Mechanisms of removal of heavy metals and arsenic from water by TiO2-heterogeneous photocatalysis

2015 ◽  
Vol 87 (6) ◽  
pp. 557-567 ◽  
Author(s):  
Marta I. Litter
Keyword(s):  
Direct Reduction ◽  
Ionic Species ◽  
Heterogeneous Photocatalysis ◽  
Semiconductor Surface ◽  
Simultaneous Treatment ◽  
Radical Oxidation ◽  
Photogenerated Electrons ◽  
Removal Of Heavy Metals ◽  
Solid Form

AbstractThis article is an overview of recent work performed in our laboratory on TiO2 heterogeneous photocatalysis of aqueous systems containing toxic forms of chromium, arsenic, lead, uranium and mercury. The cases of chromium and arsenic are treated in profundity. Photocatalytic treatments can convert the ionic species into their metallic solid form and deposit them over the semiconductor surface, or transform them into less toxic soluble species. When a transformation to the zerovalent state is possible, this allows the recovery of the metal from the waters, with an important economical return. Three types of mechanisms can be considered, all of them taking place through successive thermodynamically allowed monoelectronic electron transfer steps: (a) direct reduction by photogenerated electrons; (b) indirect reduction by intermediates generated by hole or hydroxyl radical oxidation of electron donors (reducing radicals); (c) oxidative removal by holes or hydroxyl radicals. Fundamentals of oxidative or reductive heterogeneous photocatalysis are described, with special emphasis on the role of organic donors present in the medium acting as synergists. This indicates the possibility of simultaneous treatment of pollutants of different chemical structure and properties present in the same medium.

Introduction to geomicrobiology

2018 ◽  
Author(s):  
David L. Kirchman
Keyword(s):  
Fossil Fuels ◽  
Solid Phase ◽  
Direct Reduction ◽  
Iron Oxidation ◽  
Mineral Dissolution ◽  
Precipitation Process ◽  
Soluble Ions ◽  
Chemolithoautotrophic Bacteria ◽  
The Impact

Geomicrobiology, the marriage of geology and microbiology, is about the impact of microbes on Earth materials in terrestrial systems and sediments. Many geomicrobiological processes occur over long timescales. Even the slow growth and low activity of microbes, however, have big effects when added up over millennia. After reviewing the basics of bacteria–surface interactions, the chapter moves on to discussing biomineralization, which is the microbially mediated formation of solid minerals from soluble ions. The role of microbes can vary from merely providing passive surfaces for mineral formation, to active control of the entire precipitation process. The formation of carbonate-containing minerals by coccolithophorids and other marine organisms is especially important because of the role of these minerals in the carbon cycle. Iron minerals can be formed by chemolithoautotrophic bacteria, which gain a small amount of energy from iron oxidation. Similarly, manganese-rich minerals are formed during manganese oxidation, although how this reaction benefits microbes is unclear. These minerals and others give geologists and geomicrobiologists clues about early life on Earth. In addition to forming minerals, microbes help to dissolve them, a process called weathering. Microbes contribute to weathering and mineral dissolution through several mechanisms: production of protons (acidity) or hydroxides that dissolve minerals; production of ligands that chelate metals in minerals thereby breaking up the solid phase; and direct reduction of mineral-bound metals to more soluble forms. The chapter ends with some comments about the role of microbes in degrading oil and other fossil fuels.

Clinical and pathogenetic role of state of prooxidant-antioxidant regulation in patients with purulent meningitis in the dynamics of disease

2014 ◽  
Vol 18 (4 (72)) ◽  
Author(s):  
D. A. Zadyraka ◽  
E. V. Riabokon
Keyword(s):  
Free Radical ◽  
Conventional Treatment ◽  
Free Radical Oxidation ◽  
Oxidative Modification ◽  
Blood Proteins ◽  
Radical Oxidation ◽  
Pathogenetic Role ◽  
Purulent Meningitis ◽  
Laboratory Changes

The paper shows, that patients with purulent meningitis on the background of severe clinical and laboratory changes had a disturbance of prooxidant-antioxidant regulation with a shift towards activation of free radical oxidation. In the dynamics of the disease, after 7-10 days of conventional treatment, against the background of a reduction of cephalic and meningeal syndromes intensity, a normalization of liquor and hemogram indices, in most patients there was a further decrease in catalase activity and an increase of nitrites, of parameters of spontaneous and induced oxidative modification of blood proteins that remained when the patients were discharged, compared with healthy people.

scholarly journals Anti-inflammatory role of curcumin in Lipopolysaccharide treated A549 cells at global proteome level and on mycobacterial infection

2019 ◽  
Author(s):  
Suchita Singh ◽  
Rakesh Arya ◽  
Rhishikesh R Bargaje ◽  
Mrinal Kumar Das ◽  
Subia Akram ◽  
...  
Keyword(s):  
Isotope Labeling ◽  
Small Cell Lung Carcinoma ◽  
Bacterial Load ◽  
Critical Role ◽  
A549 Cells ◽  
Molecular Evidence ◽  
Simultaneous Treatment ◽  
Cell Lung Carcinoma ◽  
Anti Inflammatory

AbstractA diet derived agent Curcumin (Diferuloylmethane), demonstrated its clinical application in inflammation, infection and cancer conditions. Nevertheless, its impact on the proteome of epithelial cells of non-small cell lung carcinoma (NSCLC) is yet to be explored. We employed a stable isotope labeling method for cell culture (SILAC) based relative quantitative proteomics and informatics analysis to comprehend global proteome change in A549 cells treated with curcumin and/or Lipopolysaccharide (LPS). Pretreated A549 cells were infected with Mycobacterium tuberculosis H37Rv strain to monitor bacterial load. With exposure to curcumin and LPS, out of the 1492 identified proteins, 305 and 346 proteins showed deregulation respectively. The expression of BID and AIFM1 mitochondrial proteins which play critical role in apoptotic pathway were deregulated in curcumin treated cells. Higher mitochondria intensity was observed in curcumin treated A549 cells than LPS treatment. Simultaneous treatment of curcumin and LPS neutralized the effect of LPS. Curcumin and/or LPS pretreated A549 cells infected with H37Rv, showed successful bacterial internalization. LPS treated A549 cells after infection showed increased bacterial load than curcumin compared to non-treated infected cells. However, simultaneous treatment of curcumin and LPS neutralized the effect of LPS. This study generated molecular evidence to deepen our understanding of the anti-inflammatory role of curcumin and may be useful to identify molecular targets for drug discovery.

Mechanism of radiation purification of polluted water and wastewater

2001 ◽  
Vol 44 (5) ◽  
pp. 131-139 ◽  
Author(s):  
A.K. Pikaev
Keyword(s):  
Municipal Wastewater ◽  
Paper Mill ◽  
Petroleum Products ◽  
Polluted Water ◽  
Water Radiolysis ◽  
Primary Products ◽  
Removal Of Heavy Metals ◽  
Water And Wastewater ◽  
Cadmium Lead

The paper summarizes the results of the studies on radiation purification of polluted water and wastewater conducted in the author's laboratory in cooperation with other institutions. The removal of heavy metals (cadmium, lead, chromium and mercury) from water and wastewater, the purification of wastewater from surfactant and petroleum products, molasses distillery slops, municipal wastewater in the aerosol flow, river water from colored natural organic pollutants, wastewater of dyeing complex and paper mill, the decomposition of some dyes, hydrogen peroxide, chlorine-containing organic compounds, formic acid, etc. were investigated in detail. As a rule, electron-beam treatment in combination with ordinary methods (biological, coagulation, adsorption, flotation, etc.) was used. The main attention is paid to the mechanism of purification of the studied systems. The role of redox reactions of primary products of water radiolysis and secondary short-lived species formed from pollutants, formation of precipitates capturing the pollutants etc. is discussed.

In situ synthesis of hierarchical nitrogen-doped MoS2 microsphere with an excellent visible light-driven photocatalytic nitrogen fixation ability

2020 ◽  
Vol 13 (05) ◽  
pp. 2051031
Author(s):  
Abulikemu Abulizi ◽  
Hujiabudula Maimaitizi ◽  
Dilinuer Talifu ◽  
Yalkunjan Tursun
Keyword(s):  
Visible Light ◽  
High Performance ◽  
Nucleation Site ◽  
Active Species ◽  
Nitrogen Doped ◽  
Photogenerated Electrons ◽  
The Hierarchical Structure ◽  
Visible Light Driven

A photocatalyst of high-performance hierarchical nitrogen-doped MoS2 (N-MoS2) microsphere was fabricated by an in situ hydrothermal method in the presence of cetyltrimethylammonium bromide (CTAB). The as-prepared N-MoS2 microsphere was self-assembled by extremely thin interleaving petals, where CTAB acts as a nucleation site for the formation of the interleaving petals due to the strong interaction between CTA+ and [Formula: see text]. N-MoS2 showed higher N2 fixation ability (101.2 [Formula: see text] mol/g(cat)h) than the non-doped MoS2 under the visible light irradiation, and the improved photocatalytic activity could be ascribed to that the doped N narrows the band gap, and the surface reflecting and scattering effect caused by the hierarchical structure enhance the light adsorption. The trapping experiment of active species was also investigated to evaluate the role of photogenerated electrons in the photocatalytic reaction process. Meanwhile, the possible mechanism for the formation and excellent photocatalytic performance of N-MoS2 microsphere were also presented.

Role of rGO to improve the performance of BiVO4 nanostructures for efficient removal of heavy metals

2019 ◽  
Vol 10 (5) ◽  
pp. 1421-1432
Author(s):  
Muhammad Bilal Tahir ◽  
Tahir Iqbal ◽  
Habiba Kiran ◽  
Sumera Afsheen ◽  
Shabbir Muhammad ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Efficient Removal ◽  
Removal Of Heavy Metals

scholarly journals Interaction of Small Ionic Species With Phospholipid Membranes: The Role of Metal Coordination

2019 ◽  
Vol 5 ◽  
Author(s):  
Chanh Thi Minh Le ◽  
Aamd Houri ◽  
Nimalka Balage ◽  
Brian J. Smith ◽  
Adam Mechler
Keyword(s):  
Ionic Species ◽  
Metal Coordination ◽  
Phospholipid Membranes
Sign in / Sign up

Export Citation Format

Share Document