Adsorption Of Mn Research Articles

Removal of Ni (II), Mn (II) and Zn (II) from crude yellow cake aqueous solution by cross-linked chitosan and polyvinyl alcohol

The removal of Ni (II), Mn (II) and Zn (II) from crude yellow cake onto chitosan cross-linked by Epichlorohydrin (CS-ECH) and polyvinyl alcohol (PVA) were investigated in nitrate solutions. The influence of contact time, pH, temperature and initial metal concentrations on the adsorption processes were investigated using batch modes. Langmuir and Fruindlish models were used for investigation of adsorption isotherm. The results showed that the equilibrium adsorption behavior of metal ions onto CS-ECH and PVA could be fitted to Langmuir model. The total maximum adsorption capacity of CS-ECH and PVA were calculated, and the results indicate the higher values of CS-ECH than PVA, due to the properties of chemical structure of CS-ECH. The adsorption kinetics parameters were also tested using pseudo-first-order, pseudo-second-order models, and interparticle diffusion models. The results indicate the adsorption processes of metal ions on both CS-ECH and PVA followed the pseudo-first-order and the pseudo-second-order models which meaning the mixed adsorption, except the adsorption of Mn (II) on PVA is only described by the pseudo-second-order equation. The results indicate the adsorption processes of metal ions followed the pseudo-second-order models for both CS-ECH and PVA. Otherwise, the values of thermodynamic parameters (ΔHoads, ΔSoads, and ΔGoads) of metal ions removal by CS-ECH and PVA exhibit the spontaneity, and exothermicity of adsorption processes.

Sorption Isotherm Analysis of Trace Metals on a Sandy Textured Coconut Growing Soil

The nature of adsorption of trace metallic plant nutrients, Cu, Mn and Zn, on a coconut growing sandy textured soil (Madampe series) was investigated in 0.050 M KNO₃ medium. Different adsorption parameters, <em>viz </em>contact time, soil mass, initial concentration and pH were optimized for the study. Variation of the mass of each metal ion sorbed on soil and the initial concentration at constant pH was investigated to understand the nature of adsorption. Further, the data at adsorption equilibrium were fitted to two commonly used isotherm models, namely, Langmuir and Freundlich. The optimum parameters were determined as, shaking time: 3 hours; settling time: 30 minutes; soil mass: 1 g; pH: 5-7; and initial concentrations for Mn(II) and Zn(II): 20 mg/L and 15 mg/L, respectively. The experimental data of Mn(II) and Zn(II) lead to regression coefficients (R2) of 0.957 to 0.970, respectively, for the Langmuir model and 0.812 to 0.925, respectively, for the Freundlich model. Although the Langmuir model fitted better with respect to R2 values, both Langmuir and Freundlich models could be used to illustrate the trace metal sorption on the soil. Initially, trace metal ions probably interacted with specific sites where soil surface is homogeneous; this was followed by iteration at nonspecific sites leading to multilayers or through the different modes of mass transfer fulfilling the conditions of the Freundlich model. The adsorption capacity of soil for the three trace metal ions varied in the order of Cu (II) &gt; Zn(II) &gt; Mn(II).

Chitosan/activated coal composite as an effective adsorbent for Mn(VII): Modeling and interpretation of physicochemical parameters

Chitosan was impregnated into porous activated coal to produce a multifunctional chitosan/activated coal (Cs/Ac) composite. The resulted Cs/Ac was characterized and utilized as a cost–effective adsorbent for Mn(VII) at altered temperatures (i.e., 25, 35, and 45 °C). The adsorption results were fitted to classical as well as advanced statistical physics models. The Freundlich equation described well the achieved experimental data at all temperatures. Enhancing the Langmuir adsorption capacity from 203.26 to 224.03 mg/g with temperature indicated that Mn(VII) adsorption was an endothermic process. Steric, energetic and thermodynamics data of the double layer model with two energy sites (i.e., the best fit statistical model) were completely interpreted. The number of Mn(VII) per adsorption site (n) was between 0.76 and 0.92 suggested the presence of multi–docking and multi–interactions mechanisms. The active sites density (NM) of the Cs/Ac decreased with improving temperature. Energetically, Mn(VII) uptake by Cs/Ac was governed by physical interactions (i.e., adsorption energy <40 kJ/mol). Macroscopically, the interaction between Mn(VII) and Cs/Ac was spontaneous. Overall, modification of the Ac by the used marine biomass (Cs) produced a promising Mn(VII) adsorbent and also, the application of physical analysis offered a deep interpretation for the adsorption mechanism.

Investigation of Adsorption Kinetics and the Isotherm Mechanism of Manganese by Modified Diatomite.

Natural diatomite modified by acetic acid (C-D) and sodium hydroxide (Na-D) for adsorbing manganese (Mn) was studied. The construction and morphology of the modified diatomite were then characterized by different efficient and accurate detection methods (Fourier transform infrared, scanning electron microscopy, and Brunauer–Emmett–Teller), and it was proved that C-D and Na-D increased the surface area and void volume compared to natural diatomite, and the modification of diatomite with acetic acid and alkali also significantly changed the structure of the functional groups of diatomite, especially in Na-D. Therefore, the adsorption rate of Mn by C-D and Na-D was higher than that of natural diatomite. The optimum conditions of Mn adsorption for C-D and Na-D were pH 5.0, 40 °C, 30 min and pH 5.0, 40 °C, 120 min, respectively, and this was best illustrated by pseudo-second-order kinetics. The Mn adsorption isotherm models showed that Mn adsorption on C-D and Na-D was stable, and the Langmuir adsorption isotherm model fitted adsorption processes of natural diatomite, C-D, and Na-D well as their correlation coefficients were 0.931, 0.940, and 0.991, respectively. These results suggested that modified diatomite with acetic acid and sodium hydroxide significantly increased the adsorption rate of Mn, which had an important application prospect for the remediation of Mn pollution in soil and water.

Kinetics of Mn(II) adsorption and catalytic oxidation on the surface of ferrihydrite

Mn(II) adsorption-oxidation on iron (Fe) oxides (e.g., ferrihydrite) occurs in various soils and sediments, significantly affecting the toxicities and bioavailabilities of Mn and other associated elements. However, the detailed processes of Mn(II) adsorption-oxidation on ferrihydrite remain elusive. In this study, the Mn(II) (2 mM) adsorption-oxidation kinetics on different masses of ferrihydrite (0.25, 0.50, 1.00, and 1.25 g) at pH 7 were determined using batch kinetic studies combined with X-ray diffraction, transmission electron microscopy, and wet chemistry analyses. The results indicated that the low-concentration Mn(II) adsorption-oxidation on ferrihydrite occurred in two steps. First, Mn(II) was adsorbed onto ferrihydrite, where it was partially oxidized by the catalytic effect of ferrihydrite, within ~0–60 min; subsequently, the remaining Mn(II) underwent autocatalytic oxidation on the previously generated Mn (oxyhydr)oxides. The initial adsorption-oxidation behaviors of Mn(II) on the ferrihydrite surface determined the kinetics of Mn(II) removal and oxidation, and therefore the amounts and types of Mn (oxyhydr)oxides formed. Furthermore, the specific characteristics of Mn(II) adsorption-oxidation on ferrihydrite showed a strong dependence on the Fe/Mn molar ratio. When this ratio was below 16.35, the initial process was dominated by Mn(II) adsorption onto ferrihydrite, with slight oxidation generating hausmannite (~0–60 min), followed by the catalytic oxidation of Mn(II) on the formed hausmannite, generating manganite or groutite. Conversely, when the Fe/Mn molar ratio was above 32.7, the reactions primarily involved Mn(II) adsorption onto ferrihydrite with minor oxidation to form Mn(III/IV) (oxyhydr)oxides (~0–60 min), followed by the autocatalytic oxidation of Mn(II) on the freshly-generated Mn(III/IV) (oxyhydr)oxides, forming Mn(III) (oxyhydr)oxides, i.e., feitknechtite. These results provide further insight into the interaction between Fe and Mn, Mn(II) removal, and Mn (oxyhydr)oxide formation in the environment.

New perception of Zn(II) and Mn(II) removal mechanism on sustainable sunflower biochar from alkaline batteries contaminated water

The combination of several methods (X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray analysis, infrared spectroscopy) was applied to study the changes that have occurred during the adsorption of Zn(II) and Mn(II) ions on a carbonized sunflower sample for understanding a mechanism of heavy metals adsorption. Sunflower biochar was obtained from the stem and inflorescences sunflower wastes through pyrolysis at 600 °C for 30 min. According to the infrared spectroscopy and Boehm titration data, this carbonized material has acidic and basic functional groups on its surface, but they do not participate in the metal ions adsorption. However, the synthesized carbon proved to be a sustainable high-effective adsorbent for zinc(II) and manganese(II) ions removal with adsorption capacity 138.3 mg g−1 of Zn2+ and 45.4 mg g−1 for Mn2+. Surface analysis of the carbonized material by energy dispersive X-ray analysis, X-ray diffraction, and X-ray photoelectron spectroscopy indicated the presence of soluble and insoluble inorganic salts, such as KCl, NaCl, NaHCO3, KHCO3, CaCO3, MgCO3. It was established, that during the adsorption process, soluble salts are washed away, and new insoluble ones are formed assisting by Zn(II) and Mn(II) ions. It has been revealed that the adsorptive removal of Zn2+ and Mn2+ is caused by the precipitation mechanism. The efficiency of removing Zn(II) and Mn(II) ions from water contaminated with battery waste by the same mechanism is shown.

Removal of Mn(II) from Acidic Wastewaters Using Graphene Oxide-ZnO Nanocomposites.

Pollution due to acidic and metal-enriched waters affects the quality of surface and groundwater resources, limiting their uses for various purposes. Particularly, manganese pollution has attracted attention due to its impact on human health and its negative effects on ecosystems. Applications of nanomaterials such as graphene oxide (GO) have emerged as potential candidates for removing complex contaminants. In this study, we present the preliminary results of the removal of Mn(II) ions from acidic waters by using GO functionalized with zinc oxide nanoparticles (ZnO). Batch adsorption experiments were performed under two different acidity conditions (pH1 = 5.0 and pH2 = 4.0), in order to evaluate the impact of acid pH on the adsorption capacity. We observed that the adsorption of Mn(II) was independent of the pHPZC value of the nanoadsorbents. The qmax with GO/ZnO nanocomposites was 5.6 mg/g (34.1% removal) at pH = 5.0, while with more acidic conditions (pH = 4.0) it reached 12.6 mg/g (61.2% removal). In turn, the results show that GO/ZnO nanocomposites were more efficient to remove Mn(II) compared with non-functionalized GO under the pH2 condition (pH2 = 4.0). Both Langmuir and Freundlich models fit well with the adsorption process, suggesting that both mechanisms are involved in the removal of Mn(II) with GO and GO/ZnO nanocomposites. Furthermore, adsorption isotherms were efficiently modeled with the pseudo-second-order kinetic model. These results indicate that the removal of Mn(II) by GO/ZnO is strongly influenced by the pH of the solution, and the decoration with ZnO significantly increases the adsorption capacity of Mn(II) ions. These findings can provide valuable information for optimizing the design and configuration of wastewater treatment technologies based on GO nanomaterials for the removal of Mn(II) from natural and industrial waters.

Adsorption of Metal Ion Manganese (Mn) in Sodium Silicate Solution using Chitosan

High purity Silica precipitate is very potential materials which can be utilized for many applications for high grade silicon, filler, photovoltaic, catalytic chemical, etc. Indonesia has abundant natural resources including quartz sand as raw materials for making high purity silica precipitate. Silica precipitate is made by roasting quartz sand forming sodium silicate solution. In order to obtain high purity silica precipitate, purification of sodium silicate solution is needed. In this study, purification of sodium silicate solution is performed by adsorption process of metal ion manganese (Mn) using chitosan as adsorbent. The experiment was done using batch technique. The variation of adsorption process was performed to get optimum conditions such as sample concentration, adsorbent mass, contact time, pH and temperature. The adsorption of metal ions of Mn was analyzed by atomic adsorption spectroscopy. The result of experiment shows that the best mass of chitosan for Mn adsorption process is 0.2 grams which gives percentage adsorption of 56.63%. The optimum contact time is 30 minutes, it results percentage adsorption of 52.5%. The optimum pH 3 gives adsorption percentage of 58.67%. And the best temperature for adsorption is at 60 °C with the percentage adsorption of 65.72%. Adsorption mechanism of metal ion Mn follow the isotherm model of langmuir and freundlich with the linearity value of R2 = 0.99 and 0.98 respectively.

A green method for Mn2+ and NH4+-N removal in electrolytic manganese residue leachate by electric field and phosphorus ore flotation tailings

• Electric field and POFTs were used for Mn 2+ and NH 4 + -N removal in EMRL firstly. • The treated EMRL can be discharged to the standard (GB8978–1996). • The phosphate precipitation obtained could be used as market fertilizer. • This study provided a new idea for EMRL harmless disposal and POFTs utilization. High concentrations of manganese (Mn 2+ ) and ammonia nitrogen (NH 4 + -N) in electrolytic manganese residue leachate (EMRL) have seriously polluted the environment. In this study, electric field and phosphorus ore flotation tailings (POFTs) were used for Mn 2+ and NH 4 + -N removal in EMRL firstly. The effects of the liquid acid ratios, reaction temperature, current density, initial pH and stable pH of the solution, characteristics of EMRL and POFTs, and removal mechanism of NH 4 + -N and Mn 2+ were investigated. The results indicated that an electric field enhanced the leaching of POFTs and promoted the adsorption and precipitation of Mn 2+ and NH 4 + -N. The concentrations of Mn 2+ , NH 4 + -N, PO 4 3− and F − in EMRL were 0.12 mg/L, 9.2 mg/L, 0.09 mg/L, and 0.24 mg/L, respectively, which were within the permitted level for the integrated wastewater discharge standard (GB8978-1996) after adjusting the second stable pH to 10.0. Mn 2+ was mostly remove in the form of Mn(OH) 2 , MnOOH, Mn 5 (OH) 4 (PO 4 ) 2 and MnO 2 . NH 4 + -N was mostly remove as NH 4 MgPO 4 ·6H 2 O. The phosphate precipitation obtained could be used as market fertilizer. This study provided a new research idea for EMRL harmless disposal and POFTs resource utilization.

Simultaneous Removal of Arsenic and Manganese from Synthetic Aqueous Solutions Using Polymer Gel Composites.

The groundwater in approximately 50% of the Bangladesh landmass contains Mn concentrations greater than the limit prescribed by the WHO drinking water guidelines. Although studies have suggested that γ-FeOOH can effectively remove Mn from water, its practicability has not been investigated, considering that the additional processes required to separate the adsorbents and precipitates are not environment-friendly. To improve the efficiency of adsorptive Mn-removal under natural conditions, we employed a cationic polymer gel composite, N,N’-Dimethylaminopropyl acrylamide, methyl chloride quaternary (DMAPAAQ) loaded with iron hydroxide (DMAPAAQ + FeOOH), and a non-ionic polymer gel composite, N,N’-Dimethylacrylamide (DMAA) loaded with iron hydroxide (DMAA + FeOOH). DMAPAAQ + FeOOH exhibited a higher As removal efficiency under natural conditions while being environment-friendly. Our results suggest that the higher efficiency of the cationic gel composite is owed to the higher γ-FeOOH content in its gel structure. The maximum adsorption of Mn by DMAPAAQ + FeOOH was 39.02 mg/g. Furthermore, the presence of As did not influence the adsorption of Mn on the DMAPAAQ + FeOOH gel composite and vice versa. DMAPAAQ adsorbed As and the γ-FeOOH particles simultaneously adsorbed Mn. Our findings can serve as a basis for the simultaneous removal of contaminants such as As, Mn, Cr, and Cd.

Mn (II) Adsorption on Activated Carbon Derived from Amaro (&lt;i&gt;Spondias pinnata&lt;/i&gt;) Seed Stone

Amaro (Spondias pinnata) seed stone powder was activated using phosphoric acid and carbonized in a muffle furnace at three different temperatures, viz. 300, 400 and 500oC (PAC-300, PAC-400 and PAC-500) to produced Activated Carbons (ACs). Thus, obtained ACs are characterized using Boehm titration, iodine number and scanning electron microscopy (SEM). The observed results attributed that PACs contained irregular sized and shaped particles with well-developed pores, which mostly consisted of carboxyl and phenolic functional groups. Among the ACs, PAC-400 had a highest values of methylene blue number, iodine number and specific surface area, which were 181mg/g, 371.02 mg/g and 582 m2/g, respectively. For the 150 mg/L of methylene blue concentration the adsorption capacity of all the PACs was 100% and the adsorption isotherm followed Langmuir isotherm with Qmax of 256.41 mg/g. Within 2 hours at pH 5, PAC-400 removed as high as 94% of Mn(II) ion from 25 mg/L and up to 40% from 400 mg/L concentration of manganese from an aqueous solution. The adsorption kinetics described pseudo second order kinetics indicating chemisorption. All the results attributed that the phosphoric acid activated amaro seed stone can be used as efficient adsorbent to absorb manganese from an aqueous solution.

A comparison between ferrochrome slag and gold mine tailings based geopolymers as adsorbents for heavy metals in aqueous solutions: Analyzing reusability and sustainability

Ferrodirome slag (FeCr-GP) and gold mine tailings (GMT-GP) based geopolymers were synthesized and used as adsorbents of heavy metals in aqueous solutions. Batchwise adsorption experiments were used to determine the effect of solid loading (S/L), temperature and time on the adsorption of Cu, Ni and Mn. X-ray diffraction studies showed that GMT-GP was amorphous with calcium aluminium silicate hydrate as the geopolymerization product leading to an increased surface area while GMT-GP had a significant reduction in the intensity of crystalline peaks as compared to the precursor. FeCr-GP could adsorb above 99% of the metal ions (Cu2+, Ni2+ and Mn2+) in solution with an initial metal concentration of 400 ppm at 298, while GMT-GP could only adsorb at least 98% of the metal with an initial metal concentration of 200 ppm. The adsorption was accompanied by a pH rise from 2.3 to 4.5 and 4.8 for GMT-GP and FeCr-GP, respectively. The maximum adsorption capacity of FeCr-GP was double that of GMT-GP. FeCr-GP could be desorbed using HCl and reverse osmosis water and could be used for a further three cycles without significant loss in adsorbing ability, while desorption of GMT-GP resulted a reduction in adsorption capability.

Adsorption of Mn+7 ions on chitosan/cellulose composite: experimentally and theoretically approaches

Water pollution is threatening the environment, humans and all living organisms. Therefore, it is crucial to apply efficient, safe and cheap ways to keep water clean. In this regard, natural wastes (algae, fruits, etc) can be used as energy sources to compensate the shortage of resources and energy. In our study, well washed and grinded Fucus spiralis (FS) and Sargassum muticum (SM) were impregnated with chitosan (CH) to obtain new composites (FS-CH and SM-CH). The new campsites were then used as adsorbents for Mn+7 metal ion from wastewater. To characterize these composites, we apply IR and SEM tests. This characterization was done on various factors, temperature, composite weight, pH, metal ion adsorption isotherms, kinetics, thermodynamics, time and the initial concentration of Mn+7. The results showed that the metal ion removal percentage was inversely proportional to temperature. The metal ion removal percentage was consistent when the weight of composite changes from 0.05 g to 0.3 g for (FS-CH), whereas it was consistent till 0.2 g then decreased when the weight of composite changes from 0.2 g to 0.3 g for (SM-CH). The metal ion removal percentage was also consistent under pH 0-6 then decreased. The metal ion removal percentage was directly proportional to time. The reusability was 100% in the second time then decreased at 3rd and 4th times. The thermodynamic results showed that the adsorption of the metal ion Mn+7 onto (FS-CH and SM-CH) was spontaneous and exothermic process. Langmuir, Freundlich, Temkin isotherm and first second order model, order, Intraparticle diffusion kinetic model, Elovich kinetic models were applied on the adsorption isotherm of Mn+7 onto (FS-CH and SM-CH). Quantum mechanics calculations were carried out using DFT methods to compute ESP, Frontier molecular orbitals and global properties. Also, QMAIM was performed to analysis and calculate the types of interactions between chitosan/cellulose composite and Mn+7 ions in gas and water phases. The binding energy between Mn+7 and chitosan/cellulose composite was calculated in gas and water.

Adsorption of Mn2+ from Aqueous Solution Using Manganese Oxide-Coated Hollow Polymethylmethacrylate Microspheres (MHPM)

Results of investigation on adsorption of Mn2+ from aqueous solution by manganese oxide-coated hollow polymethylmethacrylate microspheres (MHPM) are reported here. This is the first report on Mn-coated hollow polymer as a substitute for widely used materials like green sand or MN-coated sand. Hollow polymethylmethacrylate (HPM) was prepared by using a literature procedure. Manganese oxide (MnO) was coated on the surface of HPM (MHPM) by using the electroless plating technique. The HPM and MHPM were characterized by using optical microscopy (OM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Optical and scanning micrographs were used to monitor the surface properties of the coated layer which revealed the presence of MnO on the surface of HPM. TGA showed the presence of 4-5% of MnO in MHPM. Adsorption isotherm studies were carried out as a function of pH, initial ion concentration, and contact time, to determine the adsorption efficiency for removal of Mn2+ from contaminated water by the synthesized MHPM. The isotherm results showed that the maximum adsorption capacity of MnO-coated HPM to remove manganese contaminants from water is 8.373 mg/g. The obtained [Formula: see text] values of Langmuir isotherm and Freundlich isotherm models were 1 and 0.87, respectively. Therefore, [Formula: see text] magnitude confirmed that the Langmuir model is best suited for Mn2+ adsorption by a monolayer of MHPM adsorbent. The material developed shows higher adsorption capacity even at a higher concentration of solute ions, which is not usually observed with similar materials of this kind. Overall findings indicate that MHPM is a very potential lightweight adsorbent for removal of Mn2+ from the aqueous solution because of its low density and high surface area.

Modelling the adsorption of iron and manganese by activated carbon from teak and shea charcoal for continuous low flow

Nearly 6494 boreholes with iron (Fe) and manganese (Mn) concentrations above permissible limits of 0.3 mg/L and 0.4 mg/L respectively in Ghana have been abandoned because of ineffective water treatment solutions. Activated carbon prepared from teak (Tectona grandis) and shea (Vitellaria paradoxa) charcoal (ACM), of effective grain sizes 0.075–0.2 mm and 0.2–2.0 mm was found to achieve 92.5–100% Fe and Mn removal in batch tests. The experiments, which were repeated for natural groundwater with a low flow similar to boreholes simulated with handpumps and limited mechanized water systems achieved similar Fe and Mn adsorption levels. Data on Fe and Mn adsorption for varying ACM mass and grain sizes, using fixed columns in continuous flow tests were fitted to Adam-Bohart, Thomas and Yoon-Nelson adsorption models to generate data for improvement in water treatment designs. The objective of this modelling process is to develop a prediction mechanism for ACM mass and grain size needed for the design of Fe and Mn removal plants for groundwater with various characteristics. Adsorption constants obtained for Yoon-Nelson; 0.3095 and Adams-Bohart; 0.07335 at R2 values of 0.9728 and 0.9841 respectively are appropriate for generating ACM mass needed, when the target contaminant is Fe and Mn

First principles study of electrical and magnetic properties of two-dimensional ferromagnetic semiconductors CrI&lt;sub&gt;3&lt;/sub&gt; adsorbed by atoms

Recent experimental discovery of intrinsic ferromagnetism (FM) in chromium triiodide (CrI&lt;sub&gt;3&lt;/sub&gt;) monolayer opens a new way to low-dimensional spintronics. Two-dimensional (2D) CrI&lt;sub&gt;3&lt;/sub&gt; monolayer is of great significance for its magnetic and electronic properties. Generally, surface atomic adsorption is an effective way to modify the physical properties of layered magnetic materials. Here in this work, we use the first-principles method based on density functional theory (DFT) to systematically study the electronic structure and magnetic properties of 2D CrI&lt;sub&gt;3&lt;/sub&gt; monolayers that have adsorbed other metal atoms (specifically, alkali (alkaline earth) metal (Li, K and Mg), transition metal (Ti, V, Mn, Fe, Co and Ni) and non-metal (N, P, O and S) atoms). Our results show that the metal atoms tend to be adsorbed in the center of the ring formed by the six I atoms and stay at the same height as Cr atoms, while the positions of the optimized non-metal atoms are in the ring formed by the six I atoms and depend on the type of the atoms. The adsorption of atoms (except for Ti and Mn atoms) does not change the intrinsic ferromagnetic semiconducting properties of CrI&lt;sub&gt;3&lt;/sub&gt; monolayer. The CrI&lt;sub&gt;3&lt;/sub&gt; monolayers with Ti or Mn adsorption are antiferromagnetic semiconductors. Moreover, we find that the adsorption of different atoms regulates the local magnetic moments of Cr atoms. The adsorption of metal atoms increases the local magnetic moments of Cr atoms, but not exceeding 4&lt;i&gt;μ&lt;/i&gt;&lt;sub&gt;B&lt;/sub&gt;. However, the adsorption of non-metallic atoms makes the local magnetic moments of Cr atoms diversified. The adsorption of O and N atoms retain the local magnetic moment of Cr atoms, while the adsorption of P and S atoms increase the local magnetic moment. By combining the projected density of states, we analyze in detail the local magnetic moments of Cr atoms. The increase of the local magnetic moments of Cr atoms is directly related to the charges transferring. Our results provide new ideas for regulating the performance of the magnetism of 2D intrinsic ferromagnetic semiconductor CrI&lt;sub&gt;3&lt;/sub&gt;, which will have potential applications in the spintronics in the future.

Parasitic electrodeposition in Zn-MnO2 batteries and its suppression for prolonged cyclability

The utilization of mildly acidic electrolyte and corresponding Mn salt pairing unlocked a path toward highly rechargeable Zn-MnO2 batteries, but long-term feasibility of these cathode-preserving strategy under practical conditions is never verified. In this study, in-situ MnO2 electrodeposition occurring in the battery recharging process is discovered to be a side reaction that substantially nullifies the practicality of the strategy. Particularly, it is identified to be responsible for irreversibly converting the electrolyte Mn ions to electrochemically passive species and triggering battery performance deterioration. These newfound recognitions lead to the formulation of a kinetic inhibition strategy, which is executed through an unconventional cathode electrode design. Specifically, graphite nanosheets with limited surface defects are incorporated into MnO2 electrodes to hinder the rate determining Mn adsorption process and thus effectively suppress the electrodeposition reaction. The resulting thin film binder-free MnO2 electrodes achieve near-full one-electron capacity reversibly for over 600 cycles, with an average columbic efficiency of ~99.8%. Overall, this study reveals the importance of suppressing MnO2 electrodeposition in Zn-MnO2 batteries and provides a contrasting view on key factors that dictate the stability of the system.

Modulation of electronic structure properties in bilayer phosphorene nanoribbons by transition metal atoms

To explore the novel properties and applications of two-dimensional black phosphorene, we perform a first-principles study on the modulation of the structure and electronic properties of bilayer phosphorene nanoribbons (BPNRs) by using transition metal (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) atoms. For one-dimensional zigzag-edge AA-stacked bilayer phosphorene nanoribbons with hydrogen passivation, we find that the atomic stacking of the BPNRs reorders from the AA to the AE stacking. The AE-stacked structure is the most stable structure for one-dimensional zigzag BPNRs. All the BPNRs with widths N = 4–10 exhibit semiconductor character with indirect band gaps (1.17, 1.01, 0.92, 0.84, 0.75, 0.74, and 0.72 eV), which gradually decrease with increasing nanoribbon width. The adsorption energies show that all the TM atom-adsorbed 4-BPNR compound systems [PTMP] can form stable structures, however, the most stable structures have different adsorption energies (−9.38, −10.73, −13.19, −8.26, −13.68, −9.73, −10.41, −10.33, and −5.98 eV) for different TM (Sc, Ti, V, Cr, Mn, Fe, Co, Ni and Cu) atoms. The calculated bond lengths, charge transfer, and difference charge density of [PMnP] systems indicate that there are strong chemical interactions between the TM atoms and their adjacent P atoms in the BPNRs, resulting in the formation of TM-P ionic bonds. The adsorption of TM atoms induces various electronic structures in 4-BPNR. The [PTMP]1 systems exhibit metallic properties with the adsorption of Sc, Co, and Cu atoms, and semiconductor properties with the adsorption of Ti, V, Cr, Mn, Fe, and Ni atoms with band gaps of 0.30, 0.18, 0.19, 0.20, 0.61, and 0.08 eV, respectively. The Ni and Cu adsorption systems show magnetic quenching with no magnetic moments in all the compound systems [PTMP]. The [PCrP]1 has the maximum magnetic moment of approximately 3.62 μB amongst all the [PTMP]1 systems, while the [PVP]1 and [PMnP]1 systems have magnetic moments of 1.66 μB and 1.84 μB, respectively. Our results show that TM atom-adsorbed bilayer phosphorene nanoribbons exhibit tunable electronic structures and magnetic properties for potential applications in nanoelectronics.

Ca-ALGINAT UNTUK ADSORPSI Fe DAN Mn PADA AIR GAMBUT

Ca-alginate for the adsorption of Fe and Mn in peat water has been carried out using a batch method. Brownish water color, low pH, and high content of Fe and Mn metals are obstacles in direct utilization of peat water. Peat water treatment can be done by the adsorption method. The stages of this study began with the preparation of the adsorbent by dripping Na-alginate solution into a variety of CaCl2 solution concentrations. Furthermore, the adsorption of peat water was carried out by batch method with variations in the contact time and mass of the adsorbent to get the adsorbent with the highest % removal. The optimal contact time for Fe and Mn adsorption on peat water is 6 hours. The optimal % removal value for the influence of Fe adsorption contact time for Ca-alginate variations of 0.1 M and 0.2 M CaCl2 solution were 20.38% and 21.19%, respectively. The optimal % removal value for the influence of Mn adsorption contact time for Ca-alginate variations of 0.1 M and 0.2 M CaCl2 solution were 30.98% and 41.37%, respectively. The optimal mass of adsorbent for Fe and Mn adsorption in peat water is 0.75 g. The optimal % removal value for the influence of Fe adsorption mass adsorption for Ca-alginate variations of 0.1 M and 0.2 M CaCl2 solution were 79.28% and 21.67%, respectively. The optimal % removal value for the mass effect of Mn adsorption adsorption for Ca-alginate variation of 0.1 M and 0.2 M CaCl2 solution respectively at 24.44% and 26.13%.

Characterization and mechanism of Mn(II)-based mixotrophic denitrifying bacterium (Cupriavidus sp. HY129) in remediation of nitrate (NO3−-N) and manganese (Mn(II)) contaminated groundwater

The co-contamination of groundwater with nitrate (NO3−-N) and manganese (Mn(II)) is a global issue that needs to be efficiently remediated. In this research, a novel denitrifying and manganese-oxidizing strain HY129 was isolated from the sediments sample of a drinking water and identified as Cupriavidus sp. HY129. The remediation ability of strain HY129 regarding the nitrate and Mn(II) pollution were investigated. The removal efficiency of nitrate and Mn(II) were 99.81% (0.229 mgL−1 h−1) and 87.24% (0.233 mgL−1 h−1) in bacterial culture after 72 h, respectively. Moreover, the addition of Mn(II) significantly enhanced the denitrification process, while excessive concentration of Mn(II) caused more NO2−-N accumulation. The impacts of adsorption and oxidation activity on Mn(II) removal were investigated. Protein in extracellular polymeric substance (EPS) which produced in the Mn-oxidizing process was speculated to be the main cause of extracellular adsorption of Mn(II). Characterization of biogenic manganese oxides (BMO) confirmed the formation of high-valent manganese and the trapping experiment with sodium pyrophosphate (NaPP) demonstrated the existence of Mn(III)-intermediates. Furthermore, multicopper oxidase gene amplification provided evidence for the molecular biology of Mn(II) oxidation by strain HY129.