Scanning Electron Microscopy Coupled With Energy Dispersive X-ray Research Articles

Differentiation of petro-sourced plastic microfilaments from organic microfilaments by SEM-EDX in environmental samples

Quantifying microplastics (MPs) in marine environments is challenging due to the complexities of differentiation from other materials. This study aims to distinguish petro-sourced plastic microfilaments from organic ones in environmental samples using scanning electron microscope coupled with energy dispersive X-ray (SEM-EDX) analysis. Therefore, 38 particles resembling MPs (PRMPs) from sediments and organisms in Madagascar were analyzed. MPs identification thresholds were determined from SEM-EDX analysis of macroplastics and seaweed, the primary sources of microfilaments. SEM-EDX results of the 38 PRMPs were compared with identification/misidentification made by five MPs observation experts. Results indicated that a carbon/oxygen (C/O) ratio >1 distinguished macroplastics and MPs from other sources (seaweed and organic microfilaments). SEM-EDX analysis identified 81.58% of PRMPs as MPs. The average error made by one observer was 36.32%. These findings highlight the need for a method to assess identification error in MPs quantification and recommend SEM-EDX analysis of microfilaments to gauge observer error.

THE INTERACTION BETWEEN A WHITE MATERIAL INSIDE AND OUTSIDE A POTTERY VESSEL FROM EASTERN EIN-SHAMS, EGYPT

This work aims to investigate a pottery vessel from eastern EIN-Shams, Egypt, lying in sandy soil from citizen lands, returning to the New Kingdom-Egypt. This pottery vessel was covered with white material from inside and outside. In terms of origin, this vessel is made of buff-colored clay; it has big pores, many cracks, and large missing areas filled with that material, with an uneven surface texture, that strongly bonds with the body pores, and shrinks away from the edges in some areas, in this way obscuring the original surface. In this respect, several physicochemical investigations in terms of chemical composition, physical properties, and nature of this white material were performed, to analyze the influence of it on the ancient pottery vessel. The analytical methods used in this research were USB digital microscopy, X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX), and differential thermal analysis (DTA). The results of the USB digital microscopy showed the presence of gypsum crystals, large, flaked pottery surfaces, and quartz. SEM-EDX revealed the presence of organic fibers, chloride salts in a significant percentage, iron, and aluminum oxides. XRD investigation emphasizes the presence of gypsum and sodium chloride salts. DTA results revealed that the firing temperatures of the pottery vessel range between around 750-800°C.

Synthesis, Characterization, and Biosorption of Cu2+ and Pb2+ Ions from an Aqueous Solution Using Biochar Derived from Orange Peels.

In this study, orange peel (OP) biochar was used as a bio-sorbent for the removal of copper and lead from wastewater in single and binary systems. The equilibrium and kinetic studies were conducted at a pH value of 5, which was the maximum adsorption pH value for both metal ions. The equilibrium studies were investigated at a varying initial concentration (10-200 mg/L) with a constant dosage of 0.1 g, while the kinetic studies were conducted at a fixed initial concentration of 200 mg/L with a constant dosage of 1 g/L for both single and binary systems. The maximum adsorption capacity of the orange peel biochar was 28.06 mg/g, 26.83 mg/g, 30.12 mg/g and 27.71 mg/g for single Cu2+, binary Cu2+, single Pb2+ and binary Pb2+ systems, respectively. The Langmuir isotherm model fitted the experimental data, suggesting that adsorption occurred on a monolayer, while the pseudo-second-order model performed well with the kinetic data. The point of zero charge (pHpzc) of the orange peel biochar was found to be 10.03, which revealed that the surface of the bio-sorbent contains basic groups. A Fourier infrared transform (FTIR) spectroscope and scanning electron microscope, coupled with energy dispersive x-ray (SEM-EDX) and x-ray diffraction analyses, were used to determine the functional groups, surface morphology, and inorganic elements present on the surface of the bio-sorbent, respectively. The results obtained have shown that orange peel biochar is efficient for the removal of Cu2+ and Pb2+ ions from an aqueous solution.

Enhancing thermal insulation with phosphate washing sludge waste as an inorganic foaming agent in porous acid-based geopolymers: Formulation and processing optimization

This study explores the potential utilization of phosphate washing sludge (PWS), a calcium carbonate-rich by-product of phosphate mining, as an inorganic foaming agent in the production of porous acid-based geopolymers. The investigation focused on evaluating the impact of various factors, including phosphoric acid concentration (ranging from 8 M to 12 M), liquid/solid (L/S) ratio (0.8 to 1.2), and the amount of PWS added (ranging from 0 wt% to 50 wt%), on the properties of the resulting geopolymers, such as porosity, density, thermal conductivity, and compressive strength. To optimize the formulation and processing parameters of porous acid-based geopolymers, a surface response methodology using statistical modeling was employed. This approach facilitated a systematic examination of the different factors influencing the properties of geopolymers. The raw materials involved in the study, namely kaolinitic clay, PWS, and the produced geopolymers, were characterized using various techniques such as X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Scanning Electron Microscope coupled with Energy Dispersive X-Ray (SEM/EDX), laser particle size analysis, and mapping. The results revealed that the combination of a phosphoric acid concentration of 10 M, a L/S ratio of 0.88, and the addition of 16 wt% PWS yielded the best performance in terms of porosity, compressive strength, and thermal conductivity, with values of 29.4 %, 13.8 MPa, and 0.0931 W/m.K, respectively. Additionally, a mathematical model was developed to predict optimal parameter combinations for desired performance characteristics. This research holds promise for the development of cost-effective thermal insulation materials for building applications.

Dynamic investigation on potassium migration and transformation during biochar combustion and its correlation with combustion reactivity

For agricultural biomass combustion, K migration and transformation is a key factor affecting boiler operation and reaction characteristics. In this study, dynamic K migration and transformation characteristics during rice straw char combustion process under different O2 concentrations were studied using chemical fractionation analysis (CFA), X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX). Furthermore, the correlation between K migration/transformation and char combustion reactivity was discussed. The results showed that most of K in rice straw char was H2O-soluble K. And the main forms of H2O-soluble K and insoluble K are KCl and KAlSi3O8, respectively. As reaction proceeded, the contents of H2O-soluble K and insoluble K decreased but those of NH4Ac-soluble K and HCl-soluble K increased. Most of the released K is H2O-soluble K. H2O-soluble K would be transformed into NH4Ac-soluble K and HCl-soluble K, and some insoluble K would be transformed into H2O-soluble K. The increase of O2 concentration would stimulate the transformation of H2O-soluble K into NH4Ac-soluble K, HCl-soluble K and released K. However, the reaction to form K-aluminosilicate was hardly found during the combustion process at 400 ℃. Ultimately, it is found that H2O-soluble K is the key occurrence form K affecting the combustion characteristics of rice straw char.

Synthesis of novel Si–P–N complex coating for the fabrication of flame-retardant and hydrophobic cotton textile potentially suitable for rail seat cover

In this study, we fabricated a fancy cotton textile with sustained flame retardancy and hydrophobicity by dip coating the fabric with two complex solutions (CS). Solutions A and B consisted of chitosan, urea, phytic acid, tetraethyl orthosilicate, and hexamethyldisiloxane, which were rich in silica (Si), phosphate (P), and amide (N). The chemical interaction and surface morphology of the CS coated on the textile were verified by Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy coupled with energy-dispersive X-ray (SEM-EDX) spectrometry. Thermogravimetric analysis, differential scanning calorimetry, an ASTM D6413 vertical flame test, and cone-calorimeter test were conducted to study the thermal and flame-retardant properties. The IR spectral peaks at 730, 820, and 1540 cm−1 are the main evidence for chemical interaction, and a uniform distribution can be seen in the SEM-EDX analysis. The thermal stability was significantly enhanced by producing char from 6.7 to 33.5 % at 700 °C. Surprisingly, the cotton textile exhibited self-extinguishing behavior. This was evidenced by the shortened burning length from 300 to 84 mm during 12 s of flame exposure in the VF test, as well as reductions in the peak heat-release rate and total heat release rate from 203 to 21 kW/m2 and from 20.1 to 2.8 MJ/m2, respectively. The hydrophobicity of the textile increased upon application of the CS coating, with a contact angle (CA) of 127°. Practical examination confirmed that the treated fabric was well suited for seat upholstery.

Chemical modification of Macadamia-derived activated carbon for remediation of selected heavy metals from wastewater

In this study, Macadamia-derived activated carbon was utilized for the remediation of selected heavy metals from wastewater samples. The selected heavy metals include Pb (II), Fe (III), Cd (II), and Zn (II). The activated carbon used in the study was modified with KMnO4 and HNO3 to increase the content of the oxygen-containing functional groups on the adsorbent surface. Both the unmodified activated carbon (UAC) and modified activated carbon (MAC) adsorbents were employed throughout the study for comparative purposes in a multi-metallic system. The adsorbents were characterised using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray (SEM/EDX) analysis, and elemental (CHNS) analysis. Elemental analysis revealed an increased oxygen content from UAC to the MAC adsorbent from 8.34 % to 22.87 %. Scanning electron microscopy revealed a morphological contrast in the surfaces of both adsorbents. Optimal conditions for the carbon sorbents were observed at a pH 5, adsorbent mass of 0.2 g, initial concentration of 50 mg L-1, 4 h contact time, and a temperature of 298 K. Overall performance in removal efficiencies were recorded to be 74.74 % for UAC and 87.39 % for MAC. The MAC displayed superior removal efficiencies for Pb (II), and Fe (III) as compared to Cd (II) and Zn (II). Both adsorbents were applied in the treatment of acid mine drainage and leachate samples and the results indicated successful heavy metal remediation using the MAC adsorbent. Two-parameter and three-parameter adsorption isotherm models were fit to the experimental data, and it was found that the Langmuir model was better suited to the equilibrium data as opposed to the other models. The adsorption kinetics were best described using the pseudo-second-order model. Maximum adsorption capacities produced for UAC and MAC were found to be 3.00 and 3.50 mg g−1 respectively.

Enhanced Phosphorus Removal during Municipal Wastewater Treatment by the Biological Aeration Filter with Modified Steel Slags

Excessive phosphorus in aquatic environments can lead to eutrophication, posing a significant deterioration of water quality. In this study, modified steel slag was used as a novel filter media in the biological aeration filter (BAF) to achieve a bioinduced phosphorus crystallization process for simultaneous removal and recovery of phosphorus from municipal wastewater. Phosphorus removal efficiency could reach 80% during 4 days of operation due to high adsorption capacity of the modified steel slag in the single BAF reactor, but the phosphorus removal efficiency decreased to 30% after 30 days of operation. The phosphorus removal efficiency of the BAF system increased to 70% under alternating anaerobic-aerobic (A/O) operation condition. Concentration of PO43−-P in anaerobic effluent reached 19.9 mg/L at 68 days of operation and exceeded that in influent (10.6 mg/L), indicating that phosphorus accumulating organisms (PAOs) were successfully enriched in the alternating A/O BAF system. Hydroxyapatite (HAP) crystals formation was confirmed based on analysis of scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX) and X-ray diffraction (XRD). The proposed phosphorus removal mechanism suggests that the release of phosphorus from PAOs and the release of Ca2+ and OH− from the modified steel slag is beneficial to HAP crystals formation. These results indicated that the bioinduced phosphorus crystallization process achieved to improve phosphorus removal efficiency of the alternating A/O BAF system. This finding is a significant improvement to both biological and crystallization phosphorus removal processes, and has significant potential application for removal and recovery of phosphorus in wastewater treatment.

Preparation, Characterization and Application of Sulphuric Acid-Treated Soursop (Annona muricata L.) Seeds Powder in the Adsorption of Cu(II) Ions

This work presented the adsorption of Cu(II) ions using agriculture waste coming from soursop (Annona muricata L.) seeds. The chemical treatment performed on Annona muricata L. seeds was carried out using 1.0 M H2SO4 solutions. The Fourier-transform infrared (FTIR) spectrophotometer, scanning electron microscope coupled with energy dispersive X-ray (SEM-EDX), pH of point-zero-charge (pHPZC), and pHslurry analyses were done to characterize the surface properties of the adsorbent. Experimental conditions such as contact time, adsorbent dosage, pH, and initial Cu(II) ion concentrations, all of which could affect Cu(II) ions adsorption, were studied. The adsorption kinetics was successfully described by the pseudo-second-order model. The Langmuir and Freundlich models were applied to interpret the Cu(II) ions’ adsorption at equilibrium. The isotherm data fitted well with the Freundlich model and the maximum adsorption capacity was 187.83 mg.g-1 based on the Langmuir model.

Confirmation of the systematic presence of tin particles in fallopian tubes or uterine horns of Essure implant explanted patients: A study of 18 cases with the same pathological process

ObjectiveTo examine associations between local and systemic symptoms and the wear of the tin weld of Essure implants. Designstudy of a series of cases. SettingsTwo French hospitals. ParticipantsEighteen patients explanted by hysterectomy and salpingectomy for removal of their Essure implants between September 2019 and July 2020, have had a common anatomopathological process. Main outcome measuresanatomopathological examination by optical microscopy and mineralogical analysis of the fallopian tube or uterine horn with scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX). Evaluation of local and systemic symptoms with a questionnaire. Examination of blood metal assays (nickel, chromium, and tin). Resultsanatomopathological examination highlights foreign body granulomas, fibrosis, adenomyosis, nonspecific inflammation, cysts and myomas in the Fallopian tubes, uterine horns, or both and mentions the presence of foreign bodies in seven cases. SEM-EDX analyses showed, systematically, the presence of tin particles integrated in the wall near the weld, generally in clusters, and with a size ranging from about one micron to several dozen microns. The questionnaire shows that the most frequent local symptoms were pelvic pain, urinary disorders, bleeding, and pains during intercourse. The most common systemic symptoms were: asthenia, visual disturbances, amnesia, giddiness, dorsal pains, headaches, and joint pains. The majority of local and systemic symptoms decreased after explantation, but sometimes incompletely. Before explantation, high levels of nickel, tin and chromium were observed in 11/17, 1/7 and 2/17 patients. After explantation, tin levels were high in 3/11 patients. Conclusionsour new anatomopathological process systematically demonstrates the presence of tin particles in tissue near the weld. These particles could be responsible for granulomatous inflammations as well as local symptoms. Many of the systemic symptoms are consistent with chronic organotin poisoning but further studies are needed to find out whether tin from the solder can be converted to organotin in the patients' bodies.

Study of Physico-Chemical Interactions during the Production of Silver Citrate Nanocomposites with Hemp Fiber.

In the study presented in this paper, the results obtained by producing nanocomposites consisting of a silver citrate thin layer deposited on hemp fiber surfaces are analyzed. Using the pulsed laser deposition (PLD) method applied to a silver target with impurities of nickel and iron, the formation of the silver citrate film is performed in various ways and the results are discussed based on Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy coupled with Energy Dispersive X-ray (SEM-EDX) spectroscopy analyses. A mechanism of the physico-chemical processes that take place based on the FTIR vibrational modes and the elemental composition established by the SEM-EDS analysis is proposed. Inhibition of the fermentation process of Saccharomyces cerevisae is demonstrated for the nanocomposite material of the silver citrate thin layer, obtained by means of the PLD method, on hemp fabric. The usefulness of composite materials of this type can extend from sensors and optoelectronics to the medical fields of analysis and treatment.

Sodium alginate encapsulated Moroccan clay as eco-friendly and efficient adsorbent for copper ions from aqueous medium

Water pollution with copper (Cu) has a significant impact on the environment and human health. Within this context, the present study aims to synthesize a composite bead based on Moroccan natural clay from Chaouia (CH) and sodium alginate (Na-AL) as adsorbents to remove copper ions from aqueous solution. The adsorbents were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy coupled with Energy Dispersive X-ray (SEM-EDX) and Thermogravimetric Analysis (TGA). The effect of adsorbent dose, kinetic time, initial concentration of copper ions and temperature were investigated. Nonlinear regression was applied to fit the isothermal and kinetic models. The results showed that the clay is composed of kaolinite and quartz and the SEM confirmed the successful incorporation of sodium alginate into the clay. The adsorption process follows the Langmuir isotherm with a maximum adsorption capacity of 48.24 and 92.44 mg.g−1 for the clay (CH) and the beads composite designated as (CH@AL), respectively. Pseudo-second-order model best described the kinetic data. Moreover, the thermodynamics of the adsorption was spontaneous and endothermic. All of these results proved that the used adsorbents are eco-friendly and efficient for the adsorption of Cu(II) ions.

Grinding Behaviour of Microwave-Irradiated Mining Waste

The combined microwave-assisted sorting and microwave-assisted comminution of minerals has been proposed to reduce the huge grinding energy consumption in mineral processing. However, gangue minerals would be discarded after the sorting process despite the microwave energy absorbed during their treatment. Therefore, this paper investigates the effect of microwave pretreatment on the Bond work index (BWI) of quartz and calcite samples, as they represent the dominant gangues in many ores and are key inputs in the cement industry, which requires intensive grinding. The samples were characterized using a scanning electron microscope coupled with energy dispersive X-ray (SEM-EDX), and Fourier transform infrared (FTIR) and X-ray diffraction (XRD) methods. The BWIs of the two samples were determined before and after the microwave treatment (2.45 GHz, 1.7 kW) at 2, 4 and 6 minutes. SEM image analyses of the untreated and microwave-treated samples were performed using ImageJ software. The results showed that after 4 minutes of radiation treatment, the BWI of the studied quartz was reduced by 13.83%, while that of the calcite increased by 15.59%. The results of the SEM image analysis indicated that the quartz developed more cracks than the calcite under the same microwave treatment conditions. Based on these findings, microwave pretreatment is suitable to reduce the grinding energy of the studied quartz, but offers no energy-saving benefit to the studied calcite.

Responses of Moringa oleifera to alteration in soil properties induced by calcium nanoparticles (CaNPs) on mineral absorption, physiological indices and photosynthetic indicators

BackgroundThe application of nanofertilisers in agriculture has been widely utilised due to their distinct characteristics and negative impacts of conventional chemical fertilisers. This study thus examined the influence of calcium nanoparticles (CaNPs) on soil composition vis-à-vis performance parameters in Moringa oleifera L exposed to water, 100 mg Ca(NO3)2kg−1 soil and 100, 75 and 50 mg CaNPs kg−1 soil. Soil morphology was determined with a scanning electron microscope coupled with energy dispersive x-ray (SEM-EDX) and elemental composition in both soils and M. oleifera roots determined with inductively coupled plasma-optical emission spectrometer (ICP-OES).ResultsThe CaNP-amended soils were more crystalline, more fertile and had reduced salinity. An increase in immobilisation percentage of heavy metals, improvement in physiological parameters (percentage germination, vigour indices, relative water contents, lengths of roots and shoots) and photosynthetic efficiency in M. oleifera were recorded.ConclusionThis study has demonstrated that CaNPs could improve soil composition for better plant performance and can act as nanofertilisers mobilising essential nutrients.Graphical abstract

Chemical and Mineralogical Characterization of Saudi-Pyrophyllite ore and its Potential Applications

Purpose: Due to the importance of pyrophyllite as an economical alternative to several minerals such as kaolin, talc, and feldspar in different industrial applications, there is an intention in Saudi Arabia to exploit pyrophyllite in the industry. Since there were no sufficient studies conducted to characterize pyrophyllite in Saudi Arabia, this paper aims to study the chemical and mineralogical characterization of Saudi pyrophyllite ore grades and propose its potential applications besides proposing beneficiation strategies for the low-grade one. Method: In this study, two different grades pyrophyllite ore samples, from a pyrophyllite deposit in western Saudi Arabia, were characterized for their potential applications. Microscopic studies, X-ray fluorescence (XRF), scanning electron microscope coupled with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD) were used for chemical and mineralogical characterization of the studied samples. Results: Microscope and XRD results have shown that the ore samples (labeled grade A and grade B) consist mainly of pyrophyllite associated with quartz and feldspar in addition to minor amounts of muscovite, chlorite, and siderite as impurity minerals. Moreover, the results indicated that the impurities are oxide and sulfide minerals (i.e., pyrite, hematite). According to XRF analysis results, grade A contains high alumina (27.03% Al2O3) and low iron (0.4% Fe2O3) whereas; grade B contains a high iron content (2.06% Fe2O3) and lower alumina (24.05 % Al2O2). It is predicted that the grade A with high alumina content can be used directly in fillers, refractories, fiberglass, whiteware ceramics, white cement, porcelain, and cosmetic applications. As for grade B, high iron content limits its industrial applications. Therefore, it needs to be treated to remove ferrous impurities before supply to pyrophyllite market. Conclusion: Based on analytical results, grade A with high alumina content can be used directly in fillers, refractories, fiberglass, whiteware ceramics, white cement, porcelain, and cosmetic applications. Furthermore, grade B needs to upgrade due to high iron content before being used in the industry.

Evaluation of high-temperature pyrolysis and CO2 gasification performance of bituminous coal in an entrained flow gasifier

This study used an entrained flow gasifier to assess the pyrolysis and gasification performance of Bangladeshi Barapukurian bituminous coal. The pyrolysis and CO2 gasification were conducted at temperatures of 1000°C–1400 °C under atmospheric pressure. The carbon conversion, syngas yield and pollutant emissions of coal using two different particle size of 90–106 and 250–300 μm have been analysed under CO2 concentration of 10–80 vol%. Solid residue (char/ash) was analysed by using scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX) and X-ray diffraction (XRD) methods. Results show that the release of volatile matter increases up to the temperature of 1200 °C. However, the temperature needs to increase at 1400 °C for the complete carbon conversion. Based on the CO/H2 ratio, syngas conditioning is required while using a temperature of 1200 °C or above, especially over the stoichiometric CO2 concentrations. Considering the heating value of syngas for power generation, the use of CO2 should be limited to less than 20% at a temperature of 1200–1400 °C. Particle size is important for carbon conversion but there is no significant impact on the heating value of syngas. Installation of the syngas cleaning system is required to drop the pollutants emission from the ppmv range to the ppbv range.

Evaluation of anaerobic membrane bioreactor (AnMBR) treating confectionery wastewater at long-term operation under different organic loading rates: Performance and membrane fouling

An anaerobic membrane bioreactor (AnMBR) system treating confectionery wastewater was operated for 247 days at various organic loading rates (OLRs) of 1.1, 2.2, 4.4, 6.6 and 7.9 kg COD m−3 d−1 to determine sustainable OLR. In this study, up to 99% COD removal efficiency was obtained at all OLRs, and the maximum methane production of 0.26 m3 kg−1 CODremoved was achieved at OLR 7.9 kg COD m−3 d−1. Next Generation Sequencing (NGS) analysis showed that the dominance of hydrogenotrophic methanogens shifted to acetoclastic methanogens after OLR value of 4.4 kg COD m−3 d−1, which caused a decrease in the biogas methane composition. The increase in OLR, negatively affected the membrane filtration performance. After OLR value of 4.4 kg COD m−3 d−1, TMP, filtration resistance and EPS/SMP production increased sharply. These results indicated that the AnMBR system could be efficiently operated efficiently at OLR 4.4 kg COD m−3 d−1. Membrane fouling mechanism was evaluated using Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX), and contact angle measurements after 247 days of operation. The results demonstrated that the membrane fouling mechanism can be attributed to cake layer formation which mainly consisted of protein and carbohydrate. In this study, the efficient treatment of confectionery wastewater showed that the AnMBR system could be applied to high-strength organic wastewater such as industries of beverage, beer, dairy, and sugar product. Filtration performance should be enhanced with further investigations.

Oxidation of chalcopyrite in air-equilibrated acidic solution: Inhibition with phenacyl derivatives

Abstract The effects of 4-(2-hydroxyphenyl)-2-(morpholin-4-yl)-1,3-thiazole (Pr02), 1-(3,5-dibromo-2-hydroxyphenyl)- 1-oxoethan-2-yl-N,N-diethyldithiocarbamate (Pr04) and 1-(5-bromo-2-hydroxy-3-methylphenyl)-1-oxoethan-2-yl-O- ethyl xanthate (Pr06) on the aqueous oxidation of chalcopyrite (CuFeS2) in air-equilibrated solution at a temperature of 25 °C and a pH of 2.5 were studied. The effects were investigated by using potentiodynamic polarization, electro- chemical impedance spectroscopy (EIS), scanning electron microscopy coupled with energy dispersive X-ray (SEM/EDX) analysis, aqueous batch experiments, Fourier transform infrared (FTIR) spectroscopy, Raman scattering and quantum chemical calculations. It is found that the anodic current densities decrease in the order of EtOH > Pr02 > Pr04 > Pr06. These results, along with those of the EIS measurements, show that Pr02, Pr04 and Pr06 are effective anodic inhibitors of chalcopyrite aqueous oxidation. Both Raman scattering and FTIR spectroscopy indicate that the elemental sulfur, polysulfide and ferric oxyhydroxides that form on the surface of the mineral are not responsible when it comes to the aqueous oxidation inhibition of chalcopyrite. Quantum chemical calculations show that the adsorption of the tested compounds on the chalcopyrite surface is energetically favorable and so, it can explain the inhibiting effects that were observed.

Hydroquinone-Based Fabrication of Gold Nanorods with a High Aspect Ratio and LSPR Greater than 850 nm to Be Used as a Surface Plasmon Resonance Platform for Rapid Detection of Thiophanate Methyl

The use of gold nanorods (AuNRs) as surface-enhanced Raman scattering (SERS) substrates has gained much attraction due to their remarkably aspect-ratio-dependent plasmonic properties. In this report, we described the development of AuNRs with a high aspect ratio and longitudinal surface plasmon resonance (LSPR) >850 nm through a hydroquinone-based fabrication with minor modifications. The synthesis started with the reduction of chloroauric acid (HAuCl4) by sodium borohydride (NaBH4) to make gold nanoseeds from which AuNRs were grown with the aid of silver nitrate (AgNO3), HAuCl4, cetyltrimethylammonium bromide (CTAB), and hydroquinone (HQ). Scanning electron microscopy coupled with energy-dispersive X-ray (SEM-EDX), Transmission electron microscope (TEM), X-ray diffraction (XRD) and Ultra-violet-Visible spectroscopy (UV-Vis) were performed to study the shape, size, and structural and optical properties of AuNRs, respectively. The results showed that AuNRs with high aspect ratios (AR > 3) were single crystals with a heterogenous size distribution, and that the growth of Au nanoseeds into AuNRs took place along the [001] direction. AuNRs exhibited two plasmon resonance peaks at 520 nm and 903 nm, while gold nanoseeds had only a plasmon resonance peak at 521 nm. The as-synthesized AuNRs also showed SERS effects for thiophanate methyl, a broad-spectrum fungicide, with the limit of detection down to 5 mg/L of the fungicide. AuNR-coated glass can serve as a SERS-based sensing platform for rapid detection of thiophanate methyl with high sensitivity and reproducibility.

Synthesis of iron modified sugarcane bagasse activated carbon for oxidation degradation of malachite green

Iron (II, III) oxide (Fe3O4), activated carbon (AC) and Fe3O4/AC composites at various weight ratios (1:1, 3:1 and 1:3) were synthesised successfully using chemical impregnation method. The synthesised composite samples were then analysed by using scanning electron microscope coupled with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR). Heterogeneous photo Fenton and Fenton-like processes were applied in degrading malachite green. Fe3O4/AC composite samples showed higher catalytic activity as compared to pure Fe3O4 and AC. The composite of Fe3O4/AC at weight ratio of 1:1 (FeAC11) was determined to be the optimal mixing weight ratio as it possessed the highest heterogeneous photo Fenton and Fenton-like degradation efficiency of malachite green. The highest degradation efficiency of malachite green was achieved at initial dye concentration of 30 ppm, FeAC11 dosage of 0.8 g/L, solution pH of 5, 4 mM of H2O2 with the degradation efficiency of 89.22 % after 3 min. The composite sample FeAC11 depicted high stability as only little amount of leached iron (about 4 mg/L) was detected by inductively coupled plasma optical emission spectrometry (ICP-OES). Pseudo second-order kinetic was best fitted to the reaction kinetic of heterogeneous photo Fenton and Fenton-like on the degradation of malachite green at different solution pH.