Pedological data for the study of soils developed over a limestone bed in a humid tropical environment.

Lithological characteristics interact with other factors of soil formation to define soil genesis. This becomes more interesting as data on the mineral and elemental oxide components of soils developed from limestone are rarely available in the humid tropical environment. The present study investigated the elemental oxide content, forms of sesquioxides, and clay mineral species in some limestone soils. Soil samples were obtained from three (3) crestal soil profile pits and analyzed for elemental content by the use of an X-ray fluorescence spectrometer, and sesquioxide forms by inductively coupled plasma-mass spectrometer. Analyses were done in triplicates. The mineralogy of the clay fraction was determined on the A, B, and C horizon samples using an X-ray diffraction technique. The occurrence of SiO2 (203-277 g/kg), Al2O3 (65-105 g/kg), and Fe2O3 (14-95 g/kg) in substantial amounts over MnO2, ZrO2, and TiO2 with negligible quantities of CaO suggested comparatively more developed soils in the Agoi Ibami and Mfamosing tropical rainforests. Crystalline form of Fe was dominant over amorphous form, with indications of the co-migration of dithionite Fe with clay to the B horizons of the soils. Quartz, kaolinite, montmorillonite, and chlorite-vermiculite-montmorillonite interlayered minerals dominated the clay mineralogy of the studied soils. Mineral transformation places the soils at the transitory stage from the intermediate to the complete stage of soil development. The expanding clay minerals are most likely to increase plant nutrient adsorption and soil fertility status to accommodate the cultivation of a wider range of crops.

Release characteristics of heavy metals from electrolytic manganese residue under varying environmental factors.

High levels of manganese (Mn) and other heavy metals from electrolytic manganese residue (EMR) stockpiled would be released into the environment under natural conditions. A batch-leaching test was carried out to investigate the release characteristics of heavy metals from EMR with different storage times under simulated environmental conditions such as acid rain with different pH (3.0, 4.5, 5.6, and 7.0) at contact times of 1, 2, 4, 6, and 12 h; liquid to solid ratio (L/S) (5:1, 10:1, 20:1, and 30:1); and temperature (15, 25, 35, and 45 °C). The results showed that low pH (3.0 and 4.5) and high temperature (35 and 45 °C) could significantly promote heavy metal leaching from EMRs and increasing the L/S ratio above 20:1 mL/g significantly decreased heavy metal leachate concentrations due to dilution effect. Cr, Mn, and Pb concentrations in leachate increased almost continuously throughout the leaching process, while Zn decreased slightly at the 12th hour. Meanwhile, heavy metal concentrations in EMR1 (fresh EMR) were higher than in EMR2 (out stockpiled for more than 3 months). The concentrations of Mn, Pb, and Zn in leachates from EMRs at pH 3.0 and 4.5 leaching far exceeded the allowable maximum discharge concentrations for pollutants of the integrated wastewater discharge standard in China (GB8978-1996) by 57.5-59.0, 1.3-4.3, and 1.1-1.8 and 53.5-56.0, 3.04-7.25, and 1.0-1.91 times, respectively. Additionally, the Mn concentrations from both EMR leachates at pH 7.0 were above the national safe emission threshold. The morphological structure of EMRs changed after leaching, and XRD analysis showed the disappearance of MnO2, SiO2, FeS2, and CaSO4. The XPS revealed that Cr, Mn, Pb, and Zn existed as Cr3+, MnO, PbSO4, and ZnSiO3, respectively, after leaching. The study concluded that Mn, Pb, and Zn from EMRS leached by acid rain might pose a high potential environmental risk. Therefore, developing appropriate disposal techniques for EMR is necessary to prevent heavy metal pollution.

Iron and manganese mobilisation due to dam height increase for a tropical reservoir in South East Asia.

The aim of this research was the analysis of the effect of a dam height raise on the water quality of a tropical reservoir used for drinking water purposes in South East Asia. Analyses of iron, manganese, pH and ammonia were performed over a 5-year period from daily water sampling at the reservoir. In addition, high-frequency monitoring data of nitrate, ammonium, pH and blue-green algae were obtained using a monitoring probe. The results showed that due to the raising of the reservoir water level, previously oxic sediments became submerged, triggering an increase in iron and manganese in particular due to the establishment of reducing conditions. Manganese concentrations with values up to 4 mg L-1 are now exceeding guideline values. The analysis strongly indicated that both iron and manganese have a seasonal component with higher iron and manganese concentrations during the wet season. Over a three-year period afterwards, concentrations did not go back to pre-raise levels. The change in water quality was accompanied by a change in pH from previous values of around 5 to pH values of around 6.5. Geochemical simulations confirmed the theory that the increasing concentrations of iron and manganese are due to the dissolution of MnO2 and ferric oxyhydroxides oxidising organic matter in the process. This study showed that changes in reservoir water levels with the establishment of reducing conditions can have long-term effects on the water quality of a reservoir.

Geothermobacter hydrogeniphilus sp. nov., a mesophilic, iron(III)-reducing bacterium from seafloor/subseafloor environments in the Pacific Ocean, and emended description of the genus Geothermobacter.

A novel mesophilic, anaerobic, mixotrophic bacterium, with designated strains EPR-MT and HR-1, was isolated from a semi-extinct hydrothermal vent at the East Pacific Rise and from an Fe-mat at Lo'ihi Seamount, respectively. The cells were Gram-negative, pleomorphic rods of about 2.0 µm in length and 0.5 µm in width. Strain EPR-MT grew between 25 and 45 °C (optimum, 37.5-40 °C), 10 and 50 g l-1 NaCl (optimum, 15-20 g l-1) and pH 5.5 and 8.6 (optimum, pH 6.4). Strain HR-1 grew between 20 and 45 °C (optimum, 37.5-40 °C), 10 and 50 g l-1 NaCl (optimum, 15-25 g l-1) and pH 5.5 and 8.6 (optimum, pH 6.4). Shortest generation times with H2 as the primary electron donor, CO2 as the carbon source and ferric citrate as terminal electron acceptor were 6.7 and 5.5 h for EPR-MT and HR-1, respectively. Fe(OH)3, MnO2, AsO4 3-, SO4 2-, SeO4 2-, S2O3 2-, S0 and NO3 - were also used as terminal electron acceptors. Acetate, yeast extract, formate, lactate, tryptone and Casamino acids also served as both electron donors and carbon sources. G+C content of the genomic DNA was 59.4 mol% for strain EPR-MT and 59.2 mol% for strain HR-1. Phylogenetic and phylogenomic analyses indicated that both strains were closely related to each other and to Geothermobacter ehrlichii, within the class δ-Proteobacteria (now within the class Desulfuromonadia). Based on phylogenetic and phylogenomic analyses in addition to physiological and biochemical characteristics, both strains were found to represent a novel species within the genus Geothermobacter, for which the name Geothermobacter hydrogeniphilus sp. nov. is proposed. Geothermobacter hydrogeniphilus is represented by type strain EPR-MT (=JCM 32109T=KCTC 15831T=ATCC TSD-173T) and strain HR-1 (=JCM 32110=KCTC 15832).

Community structure of bacterioplankton and its relationship with environmental factors in the upper reaches of the Heihe River in Qinghai Plateau.

Planktonic microorganisms play a key role in the biogeochemical processes of the aquatic system, and they may be affected by many factors. High-throughput sequencing technology was used in this study to investigate and study the bacterioplankton community of water bodies in the upper reaches of the Heihe River Basin in Qinghai Plateau. Results showed that Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria are the predominant phyla in this river section, while the main genera are Thiomonas, Acidibacillus, Acidocella, Rhodanobacter, Acidithiobacter and Gallionella, which are autochthonous in the acid-mine drainage. Additionally, total nitrogen, total phosphorus, permanganate index and pH are significantly correlated with the bacterioplankton abundance and are the main limiting factors for the spatial distribution of the bacterioplankton. PICRUSt inferred that the mainstream microbial assemblages had a higher abundance of KOs belong to metabolism of terpenoids and polyketides, while the tributary had higher abundance of KOs belong to the immune system. The relationship between bacterioplankton community composition and environmental factors in the Heihe River basin was discussed for the first time in this study, which provides a theoretical basis for the healthy, orderly development of the water environment in the Heihe River Basin.

Relative bioavailability of manganese in relation to proteinate and sulfate sources for broiler chickens from one to 20 d of age.

The objective of this study was to evaluate the relative bioavailability (RB) of manganese (Mn) proteinate compared to Mn sulfate for broilers fed a diet based on corn and soybean meal for 20 d. The diets of 1,350 male Cobb broilers were supplemented with 0, 35, 70, 105, or 140 mg of Mn/kg of feed in the form of Mn sulfate or Mn proteinate. Weight gain, feed intake, feed conversion, bone strength, and Mn concentration in the tibia and liver, as well as the concentration of type I collagen in the tibia, were evaluated. No differences were observed for performance variables (P > 0.05) or for type I collage concentration in broiler tibia (P > 0.05), regardless of the source and level of supplementation used. Relative bioavailability was determined using bone strength values and Mn concentration in the tibia and liver, assuming Mn sulfate as the standard source (100%) by the slope-ratio method. The RB of Mn proteinate based on bone strength was 111%, based on liver Mn concentration was 128%, and based on tibia Mn concentration was 105%. Manganese proteinate was more bioavailable than Mn sulfate; it can be an important source of supplementation to improve bone quality in broilers.

Bright Mn-doped carbon dots for the determination of permanganate and L-ascorbic acid by a fluorescence on-off-on strategy.

A one-pot hydrothermal synthesis of manganese-doped carbon dots (Mn-CDs) is reported for fluorescent "on-off-on" determination of Mn(VII) and L-ascorbic acid (L-AA) in aqueous solution and living cells. Mn-CDs were prepared by using sulfanilic acid, tetrakis(hydroxymethyl)phosphonium chloride, and Mn(II) chloride as precursors. Mn-CDs were characterized by several spectroscopic methods and microscopic techniques. Mn-CDs show distinctly long fluorescence lifetime (12.39 ± 0.07 ns) and high absolute fluorescence quantum yield (around 37%) with excitation and emission wavelengths of 362 and 500 nm, respectively. Mn-CDs exhibit no significant cytotoxicity to human cervical carcinoma HeLa cells and human embryonic kidney HEK-293T cells at 200 µg mL-1 level after 48 h incubation. The fluorescence of Mn-CDs at 500 nm (excited at 362 nm) is quenched efficiently by Mn(VII) and can be further recovered after the addition of L-AA, resulting in a fluorescent "on-off-on" assay for the determination of Mn(VII) and L-AA. Under optimal experimental conditions, the linear response covers the 3 to 150 µM Mn(VII) concentration range and the 3 to 140 µM L-AA concentration range. This method offers relatively low detection limits of 0.66 µM for Mn(VII) and 0.90 µM for L-AA. This strategy was applied to visual determination of Mn(VII) and L-AA in living HeLa cells with satisfying results. Graphical abstract Schematic presentation of bright Mn-CD-based fluorescence "on-off-on" assay for both Mn(VII) and L-AA. This fluorescent assay possessed low detection limit of 0.66 µM for Mn(VII) and 0.90 µM for L-AA. This strategy was applied for visual determination of Mn(VII) and L-AA in living HeLa cells with satisfying results.

Analytical quantification of aqueous permanganate: Direct and indirect spectrophotometric determination for water treatment processes.

Three spectrophotometric methods have been developed and compared for the quantification of low concentrations (0.03-63 µM) of aqueous permanganate in neutral pH conditions. Although permanganate is a widely used oxidant in drinking water and wastewater treatment, no widely accepted method of quantification has been reported to date. While one method presented does not require the need for any reagent chemicals (direct spectrophotometric analysis), it yielded a relatively low molar absorption coefficient of 3340 M-1 cm-1 at 525 nm and a level of detection (LOD) and quantification (LOQ) of 0.45 and 1.51 µM, respectively. Some instability of permanganate species during direct quantification was found to occur over 60 min, with a total decrease of 0.002 (arbitrary units) of absorbance, equivalent to a decrease in concentration of 0.6 µM. Beyond 60 min, no further degradation was observed. Indirect spectrophotometric analyses using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and sodium iodide (NaI) provided a significantly more sensitive method for permanganate quantification, yielding molar absorption coefficients of 140,030 and 61,130 M-1 cm-1, respectively. The LOD and LOQ were determined to be 0.01 and 0.03 µM for the ABTS method and 0.02 and 0.08 µM for the NaI method, respectively. Although conservative and accurate limits of quantification for both the ABTS and NaI methods are presented, which should be sufficient of most practical applications, lower limits may be possible with further refinement of the methods.

Safranin O-functionalized cuboid mesoporous silica material for fluorescent sensing and adsorption of permanganate.

Incorporation of dual functions, i.e., sensing and adsorption, into one single organic-inorganic hybrid material for the detection and removal of toxic permanganate (MnO4-) ions is of great importance, representing a challenging and new task in the design and application of new functional materials. However, most of the reported materials display only one function as either sensing probes or adsorbents. In this work, a fluorescent cuboid mesoporous silica-based hybrid material (SiO2@SFNO) is first prepared by the covalent coupling of a new safranin O-based fluorophore (2,8-dimethyl-5-phenyl-3,7-bis(3-(3-(triethoxysilyl)propyl)ureido)phenazin-5-ium chloride) (SFNO) and newly-made cuboid mesoporous silica, which showed selective dual-functional activities towards MnO4- and green emission at 575 nm with a long-range excitation wavelength that is suitable for bio-imaging application. The design of this SiO2@SFNO material is based on the position of -NHCONH- groups, which are mainly responsible for the strong and selective coordination with MnO4-. SiO2@SFNO is responsive to MnO4- at parts per billion (67 ppb) level; it also displays high adsorption ability (292 mg g-1) to MnO4- in aqueous solutions. The fluorescence responses of MnO4-in vivo (limnodrilus claparedianus and zebrafish) demonstrate the possibility of further application in biology. Interestingly, this SiO2@SFNO material is also capable of monitoring trace amounts of Hg2+ and Cu2+ in living organisms, holding great potential in bio-related applications.

One-step microwave synthesis of N,S co-doped carbon dots from 1,6-hexanediamine dihydrochloride for cell imaging and ion detection.

As a new member of the fluorescent carbon nanomaterial family, carbon dots (CDs) not only have outstanding photoluminescence properties and small size characteristics, but also contain favourable low cytotoxicity and biocompatibility, which could be the best choice to detect of ions to replace quantum dots for ions detection. Here, the N,S co-doped carbon dots (N/S-CDs) was synthesized by one-step microwave using 1,6-hexanediamine dihydrochloride and dimethyl sulfoxide as precursors, and their morphology and structure were characterized by TEM, XRD, XPS and FTIR. The optimal emission wavelength of the CDs was 512 nm with green fluorescence, and was red-shifted gradually as the excitation wavelength aggrandized. The synthesized CDs owned a well quantum yield of 24 %. It was further applied for the detection of MnO4- and Cr2O72- with an excellent detection limit of 0.34 µM and 0.23µM, respectively. Cr2O72- did not influence the N/S-CDs PL response of MnO4- in the presence of excessive Pb2+. Moreover, the obtained N/S-CDs demonstrated preeminent biocompatibility and could be resoundingly applied for cellular imaging.

Facile in situ synthesis of cellulose microcrystalline-manganese dioxide nanocomposite for effective removal of Pb(II) and Cd(II) from water.

A novel cellulose microcrystalline-manganese dioxide nanocomposite (CMC-NMO) was synthesized by the redox reaction between potassium permanganate and ethanol based on cellulose microcrystalline. The cellulose microcrystalline (CMC) as support providing growth sites for the manganese dioxide nanowhiskers produced by the redox reaction and its application for Pb(II) and Cd(II) removal from aqueous was investigated. The characterization of as-synthesized material was revealed by various spectroscopic and microscopic techniques. Infrared-transform infrared (FITR) indicates that the incorporation of manganese oxide to CMC does not change the initial structure of it. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) data show that the manganese dioxide nanowhiskers with a few nanometers are uniformly dispersed on the surface of cellulose. Kinetics experiments reveal that Pb(II) and Cd(II) adsorption on CMC-NMO is a fast process and pseudo-second-order model fits the adsorption better. The maximum adsorption capacities of Pb(II) and Cd(II) obtained from the Langmuir model are 290.8 mg/g and 67.4 mg/g, respectively. The mechanism is mainly attributed to surface complexation and electrostatic attraction by energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis. In addition, depth removal experiments show that the residual concentrations of Pb(II) and Cd(II) in natural water after adsorption are lower than 0.01 mg/L. The regeneration and cyclic utilizing studies indicate that CMC-NMO has good adsorption stability. Therefore, the results indicate that this material can be employed as a potential adsorbent for current serious Pb(II) and Cd(II) pollution caused by industrial emissions. Graphical abstract.

Catalytic removal of toluene over manganese oxide-based catalysts: a review.

It is necessary to control the emissions of toluene, which is hazardous to both human health and the atmosphere environment and has been classified as a priority pollutant. Manganese oxide-based (Mn-based) catalysts have received increased attention due to their high catalytic performance, good physicochemical characteristic, availability in various crystal structures and morphologies, and being environmentally friendly and low cost. These catalysts can be classified into five categories, namely single manganese oxide, Mn-based composite oxides, Mn-based special oxides, supported Mn-based oxides, and Mn-based monoliths. This review focused on the recent progress on the five types of Mn-based catalysts for catalytic removal of toluene at low temperature and further systematically summarized the strategies improving catalysts, including improving synthetic methods, incorporating MnOx with other metal oxides, depositing Mn-based oxides on proper supports, and tuning the supports. Moreover, the effect of coexisting components, the reaction kinetics, and the oxidation mechanisms toward the removal of toluene were also discussed. Finally, the future research direction of this field was presented.

Transformations of organic micropollutants undergoing permanganate/bisulfite treatment: Kinetics, pathways and toxicity.

Permanganate/bisulfite (PM/BS) is a relatively new advanced oxidation process that can degrade organic micropollutants at extraordinary high rates. In this study, the degradability of PM/BS process towards different representative types of compounds was studied by investigating the kinetics, reaction site specificity and transformation chemistry. Acesulfame (ACE) and carbamazepine (CBZ) were two typical compounds containing olefinic moieties. Sucralose (SUC) was selected as a reference compound, and it is without aromatic and olefinic moieties. The kinetics results indicated that ACE and CBZ were effectively degraded while SUC was not. Preferred reaction sites of Mn3+ species was elucidated by identification of the ACE-transformation products (TPs) and CBZ-TPs with UHPLC-QTOF-MS. Seventeen ACE-TPs including two new compounds and eleven CBZ-TPs produced during the PM/BS process were identified and characterized. Transformation pathways revealed that cleavage of olefinic double bonds was the main reaction mechanism. Chemical structures containing electron-donating groups preferentially reacted with electrophilic Mn3+ species during the process. In addition, transformation products of ACE and CBZ during PM/BS process did not induce higher toxicity. This study provides a preliminary interpretation on the selectivity of PM/BS process according to the micropollutants' chemical structures, which hope to shed light on the future development of PM/BS treatment.

Comparative analysis of urban road dust compositions in relation to their potential human health impacts.

This study investigated the chemical components of fine urban road dust from seven sampling sites, based on which we could predict potential human health effects. The elemental compositions, including the contents of metals and volatile or semivolatile organic compounds, were determined to establish comprehensive chemical profiles of solid road dust. The chemical profiles, consisting of C: H ratio, metal contents, and relative abundances of organic compounds, provided a chemical signature for road dust. To overall cytotoxicity values ranging between 7 and 58%, water extracts contributed less than 15%, and cell death mainly occurred via direct contact with solid-phase components, which possibly indicates that the selected chemical profile of solid-phase road dust components could serve as a strong predictor for BJ and WI-38 cytotoxicity. Pure metal oxides (Cr2O3, CuO, Fe2O3, MnO2, NiO, or ZnO) exhibited a positive dose-response, and the corresponding metal contents in solid road dust were well correlated with cell viability. The principal component analysis (PCA) results suggested that the metal contents were stronger predictors of cytotoxicity than the benzene derivative or hydrocarbon contents. The chemical profiles established in this study could be further utilized to identify candidate health hazard factors in road dust.

Facile Preparation of Boron and Nitrogen Codoped Green Emission Carbon Quantum Dots for Detection of Permanganate and Captopril.

A hydrothermal strategy for preparing boron and nitrogen codoped carbon quantum dots was studied using the precursors of p-amino salicylic acid, boric acid and ethylene glycol dimethacrylate. The boron and nitrogen codoped carbon quantum dots have high fluorescence intensity, good monodispersity, high stability, superior water solubility, and a fluorescence quantum yield of 19.6%. Their average size is 5 nm. Their maximum excitation and emission wavelengths are 380 and 520 nm, respectively. Permanganate (MnO4-) quenched boron and nitrogen codoped carbon quantum dots fluorescence through inner filter effect and static quenching effects. The linear relation between quenching efficiency and MnO4- concentration ranged from 0.05 to 60 µmol/L with a detection limit of 13 nmol/L. In the presence of captopril, MnO4- was reduced to Mn2+ and the fluorescence of boron and nitrogen codoped carbon quantum dots was recovered. The linear range between recovery and captopril concentration was from 0.1 to 60 µmol/L. The limit of detection was 0.03 µmol/L. The developed method can be employed as a sensitive fluorescence sensing platform for MnO4-. It has been successfully used for captopril detection in mouse plasma.

Enhancing phytoextraction of potentially toxic elements in a polluted floodplain soil using sulfur-impregnated organoclay.

Enhancing metals phytoextraction using gentile mobilizing agents might be an appropriate approach to increase the phytoextraction efficiency and to shorten the phytoremediation duration. The effect of sulfur-impregnated organoclay (SIOC) on the redistribution of potentially toxic elements (PTEs) among their geochemical fractions in soils and their plant uptake has not yet been studied. Therefore, our aim is to investigate the role of different SIOC application doses (1%, 3% and 5%) on operationally defined geochemical fractions (soluble + exchangeable; bound to carbonate; manganese oxide; organic matter; sulfide; poorly- and well-crystalline Fe oxide; and residual fraction) of Cd, Cr, Cu, Ni, Pb, and Zn, and their accumulation by pea (Pisum sativum) and corn (Zea mays) in a greenhouse pot experiment using a polluted floodplain soil. The SIOC caused a significant decrease in soil pH, and an increase in organic carbon and total sulfur content in the soil. The addition of SIOC increased significantly the soluble + exchangeable fraction and bioavailability of the metals. The SIOC leads to a transformation of the residual, organic, and Fe-Mn oxide fractions of Cd, Cu, Ni, and Zn to the soluble + exchangeable fraction. The SIOC addition increased the potential mobile (non-residual) fraction of Cr and Pb. The SIOC increased the sulfide fraction of Cr, Ni, and Zn, while it decreased the same fraction for Cd, Cu, and Pb. The effect of SIOC on the redistribution of metal fractions increased with enhancing application dosages. Pea accumulated more metals than corn with greater accumulation in the roots than shoots. Application of the higher dose of SIOC promoted the metals accumulation by roots and their translocation to shoots of pea and corn. Our results suggest the potential suitability of SIOC for enhancing the phytomanagement of PTEs polluted soils and reducing the environmental risk of these pollutants.

A heterometallic sodium(i)-europium(iii)-organic layer exhibiting dual-responsive luminescent sensing for nitrofuran antibiotics, Cr2O72- and MnO4- anions.

The detection of nitrofuran antibiotics and toxic inorganic anions is currently necessary and challenging because their abuse and/or residuals have caused severe environmental pollution and illness. A heterometallic two-dimensional (2D) layered complex, {[Eu2Na(Hpddb)(pddb)2(CH3COO)2]·2.5(DMA)}n (1), was solvothermally synthesized and structurally and photophysically characterized. Pairs of acetate aggregated {Eu2Na(CH3COO)2} chains are periodically interconnected by V-shaped 4,4'-(pyridine-2,6-diyl)dibenzolate (pddb) linkers. More interestingly, the layered complex exhibits a bright red emission and can efficiently discriminate nitrofuran antibiotics by luminescent quenching with a strong quenching constant (Ksv) and low detection limit (LOD) of 4.93 × 104 M-1 and 0.64 µM for nitrofurazone, 4.42 × 104 M-1 and 0.68 µM for nitrofurantoin as well as 2.13 × 104 M-1 and 1.06 µM for furazolidone. Additionally, 1 can also probe trace amounts of toxic Cr2O72- and MnO4- anions with Ksv = 6.45 × 103 M-1 and LOD = 5.35 µM for Cr2O72- and Ksv = 2.84 × 103 M-1 and LOD = 5.99 µM for MnO4- anions. These interesting results indicate that heteromatallic coordination polymers can serve as favorable dual- or even multiple-responsive luminescence sensors to selectively recognize different kinds of contaminants.

A novel manganese oxidizing bacterium-Aeromonas hydrophila strain DS02: Mn(II) oxidization and biogenic Mn oxides generation.

The extensive applications of biogenic manganese oxides (BioMnOx) generated by manganese oxidizing bacteria (MOB) have attracted considerable attentions. In this study, we report on a novel MOB that has been isolated from sediments and identified as Aeromonas hydrophila strain DS02. The Mn(II) oxidation activity of strain DS02 under Mn(II) stress and the application of the associated BioMnOx products were investigated. Nearly 90.0% (495 mg L-1) of the soluble Mn(II) were removed and 45.6% (240 mg L-1) was converted to Mn(III/IV). Fitting the XPS data showed that Mn(IV)-oxide is the major component (82.0%) of the flake-shaped BioMnOx, corresponding to an average Mn oxidation number of 3.71. When the BioMnOx were coupled with the PMS activation, a 99.5% catalytic degradation of 2,4-dimethylaniline was observed after 80 min, revealing a high degradation efficiency.

Comparison on surface properties and desulfurization of MnO2 and pyrolusite blended activated carbon by steam activation.

In this study, MnO2 and pyrolusite were used as the catalysts to prepare modified activated carbon, that is, AC-Mn and AC-P, respectively, from coals by blending method and steam activation. The Brunauer-Emmett-Teller (BET) results indicated that the AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The relative contents of basic functional groups (i.e., C = O, π-π*) on AC-P were slightly lower than those on AC-Mn, while both contained the same main metal species, namely, MnO. The desulfurization results showed that with 3 wt% of blending ratio, AC-Mn3 and AC-P3 had higher sulfur capacities at 220 and 205 mg/g, respectively, which were much higher than for the blank one (149.6 mg/g). Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn, which might be attributed to the existence of other metals in pyrolusite. After the desulfurization process, MnO were gradually transferred into MnSO4, and the relative contents of basic functional groups decreased evidently for both AC-Mn3 and AC-P3. The results demonstrated that pyrolusite could be one good alternative to MnO2 to prepare modified activated carbon for desulfurization. IMPLICATIONS: MnO2 and pyrolusite were used as the additives to prepare modified activated carbon from coals by a blending method and by steam activation, that is, AC-Mn and AC-P, respectively. The AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The AC-Mn and AC-P had higher sulfur capacities than a blank one. Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn. The results demonstrated that pyrolusite could be one good alternative to MnO2 to prepare modified activated carbon for desulfurizatio.

T1-Mediated Nanosensor for Immunoassay Based on an Activatable MnO2 Nanoassembly.

Current magnetic relaxation switching (MRS) sensors for detection of trace targets in complex samples still suffer from limitations in terms of relatively low sensitivity and poor stability. To meet this challenge, we develop a longitudinal relaxation time (T1)-based nanosensor by using Mn2+ released from the reduction of a MnO2 nanoassembly that can induce the change of T1, and thus can greatly improve the sensitivity and overcome the "hook effect" of conventional MRS. Through the specific interaction between antigen and the antibody-functionalized MnO2 nanoassembly, the T1 signal of Mn2+ released from the nanoassembly is quantitatively determined by the antigen, which allows for highly sensitive and straightforward detection of targets. This approach broadens the applicability of magnetic biosensors and has great potential for applications in early diagnosis of disease biomarkers.