to non-modified montmorillonite. In addition, the desorption of TC from modified montmorillonite was still high up to 40% of adsorbed TC. However, simultaneous adsorption and photodegradation of TC were detected and almost no antimicrobial activity was detected after 180 min of visible light irradiation, which could be due to the photo-Fenton degradation of TC on the modified montmorillonite surface. In the porous structures of modified montmorillonite high ˙OH radicals were created in the photo-Fenton reaction and were measured using the Coumarin technique. The ˙OH radicals help the degradation of TC as proposed in an oxidation process. Surprisingly, more than 90 % of antimicrobial activity of the TC decreased under visible light (after 180 min) when desorbed from nanoporous Fe-saturated montmorillonite compared to natural montmorillonite. To the best of our knowledge, this is the first time that such a high TC desorption rate from an adsorbent with the least remained antimicrobial activity is reported which makes nanoporous Fe-saturated montmorillonite a perfect separation substance of TC from the environment.

Photodegradation Studies on Orange G and Acid Blue 113: New Doped Rare Earth Nanometal Oxides as Visible Light Active Photo Catalyst

2014 ◽  
Vol 938 ◽  
pp. 257-262
Author(s):  
G.A. Suganya Josephine ◽  
Arumugam Sivasamy
Keyword(s):  
Rare Earth ◽  
Visible Light ◽  
Kinetic Studies ◽  
Degradation Process ◽  
Oh Radicals ◽  
Time Duration ◽  
Ph Variation ◽  
Orange G ◽  
Acid Blue 113 ◽  
Acid Blue

Dyes are a source of serious pollutants from different industrial outlets and show a major contribution in polluting the environment. In the present study two dyes namely Orange G and Acid Blue 113 were compared for their photodegradation efficiency employing rare earth nanometal oxide as a visible active photocatalyst. The prepared catalyst was nanocrystalline form with particle size 70 nm and the surface of the catalyst was highly porous and rough which facilitates the absorption of the dye further enhance the photo degradation which were confirmed by various characterization techniques. Effect of pH, variation of catalyst dosage, variation of initial dye concentration and kinetic studies were conducted for both the dyes. The reaction followed a pseudo first order kinetics. The activity of the prepared catalyst was higher when compared to a commercially used metal oxide. Reusability studies proved that the catalyst prepared was very active even upto the third cycle. The degradation process was initiated by the attack of the OH radical generated in the in-situ process via visible light irradiation. EPR spin trapping technique was employed to confirm the presence of OH radicals. The prepared catalyst degraded the dye molecules of interest in lesser time duration by absorption of visible light, thereby reducing the cost of photodegradation.

New Porous Visible Light Active Photocatalysts of MOx-Titanate (M = Cr, Ni) Nanohybrids

2006 ◽  
Vol 45 ◽  
pp. 779-786
Author(s):  
S.J. Hwang ◽  
T.W. Kim
Keyword(s):  
Photocatalytic Activity ◽  
Metal Oxide ◽  
Visible Light ◽  
Layer By Layer ◽  
Narrow Bandgap ◽  
Visible Light Active ◽  
Visible Light Driven ◽  
Oxide Particles ◽  
Adsorption Desorption ◽  
First Time

We have synthesized for the first time efficient visible light active photocatalysts of porous MOx-Ti1.83O4 (M = Ni, Cr) heterostructure through an exfoliation-restacking route. XRD, SEM, TEM, and XAS results reveal that the titanate nanosheets and the nanosized metal oxide particles are well ordered in layer-by-layer way. N2 adsorption-desorption isotherm and diffuse UV-vis spectroscopic analyses demonstrate that the present nanohybrids have a large surface area (~190-240 m2/g) and a narrow bandgap (~1.6-2.4 eV), which are ascribable to the formation of porous structure and a coupling of the wide bandgap titanate and the narrow bandgap metal oxide species, respectively. These nanohybrids show an enhanced photocatalytic activity to effectively decompose organic compounds under the irradiation of visible light. The present results highlight that the exfoliation-restacking route can provide a very powerful way of developing novel heterostructured materials with efficient visible light driven photocatalytic activity.

Novel p–n junction UiO-66/BiOI photocatalysts with efficient visible-light-induced photocatalytic activity

2018 ◽  
Vol 77 (5) ◽  
pp. 1441-1448 ◽  
Author(s):  
Yuejin Li ◽  
Xili Shang ◽  
Changhai Li ◽  
Xiaoming Huang ◽  
Jingjing Zheng
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Salicylic Acid ◽  
Visible Light ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Uv Visible ◽  
Adsorption Desorption ◽  
Junction Structure ◽  
First Time

Abstract Novel visible-light-induced UiO-66/BiOI photocatalysts with a p–n junction structure have been prepared for the first time through a facile hydrothermal method. The prepared photocatalysts were characterized using the powder X-ray diffraction, high resolution transmission electron microscopy, scanning electron microscopy, UV–visible diffuse reflectance spectra, and N2 adsorption–desorption (Brunauer–Emmett–Teller) techniques respectively. The photodegradation performances of UiO-66/BiOI photocatalysts were evaluated by photodegrading salicylic acid under visible-light irradiation. The UiO-66/BiOI composites displayed much higher photocatalytic efficiencies than pure BiOI under visible light. When the content of UiO-66 was 5.2 wt%, the composite (UiO-66/BiOI-2) has the best photocatalytic activity. Most of the salicylic acid molecules can be degraded in 100 min. The degradation rate of UiO-66/BiOI-2 samples is higher than single BiOI and UiO-66. The enhanced photocatalytic performance of UiO-66/BiOI may be ascribed to the formation of p–n heterojunctions between BiOI and UiO-66, which facilitates the transfer and separation of the photogenerated charge carriers. After recycling of the photocatalyst for five times for the photodegradation of salicylic acid, more than 85% of salicylic acid could still be degraded in the fifth cycle, implying that the as-prepared photocatalysts are highly stable.

scholarly journals Photocatalytic Degradation of Ethiofencarb by a Visible Light-Driven SnIn4S8 Photocatalyst

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1325
Author(s):  
Chiing-Chang Chen ◽  
Janah Shaya ◽  
Kyriaki Polychronopoulou ◽  
Vladimir B. Golovko ◽  
Siriluck Tesana ◽  
...  
Keyword(s):  
Visible Light ◽  
Catalytic Efficiency ◽  
Degradation Process ◽  
Active Species ◽  
Operating Conditions ◽  
Gas Chromatography Mass Spectrometry ◽  
Oh Radicals ◽  
Amide Bonds ◽  
Electronic Spin ◽  
Visible Light Driven

This work reports the preparation and detailed characterization of stannum indium sulfide (SnIn4S8) semiconductor photocatalyst for degradation of ethiofencarb (toxic insecticide) under visible-light irradiation. The as-prepared SnIn4S8 showed catalytic efficiency of 98% in 24 h under optimal operating conditions (pH = 3, catalyst dosage of 0.5 g L−1). The photodegradation reaction followed pseudo-first-order kinetics. The major intermediates have been identified using gas chromatography/mass spectrometry. •O2− and •OH radicals appeared to be the primary active species in the degradation process as revealed by scavenger and electronic spin resonance studies, while photogenerated holes had a secondary role in this process. A plausible mechanism involving two routes was proposed for ethiofencarb degradation by SnIn4S8 after identifying the major intermediate species: oxidative cleavage of the CH2-S and the amide bonds of the carbamate moiety. Lastly, SnIn4S8 was found to be efficient, stable, and reusable in treating real water samples in three successive photodegradation experiments. This study demonstrates the prospect of SnIn4S8 photocatalysis in treatment of natural and contaminated water from extremely toxic organic carbamates as ethiofencarb.

Photo-catalytic Study of Malachite Green Dye Degradation Using Rice Straw Extracted Activated Carbon Supported ZnO Nano-particles

2020 ◽  
Vol 10 (6) ◽  
pp. 849-859
Author(s):  
Radwa A. El-Salamony ◽  
Abeer A. Emam ◽  
Nagwa A. Badawy ◽  
Sara F. El-Morsi
Keyword(s):  
Activated Carbon ◽  
Visible Light ◽  
Rice Straw ◽  
Malachite Green ◽  
Dye Degradation ◽  
Nano Particles ◽  
Oh Radicals ◽  
Impregnation Method ◽  
Photo Degradation ◽  
Malachite Green Dye

Objective: ZnO nanoparticles were synthesized using wet impregnation method, and activated carbon from rice straw (RS) prepared through chemical route. Methods: The nano-composites ZnO-AC series were prepared with different ZnO:AC ratio of 10, 20, 50, and 70% to optimize the zinc oxide nanoparticles used. The obtained composites were characterized by FE-SEM, XRD, SBET, and optical techniques then used for the photo-degradation of Malachite green dye (MG) under visible light. Results: It was found that 10ZnO-AC exhibited excellent visible light photo-catalytic performance. The ·OH radicals’ formation is matching with photo-activity of the prepared composites. The photo-degradation efficiency of MG increased from 63% to 93%, when the 10ZnO-AC photocatalyst amount was increased from 0.5 to 6 g/L. Conclusion: The GC-MS technique was used to analyze the intermediates formed; up to 15 kinds of chemicals were identified as the degradation products.

scholarly journals An Indoor Visible Light Positioning System Using Tilted LEDs with High Accuracy

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 920
Author(s):  
Neha Chaudhary ◽  
Othman Isam Younus ◽  
Luis Nero Alves ◽  
Zabih Ghassemlooy ◽  
Stanislav Zvanovec ◽  
...  
Keyword(s):  
Visible Light ◽  
Polynomial Regression ◽  
Power Level ◽  
Least Square ◽  
Line Of Sight ◽  
Received Power ◽  
Strength Based ◽  
Complex Linear ◽  
Linear Least Square ◽  
First Time

The accuracy of the received signal strength-based visible light positioning (VLP) system in indoor applications is constrained by the tilt angles of transmitters (Txs) and receivers as well as multipath reflections. In this paper, for the first time, we show that tilting the Tx can be beneficial in VLP systems considering both line of sight (LoS) and non-line of sight transmission paths. With the Txs oriented towards the center of the receiving plane (i.e., the pointing center F), the received power level is maximized due to the LoS components on F. We also show that the proposed scheme offers a significant accuracy improvement of up to ~66% compared with a typical non-tilted Tx VLP at a dedicated location within a room using a low complex linear least square algorithm with polynomial regression. The effect of tilting the Tx on the lighting uniformity is also investigated and results proved that the uniformity achieved complies with the European Standard EN 12464-1. Furthermore, we show that the accuracy of VLP can be further enhanced with a minimum positioning error of 8 mm by changing the height of F.

scholarly journals Fe3O4@Pt nanoparticles to enable combinational electrodynamic/chemodynamic therapy

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Tong Chen ◽  
Qiang Chu ◽  
Mengyang Li ◽  
Gaorong Han ◽  
Xiang Li
Keyword(s):  
Fenton Reaction ◽  
Pt Nanoparticles ◽  
Therapeutic Modality ◽  
Ros Generation ◽  
Tumor Treatment ◽  
Superior Efficacy ◽  
Platinum Nanocrystals ◽  
First Time

AbstractElectrodynamic therapy (EDT) has recently emerged as a potential external field responsive approach for tumor treatment. While it presents a number of clear superiorities, EDT inherits the intrinsic challenges of current reactive oxygen species (ROS) based therapeutic treatments owing to the complex tumor microenvironment, including glutathione (GSH) overexpression, acidity and others. Herein for the first time, iron oxide nanoparticles are decorated using platinum nanocrystals (Fe3O4@Pt NPs) to integrate the current EDT with chemodynamic phenomenon and GSH depletion. Fe3O4@Pt NPs can effectively induce ROS generation based on the catalytic reaction on the surface of Pt nanoparticles triggered by electric field (E), and meanwhile it may catalyze intracellular H2O2 into ROS via Fenton reaction. In addition, Fe3+ ions released from Fe3O4@Pt NPs under the acidic condition in tumor cells consume GSH in a rapid fashion, inhibiting ROS clearance to enhance its antitumor efficacy. As a result, considerable in vitro and in vivo tumor inhibition phenomena are observed. This study has demonstrated an alternative concept of combinational therapeutic modality with superior efficacy.

scholarly journals First thermal studies on visible-light-switchable negative T-type photochromes of a nitrile-rich series

RSC Advances ◽  
2021 ◽  
Vol 11 (34) ◽  
pp. 21097-21103
Author(s):  
Mikhail Yu. Belikov ◽  
Mikhail Yu. Ievlev
Keyword(s):  
Thermal Stability ◽  
Visible Light ◽  
Temperature Effect ◽  
Thermal Studies ◽  
First Time ◽  
Thermal Stability Of

The temperature effect on the thermal stability of both the initial and photoinduced forms of nitrile-rich T-type photochromes was studied for the first time.

scholarly journals Bactericidal activity of three different antiseptic ophthalmic preparations as surgical prophylaxis

2021 ◽  
Author(s):  
Daniele Tognetto ◽  
Marco R. Pastore ◽  
Gian Marco Guerin ◽  
Giuliana Decorti ◽  
Martina Franzin ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Povidone Iodine ◽  
Bacterial Load ◽  
Viable Cells ◽  
Polyethylene Glycol 1000 ◽  
Oil Concentration ◽  
Short Time ◽  
First Time ◽  
Antiseptic Solutions

Abstract Purpose In the era of antibiotic resistance, there is an increased interest in antiseptic solutions that might represent a reliable option for ocular surface disinfection. The objective of this study is to compare for the first time three different antiseptic ophthalmic preparations to assess their in vitro antimicrobial activity. Methods The antiseptic activity of three commercial ophthalmic solutions, IODIM (povidone-iodine 0.6% in hyaluronic acid vehicle—Medivis, Catania, Italy), OZODROP (nanoemulsion with ozonated oil—concentration not specified—FBVision, Ophthalmic Pharmaceuticals, Rome, Italy), and DROPSEPT (chlorhexidine 0.02% and vitamin E 0.5% Tocopherol Polyethylene Glycol 1000 Succinate—TPGS, Sooft Italia, Montegiorgio, Italy), was tested in vitro on six reference strains by time-killing assays. Viable cells were evaluated after 1, 15, 30 min; 2, 6, and 24 h exposure by seeding 100 µl of the suspension (or appropriate dilutions) on LB agar or Sabouraud-dextrose agar. All plates were incubated at 37 °C for 24 h and evaluated by manually counting the colonies. Results IODIM solution showed a very rapid microbicidal activity: the number of viable cells for all the tested strains was under the detection limit (less than 10 CFU/ml) already after 1 min exposure, and this result was maintained at every incubation time. The rapid antimicrobial activity of povidone-iodine was not replicated when testing the other two antiseptics. Conclusions The study reports the great efficacy in reducing bacterial load in a very short time of povidone-iodine 0.6% compared with other antiseptic preparations.

Sign in / Sign up

Export Citation Format

Share Document