scholarly journals Microcystis aeruginosa Synergistically Facilitate the Photocatalytic Degradation of Tetracycline Hydrochloride and Cr(VI) on PAN/TiO2/Ag Nanofiber Mats

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 628 ◽  
Author(s):  
Lei Wang ◽  
Changbo Zhang ◽  
Rong Cheng ◽  
Jafar Ali ◽  
Zhenbo Wang ◽  
...  
Keyword(s):  
Microcystis Aeruginosa ◽  
High Efficiency ◽  
Reaction Rate Constant ◽  
Active Species ◽  
Harmful Algae ◽  
Cyanobacterial Blooms ◽  
Tetracycline Hydrochloride ◽  
Algae Blooms ◽  
Secondary Pollutants ◽  
Nanofiber Mats

Cyanobacterial blooms can cause serious damage to aquatic ecosystems. However, we have demonstrated that typical algae-blooming species Microcystis aeruginosa (M. aeruginosa) combined with photocatalysts could synergistically facilitate the photodecontamination of tetracycline hydrochloride (TC) and Cr(VI). In this study, for the first time, harmful algae were successfully converted into photoreactive bionano hybrid materials by immobilizing M. aeruginosa cells onto polyacrylonitrile (PAN)-TiO2/Ag hybrid nanofibers, and their photocatalytic activity was evaluated. The addition of M. aeruginosa significantly improved the photodecontamination, and the reaction rate constant (k) values of TC and Cr(VI) degradation by M. aeruginosa-PAN/TiO2/Ag nanofiber mats were 2.4 and 1.5-fold higher than that of bare PAN/TiO2/Ag nanofiber. Photoreaction caused damage to algae cells, but no microcystin was found that had been photodegraded simultaneously. The effects of various active species were also investigated, and the photodegradation mechanism was proposed. Recycling tests revealed that this flexible M. aeruginosa-PAN/TiO2/Ag hybrid mat had potential application in the removal of mixed organic and inorganic pollutants with high efficiency and without secondary pollutants. Thus, harmful algae blooms could serve as an efficient materials to remove toxic pollutants in a sustainable way under visible light irradiation.

scholarly journals Chemical Characterization of Microcystis aeruginosa for Feed and Energy Uses

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3013
Author(s):  
Larissa Souza Passos ◽  
Éryka Costa Almeida ◽  
Claudio Martin Pereira de Pereira ◽  
Alessandro Alberto Casazza ◽  
Attilio Converti ◽  
...  
Keyword(s):  
Microcystis Aeruginosa ◽  
Animal Feed ◽  
Renewable Energy Sources ◽  
Chemical Characterization ◽  
Cyanobacterial Blooms ◽  
Energy Sources ◽  
Carbohydrate Source ◽  
Heating Value ◽  
Adverse Health Effects ◽  
Degradation Reactions

Cyanobacterial blooms and strains absorb carbon dioxide, drawing attention to its use as feed for animals and renewable energy sources. However, cyanobacteria can produce toxins and have a low heating value. Herein, we studied a cyanobacterial strain harvested during a bloom event and analyzed it to use as animal feed and a source of energy supply. The thermal properties and the contents of total nitrogen, protein, carbohydrate, fatty acids, lipid, and the presence of cyanotoxins were investigated in the Microcystis aeruginosa LTPNA 01 strain and in a bloom material. Microcystins (hepatotoxins) were not detected in this strain nor in the bloom material by liquid chromatography coupled to mass spectrometry. Thermogravimetric analysis showed that degradation reactions (devolatilization) initiated at around 180 °C, dropping from approximately 90% to 20% of the samples’ mass. Our work showed that despite presenting a low heating value, both biomass and non-toxic M. aeruginosa LTPNA 01 could be used as energy sources either by burning or producing biofuels. Both can be considered a protein and carbohydrate source similar to some microalgae species as well as biomass fuel. It could also be used as additive for animal feed; however, its safety and potential adverse health effects should be further investigated.

scholarly journals Evidence of Quorum Sensing in Cyanobacteria by Homoserine Lactones: The Origin of Blooms

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1831
Author(s):  
Natalia Herrera ◽  
Fernando Echeverri
Keyword(s):  
Cell Proliferation ◽  
Quorum Sensing ◽  
Microcystis Aeruginosa ◽  
Industrial Effluents ◽  
Cyanobacterial Blooms ◽  
Cylindrospermopsis Raciborskii ◽  
Bacterial Communication ◽  
Homoserine Lactones ◽  
Exogenous Compounds ◽  
Almost All

Although several theories have been postulated to explain cyanobacterial blooms, their biochemical origin has not yet been found. In this work, we explore the existence of bacterial communication, called quorum sensing, in Microcystis aeruginosa and Cylindrospermopsis raciborskii. Thus, the application of several known acylhomoserine lactones to cultures of both cyanobacteria causes profound metabolic. At 72 h post-application, some of them produced substantial increases in cell proliferation, while others were inhibitors. There was a correlation with colony-forming activity for most of them. According to ELISA analysis, the microcystin levels were increased with some lactones. However, there was a clear difference between M. aeruginosa and C. raciborskii culture since, in the first one, there was an inducing effect on cell proliferation, while in C. raciborskii, the effects were minor. Besides, there were compound inhibitors and inducers of microcystins production in M. aeruginosa, but almost all compounds were only inducers of saxitoxin production in C. raciborskii. Moreover, each lactone appears to be involved in a specific quorum sensing process. From these results, the formation of cyanobacterial blooms in dams and reservoirs could be explained since lactones may come from cyanobacteria and other sources as bacterial microflora-associated or exogenous compounds structurally unrelated to lactones, such as drugs, industrial effluents, and agrochemicals.

scholarly journals Ionic Liquid-Assisted Synthesis of Ag3PO4 Spheres for Boosting Photodegradation Activity under Visible Light

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 788
Author(s):  
Beibei Zhang ◽  
Lu Zhang ◽  
Yulong Zhang ◽  
Chao Liu ◽  
Jiexiang Xia ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Visible Light ◽  
High Efficiency ◽  
Chemical Precipitation ◽  
Active Species ◽  
Precipitation Method ◽  
Dihydrogen Phosphate ◽  
Xrd Pattern ◽  
Simple Chemical ◽  
Visible Light Driven

In this work, a simple chemical precipitation method was employed to prepare spherical-like Ag3PO4 material (IL-Ag3PO4) with exposed {111} facet in the presence of reactive ionic liquid 1-butyl-3-methylimidazole dihydrogen phosphate ([Omim]H2PO4). The crystal structure, microstructure, optical properties, and visible-light photocatalytic performance of as-prepared materials were studied in detail. The addition of ionic liquids played a crucial role in forming spherical-like morphology of IL-Ag3PO4 sample. Compared with traditional Ag3PO4 material, the intensity ratio of {222}/{200} facets in XRD pattern of IL-Ag3PO4 was significantly enhanced, indicating the main {111} facets exposed on the surface of IL-Ag3PO4 sample. The presence of exposed {111} facet was advantageous for facilitating the charge carrier transfer and separation. The light-harvesting capacity of IL-Ag3PO4 was larger than that of Ag3PO4. The photocatalytic activity of samples was evaluated by degrading rhodamine B (RhB) and p-chlorophenol (4-CP) under visible light. The photodegradation efficiencies of IL-Ag3PO4 were 1.94 and 2.45 times higher than that of Ag3PO4 for RhB and 4-CP removal, respectively, attributing to a synergy from the exposed {111} facet and enhanced photoabsorption. Based on active species capturing experiments, holes (h+), and superoxide radical (•O2−) were the main active species for visible-light-driven RhB photodegradation. This study will provide a promising prospect for designing and synthesizing ionic liquid-assisted photocatalysts with a high efficiency.

scholarly journals Superior Degradation Performance of Nanoporous Copper Catalysts on Methyl Orange

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 913
Author(s):  
Jinyi Wang ◽  
Sen Yang
Keyword(s):  
Activation Energy ◽  
Methyl Orange ◽  
High Efficiency ◽  
Low Cost ◽  
Degradation Process ◽  
Copper Catalysts ◽  
Reaction Rate Constant ◽  
Nanoporous Structure ◽  
Intra Particle Diffusion ◽  
Different Temperatures

The development of low-cost and high-efficiency catalysts for wastewater treatment is of great significance. Herein, nanoporous Cu/Cu2O catalysts were synthesized from MnCu, MnCuNi, and MnCuAl with similar ligament size through one-step dealloying. Meanwhile, the comparisons of three catalysts in performing methyl orange degradation were investigated. One of the catalysts possessed a degradation efficiency as high as 7.67 mg·g−1·min−1. With good linear fitting by the pseudo-first-order model, the reaction rate constant was evaluated. In order to better understand the degradation process, the adsorption behavior was considered, and it was divided into three stages based on the intra-particle diffusion model. Three different temperatures were applied to explore the activation energy of the degradation. As a photocatalytic agent, the nanoporous structure of Cu/Cu2O possessed a large surface area and it also had low activation energy, which were beneficial to the excellent degradation performance.

Harmful algae blooms removal from fresh water with modified vermiculite

2013 ◽  
Vol 35 (3) ◽  
pp. 340-346 ◽  
Author(s):  
Chunguang Miao ◽  
Yi Tang ◽  
Hong Zhang ◽  
Zhengyan Wu ◽  
Xiangqin Wang
Keyword(s):  
Fresh Water ◽  
Harmful Algae ◽  
Harmful Algae Blooms ◽  
Algae Blooms

scholarly journals Using a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of <i>Microcystis aeruginosa</i>

2013 ◽  
Vol 10 (12) ◽  
pp. 8139-8157 ◽  
Author(s):  
M. W. Matthews ◽  
S. Bernard
Keyword(s):  
Optical Properties ◽  
Microcystis Aeruginosa ◽  
Cyanobacterial Blooms ◽  
Shell Layer ◽  
Sphere Model ◽  
Homogeneous Population ◽  
Chl A ◽  
Inherent Optical Properties ◽  
Gas Vacuoles ◽  
The Impact

Abstract. A two-layered sphere model is used to investigate the impact of gas vacuoles on the inherent optical properties (IOPs) of the cyanophyte Microcystis aeruginosa. Enclosing a vacuole-like particle within a chromatoplasm shell layer significantly altered spectral scattering and increased backscattering. The two-layered sphere model reproduced features in the spectral attenuation and volume scattering function (VSF) that have previously been attributed to gas vacuoles. This suggests the model is good at least as a first approximation for investigating how gas vacuoles alter the IOPs. Measured Rrs was used to provide a range of values for the central value of the real refractive index, 1 + ε, for the shell layer using measured IOPs and a radiative transfer model. Sufficient optical closure was obtained for 1 + ε between 1.1 and 1.14, which had corresponding Chl a-specific phytoplankton backscattering, bbφ*, between 3.9 and 7.2 × 10−3 m2 mg−1 at 510 nm. The bbφ* values are in close agreement with the literature and in situ particulate backscattering measurements. Rrs simulated for a population of vacuolate cells was greatly enlarged relative to a homogeneous population. A sensitivity analysis of empirical algorithms for estimating Chl a in eutrophic/hypertrophic waters suggests these are robust under variable constituent concentrations and likely to be species-sensitive. The study confirms that gas vacuoles cause significant increase in backscattering and are responsible for the high Rrs values observed in buoyant cyanobacterial blooms. Gas vacuoles are therefore one of the most important bio-optical substructures influencing the IOPs in phytoplankton.

scholarly journals Role of Aerosolized Coal Fly Ash in the Global Plankton Imbalance: Case of Florida's Toxic Algae Crisis

2019 ◽  
pp. 1-24
Author(s):  
Mark Whiteside ◽  
J. Marvin Herndon
Keyword(s):  
Fly Ash ◽  
Marine Mammals ◽  
Salt Water ◽  
Harmful Algal Bloom ◽  
Coal Fly Ash ◽  
Harmful Algae ◽  
Cyanobacterial Blooms ◽  
Red Tides ◽  
Blue Green Algae ◽  
Tropospheric Aerosol

Red tide is the term used in Florida (USA) and elsewhere to describe a type of marine harmful algal bloom (HAB) that grows out of control and produces neurotoxins that adversely affect humans, birds, fish, shellfish, and marine mammals. HABs are becoming more abundant, extensive, and closer to shore, and longer in duration than any time in recorded history. Our objective is to review the effects the multifold components of aerosolized coal fly ash as they relate to the increasing occurrences of HABs. Aerosolized coal fly ash (CFA) pollutants from non-sequestered coal-fired power plant emissions and from undisclosed, although “hidden in plain sight,” tropospheric particulate geoengineering operations are inflicting irreparable damage to the world’s surface water-bodies and causing great harm to human health (including lung cancer, respiratory and neurodegenerative diseases) and environmental health (including major die-offs of insects, birds and trees). Florida’s ever-growing toxic nightmare of red tides and blue-green algae is a microcosm of similar activity globally. Atmospheric deposition of aerosol particulates, most importantly bioavailable iron, has drastically shifted the global plankton community balance in the direction of harmful algae and cyanobacterial blooms in fresh and salt water. Proposed geoengineering schemes of iron fertilization of the ocean would only make a bad situation unimaginably worse. Based on the evidence presented here, the global spread of harmful algae blooms will only be contained by rapidly reducing particulate air pollution both by implementation of universal industrial particulate-trapping and by the immediate halting of jet-sprayed particulate aerosols. Corrective actions depend not only on international cooperation, but on ending the deadly code of silence throughout government, academe, and media on the subject of ongoing tropospheric aerosol geoengineering. Long-standing weather control, climate intervention, and geoengineering operations have come to threaten not only all humans but the entire web of life on Earth.

scholarly journals Enhanced Photocatalytic Reduction of Cr(VI) by Combined Magnetic TiO2-Based NFs and Ammonium Oxalate Hole Scavengers

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 72 ◽  
Author(s):  
Yin-Hsuan Chang ◽  
Ming-Chung Wu
Keyword(s):  
Organic Contaminants ◽  
High Efficiency ◽  
Ammonium Oxalate ◽  
Reaction Rate Constant ◽  
Electron Hole ◽  
Tio2 Nanofibers ◽  
Tio2 Photocatalysts ◽  
Survival And Development ◽  
Hole Scavenger ◽  
Separation Behavior

Heavy metal pollution of wastewater with coexisting organic contaminants has become a serious threat to human survival and development. In particular, hexavalent chromium, which is released into industrial wastewater, is both toxic and carcinogenic. TiO2 photocatalysts have attracted much attention due to their potential photodegradation and photoreduction abilities. Though TiO2 demonstrates high photocatalytic performance, it is a difficult material to recycle after the photocatalytic reaction. Considering the secondary pollution caused by the photocatalysts, in this study we prepared Ag/Fe3O4/TiO2 nanofibers (NFs) that could be magnetically separated using hydrothermal synthesis, which was considered a benign and effective resolution. For the photocatalytic test, the removal of Cr(VI) was carried out by Ag/Fe3O4/TiO2 nanofibers combined with ammonium oxalate (AO). AO acted as a hole scavenger to enhance the electron-hole separation ability, thereby dramatically enhancing the photoreduction efficiency of Cr(VI). The reaction rate constant for Ag/Fe3O4/TiO2 NFs in the binary system reached 0.260 min−1, 6.95 times of that of Ag/Fe3O4/TiO2 NFs in a single system (0.038 min−1). The optimized Ag/Fe3O4/TiO2 NFs exhibited high efficiency and maintained their photoreduction efficiency at 90% with a recyclability of 87% after five cycles. Hence, taking into account the high magnetic separation behavior, Ag/Fe3O4/TiO2 NFs with a high recycling capability are a potential photocatalyst for wastewater treatment.

Sign in / Sign up

Export Citation Format

Share Document