scholarly journals High Efficiency Mercury Sorption by Dead Biomass of Lysinibacillus Sphaericus—New Insights into the Treatment of Contaminated Water

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1296 ◽  
Author(s):  
Vega-Páez ◽  
Rivas ◽  
Dussán-Garzón
Keyword(s):  
Metal Binding ◽  
High Efficiency ◽  
Immobilized Cells ◽  
Graphite Furnace ◽  
Toxic Metal ◽  
Bacterial Biomass ◽  
Sem Analysis ◽  
Mercury Chloride ◽  
Dead Cell ◽  
Lysinibacillus Sphaericus

Mercury (Hg) is a toxic metal frequently used in illegal and artisanal extraction of gold and silver which makes it a cause of environmental poisoning. Since biosorption of other heavy metals has been reported for several Lysinibacillus sphaericus strains, this study investigates Hg removal. Three L. sphaericus strains previously reported as metal tolerant (CBAM5, Ot4b31, and III(3)7) were assessed with mercury chloride (HgCl2). Bacteria were characterized by scanning electron microscopy coupled with energy dispersive spectroscopy (EDS-SEM). Sorption was evaluated in live and dead bacterial biomass by free and immobilized cells assays. Hg quantification was achieved through spectrophotometry at 508 nm by reaction of Hg supernatants with dithizone prepared in Triton X-114 and by graphite furnace atomic absorption spectroscopy (GF-AAS). Bacteria grew up to 60 ppm of HgCl2. Non-immobilized dead cell mixture of strains III(3)7 and Ot4b31 showed a maximum sorption efficiency of 28.4 µg Hg/mg bacteria during the first 5 min of contact with HgCl2, removing over 95% of Hg. This process was escalated in a semi-batch bubbling fluidized bed reactor (BFB) using rice husk as the immobilization matrix leading to a similar level of efficiency. EDS-SEM analysis showed that all strains can adsorb Hg as particles of nanometric scale that can be related to the presence of S-layer metal binding proteins as shown in previous studies. These results suggest that L. sphaericus could be used as a novel biological method of mercury removal from polluted wastewater.

scholarly journals Relationship Between Immobilization of Cells and Characterization of Binding Sites and of Cell-Free Bacteria and Immobilized Metal Biosorbents

2021 ◽  
Author(s):  
Mostafa G. Fadl ◽  
Zenat Kamel Mohamed
Keyword(s):  
Metal Ions ◽  
Binding Sites ◽  
Metal Uptake ◽  
High Efficiency ◽  
Immobilized Cells ◽  
Bacterial Biomass ◽  
Resistant Bacteria ◽  
Bacterial Cells ◽  
Isolation And Identification ◽  
Charge Interaction

Abstract Cell immobilization is preferred. Immobilized cells have been traditionally used for the treatment of sewage. The techniques employed for immobilization of cells are almost the same as those used for immobilization of enzymes with appropriate modifications. Entrapment and surface attachment techniques are commonly used. Gels, and to some extent membranes, are employed. Certain microorganisms were found to amass metallic components at a high limit Was Known as Bacterial Biosorption, Potent metal biosorbents among microorganisms, at low pH esteems, cell divider ligands are protonated and contend essentially with metals for official. With expanding pH, more ligands, such as amino and carboxyl groups, could be exposed, leading to attraction between these negative charges and the metals and consequently incremental biosorption onto the cell surface. Starting with isolation and identification of heavy metal-resistant bacteria from rock ore. Studying Factors Affecting Uranium Biosorption, Optimization of bacterial growth conditions and optimum for metal uptake by free and immobilized bacterial cells. All this evidence suggest that functions groups Represented in our study are responsible for metal uptake in our bacterial biomass beside change in peaks position which assigned for its groups confirm biosorption of metal ions from waste due to ions charge interaction comparing with immobilized we found increase in no of binding sites indicate that immobilized bacterial have high efficiency for metal up take which also change in peaks position which assigned for its groups confirm biosorption of metal ions from waste due to ions charge interaction, Where the high biosorption yield obtained by bacteria.

scholarly journals Organic Nanoparticles Based on D-A-D Small Molecule: Self-Assembly, Photophysical Properties, and Synergistic Photodynamic/Photothermal Effects

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 502
Author(s):  
Liangliang Yue ◽  
Haolan Li ◽  
Qi Sun ◽  
Xiaogang Luo ◽  
Fengshou Wu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Organic Molecule ◽  
High Efficiency ◽  
Photophysical Properties ◽  
Coupling Reaction ◽  
Ros Generation ◽  
Dead Cell ◽  
Minimal Invasiveness ◽  
Sonogashira Coupling Reaction ◽  
Potential Strategy

Cancer is one of the major diseases threatening human health. Traditional cancer treatments have notable side-effects as they can damage the immune system. Recently, phototherapy, as a potential strategy for clinical cancer therapy, has received wide attention due to its minimal invasiveness and high efficiency. Herein, a small organic molecule (PTA) with a D-A-D structure was prepared via a Sonogashira coupling reaction between the electron-withdrawing dibromo-perylenediimide and electron-donating 4-ethynyl-N,N-diphenylaniline. The amphiphilic organic molecule was then transformed into nanoparticles (PTA-NPs) through the self-assembling method. Upon laser irradiation at 635 nm, PTA-NPs displayed a high photothermal conversion efficiency (PCE = 43%) together with efficient reactive oxygen species (ROS) generation. The fluorescence images also indicated the production of ROS in cancer cells with PTA-NPs. In addition, the biocompatibility and photocytotoxicity of PTA-NPs were evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and live/dead cell co-staining test. Therefore, the as-prepared organic nanomaterials were demonstrated as promising nanomaterials for cancer phototherapy in the clinic.

scholarly journals The Influence of Slag Tapping Method on the Efficiency of Stabilization Treatment of Electric Arc Furnace Carbon Steel Slag (EAF-C)

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 706 ◽  
Author(s):  
Davide Mombelli ◽  
Andrea Gruttadauria ◽  
Silvia Barella ◽  
Carlo Mapelli
Keyword(s):  
Chemical Composition ◽  
Carbon Steel ◽  
Steel Slag ◽  
Toxic Metal ◽  
Electric Arc Furnace ◽  
Sem Analysis ◽  
Electric Arc ◽  
Arc Furnace ◽  
Stabilization Treatment ◽  
Electric Arc Furnace Slag

Studies conducted over the past 10 years have demonstrated the technical suitability of the electric arc furnace slag as an alternative to natural stone in several applications. Steel slag can be profitably used as a road surface layer, for foundations and embankments, or for concrete aggregates. However, a strong limitation to their use is due to the presence of toxic metals (Ba, Cr, V, Mo, etc.) that can be released into the environment in particular conditions, especially for unbound products in which the slag can come into contact with water. Recent studies have investigated the role of chemical composition and microstructure of slag on toxic metal leaching, allowing for the design of suitable stabilization treatments for hindering such leaching. In this work, four batches of electric arc furnace carbon steel slag underwent a stabilization treatment and the obtained results were compared. In two batches, the stabilizer was added directly in the slag pot and the slag was cooled down in the same pot. The other two batches were stabilized during the downfall from slag door to slag pit. Several slag samples were collected before and after the stabilization treatment and were characterized by means of ED-XRF, XRD, and SEM analysis. Leaching tests were carried out in agreement with EN 12457-2 standard on 4 mm granulated slag, and the leachate concentration was compared with the current Italian limits listed in D.M. 3 August 2005 N. 201 and D.M. 5 April 2006 N. 186. The results clearly indicated that the cooling in the slag pot improved the efficiency of the stabilization treatment, leading to a complete transformation of the microstructure by a full development of homogeneous gehlenite matrix and a coarsening of Cr-spinels, assuring better toxic metal retention behavior. On the contrary, stabilization in the slag-pit was rapid and reduced the interaction between slag and stabilizer, leading only to partial transformation of larnite into gehlenite, and also reducing the coarsening of Cr-spinel. In addition, a layering effect was observed, resulting in an inhomogeneous product from top to bottom in terms of chemical composition, microstructure, and leaching behavior.

scholarly journals Numerical Modelling Analysis for Carrier Concentration Level Optimization of CdTe Heterojunction Thin Film–Based Solar Cell with Different Non-Toxic Metal Chalcogenide Buffer Layers Replacements: Using SCAPS-1D Software

2021 ◽  
Author(s):  
Samer H. Zyoud ◽  
Ahed H. Zyoud ◽  
Naser M. Ahmed ◽  
Atef Abdekader
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Carrier Concentration ◽  
Buffer Layer ◽  
High Efficiency ◽  
Toxic Metal ◽  
Absorber Layer ◽  
Buffer Layers ◽  
Cds Thin Film

Cadmium telluride (CdTe), a metallic dichalcogenide material, has been utilized as an absorber layer for thin film-based solar cells with appropriate configurations, and the SCAPS-1D structures program has been used to evaluate the results. In both known and developing thin film photovoltaic systems, a CdS thin film buffer layer has been frequently employed as a traditional n-type heterojunction partner. In this study, numerical simulation was used to find a suitable non-toxic material for the buffer layer instead of CdS, among various types of buffer layers (ZnSe, ZnO, ZnS, and In2S3), and carrier concentrations for the absorber layer (NA) and buffer layer (ND) were varied to determine the optimal simulation parameters. carrier concentrations (NA from 2 x 1012 cm-3 to 2 x 1017 cm-3 and ND from 1 x 1016 cm-3 to 1 x 1022 ??−3) have been differed. The results showed that the CdS as buffer layer based CdTe absorber layer solar cell has the highest efficiency (?%) of 17.43%. Furthermore, high conversion efficiencies of 17.42% and 16.27% have been found for ZnSe and ZnO based buffer layers, respectively. As a result, ZnO and ZnSe are potential candidates for replacing the CdS buffer layer in thin-film solar cells. Here, the absorber (CdTe) and buffer (ZnSe) layers were chosen to improve the efficiency by finding the optimal density of the carrier concentration (acceptor and donor). The simulation findings above provide helpful recommendations for fabricating high-efficiency metal oxide-based solar cells in the lab.

scholarly journals Bioremoval of Different Heavy Metals in Industrial Effluent by the Resistant Fungal Strain Aspergillus niger

2021 ◽  
Vol 20 (4) ◽  
Author(s):  
K. J. Naveen Kumar ◽  
J. Prakash
Keyword(s):  
Heavy Metals ◽  
Aspergillus Niger ◽  
Metal Binding ◽  
Metal Removal ◽  
Low Cost ◽  
Heavy Metal Removal ◽  
Industrial Effluent ◽  
Toxic Metal ◽  
Differential Pulse ◽  
Toxic Heavy Metals

Developing countries are increasingly concerned with pollution due to toxic heavy metals in the environment. Unlike most organic pollutants which can be destroyed, toxic metal ions released into the environment often persist indefinitely circulating and eventually accumulating throughout the food chain thus posing a serious threat to mankind. The use of biological materials for heavy metal removal or recovery has gained importance in recent years due to their good performance and low cost. Among the various sources, both live and inactivated biomass of organisms exhibits interesting metal binding capacities. Their complex cell walls contain high content of functional groups like amino, amide, hydroxyl, carboxyl, and phosphate which have been implicated in metals binding. In the present study, Aspergillus niger was used to analyze the metal uptake from an aqueous solution. The determination of Cu+2, Pb+2, Cd+2, Zn+2, Co-2 and Ni+2 in samples was carried out by differential Pulse Anodic Voltammetry (DPASV) and the Voltammograms. Production of oxalic acid was carried out by submerged fermentation. The organism used in the present study has the ideal properties to sequester toxic metals and grow faster.

scholarly journals Characterization of Binding Sites and Optimization of Cell Free Bacteria Condition for Metal Bio-Sorbents

2021 ◽  
Author(s):  
Dr. Mostafa G. Fadl ◽  
Zenat Kamel Mohamed
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Binding Sites ◽  
Metal Uptake ◽  
High Efficiency ◽  
Bacterial Biomass ◽  
Resistant Bacteria ◽  
Bacterial Cells ◽  
Isolation And Identification ◽  
Charge Interaction

Bacteria a Microscopic organisms are the most inexhaustible and flexible of microorganisms and constitute a huge division of the whole living earthly biomass, certain microorganisms were found to amass metallic components at a high limit Was Known as Bacterial Bio-sorption Due to their little size, capacity to become under controlled conditions, and their Accommodation to an extensive variety of ecological situations; Potent metal bio-sorbents among microorganisms, at low pH esteems, cell divider ligands are protonated and contend essentially with metals for official. With expanding pH, more ligands, such as amino and carboxyl groups, could be exposed, leading to attraction between these negative charges and the metals, and consequently increment bio-sorption onto the cell surface. Starting with Isolation and identification of heavy metal-resistant bacteria from rock Ore. Studying Factors Affecting Uranium Bio-sorption, Optimization of bacterial growth conditions and optimum for metal uptake by free and immobilized bacterial cells and Desorption ratio of uranium ions adsorbed by Coli. /alginate, All this evidence suggest that functions groups Represented in our study are responsible for metal uptake in our bacterial biomass beside change in peaks position which assigned for it's groups confirm bio-sorption of metal ions from waste due to ions charge interaction comparing with immobilized we found increase in no of binding sites indicate that immobilized bacterial have high efficiency for metal up take which also change in peaks position which assigned for its groups confirm bio-sorption of metal ions from waste due to ions charge interaction, Where the high bio-sorption yield obtained by bacteria, the Uranium & heavy metal bioremediation process expects microorganisms to be joined to a strong surface.

scholarly journals Bioremediation of Hexavalent Chromium by Chromium Resistant Bacteria Reduces Phytotoxicity

2020 ◽  
Vol 17 (17) ◽  
pp. 6013
Author(s):  
Shanewaz Hossan ◽  
Saddam Hossain ◽  
Mohammad Rafiqul Islam ◽  
Mir Himayet Kabir ◽  
Sobur Ali ◽  
...  
Keyword(s):  
Bacterial Biomass ◽  
Dry Weight ◽  
Sem Analysis ◽  
Luria Bertani ◽  
Isotherm Models ◽  
Resistant Bacteria ◽  
Infrared Analysis ◽  
Relative Reduction ◽  
Tannery Effluent ◽  
Luria Bertani Broth

Chromium (Cr) (VI) has long been known as an environmental hazard that can be reduced from aqueous solutions through bioremediation by living cells. In this study, we investigated the efficiency of reduction and biosorption of Cr(VI) by chromate resistant bacteria isolated from tannery effluent. From 28 screened Cr(VI) resistant isolates, selected bacterial strain SH-1 was identified as Klebsiella sp. via 16S rRNA sequencing. In Luria–Bertani broth, the relative reduction level of Cr(VI) was 95%, but in tannery effluent, it was 63.08% after 72 h of incubation. The cell-free extract of SH-1 showed a 72.2% reduction of Cr(VI), which indicated a higher activity of Cr(VI) reducing enzyme than the control. Live and dead biomass of SH-1 adsorbed 51.25 mg and 29.03 mg Cr(VI) per gram of dry weight, respectively. Two adsorption isotherm models—Langmuir and Freundlich—were used for the illustration of Cr(VI) biosorption using SH-1 live biomass. Scanning electron microscopy (SEM) analysis showed an increased cell size of the treated biomass when compared to the controlled biomass, which supports the adsorption of reduced Cr on the biomass cell surface. Fourier-transform infrared analysis indicated that Cr(VI) had an effect on bacterial biomass, including quantitative and structural modifications. Moreover, the chickpea seed germination study showed beneficial environmental effects that suggest possible application of the isolate for the bioremediation of toxic Cr(VI).

Contribution of arbuscular mycorrhizal symbiosis to in vitro root metal uptake: from trace to toxic metal conditionsThis paper is one of the papers presented at the 50th Annual Meeting of the Canadian Society of Plant Physiologists (CSPP) held at the University of Ottawa, Ontario, in June 2008. Other papers from this meeting are presented in the July 2009 Special Issue of Botany.

Botany ◽  
2009 ◽  
Vol 87 (10) ◽  
pp. 913-921 ◽  
Author(s):  
Patrick Audet ◽  
Christiane Charest
Keyword(s):  
Metal Binding ◽  
Toxic Metal ◽  
In Vitro Study ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Mycorrhizal Symbiosis ◽  
Relative Contribution ◽  
Am Symbiosis ◽  
Metal Contaminant

This in-vitro study investigated the role of arbuscular mycorrhizal (AM) symbiosis in root metal acquisition and stress tolerance from two experiments using a carrot root-organ culture system, and involving the essential micronutrient zinc as a typical metal contaminant. We demonstrated that the AM symbiosis plays a dual role in root metal acquisition by increasing nutrient uptake via mycorrhizal “enhanced uptake” at low (trace) metal concentrations in the growth medium, but then lessening the uptake through “metal-binding” processes at high (toxic) concentrations. Furthermore, we also observed the relative contribution of hyphal uptake and translocation to roots, which led us to suggest that the enhanced uptake and metal-binding processes likely occur simultaneously and (or) independently. Ultimately, symptoms of metal toxicity toward both the roots and AM fungi at the highest Zn exposure concentrations was observed. From this finding, a critical toxicity burden likely exists arising from conditions ranging from trace to toxic metal extremes.

scholarly journals Lanthanum Role in the Graphite Formation in Gray Cast Irons

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1146
Author(s):  
Eduard Stefan ◽  
Iulian Riposan ◽  
Mihai Chisamera ◽  
Stelian Stan
Keyword(s):  
High Efficiency ◽  
Original Data ◽  
Sem Analysis ◽  
The Body ◽  
Gray Cast ◽  
Silicate Layer ◽  
Carbon Equivalent ◽  
Cast Irons ◽  
Nucleation Sites ◽  
Gray Cast Irons

The present paper reviews original data obtained by the authors from recent separate publications with additional unpublished data, specifically concerning the Lanthanum (La)’s role in the solidification pattern and graphite formation in gray cast irons. Iron melting at 0.018–0.056%S, a 3.7–4.1% carbon equivalent (CE) and less than 0.005%Alresidual are inoculated with La-bearing FeSi alloys at different associations with other inoculating elements. Complex Al-La small inclusions as possible better nucleation sites for (Mn,X)S compounds and La-Ca presence in the body of these sulfides, which possibly provide better nucleation sites for flake graphite, are identified in 0.026%S cast iron. At a lower sulfur content (0.018%S), La,Ca,Al-FeSi alloy still has a high efficiency, but more complex La-bearing alloys are recommended for a higher dendritic austenite amount (LaBaZrTi–FeSi) or for lower eutectic recalescence (LaBaZr–FeSi). La has limited but specific benefits at 0.05–0.06%S irons, including favorable graphitizing factors (a higher amount of graphite precipitated at the end of solidification), lower eutectic recalescence, and a lower value of the first derivative at the end of solidification. When La,Ca,Ba,Al,Zr,S-FeSi treatment (0.035%S base iron) is used, Scanning Electron Microscopy (SEM) analysis finds that the first formed micro-compound is a complex Al-silicate (Zr,La,Ca,Ba presence), which supports the nucleation of the second compound (Mn,Ca,La)S type. At the sulfide-graphite interface, there is a visible thin (nano size) Al-silicate layer (O-Al-Si-Ca-La system), which is more favorable for graphite nucleation (it has better crystallographic compatibility). La is identified in all three important areas of nucleants (the first is formed oxidic nucleus, the second is nucleated Mn-sulfide and the third is a sulfide-graphite interface), thereby increasing the efficiency of graphite nucleation sites.

Surface functionalization of MIL-101(Cr) by aminated mesoporous silica and improved adsorption selectivity toward special metal ions

2019 ◽  
Vol 48 (16) ◽  
pp. 5384-5396 ◽  
Author(s):  
Xueping Quan ◽  
Zhongqiao Sun ◽  
Hao Meng ◽  
Yide Han ◽  
Junbiao Wu ◽  
...  
Keyword(s):  
Waste Water ◽  
Mesoporous Silica ◽  
Metal Ions ◽  
Surface Functionalization ◽  
High Efficiency ◽  
Toxic Metal ◽  
Adsorption Selectivity ◽  
Important Target ◽  
Solid Adsorbents ◽  
Excellent Selectivity

Developing novel solid adsorbents with high efficiency and excellent selectivity is always an important target in the removal of toxic metal ions from waste water.

Sign in / Sign up

Export Citation Format

Share Document