Metals Mn Research Articles

High Specific Surface Area TiO2 Aerogels Incorporated in situ with Co/Mn Oxides as Stable Electrochemical Capacitor Electrodes

Nanocomposite aerogels comprised of TiO2 and metal (Co and Mn) oxides are synthesized via an in situ sol–gel method in this study, and their structural, compositional and electrochemical properties are evaluated for possible applications as electrodes in energy storage devices. The inclusion of metallic oxides into TiO2 aerogels hinder the formation of titania crystalline phases, preserved particle sizes close to their original dimensions and yielded higher specific surface areas compared to pure TiO2 aerogels after heat treatment. High specific surface areas in aerogels positively affect the electrochemical properties, allowing a high electrochemical activity of the electrodes, in addition to intensifying the transport of ions and solvents through the mesoporous network of this material. Evaluation of the electrochemical properties of the aerogel‐based nanocomposites involves galvanostatic charge–discharge, cyclic voltammetry, and impedance spectroscopy. The nanocomposites exhibit enhanced electrochemical properties and stable performance within the range suitable for supercapacitor applications, as indicated by the Ragone chart. Notably, aerogels with higher incorporation of cobalt and manganese oxides in TiO2 aerogels exhibit significantly elevated specific surface areas, reaching 562 and 555 m2 g−1, respectively. These values are notably high for nanocomposites, underscoring the potential of these electroactive materials for electrochemical capacitors.

Determination of Trace Heavy Metals Content of Various Herbal Drinks Marketed in Ilorin Metropolis, Nigeria

The study encompasses an evaluation of the health risk and hazard profiles of heavy metals contents in various herbal drinks (AGBO) products marketed in Ilorin metropolis, Nigeria. Twenty (20) herbal drinks samples from four (4) different study (saw-mil, Osere, Oja-oba and Oke-odo) areas were collected randomly, digested and analyzed. Zinc, Lead, Copper, Iron, Manganese, Cadmium, Chromium and Nickel were analyzed using Atomic Absorption Spectrometer. The results of this study indicated that most of the heavy metals (Zn, Pb, Cu and Mn) in the herbal drinks were below the WHO recommended permissible limits. Chromium (Cr) and Cadmium (Cd) are not detected in all of the herbal drinks analyzed. However, sample C2 and D2 among other analyzed herbal samples contained unsafe concentrations of iron (Fe) and nickel (Ni) that exceeded the WHO recommended permissible limits. From the health point of view, the EDIs value of all the herbal drinks are below the daily reference dose. The non-cancerous (HQ) and hazard index (HI) value of all the herbal samples are less than one (1). Based on the results obtained in this study, there would be a non-carcinogenic health risk and hazard effects to the people taking and consuming the herbal drinks marketed in all the study areas.

Simultaneous production of highly pure hydrogen and carbon nanofibers through COx-free methane dissociation over Ni-based catalysts: Investigation of the promotional effects of transitional metal (Mn, Zr, and Zn)

Hydrogen and carbon nanotubes are two novel and engaging research topics in clean fuel and material science. Methane decomposition is the most advantageous itinerary for the concurrent production of COx-free hydrogen and carbon filaments. The 50Ni/Al2O3 catalyst was successfully fabricated using a simple one-pot hydrothermal method, and the influence of transition metals (Zr, Mn, and Zn) was investigated as the promoter. The homogeneous accumulation of the nanoparticles with a high specific surface area of 101–147 m2.g−1 was revealed to be the consequence of the mesoporous structure's presence. The reactor tests' findings demonstrated that synthesized bimetallic catalysts are more stable and active than monometallic catalysts. Besides, the Zn-modified catalyst was shown to have the highest performance and durability. The maximal methane conversions of 65.7, 77.2, 69.6, and 51.7 % were achieved over the 50Ni-xZn/Al2O3 (defined as 50Ni-xZn/Al2O3; x = 2.5, 5, 7.5, and 10 wt%) at 650 °C and GHSV = 24,000 mL.(h.gcat)−1, respectively. A deeper look at the microstructure and textural characteristics of the aged catalysts makes it clear that the zinc promoter introduced to the 50Ni/Al2O3 sample, by increasing the growth rate of carbon fiber/nanotube, changes the structure of the formed carbons from spherical shape to very homogeneous diameter filaments and lead to the production of ordered carbon filaments with better crystallinity.

Gluconic acid as the supplementary additive realizing high-efficiency production of metal manganese with decreased dosage of toxic selenium dioxide

Minimizing the dosage of toxic SeO2 additive in electrolyte for electrochemical deposition of metal manganese without compromising the current efficiency has long been the desire for electrolytic manganese industry. Herein, by combinative usage of SeO2 and gluconic acid (GlcA) as the composite additives, 50 % of SeO2 dosage can be cut down while the current efficiency can be increased from 67 % to 90 % at the same time, realizing the energy consumption being reduced by 23 % at the optimized concentration of 1.84 g/L GlcA. The electrochemical tests and electrode surface characterizations as well as density functional theory calculations jointly imply that the addition of GlcA can greatly increase the diffusion coefficient of Mn2+ from 1.5 × 10−6 cm2/s to 5.6 × 10−5 cm2/s, accelerating the approaching of Mn2+ towards the electrode surface by decreasing the diffusion barrier energy from 17.93 kJ/mol to 11.51 kJ/mol. On the electrode surface, the SeO32− is responsible for facilitating the electrochemical deposition of metal Mn by forming the MnSe intermediate while GlcA is in charge of restraining the activation of H2O molecule for inhibiting H2 generation, synergistically contributing to the efficient production of electrolytic metal manganese. The results can provide new insights for the environmentally friendly and high-efficiency upgrading of manganese industry.

Spatial variations and health risk assessment of heavy metal levels in groundwater of Qatar

The present work’s objective is to give a comprehensive overview of the quality of groundwater in Qatar in terms of heavy metals content as well as investigating the cause and effect of the elevation in their levels above the WHO/US-EPA standards. The scope of the study included (1) physical and chemical analysis of 82 groundwater samples collected from various locations around Qatar, (2) development of ArcGIS maps depicting the variations in the levels, (3) assessment of the human health risks associated with the existing levels using three of the most used models which are: Hazard index (HI), Nemerow comprehensive pollution index (NCPI) and Incremental Lifetime Cancer Risk (ILCR). There is no extensive study ever reported to assess the health risks linked with the consumption of groundwater characterized with such heavy metals levels in Qatar. The chronic daily intake (CDI) of the investigated heavy metals (Ag, Mn, Cr, V, Mo and Sr) through ingestion and dermal pathways had a range of 1.4 × 10–5–6.7 × 10–1 mg/kg/day while the NCPI’s range was reported at 0–4.39. Moreover, the HI and ILCR were found to have a range of 0–3.2 and 5.6 × 10–4–5.5 × 10–2, respectively. The assessment of health risks, conducted in the present work, could be beneficial in building the baseline of heavy metals levels in groundwater in Qatar. This will also help in the determination of any future contamination of groundwater.

Preparation, characterization, single-crystal analysis, and cytotoxic assessment of complexes formed by Schiff base and 8-hydroxyquinoline co-ligand with Co(II), Ni(II), and Mn(II) metal ions

This study focuses on the preparation of mixed ligand complexes of Ni(II), Co(II), and Mn(II) by combining the co-ligands 2-(((4-fluorophenyl)imino)methyl)-4-methoxy-6-nitrophenol (L1) and 8-hydroxyquinoline (L2). The chemical structures of the all compounds were examined using various techniques, including 1H and 13C NMR, FT-IR, UV–Vis, TGA, molar conductivity, LC-MS/MS, elemental analysis and magnetic susceptibility. The crystal structure of the ligand L1 was determined using single crystal X-ray analysis revealing that the ligand favors the phenol-imine tautomeric form in the solid state. All complexes are suggested to have an octahedral structure. Finally, the MTT assay was used to determine the toxicity level of the mixed ligand complexes in human non-small cell lung cancer (A549) and normal bronchial epithelial cell lines (BEAS-2B). The results showed that the [Ni(L1)(L2).(H2O)2] complex (IC50: 5.97 µM) exhibited high cytotoxic activity at a lower dose than cisplatin compared to the other compounds. In contrast, the [Ni(L1)(L2).(H2O)2] complex was shown to exhibit significantly lower cytotoxic activity (IC50 > 100 s µM) in the BEAS-2B (normal bronchial epithelial cell) cell line. The other compounds [Co(L1)(L2).(H2O)2] and [Mn(L1)(L2).(H2O)2] were shown to have no significant anticancer activity in A549 cells due to their cytotoxic activity at higher doses than cisplatin (IC50 > 100 s µM).

Unveiling the earthworm-associated preferential remediation of emerging organic pollutants and heavy metals in MSW-based vermicomposting systems: Insights through the lens of multivariate techniques and novel empirical models

Studies on the efficacies of vermicomposting and composting in countering the toxic impacts of pollutant cocktails in municipal solid waste (MSW) are scarce. Moreover, further research is needed to explore earthworms' remediation preferences for various pollutants in heterogeneous vermicomposting feedstocks, such as MSW. Therefore, removal dynamics of pesticides (chlorpyrifos, cypermethrin, and carbofuran), pharmaceuticals (diclofenac and carbamazepine), and heavy metals (Pb, Zn, Cu, and Mn) in MSW-based vermicomposting (Eisenia fetida and Eudrilus eugeniae) and composting systems were evaluated through multivariate analytical techniques (principal component (PCA) and multi-factor (MFA)) on the R-platform. Both earthworms satisfactorily increased their population and augmented NPK (nitrogen, phosphorous, and potassium) availability, cation exchange, microbial biomass C&N, and their metabolic activity 2–3 folds more than composting, accompanied by a 3–4 folds reduction of organic C, pH, and bulk density. Correspondingly, heavy metals, pesticides, and pharmaceuticals decreased by 8-10-folds via earthworm's significant pollutant removal efficiencies that subsided MSW-driven ecological risks by 60–90%. PCA and MFA revealed that N, P, and K-availability, organic C, and microbial activity were the indicative attributes for heavy metal and emerging organic micropollutant (EOMP)-removal during biocomposting; however, earthworms remove pesticides faster than pharmaceuticals and heavy metals. PCA-based novel empirical models demonstrated that in MSW-only feedstock, earthworm-mediated pollutant detoxification followed the order of pesticides > pharmaceuticals > heavy metals. However, in MSW combined with cow dung (1:1 ratio) feedstock, the detoxification order shifted to pharmaceuticals > heavy metals > pesticides. Therefore, this study provides fresh insights into pollutant-focused feedstock optimization for vermicomposting through model-based approaches, advancing the eco-friendly valorization of toxic MSW.

Atomically dispersed dual iron and manganese anchored nitrogen doped reduced graphene as robust cathode catalyst for direct methanol fuel cell and aluminium air battery

A noble metal-free atomically dispersed dual metal (Fe and Mn) anchored nitrogen (N)-doped reduced graphene oxide (rGO) is synthesized as a high-performance oxygen reduction reaction (ORR) electrocatalyst for alkaline direct methanol fuel cell and aluminium-air battery (AAB). The as-synthesized FeMn-NrGO catalyst exhibits a half-wave potential of 0.84 V for ORR and a low onset potential of 0.96 Vvs (RHE). The theoretical study reveals that the synergetic coupling of Mn and Fe with pyridinic and pyrrolic nitrogen weakening adsorption bond strength of the O* intermediates to the active site of the catalyst, thereby improving the for ORR performance. The synthesized Fe3Mn1-NrGO cathode catalyst assembled alkaline direct methanol fuel cell (DMFC) demonstrates a peak power density of 65 mW/cm2 extending an effective strategy to enhance the ORR kinetics of the non-noble metal-based catalyst for fuel cell application. Furthermore, the synthesized Fe3Mn1-NrGO also exhibits excellent ORR activity in 3.5 wt% NaCl solution and demonstrates a peak power density of 11.2 mW/cm2 aqueous NaCl electrolyte-based AAB system.

Changes of the trace metals in ice core during 1915‒2016 in coastal eastern Antarctica

Antarctic trace metal records provide important information for grasping the influence of human activities on the environment over the last centuries. The CA2016-75 ice core is located along the East Antarctic Zhongshan Station–Dome A, enhances the record of metals research in the East Antarctic region, and its high-resolution supplies data support for the study of high-frequency climatic drivers and the effect of human activities on the Antarctic environment. A thorough dataset on seven trace metals (Al, Fe, Mn, Cu, Zn, Ba and Pb) in a coastal ice core in eastern Antarctica during the previous 102 years (1915–2016) is presented in this study. Pb has the lowest concentration (9.51 ± 20.95 pg g−1), and Ba has the highest concentration (36.57 ± 51.35 ng g−1). Notable variations are observed between the pre-1968 AD and post-1968 AD phases for Mn, Zn and Ba. The abrupt, remarkable increase in the concentrations coincided with the change of metal smelting production in the southern hemisphere. In addition to this, it may also be related to local Antarctic scientific research activities. Al and Fe, the primary crustal elements, are essentially obtained from soil dust; Cu shows high crustal enrichment factors (EFc, >10), indicating that it is notably affected by anthropogenic activities. Moreover, the anthropogenic activities in the Southern Hemisphere have had an impact on lead deposition in Antarctica. This study not only enriches the trace metal historical record along the Zhongshan Station–Dome A but also provides a high-resolution ice core record, which is very crucial for the reconstruction of trace metal concentration changes in the last 100 years.

Bioaccumulation and Health Risk Assessment of Potentially Toxic Metals in Citrus Limetta & Citrus Sinensis Irrigated by Wastewater.

The aim of this study was to evaluate the impact of different irrigation sources on the levels of potentially toxic metals (Cd, Cr, Fe and Mn) in the edibles of citrus fruits (Citrus sinensis and Citrus limetta). The samples of fruit, soil and water were collected from two locations (fresh water irrigated-FW I and sewage water irrigated-SW II) within the city of Sargodha. The samples utilized in the study for metal analysis were prepared utilizing the wet acid digestion method. Metal determination was performed using Atomic Absorption Spectrometry (AAS). The potentially toxic metal values in the citrus samples ranged from 0.010 to 0.063, 0.015 to 0.293, 6.691 to 11.342 and 0.366 to 0.667mg/kg for Cd, Cr, Fe and Mn, respectively. Analysis of Citrus limetta and Citrus sinensis indicated that the highest concentration of Cr, Fe and Mn is observed at the sewage water irrigation site (SW-II), whilst the minimum levels of Cr, Fe and Mn were observed at the fresh water irrigation site (FW-I). The results show that the levels of these metals in soil and fruit samples meet the acceptable guidelines outlined by USEPA and WHO. It was found that the metal pollution constitutes a potential threat to human health due to the HRI values for Cd, Cr, and Fe being above 1, despite the DIM values being below 1. Regular monitoring of vegetables irrigated with wastewater is highly recommended in order to minimise health risks to individuals.

Spectrophotometric Investigations on Some Heavy Metals Cu, Ni, Co, and Mn to Evaluate Their Environmental Toxicity

Spectrophotometric Investigations on Some Heavy Metals Cu, Ni, Co, and Mn to Evaluate Their Environmental Toxicity

Source Identification of Urban dust Heavy Metals Using in Situ and Satellite Data in Three Mega Cities of Iran.

The aim of this study was an integrative assessment of heavy metals associated with urban dust data in Iran (Ahvaz, Isfahan, and Shiraz). Samples of urban dust from four sites (traffic, industrial, residential, and Greenland) were collected, and ten heavy metal concentrations were determined using ICP_MS in each sample. The highest average concentrations of metals were at the traffic site for the Mn, Zn, and Cr metals. The PMF model indicates a higher percentage of Pb participation, which shows the importance of traffic resources. The highest non-carcinogenic risk (HI) was for the Cr and the carcinogenic risk was tolerable. To evaluate aerosol and its effects on urban dust, Aerosol Optical Depth (AOD) data were used during 2003-2023. According to the Mankendall test, the trend of AOD has been increasing in Esfahan (p_value < 0.05) and Shiraz. Although Ahvaz's AOD is about two times greater than other cities, the aerosol trend in Ahvaz is decreasing.

Impact of Metals Scrap Yard on the Presence of some Heavy Metals Concentration within Gombe Metropolis, Gombe State, Nigeria, using Atomic Absorption Spectrometry

The Metal scrap yards play a crucial role in the recycling and reuse of metals, contributing significantly to the economy and conservation of natural resources. However, the processing and storage of metal scraps can lead to the release of heavy metals such as lead, chromium and cadmium, into the environment. The presence of heavy metals in metal scrap yards poses a significant risk to nearby communities, workers and the environment, also causing air and water pollution, soil contamination, and health problem. Study of impact of metals scrap yard on the presence some of some heavy metals in soil samples was done using Atomic Absorption Spectrometer (AAS). Top soil sample were collected from eight metals scrap yards and their corresponding control areas. One gram (1 g) each of the soil samples was digested and then heated slowly and steadily, the solution appears colorless. The samples were allowed to cool and ready for analysis. The result obtained was, the mean elemental concentration element was of the order ofMn (41.022±41.202)&gt; Cu (4.416±4.274) &gt;Pb (2.685±1.399) &gt; Mg (0.500±10.122) &gt; Cr (0.460±0.187) &gt; Cd (0.125±0.027) &gt; Co (0.04±0.000)&gt; Ni (0.000±0.000). The comparison of the elemental concentration of the heavy metals of (Mn, Mg, Cu, Pd, Cr, Cd, Co and Ni) in the study area ware shows the metal scrap yard has impact in the presence of heavy metals in soil. In addition, the Contamination factor (CF), and Pollution load index (PLI) of each trace element in soil of the study area and their respective control area were all &lt; 1 which implies that they all have low contamination factors, less polluted and low contaminated.

Utilizing Microbial Fuel Cells For Simultaneous Treatment Of Solid Waste Water And Energy Generation

The proposed biocatalyst utilized in the microbial fuel cell (MFC) experiment demonstrated exo-electrogenic activity, with species such as Mycobacterium and Shewanella (Pseudomonas) sourced from sewer wastewater. Chemical parameters from the initial experimental trial did not comply with Environmental Protection Agency (EPA) limits. The total suspended solids (TSS) in the second MFC trial were the only parameter to meet the EPA threshold of 50 ppm, with influent and effluent concentrations of 96 ppm and 23.1 ppm, respectively. Consequently, supplementary treatment methods are required to achieve EPA discharge standards. The second trial indicated that the MFC setup effectively reduced metal concentrations, including Cr, Mn, Pb, and Zn, to levels that satisfy EPA surface water effluent discharge criteria. Keywords: microbial fuel cell, anode chamber, cathode chamber, wastewater, energy generation. Aims Research Journal Reference Format: Adeniyi O. A., Bakri A.J., Samuel O. Fadipe, Shakirat B. A., Adebayo O.C. &amp; Oyetunde R.A. (2024): Utilizing Microbial Fuel Cells For Simultaneous Treatment Of Solid Waste Water And Energy Generationelta. Advances in Multidisciplinary and Scientific Research Journal Vol. 10. No. 2. Pp 55-69. www.isteams.net/aimsjournal. dx.doi.org/10.22624/AIMS/V10N2P6

Biomonitoring with the Use of the Herbal Plant Taraxacum officinale as a Source of Information on Environmental Contamination.

The aim of this study was to assess the level of contamination of the common dandelion-Taraxacum officinale-with selected metals (Mn, Fe, Ni, Cu, Zn, Cd, and Pb) and to demonstrate that this plant can be used in passive biomonitoring of industrial sites. Two sample transects (the first was near a forest, an area potentially uncontaminated by analytes [A], while the second ran near a steel mill, a contaminated area [B]), each about 1.5 km long, located in Ozimek, Opole Province, Poland, were used in this study. Metals in plant and soil samples were determined by atomic absorption spectroscopy (AAS). Based on the analysis of the obtained results to determine the concentration of metals, plants at site A were more contaminated with Mn (240 mg/kg d.m.) and those at site B with Fe (635 mg/kg d.m.). Mean Pb values (8.39 mg/kg d.m.) were higher at the industrial site (B) and statistically significant at the forest site (A), together with Mn and Fe at the p < 0.001 level. The BCF values for T. officinale showed that Cu (0.473) and Zn (0.785) accumulated to an average degree on both transects. This shows that dandelion is heavily loaded with these metals. Both dandelion and soil samples showed the highest concentrations of Mn, Fe, and Zn, especially in the polluted area B, which is the result of pollution not only from the smelter (dust from electric arc furnaces in steel smelting, extraction installations in production halls transmitting pollutants into the air from molding sand, or waste from molding and core masses dumped on the heap and blown by the wind from the landfill) but also from the high anthropopressure caused by human activity-for example, heating processes or road transport. Our results confirmed that Taraxacum officinale can be successfully used as a herbal plant in passive biomonitoring to assess the quality of the environment, but it must be collected from uncontaminated areas if we want to use it like a medicinal plant.

Enhancing perhydrobenzyltoluene dehydrogenation performance with Co, Mo and Mn metal oxides: A comparative study with Pt/Al2O3 catalyst

In this study, the influence of incorporating Co, Mo and Mn oxides into Pt/Al2O3 catalyst on the dehydrogenation performance of Liquid organic Hydrogen Carrier (LOHCs) is investigated. A notable positive impact on the dehydrogenation process was observed, resulting in enhanced catalytic performance. This effect is associated with improved product desorption and a significant reduction in the by-product formation like methylfluorene. Particularly, the electron-acceptor effect exhibited by molybdenum, emerge as the key factor in enhancing catalytic performance. This effect allowed for the reduction of platinum content without compromising the productivity and selectivity and representing a significant advancement in catalyst design. These findings highlight the potential for Mo-based catalysts to serve as a promising alternatives to Pt-based catalysts in LOHC dehydrogenation processes.

Contribution of Hair Care Products in Heavy Metals Exposure in Pakistan

Products used for hair care by humans are essential for cleaning, protection, perfuming, and beautification. These are applied directly on the skin and can be a potential factor for dermal exposure to toxic metals. The present research deals with the assessment of heavy metals in the hair care products available in the local markets of Karachi, Pakistan. A total of 20 brands of shampoo and 05 brands of conditioners were collected in triplicate and analyzed for 10 heavy metals (Fe, Mn, Cr, Ni, Cu, Co, Pb, Cd, Zn, and Hg) by atomic absorption spectrophotometer. Toxic metals were found to be higher in conditioner than in shampoo of respective color and brand. Ni and Zn concentrations have exceeded the maximum permissible limits. Consumers belonging to the lower class are more vulnerable to heavy metals exposure because of the high metal content in low-cost products. These results suggested that hair care products should also be considered as one of the sources of heavy metals exposure.

MOF derived tri-metallic CoNiMn hydroxide assembled on carbon cloth for hybrid supercapacitor and hydrogen evolution

Polymetallic hydroxides are promising electrode materials for supercapacitors and electrocatalysis due to their unique physical and chemical properties. Herein, carbon cloth self-supported cobalt‑nickel‑manganese hydroxide (CoNiMn-OH/CC) composites were synthesized by a facile hydrothermal method with zeolite imidazolate framework-67 (ZIF-67) as a template. The results indicate that the hydroxides maintain the morphology of ZIF-67 template, while the addition of Mn can affect the redox behavior and enhance the electrochemical activity of metal hydroxides. Therefore, the prepared CoNiMn-OH with ultrathin edge-surface stacked nanosheets structure can promote electron/ion transfer, which induces to better charge storage kinetics and activity for supercapacitors and hydrogen evolution reaction (HER). In-situ Raman spectra combined density functional theory calculations co-revealed the reaction mechanism. The optimized CoNi3Mn1-OH nanosheets has a high specific capacity of 955.7C g−1 at 1 A g−1 and excellent rate performance with 91.1 % capacitance retention (870.7C g−1 at 10 A g−1). The hybrid supercapacitor device with CoNi3Mn1-OH as the positive electrode and activated carbon (AC) as the negative electrode has an energy density of up to 30 Wh kg−1, a power density of 0.8 kW kg−1, and excellent cycling stability (78.5 % capacity retention after 10000 cycles at 5 A g−1). In addition, the CoNi3Mn1-OH composite with tuned Ni and Mn metal ratios has a low HER overpotential of 202 mV at 10 mA cm−2.

Transition metal salt catalysed green synthesis of mesoporous silica nanoparticles

Conventionally, mesoporous silica nanoparticles are prepared by catalysing silicon alkoxides using acids or bases and are highly important in storage, delivery, and catalysis. Here, for the first time, we demonstrate that a transition metal ion (such as Ni(II), Co(II), and Mn(II)) also catalyses the hydrolysis and condensation reactions of silicon alkoxides in aqueous media without any additional acid or base to synthesize mesostructured and micro/mesostructured silica nanoparticles. An aqueous solution of a transition metal salt (specifically, nitrate salts of Ni(II), Co(II), or Mn(II), or chloride and sulphate salts of Ni(II)), 10-Lauryl ether (C12H25(OCH2CH2)10OH, C12E10) and cetyltrimethylammonium bromide (C16H33N(CH3)3Br, CTAB), and tetramethyl orthosilicate (TMOS) undergoes a precipitation reaction at room temperature, yielding ultra-small ordered mesostructured silica nanoparticles. These nanoparticles are subsequently calcined to produce mesoporous silica (meso-SiO2) with a high surface area (680–871 m2/g), large pore-volume (2.2–3.71 cm3/g), and small pore-size (1.2–3.0 nm). Moreover, the counter anions of the salts play an important role in the assembly process to obtain nanoparticles with an additional well-defined secondary pore (7.5–33.4 nm or larger). Coordinated water of the metal ion and methoxy group of the silica source react to produce a complex in which two hydroxy sides are in close vicinity to speed up the condensation reaction. We propose a hydrolysis and condensation reaction mechanism for TMOS to highlight the role of the metal ion as a catalyst.

An echellograms-based quantitative analysis method of laser-induced breakdown spectroscopy

The high-resolution broadband LIBS spectrum is typically acquired using an echelle spectrometer and array detectors. However, the full frame (i.e., echellogram) captured by detector is commonly converted to 1D spectrum for the further analysis, which would both limit the detection speed of LIBS and potentially degenerate the analytical performance. In this work, we propose an echellograms-based analysis method for the quantification of minor metal elements in steel. Two metal elements, Mn and Ti, are chosen to validate the feasibility of the analytical method. The LASSO algorithm is used to build the multivariate regression model using LIBS spectra and echellograms respectively. The analytical performance obtained with the echellograms-based model is compared with that of spectra-based model. The efficiency of the echellograms-based quantitative analysis method is demonstrated with better prediction accuracy and precision. Notably, the echellogram-based regression model involves only tens to thousands of pixels from the echellogram, which can be selectively read out using a CMOS detector. The combination of echellogram-based quantitative analysis method and CMOS detector provides new ideas for high-frequency LIBS detection.