Adsorption Of Mn Research Articles

Experimental and numerical study for the adsorption behavior of Cu(II) and Mn(II) in quartz sand

Heavy metals such as Cu(II) and Mn(II) are prevalent in the environment. The effect of heavy metals on the soils environment is based on the ability of soils to mobilize these contaminants. According to the soil decontamination perspective, examining the reaction technique between heavy metals and soil is indispensable. This study carried out experiments to investigate Cu(II) and Mn(II) adsorption behaviour in quartz sand. The isothermal adsorption results for Cu(II) and Mn(II) presented that the adsorption capacity reached the peak value when the initial concentration was about 10 mg/L. The declines of H+ ions could uprise the adsorption rate activity for Cu(II) and Mn(II) and decrease the soil ability of the desorption for Cu(II) and Mn(II) ions. The adsorption rate of Cu(II) and Mn(II) is lower than the desorption rate under the situation of a low pH range with a solid acidic and low concentration of Cu(II) and Mn(II). The Freundlich and Langmuir adsorption isotherm models were applied to investigate the adsorption isotherm of Cu(II) and Mn(II). The study results confirmed that the Freundlich model synchronous the best with the observed experimental data compared with the Langmuir solution.

Alkaline aging significantly affects Mn(II) adsorption capacity of polypropylene microplastics in water environments: Critical roles of natural organic matter and colloidal particles

Most microplastic particles may undergo various aging in water environments. In this work, surface physicochemical properties were firstly compared among pristine polypropylene (PP-pris) microplastics, and two aged ones obtained after pretreated with HCl (PP-acid) and NaOH (PP-alka). When compared with PP-pris and PP-acid, PP-alka had a much stronger Mn(II) adsorption capacity. The results regarding the role of natural organic matter and colloidal particle concentrations on adsorption demonstrated that for water solutions either containing kaolin or not, humic acid (HA) had significantly negative influence on Mn(II) adsorption capacity of PP-alka due to their complexation and competition effects, and its negative influence became enhanced with increasing kaolin concentrations. Besides, established conceptual models of adsorption were applied to comprehensively explore adsorption mechanisms of PP-alka for Mn(II) in the coexistence of HA and kaolin. An important suggestion was that in complicated adsorption-reactor system, great numbers of microplastics-kaolin heteroaggregates might be formed via ion bridging of Mn(II) and/or polymer bridging of HA. So these formed aggregates were possible to re-organize themselves, under pre-set vibration-speed conditions, for achieving a more stable structure. As a consequence, Mn(II) adsorption behaviors would be affected by changes in steric-hindrance effects of HA molecules and surface charge distribution of resultant heteroaggregates.

Manganese removal and product characteristics of a marine manganese-oxidizing bacterium Bacillus sp. FF-1.

Biogenic manganese oxides (BioMnOx) have been found all over the world, and most of them were formed by Mn(II)-oxidizing bacteria (MnOB). In this study, a MnOB designated as FF-1 was isolated from marine surface sediments in the Bohai Sea, China. This strain was identified as Bacillus sp. and can tolerate more than 5% salinity. It can grow in the presence of 0-7mM Mn(II) and pH range from 5.0 to 7.0. When the initial Mn(II) was 5mM, the percentage of Mn(II) oxidation reached the highest value of 16% after 10days of incubation. The initial pH (5.0 to 7.0) affected the percentage of Mn(II) oxidation, but the ability of the strain FF-1 to self-regulate pH resulted in the final pH being almost 7.6. The removal of Mn(II) by the strain FF-1 involves extracellular and intracellular adsorption as well as Mn(II) oxidation. Intracellular Mn adsorption contributed a small part to the total Mn removal, and extracellular adsorption was dominant in the initial stage of Mn removal. The solid products after Mn removal were a mixture of MnOx and MnCO3. The layered MnOx formed in the extracellular space could be easily collected and used for adsorption and oxidation of pollutants.

Static magnetic field enhances Cladosporium sp. XM01 growth and fungal Mn(II) oxidation

Fungal Mn oxidation is a crucial pathway in the biogeochemical cycling of toxic substances. However, few studies have aimed to promote the process of fungal Mn oxidation or systematically establish the mechanism of action. The effects of static magnetic field (SMF) treatment on the growth and Mn(II) oxidation capability of an Mn-oxidizing fungus, Cladosporium sp. XM01, were investigated. Results showed that 20.1 mT SMF treatment promoted the growth of strain XM01, and increased the Mn(II) removal rate by accelerating the adsorption and oxidation of Mn(II). In addition, the results of RNA sequencing suggested that SMF mainly stimulated energy metabolism and protein synthesis, accelerating the growth of strain XM01. Notably, KEGG pathway enrichment analysis found that SMF treatment significantly up-regulated the pathway of oxidative phosphorylation system, which is capable of stimulating the generation of superoxide (O2•−). Moreover, exposure to 20.1 mT SMF significantly promoted the activities of antioxidant enzymes including SOD and CAT. These results indicate that SMF treatment stimulates the generation of O2•− by strain XM01, and therefore, accelerates Mn(II) oxidation. This is a novel study using external SMF treatment to enhance fungal Mn(II) oxidation.

The effect of citric acid on the catalytic oxidation of Mn(II) on ferrihydrite surface

Surface-catalyzed Mn(II) oxidation is an important process for abiotic formation of various Mn (oxyhydr)oxides in nature. Previous research has shown that some complex-forming ligands (e.g., citric acid, desferrioxamine B, and tartrate) can significantly bind with Mn(II) to promote its homogeneous oxidation by dissolved O2. However, there is little to no understanding of the role played by complex-forming ligands in abiotic interfacial oxidation of Mn(II). In this study, the adsorption and oxidation of Mn(II) on ferrihydrite (Fh) surface at a range of citric acid (CIT) concentrations was investigated using batch kinetic studies combined with X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and wet chemistry analyses. The presence of CIT substantially inhibited the adsorption and oxidation of Mn(II) on Fh, whereas oxidized Mn generated certainly enhanced the degradation of CIT. However, at a high concentration of CIT (> 1 mM), the oxidation kinetics of Mn(II) were slightly accelerated due to ligand-promoted homogeneous oxidation. Moreover, the presence of CIT remarkably altered the distribution and composition of Mn(II) oxidation products by inhibiting the formation of hausmannite on Fh surface and the following auto-catalytic oxidation. At low CIT concentration (< 1 mM), the oxidation products were mostly coated on Fh surface with weaker crystallinity and higher Mn AOS, resulting in stronger reactivity. When CIT concentrations were above 1 mM, Mn(II) oxidation products were mainly distributed in the bulk solution as soluble Mn(III)-CIT/ox complexes, thereby enhancing the mobility of redox active Mn. These results suggested that CIT improved the redox activity of oxidation products and migration of active Mn in the environment although it inhibited Mn(II) oxidation on mineral surfaces.

Superoxide radical mediated Mn(III) formation is the key process in the activation of peroxymonosulfate (PMS) by Mn-incorporated bacterial-derived biochar

Biochar was used as a heterogeneous activator for peroxymonosulfate (PMS), and the activation performance strongly depended on the structure, functional groups, and modification of the biochar. In this study, a new type of modified biochar was synthesized by utilizing the Mn(II) adsorption capacity of bacteria. After one-step pyrolysis of Mn(II)-adsorbed bacterial cells at 800 °C, a Mn-incorporated bacterial-derived biochar (Mn-BBC) was successfully produced. It exhibited structural heterogeneity, with MnO located at the surface of the BBC matrix, as shown on the result of SEM and XRD. Compared to BBC, Mn-BBC showed a 10-fold increase (0.0727 min−1 versus 0.0069 min−1) of pollutant removal rate. In addition, it also showed anti-interference capacity against common water matrix (except 10 mM CO32-) and great stability/reusability. Chemical quenching, electron spin resonance, and pyrophosphate trapping indicated an indirect but important role of the superoxide, formed during the self-decomposition of PMS. The MnO on Mn-BBC can be oxidized by superoxide to produce surface Mn(III), which then binds to PMS and forms a surface complex. This complex promotes electron transfer from the pollutant to the Mn-BBC, facilitating the oxidation of the contaminants. Overall, this study confirmed the PMS activation capacity and mechanism of Mn-BBC, which expands the application of BBC-based materials derived from metal-adsorbed microbes.

Thermal-chemical modified rice husk-based porous adsorbents for Cu (II), Pb (II), Zn (II), Mn (II) and Fe (III) adsorption

Heavy metal ions contamination, a threat to ecological balance, aquatic life, and human health, co-exists in water bodies and soil systems such as mining sites, tanneries, petrochemical refineries, pesticide, fertilizer, construction, chemical industries, and others. In this study, raw rice husk and potassium hydroxide (KOH) activated novel rice husk (RH)-based adsorbents: potassium hydroxide (KOH) activated RH (KOH-RH), KOH activated RH hydrochar (KOH-RHH), and KOH activated silver (Ag) nanoparticle modified RH (AgNP-KOH-RH) were synthesized and applied on synthetic wastewater to treat hazardous heavy metal ions, Cu2+, Fe3+, Mn2+, Pb2+, and Zn2+ through fixed-bed flow column adsorption. Maximum Cu2+, Pb2+, Zn2+ uptake was obtained 7.14 mg/g, 9.02 mg/g and 8.53 mg/g, respectively by KOH-RHH. The maximum Fe3+ and Mn2+ uptake was 1.66 mg/g and 0.98 mg/g, respectively by AgNP-KOH-RH. After 1st run of adsorption, the adsorbents were recovered and re-used for 2nd adsorption run. Maximum Cu2+, Fe3+, Mn2+, Pb2+, and Zn2+ uptake was 11.98 mg/g, 9.46 mg/g, 1.29 mg/g, 19.55 mg/g and 14.58 mg/g, respectively obtained by KOH-RHH at 2nd adsorption run. AgNP-KOH-RH obtained the minimum retention time for adsorption and maximum color removal for both runs. Compared with commercial adsorbents such as coconut shell activated carbon, higher heavy metal ions adsorption capacity (>90%) and color removal have been obtained with both KOH-RHH and AgNP-KOH-RH. The adsorption kinetics was well fitted into the intra-particle diffusion (IPD) kinetics model. The detailed characterization of the adsorbents such as surface area, porosity, and surface morphology was conducted for deriving the mechanism. It can be stated that the significant adsorption capacity of heavy metals and color by KOH-RHH and AgNP-KOH-RH with repetitive adsorption runs will provide new insight into adsorption mechanisms and the development of next-generation commercial adsorbents for industrial wastewater treatment.

Isotherms of Adsorption of Heavy Metals in Soils and Sediments of the La Villa River Basin-Panamá

The study was carried out within the La Villa river basin (Herrera and Los Santos provinces). In these lands, great agricultural activity is developed, highlighting the production of corn, tomatoes, melons, watermelon, beans, peppers, sugarcane, meat and milk livestock. They are subjected to intensive use of agrochemicals and influenced by discharges of by-products from some industrial and agro-industrial companies located within the basin. The objective of the study was to determine by means of Langmuir isotherms the maximum adsorption of Mn, Zn, Cu, Pb and Cd in soils and sediments of areas with intensive agricultural activity within the La Villa river basin. Five soil and sediment samples were taken from producer´s farms in the rainy season (June-November 2016) and five samples in the dry season (January-April 2017). The total concentration of the heavy metal was determined. The isotherms of the trace metals in soils and sediments were determined in the samples taken at both times of the year by applying different concentrations of the metal in a CaCl2 0.01 M solution. High levels of Cu were found in soils and Cu, Mn, Cr and As in sediments. The Mn isotherm showed low values ​​and low adsorption force, Cu and Zn showed high adsorption values, but with low retention force. For Pb, high adsorption values ​​were observed, but very low retention force in the dry season, contrary to Cd, which obtained low adsorption values, but with a higher force. This behavior is closely related to the texture of the soils. The Cu, Zn and Mn showed high significant correlations with the clay content in the soil, contrary to the pH and the organic matter did not obtain a good correlation with the adsorption of the metals.

Insights Into the Mn(VII) and Cr(VI) Adsorption Mechanisms on Purified Diatomite/MCM-41 Composite: Experimental Study and Statistical Physics Analysis.

In this study, a purified diatomite (PD) with a concentration of diatom frustules more than 92% SiO2 was utilized to synthesize a composite of MCM-41 silica under hydrothermal conditions. The as-synthesized PD/MCM-41 composite was characterized and tested as an adsorbent for the removal of Cr(VI) and Mn(VII) ions from aqueous solution. Results of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR) revealed that the diatom frustules of the PD were coated with MCM-41 mesoporous silica. Experimental isotherms of Cr(VI) and Mn(VII) adsorption were fitted to classical and advanced statistical physics models at 25°C–55°C and pH 3. The Langmuir model estimated monolayer adsorption capacities ranging from 144.1 to 162.2 mg/g for Cr(VI) and 166.2 to 177.0 mg/g for Mn(VII), which improved with increasing the solution temperature. Steric and energetic parameters obtained from a monolayer adsorption model with one adsorption site was utilized to explain the adsorption mechanism at a microscopic level. The number of Cr(VI) and Mn(VII) ions adsorbed on PD/MCM-41 active site (n) were 1.25–1.27 for Cr(VI) and 1.27–1.32 for Mn(VII), thus suggesting multi-interaction mechanisms. The density of PD/MCM-41 active sites (D M) was a key parameter to explain the adsorption of these heavy metals. The adsorbed quantities were maximum at 55°C, thus obtaining 102.8 and 110.7 mg/g for Cr(VI) and Mn(VII), respectively. Cr(VI) and Mn(VII) adsorption energies ranged from 18.48 to 26.70 kJ/mol and corresponded to an endothermic adsorption with physical forces. Entropy, free enthalpy, and internal energy associated to the adsorption of Cr(VI) and Mn(VII) ions were calculated, thus indicating that the removal of these pollutants was spontaneous. Overall, this article offers new interpretations for the Cr(VI) and Mn(VII) adsorption mechanisms on PD/MCM-41 composite, which are relevant to contribute to the development of effective water treatment processes.

Removal of Mn and Cu Ions in Synthetic Wastewater Using Dried Cockle Shell

The potential of the dried cockle shell had been studied using an adsorption experiment to determine the effectiveness of Mn and Cu removal from wastewater. A continuous batch adsorption study was carried out to determine the optimum dosage with a range of 3 g to 24 g of dried cockle shell and contact time from 15 minutes to 150 minutes. The equilibrium data for adsorption were analysed by three isotherm models (i.e., Langmuir, Freundlich, Temkin) and three kinetic models (i.e., Pseudo-First Order, Pseudo-Second Order, Elovich) to define the best correlation for each metal adsorption. The result shows that the highest percentage removal of Mn and Cu using dried cockle shells were 77.8% and 88.9%, respectively, with an optimum dosage of 15 g and 105 minutes of optimum contact time. Among these three isotherm models, the Temkin model fitted with the equilibrium isotherm for Cu with the value of r² of 0.963, while the Langmuir model best described the experimental data for Mn with a recorded value of r² of 0.953. From the result, the cockle shell has the ability to adsorb heavy metals such as Mn by the process of a monolayer on the outer layer of the adsorbent and Cu with a Gaussian energy distribution onto a heterogeneous surface. Kinetic studies have shown that the adsorption of Cu and Mn towards the cockle shell follows Pseudo-Second Order with the determination of coefficients of 1 and 0.997, respectively. The findings from characterisation analysis found that a high percentage of CaCO₃ with 95.47% influences the adsorption of Mn and Cu from wastewater. The SEM image of dried cockle shell exhibits needle-like aragonite morphology and cubic-like calcite. Cockle shells have a great potential for removing Mn and Cu from industrial effluent. Thus, it can be used as a filter material and helps increase the economy at a modest pace by recycling low-cost waste for wastewater treatment.

Role of the Tree Species Selected in Developing Swampy Forest System for Passive Treatment of Acid Mine Drainage

Coal mining is one of economic sector that requires forestry area in Indonesia. Most of coal mining concession are forestry area loan use from the government and during mining operation facing with acid mine drainage (AMD). AMD passive treatment can be integrated with revegetation process that related with better handling of overburden (OB) with potential acid forming (PAF) during reclamation processed. The most expensive methods and uncertainty process are the use of quick lime in treatment of AMD. During operation and preparing mine closure stage need to create the effective one to comply with the regulation. “Swampy Forest (SF) system” is an alternative method of sustainable and naturally process. Selecting the appropriate tree species as a preliminary process to develop a better SF system by batch experiment in the form of a forest constructed wetland. The tree species selected are Nauclea orientalis (lonkida tree) and Melaleuca cajuputi (kayuputih tree) as non-local species then Nauclea subdita (bangkal tree) and Melaleuca leucadendron (galam tree) as local species have been selected. Local species higher in Fe and Mn adsorption in pH of AMD &lt;4 then nonlocal species higher in Fe and Mn adsorption on pH of AMD &gt;4 condition.

Alkaline Aging Significantly Affects Mn(Ii) Adsorption Capacity of Polypropylene Microplastics in Water Environments: Critical Roles of Natural Organic Matter and Colloidal Particles

Alkaline Aging Significantly Affects Mn(Ii) Adsorption Capacity of Polypropylene Microplastics in Water Environments: Critical Roles of Natural Organic Matter and Colloidal Particles

2-aminopyridine functionalized magnetic core–shell Fe3O4@polypyrrole composite for removal of Mn (VII) from aqueous solution by double-layer adsorption

• Fe 3 O 4 @PPy-AP composite is synthesized for rapid Mn (VII) adsorption from solution. • The maximum adsorption capacity of the composite is 781.25 mg g-1 at 318.15 K. • Both the N atoms in PPy and AP can adsorb Mn (VII) through coordination effect. 2-aminopyridine functionalized magnetic core–shell Fe 3 O 4 @polypyrrole structure (Fe 3 O 4 @PPy-AP composite) is fabricated to remove Mn (VII) from water. The adsorbent fully combines the easy magnetic separation of Fe 3 O 4 microspheres, the excellent corrosion resistance of PPy, as well as double-layer adsorption for Mn (VII) of PPy and AP. The effects of time, temperature and pH on the adsorption performances and adsorption mechanism are investigated in detail, for which the significance of structure of Fe 3 O 4 @PPy-AP composite is elucidated. It is clear that the adsorption process is chemical adsorption. The adsorption kinetics and isotherm is more suitable for pseudo-second order model and Freundlich model. The initial adsorption rate is 67.43 min g mg −1 , and the maximum adsorption capacity can reach 781.25 mg g −1 at 318.15 K. The film diffusion dominates the speed of the entire adsorption process. Adsorption thermodynamic calculations show that ΔS and ΔH are 198.33 J mol −1 K −1 and 37.88 kJ mol −1 , respectively, and the decreased ΔG with increasing temperature indicates that the adsorption process is endothermic and spontaneous. The Fe 3 O 4 @PPy-AP composite only loses less than 1% of Mn (VII) adsorption capacity after each adsorption–desorption cycle. This Fe 3 O 4 @PPy-AP composite with good magnetic properties and dual adsorption properties has broad application prospects in the rapid separation and adsorption of heavy metal ions.

Study on the Prevention and Control of Fe and Mn Pollution by Resistant Mixed Bacteria in Simulated Mining Area

By simulating the mining environment, the potential of the selected mixed bacteria (Pseudomonas putida, Lysinibacillus xylanilyticus, Lysinibacillus macroides, Bacillus simplex, Brevibacillus agri) to control Fe and Mn pollutants in mining environment were explored. The results showed that the selected bacteria could inhibit the release of Fe and Mn from ore into the aquifer, and the inhibition effect on Mn was significantly stronger than that on Fe. At the same time, these processes also have a certain degree of impact on the external environment, including the gradual increase of pH, the gradual decrease of oxidation-reduction potential, and the decrease of dissolved oxygen concentration. The changes of these external environmental factors will once again directly affect the degradation and immobilization of Fe and Mn. The selected mixed bacteria can also enhance the adsorption of free Fe and Mn, improve the adsorption efficiency and capacity of Fe and Mn, and slow down the desorption of Fe and Mn to water.

The Fe (II) and Mn (II) adsorption in acid mine drainage using various granular sizes of activated carbon and temperatures

Acid mine drainage (AMD) from coal mining activities contains Fe and Mn concentrations that often exceed environmental quality requirements. This study aims to determine the effect of the coal material size and temperature on the adsorption process of Fe and Mn metals contained in AMD using activated carbon made with a composition of 60% coal and 40% ZnCl2. For characterizing activated carbon, surface morphological was analyzed using SEM method, and surface area was analyzed using BET method. Meanwhile, for measuring Fe and Mn concentrations, the researchers used atomic absorption spectrophotometry. The adsorption process was carried out with various granular sizes of activated carbon (20, 28, 35, 48 and 60 mesh) and temperature (25, 35, 40, 45 and 50°C). The results showed that the maximum adsorption of Fe was 100% occurred in the treatment with an activated carbon size of 60 mesh and a temperature of 45°C, while the maximum adsorption of Mn was 11.91% in the treatment with an activated carbon size of 60 mesh and a temperature of 50°C. Furthermore, the activated carbon of coal is highly effective as an adsorbent for Fe in AMD waste but less effective for Mn.

Greener approach for fabrication of antibacterial graphene-polypyrrole nanoparticle adsorbent for removal of Mn2+ from aqueous solution

Herein, novel, efficient and multifunctional heavy metals adsorbent is developed. Graphene sheets are facilely prepared using ultrasonication process with the aid of polyethyleneglycol. Then, spherical polypyrrole nanoparticles of an average size of 150 nm are polymerized on the surface of prepared graphene sheets using green method yielding nanocomposite. The developed graphene-polypyrrole nanocomposite is exploited for removal and recovery of Mn2+ from aqueous solution. The developed graphene-based nanocomposite achieved superior adsorption efficiency for removal of Mn2+ ions than polypyrrole nanoparticles of similar particle size. The new adsorbent achieved excellent removal efficiency of Mn2+ ions recording 89%. Additionally, the smart adsorbent shows antibacterial properties toward Staphylococcus aureus bacteria providing a clear bacterial inhibition zone of 10 mm. The influence of various adsorption parameters of adsorbent dose, contact time and initial metal ions concentrations on the adsorption Mn2+ are studied and optimized. The adsorption of Mn2+ ions on the nanocomposite is also evaluated using Langmuir and Freundlich models and the adsorption isotherms of Mn2+ are suitable and described well with the Langmuir model. Therefore, this study presents a new approach for the design and engineering of safe handling and processing of antibacterial adsorbent for efficient removal and recovery of heavy metal ions from wastewater.

Adsorption of metal ions in red marine algae Lithothamnium calcareum in the treatment of industrial effluents

This study investigated the adsorption capacity of the elements Chromium (Cr), Manganese (Mn) and Zinc (Zn) to marine algae Lithothamnium calcareum by means of adsorption kinetics and batch adsorption tests, with a view to the development of a simple technique for the treatment of effluents that have a high concentration of metal ions. The algae was sieved, washed and subjected to treatment. In the adsorption kinetics, 0.2 g of algae was weighed, an amount transferred to 125 mL Erlenmeyer flasks, to which was added 15 mL of solution with a concentration of 5 mg L-1 of the metal ion. The flasks were stirred at 60 rpm for 240 minutes. In batch adsorption, 0.2 g of algae was weighed, amount transferred to 125 mL Erlenmeyer flasks, to which was added 15 mL of solution with concentrations of 5, 10, 20, 50, 100, 250 e 500 mg L-1 of the metal ion. The flasks were stirred at 60 rpm for 24 hours. In the two tests, the supernatant solutions collected were centrifuged at 2000 rpm for 5 minutes and the equilibrium concentrations of metal ions were determined by atomic absorption spectrometry. It was found that, in 240 minutes of contact, the Lithothamnium calcareum removed 15.5% of Cr, 33.0% of Mn and 8.0% of Zn in solution; and that in 24 hours of contact, at a concentration of 5 mg L-1, it removed 0.4% of Cr, 52.5% of Mn and 92.6% of Zn; and, at a concentration of 500 mg L-1, it removed 20.0% of Cr, 22.6% of Mn and 40.8% of Zn. The results showed that the Lithothamnium calcareum submitted to thermochemical treatment presented potential for use in the adsorption of Cr, Mn and Zn.

Electronic properties of transition metal embedded twin T-graphene: A density functional theory study

Twin T-graphene is a new three atomic layer thick two-dimensional carbon allotrope. In the current research, the structural and electronic properties of 3 d transition metal (TM) embedded twin T-graphene are studied utilizing density functional theory (DFT) calculations. All 3 d TM atoms transfer charge to the neighboring C atoms, and strongly get adsorbed to the sheet. Our findings reveal that the electronic properties of twin T-graphene are modulated by TM adsorption. The twin T-graphene is a semiconductor, while TM decorated twin T-graphene shows different electronic properties depending on the species and concentration of TM atoms. The semiconductor for Sc, Ti, V, Cr, and Zn adsorption, metal for Mn, Cu, and Ni adsorption, and bipolar magnetic semiconductor for Fe and Co adsorption are observed. The energy band gap of TM embedded twin T-graphene sheets with semiconducting properties decreases with increasing the concentration of TM atoms. Our results indicate that TM embedded twin T-graphene can be used in electronic and spintronic devices. • The structural and electronic properties of 3 d TM embedded twin T-graphene are investigated by density functional theory. • Twin T-graphene is a semiconductor. • Twin T-graphene shows different electronic properties depending on the species and concentration of adsorbed TM atoms.

An efficient manganese-oxidizing fungus Cladosporium halotolerans strain XM01: Mn(II) oxidization and Cd adsorption behavior

The applications of biogenic Mn oxides (BMOs) formed by Mn-oxidizing fungus in decontaminating heavy metals have attracted increasing attention. In this study, an efficient Mn-oxidizing fungus was isolated from soil and identified as Cladosporium halotolerans strain XM01. The Mn(II) adsorption and oxidation activities of this strain were investigated, showing significantly high removal and oxidation rates of soluble Mn(II) of 99.9% and 88.2%, respectively. Dynamic analysis of the Mn(II) removal process demonstrated the oxidation process of Mn(II) to Mn(III) was the rate-limiting step in the Mn(II) metabolic process. The XRD and SAED characterization showed that more layers were orderly accumulated along the c-axis with the formation of fungal BMOs, which might lead to the decrease in its specific surface area. The adsorption of Cd(II) by the formed BMOs was investigated and compared with two typical abiotic Mn oxides, indicating that the adsorption capacity decreased with the following order: immature BMO, mature BMO, δ-MnO2, acid birnessite, while the fixation capacity decreased in the order of acid birnessite, mature BMO, δ-MnO2, immature BMO. The inverse correlation between the capacity of Cd(II) adsorption and fixation of immature and mature BMOs was probably attributed to the increase in the layer stacking of BMOs. This result indicates an interesting phenomenon of high reservation of Cd(II) resulting from sequential transformation from strong adsorption to strong fixation with the formation of BMOs. This study offers considerable insights into fungal Mn oxidation mechanisms and provides theoretical guidance for fungal BMOs in heavy metals bioremediation.

The effect of edges hydrogenation and adsorption of Co and Mn atoms on spin transport properties of borophene Nanoribbons

The stability and magnetic features of bare (ZBNRs) and hydrogenated zigzag borophene nanoribbons (H-ZBNRs) are studied. The calculations are performed using density functional theory and non-equilibrium Green’s function. The results indicate that by hydrogenating borophene, the stability of nanoribbon increases. The magnetic properties of ZBNRs are affected by the hanging bond ofnanoribbon. ZBNR is a magnetic metal while by t hydrogenation, the magnetic effect is eliminated. The quantum transport properties for borophene nanoribbon at zero and low bias voltages are investigated. By increasing voltage the current increases and at the bias voltage of 0.5 V a current of about 35 µ A is observed. Moreover, the effect of Mn and Co adsorption on the surface of H-ZBNRs is investigated. The results indicate that the non-magnetic structure of H-ZBNRs becomes magnetic by adsorbing Co and Mn atoms. Also, the charge transfer is from Co and Mn atoms to borophene Nanoribbon. Our calculations indicate that the amount of current and the magnetic properties of ZBNRs could be modified by passivated of edge Nanoribbon and the TM atoms, which has a promising application in molecular magnet and Nano-electronic devices.