Total Organic Carbon Analysis Research Articles

A novel approach to measure carbonate alkalinity in aqueous solutions using a total organic carbon analyzer

Carbonate alkalinity is crucial in regulating the pH and buffering capacity of natural water systems. Thus, its accurate measurement is essential to understand various water environments that affect water quality and ecosystem health. However, conventional potentiometric titration has some limitations. It results in inaccurate measurements of carbonate alkalinity when the alkalinity levels are low or when high dissolved organic matter or inorganic ion levels exist. Herein, we propose a novel approach to accurately measure carbonate alkalinity using a total organic carbon (TOC) analyzer. An extensive study comparing the accuracy and reliability of the conventional potentiometric titration method with those of the newly developed TOC method was conducted to develop and verify highly accurate measurements of carbonate alkalinity. The TOC method has several advantages over the conventional potentiometric titration methods, such as its ability to accurately measure carbonate alkalinity in the presence of high dissolved organic matter or inorganic ion levels and its ability to provide rapid and automated measurements with high reproducibility. Because, the limit of detection, limit of quantification, and the variation coefficient of the measurements was 0.016 mM (0.2 mgC/L), 0.050 mM (0.6 mgC/L), and 3.68 % respectively. Thus, the development of a novel TOC method has significant environmental implications as it provides a reliable and accurate means to measure carbonate alkalinity in solutions containing various organic matter types.

Emission of water soluble brown carbon from different combustion sources: optical properties and functional group characterisation

Brown carbon (BrC) has a large impact on the Earth’s radiative balance. This study examined BrC’s optical characteristics, chemical functional groups, and total organic carbon (TOC) in deposited particulate matter from combustion of biomass, fossil fuels, and mosquito coil. A UV–vis spectrophotometer was used to assess BrC’s optical properties, a TOC analyzer was used to quantify TOC, and attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR) was used to identify functional group. The light absorption properties (absorption coefficient (babs-BrC), mass absorption efficiency (MAE365), absorption angstrom exponent (AAE), and refractive index (kabs-BrC)) were determined. Among biomasses, wheat straw exhibited the greatest value of babs-BrC (27.26 × 103 ± 4.09 × 103 Mm−1) whereas maize straw had the lowest value of babs-BrC (7.38 × 103 ± 1.11 × 103 Mm−1). A higher light absorption coefficient at 365 nm suggested that chromophores contributed more to the process. AAE followed this sequence - mosquito coil (5.46 ± 0.82) > biomass (5.13 ± 1.45) > fossil fuels (2.85 ± 0.32). The highest value of MAE365 (0.99 ± 0.15 m2 gC−1) and kabs-BrC (0.028 ± 0.004) was obtained in wheat straw, whereas the lowest value of MAE365 (0.07 ± 0.011 m2 gC−1) and kabs-BrC (0.002) was identified in octane. Biomasses samples showed a strong peak at ∼850, ∼1368, ∼1370, ∼1306, and near 1640 cm−1, indicating that the major component of BrC was organic nitrate R-ONO2 which is responsible to increase the light absorption properties. It also contains complex heterocyclic aromatic ring compounds, carbonyl group (C=O), and nitrogen-containing groups such as −NO 2, C≡N. The projected substantial contribution of BrC to overall light absorption is one illustration of the probable climatic effect of biomasses and fossil fuel burning in Southeast Asian region.

Development of a new CoS-Supported ZnAl2O4 catalyst for the visible photodegradation of a basic textile dye from water

The material is proven competitive for the solar treatment of wastewater from the textile industry -an essential source of water pollution worldwide. The system was prepared following a two-step hydrothermal method, showing photon absorption properties across the solar spectrum's UV and visible light regions. The main responsible species driving the photocatalytic process are proposed based on degradation experiments using appropriate scavengers. Further studies include consideration of operational parameters and cycling experiments to evaluate the stability of the catalyst. The results showed complete degradation (100%) based on dye bleaching and >90% mineralization of the dye based on total organic carbon analysis using dye concentrations of 20 ppm and catalyst loading of 1 g/l. Our findings point to sulfide-supported spinel materials as promising candidates for advanced solar oxidation technologies for wastewater treatment.

Effect of Ultraviolet Illumination on the Fixation of Silver Ions on Zinc Oxide Films and Their Photocatalytic Efficiency

This study focuses on the fabrication and characterization of nanostructured zinc oxide films deposited on glass substrates using sol–gel dip-coating methods. The thin films are functionalized with silver ions at various Ag+ concentrations (10−2, 10−3, 10−4 M) through room temperature ion fixation process with and without ultraviolet (UV) illumination. Physicochemical characterization techniques, such as employing Scanning Electron Microscopy with Energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Ultraviolet–Visible Spectroscopy and Electron Paramagnetic Resonance (EPR) techniques. The SEM-EDX and XRD confirmed a characteristic ganglia-like structure with a hexagonal crystalline structure. The photocatalytic performance and available surface area of the pure and Ag films are investigated in the removal of methylene blue dye under UV and visible light illumination and in darkness. It is observed that the photocatalytic activity increases proportionally to the Ag+ ion concentration: ZnO < Ag(10−4 M)/ZnO, < Ag(10−3 M)/ZnO < Ag(10−2 M)/ZnO. Moreover, the catalysts modified under UV illumination during the fixation treatment (Ag-UV/ZnO) exhibited a higher photocatalytic efficiency and degraded the dye in comparison with those without a light source (Ag/ZnO). The experimental results are confirmed using total organic carbon (TOC) analysis. The optimal silver concentration (10−2 M) is established, which shows the highest photocatalytic efficiency (in both cases of ion fixation treatment). The results can be used as a guideline for the development of co-catalyst-functionalized semiconductor photocatalysts.

Synergistic visible light assisted photocatalytic degradation of p-chlorophenol and rifampicin from aqueous solution using a novel g-C3N4 quantum dots incorporated α-MoO3 nanohybrid – Mechanism, pathway and toxicity studies

In this work, a simple g-C3N4 quantum dots enriched MoO3 nanohybrid was formulated for the synergistic photocatalytic degradation of an industrially active organic pollutant, p-chlorophenol (PCP) and a widely prescribed antibiotic, rifampicin (RIF). The nanohybrid was synthesised via a facile ultrasonic assisted hydrothermal method and characterized using various characterization analysis. The efficient Z-scheme charge transfer of the nanohybrid resulted in the elimination of 98% PCP and 89% RIF under visible light with a rate constant of 0.012 and 0.006 min−1 respectively. The photocatalysis was attributed to the formation of both hydroxyl (OH•) and superoxide (O2•-) radicals in the resulting nanohybrid. The intermediates formed in the course of reaction were estimated through gas chromatography-mass spectroscopy/mass spectroscopy (GC-MS/MS) analysis and a suitable degradation pathway was constructed. The structural stability and reusability of the nanohybrid was affirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis to outweigh the industrial potential of the catalyst, with 85% PCP and 80% RIF removal efficiency after six cycles of degradation. In addition, the mineralization of the pollutants was confirmed by total organic carbon analysis. Further, the toxicity of the drug and the formed intermediates was determined using ecological structure activity relationships (ECOSAR) software. On the whole, this work provides an excellent insight for the development of environment-friendly materials in a large scale for the degradation of water-based pollutants.

Butachlor (BTR) degradation by dielectric barrier discharge plasma in soil: Affecting factors, degradation route, and toxicity assessment

Over the past few decades, the frequent and excessive usage of pesticides has had detrimental effects on the soil and other habitats. In terms of removing organic contaminants from soil, non-thermal plasma has become one of the most competitive advanced oxidation methods. The study used dielectric barrier discharge (DBD) plasma to repair soil contaminated by butachlor (BTR). BTR degradation was investigated in actual soil under various experimental parameters. According to the results, DBD plasma treatment at 34.8 W destroyed 96.10% of BTR within 50 min, and this degradation was consistent with the model of first order kinetics. Boosting the discharge power, lowering the initial BTR concentration, using appropriate soil moisture content and air flow rate, and using oxygen as the working gas for discharge are all beneficial to the degradation of BTR. The changes in soil dissolved organic matter (DOM) before and after plasma treatment were assessed using a total organic carbon (TOC) analyzer. A Fourier transform infrared (FTIR) spectroscopy and an Ultra Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS) were employed to investigate the degradation of BTR. A wheat growth test showed that the best growth was achieved at 20 min of plasma soil remediation, but too long treatment would lower soil pH and thus affect wheat growth.

Study on the Effect of Main Chain Molecular Structure on Adsorption, Dispersion, and Hydration of Polycarboxylate Superplasticizers.

Polycarboxylate ether (PCE) with different main chain structures was prepared by aqueous solution free radical polymerization using unsaturated acids containing sulfonic acid groups, acrylamide groups, and carboxyl groups and isoprenyl polyoxyethylene ether (IPEG). The molecular structure was characterized by infrared spectroscopy and gel chromatography, while adsorption, dispersion, and hydration properties were studied using a total organic carbon analyzer, rheometer, and isothermal microcalorimeter, respectively. The results show that the adsorption process of PCE on cement particles is spontaneous physical adsorption. The adsorption forces are mainly electrostatic interaction, and hydrogen bonding. The introduction of sulfonic acid groups and polycarboxylic acid groups reduces the initial adsorption amount of PCE but can accelerate the adsorption rate of PCE on cement and increase the adsorption amount at the adsorption equilibrium. The introduction of acrylamide groups in the PCE main chain is beneficial to the initial dispersion of PCE and can reduce the plastic viscosity of cement slurry. PCE can delay the hydration of cement. The introduction of acrylamide groups and dicarboxylic acid groups in the PCE main chain helps prolong the induction period of cement hydration, while the introduction of sulfonic acid groups is not conducive to its retarding effect.

Methotrexate degradation in artificial wastewater using non-thermal pencil plasma jet.

The rising global cancer rate is driving up the consumption of anticancer drugs. This causing a noticeable increase in the levels of these drugs in wastewater. The drugs are not metabolized effectively by the human body, leading to their presence in human waste, as well as in the effluent from hospitals and drug manufacturing industries. Methotrexate is a commonly used drug for treating various types of cancer. Its complex organic structure makes it difficult to degrade using conventional methods. The present work proposed a non-thermal pencil plasma jet treatment for methotrexate degradation. The air plasma produced in this jet setup is electrical characterized and plasma species/radicals are identified using emission spectroscopy. The degradation of drug is monitored by studying the change in solution physiochemical properties, HPLC-UV analysis, and removal of total organic carbon, etc.Results show that a 9-min plasma treatment completely degraded the drug solution that followed first-order degradation kinetics with rate constant 0.38 min-1 and 84.54% mineralization was observed. Additionally, an increase in electrical conductivity and dissolved solids compared to virgin water-plasma interaction indicated the formation of new, smaller compounds (2,4-Diaminopteridine-6-carboxylic acid, N-(4-Aminobenzoyl)-L-glutamic acid, etc.) after drug degradation. The plasma-treated methotrexate solution also showed lower toxicity toward freshwater chlorella algae compared to the untreated solution. Finally, it can be said that non-thermal plasma jets are economically and environmentally friendly devices that have the potential to be used for the treatment of complex and resistive anticancer drug-polluted wastewaters.

Colloidal and solid phase partitioning between ferrihydrite, humic acid and copper coprecipitates

Our understanding of the interactions between Fe oxides, humic acids (C), and Cu precipitation products in the environment are limited by our ability to measure specific forms and chemical interactions. Here, we examine the effect of solution pH, Fe:C molar ratio from 1:0 to 1:3, and Cu concentration on dissolved and colloidal Cu concentrations after sorption (SOR) or coprecipitation (CPT) reactions. This included specifically measuring the colloidal phases formed using asymmetrical flow field flow fractionation coupled to a total organic carbon analyzer and an inductively coupled plasma mass spectrometer. In the case of 1:0 Fe:C reactions, more Cu was associated with bulk solids and colloidal solids in CPT reaction products, particularly at pH 5 and 6. As C content increased, precipitation reactions led to more Cu retained in the bulk solid phase at lower pH, but more in the dissolved and colloidal phase at higher pH. Of the colloids formed at pH 7, about 10% of the dissolved Cu is present as Fe–C–Cu ternary phases, with the remainder as Cu–C or inorganic Cu phases, yet at pH 6, only Fe–Cu colloids were observed. Applying an additivity approach while using a NICA-Donnan C complexation model combined with a ferrihydrite surface complexation model, the model often predicts higher than observed dissolved Cu in CPT reactions with no C present, but lower than observed dissolved Cu with C present. In applying the model specifically to colloidal phases, much lower concentrations of colloid bound Cu is predicted than observed in the 1:0 Fe:C scenario, but as C content increases, more colloidal Cu is predicted than observed. Given the availability and lability of Cu in environmental systems is assumed to correspond to dissolved Cu, this work notes some differences in the dissolved and colloidal phases formed in different contexts.

Geochemical characteristics of coal measure source rocks of Upper Carboniferous Benxi Formation in Daning-Jixian area, eastern margin of Ordos Basin

The Carboniferous-Permian in Daning-Jixian area of Ordos Basin is a typical marine-continental transitional facies deposit, with many sets of organic-rich shales, and abundant shale gas resources. Through unremitting exploration, the shale gas exploration of Shanxi Formation has achieved a major breakthrough, but the related research of Benxi Formation remains to be further studied. Therefore, based on the test and analysis of total organic carbon (TOC) content, rock pyrolysis, kerogen stable carbon isotope (δ13CPDB) and vitrinite reflectance (Ro), this paper systematically discusses the geochemical characteristics and hydrocarbon generation potential of Benxi Formation coal-bearing source rocks, in order to grasp their exploration prospect. The results show that the shale of Benxi Formation has high TOC content (averaging 5.13%) and high Ro (averaging 2.75%), showing good hydrocarbon generation potential. In addition, shale, coal and sandstone are interbedded and superimposed, which can realize the combined production of three gases, improve the yield and benefit, and further promote the exploration process of marine-continental transitional shale gas.

Polymer elution and hydraulic conductivity of polymer-bentonite geosynthetic clay liners to bauxite liquors

This study investigated the influences of polymer types (Super Absorbent Polymer, SAP and Polyanionic Cellulose, PAC), preparation methods (dry-mixed, dry-sprinkled, or wet-mixed), initial polymer loadings (1.0%, 2.5%, 5.0%, 10.0%, and 15.0%), and bauxite liquors (synthetic bauxite liquor, BLS and actual bauxite liquor, BLA) on the polymer elution and the hydraulic conductivity of polymer-bentonite geosynthetic clay liners (PB GCLs). Hydraulic conductivity, total organic carbon analysis, viscosity, scanning electron microscopy, Fourier transforms infrared spectroscopy, and X-ray diffraction tests were combined to investigate the mechanisms controlling the polymer elution and hydraulic conductivity of PB GCLs. The results demonstrated that PB GCLs with high initial polymer loading (10.0%, 15.0%) or prepared using the dry-sprinkled method had low hydraulic conductivities (< 1.0 × 10−10 m/s) and polymer eluting rates (< 10.0 mg/d). PAC-enhanced GCLs had a higher polymer eluting rate than SAP-enhanced GCLs due to the complete water solubility of linear polymer (PAC). When PB GCLs were permeated by BLS (higher ionic strength than BLA), polymer hydrogels had lower viscosity because of coiled or contracted conformation, resulting in a higher polymer eluting rate (> 50.0 mg/d) and hydraulic conductivity (> 1.0 × 10−11 m/s).

Particle-based nutrients and metal contaminants in the habitat of Unionidae mussels in the Tisza River (Hungary)

Introduction:Unioniade is a species-rich family of freshwater mussels with an almost worldwide distribution. In Central European rivers Unio crassus, Unio tumidus and Unio pictorum have relatively high populations. In order to characterize the habitats of these suspension feeders, their nutrient supply and potential metal contaminants were investigated in near-bottom suspended (NBS) sediments and bottom sediments (BS) collected at four sampling locations along the Tisza River.Methods: The grain size distribution of sediments was determined by laser-diffraction technique. The total organic carbon (TOC) and the total Kjeldahl nitrogen (TN) were measured by a TOC analyzer and automated colorimetry, respectively. The phosphorous and metal concentrations were determined by inductively coupled plasma mass spectrometry following a microwave assisted acidic extraction of sediments with aqua regia.Results: The NBS sediments contained smaller grains than the BS samples, with roughly 85%–90% of the particles being less than 60 μm, allowing these mussels to catch them. Contrarily, only 2.47%–51.8% of BS samples were less than 60 μm. The NBS sediments contained 30, 23, and 15% more organic carbon, nitrogen, and phosphorous, respectively, than the BS samples. The rounded C:N:P molar ratios in the NBS sediments were 60:4:1, whereas they were 45:3:1 in the bottom sediments. The concentration of metals was also greater in the NBS sediments with the exception of Zn at Tokaj and Fe, Al, Mn, and Cr at Szeged, where prior contaminations transported by the tributaries Bodrog and Maros are stored in the top 10 cm of BS.Discussion: On basis of the measured C:N:P molar ratios it can be stated that soil-derived organic materials are the main sources of the nutrient elements in the habitats of suspension feeders in the Tisza River. The finer NBS sediments have higher specific surface area than the BS and thereby contain more biofilms on the grains resulting in higher proportion of organic nutrients and metal ions bounded as complexes or chelates. Comparing the measured metal concentrations of sediments with the concentration limits summarized in the Consensus-Based Sediment Quality Guidelines developed for evaluation of potential risk of metal contaminants in sediments for the benthic-dwelling organisms, it can be established that only the Hg concentration exceeded the probable effect concentration.

TiO2 P25 and Kronos vlp 7000 materials activated by simulated solar light for atrazine degradation

Abstract Photocatalysis-based technologies have been proposed for the treatment of wastewater containing atrazine (ATZ), a persistent and recalcitrant pollutant. This study aims to evaluate and compare the efficiency of TiO2 P25 and TiO2 modified with carbon (C–TiO2 Kronos vlp 7000) in the photocatalytic degradation of ATZ in aqueous systems. The experiments were performed in a tubular photochemical reactor equipped with a compound parabolic collector (CPC) irradiated by simulated solar light. The materials were characterized by X-ray diffraction, infrared spectroscopy, BET specific surface area, and diffuse reflectance spectroscopy. For TiO2 P25, ATZ removals varied in the range 86–100 % after 120 min of irradiation, although the total organic carbon (TOC) analyses indicated that no significant ATZ mineralization occurred (&lt;20 %). C–TiO2 Kronos vlp 7000, on the other hand, was not able to completely remove ATZ after 120 min of irradiation. In this case, pesticide removals were 37–45 % over 120 min, while C–TiO2 performed better with regard to ATZ mineralization, with 38 % TOC removal. Given the low mineralization of atrazine, the intermediate compounds formed were identified for each photocatalytic material.

Terrestrial carbon isotope stratigraphy of the Eocene–Oligocene transition, Petrockstowe and Bovey basins, Devon, UK

The terrestrial sediments of the Petrockstowe and Bovey basins in Devon, UK were examined. Their age is considered to be Eocene and Oligocene. The sediments (kaolinitic clays, silts, sands, gravels, and lignites) from both basins were analysed for carbon isotopes of organic material, in conjunction with total organic carbon and palynological analyses used to unravel the type of and provenance of organic matter present. Within the Petrockstowe Basin, the lowermost interval examined shows a palynological distribution dominated by phytoclasts, whilst the upper part of the core is dominated by higher concentrations of palynomorphs (up to 90 %) and an increase in amorphous organic matter consistent (up to 37 %) with a change from sand-filled fluvial channels followed by an ephemeral lake or lake margin setting. Our palynological data from the South John Acres Lane Quarry section, Bovey Basin, show that within the lignites palynomorphs are high again (up to 95 %) consistent with them representing more ephemeral lakes or lake margins periodically exposed with mires. Our palynological data set further allows us to determine that isotope trends are not overly determined by the source of carbon in the basins. Our study suggests that the observed patterns were primarily produced by variations of the isotope ratios of terrestrial atmospheric carbon reservoirs. Even with our less than well constrained biostratigraphical control, the data indicate that the carbon isotope excursions seen in the Eocene and Oligocene could be associated with several transient carbon isotopic shifts (associated with the Paleocene–Eocene Thermal Maximum). Our findings therefore appear to lend support to the surface ocean and atmosphere behaving as coupled reservoirs at this time.

Structural and performance variation of PES/PVDF membranes after exposure to the pretreated feed water of CECs

In this study, the removal efficiency of chemicals of emerging concerns (CECs) was evaluated under exposure to various doses of UV/H2O2-based oxidation processes in combination with membrane filtration for three cleaning cycles. Polyethersulphone (PES) and polyvinylidene fluoride (PVDF) materials based membranes were used for this study. The chemical cleaning of the membranes was performed by immersion of the membranes into 1 N HCl followed by adding 3000 mg.L−1 NaOCl for 1hr. Degradation and filtration performance was evaluated using Liquid Chromatography with tandem mass spectrometry (LC-MS/MS) and total organic carbon (TOC) analysis. Membrane fouling analysis for assessing the comparative performance of PES and PVDF membranes was determined by specific fouling and fouling indices evaluation. Membrane characterization results show that the alkynes and carbonyl group formation are due to dehydrofluorination and oxidation of PVDF and PES membranes under the attack of foulants and cleaning chemicals, which resulted in a reduction of fluoride percentage and an increase in sulfur percentage in the PVDF and PES membranes. A decrease in the hydrophilicity of the membranes in underexposed conditions was observed and is consistent with an increase in dose. Degradation results of CECs follow with the highest removal efficiency of chlortetracycline (CTC) followed by atenolol (ATL), acetaminophen (ACT), and caffeine (CAF) degradation due to attack on the aromatic ring and the carbonyl group of CECs by OH exposure. Membrane exposed at 3 mg.L-1 dose of UV/H2O2-based CECs shows minimum alteration with higher filtration efficiency and lower fouling, particularly in PES membranes.

Study on Dispersion, Adsorption, and Hydration Effects of Polycarboxylate Superplasticizers with Different Side Chain Structures in Reference Cement and Belite Cement.

To investigate the effects of Reference cement (RC) and Belite cement (LC) systems, different molecular structures of polycarboxylate ether (PCE) were prepared through the free radical polymerization reaction and designated as PC-1 and PC-2. The PCE was characterized and tested using a particle charge detector, gel permeation chromatography, a rotational rheometer, a total organic carbon analyzer, and scanning electron microscopy. The results showed that compared to PC-2, PC-1 exhibited higher charge density and better molecular structure extension, with smaller side-chain molecular weight and molecular volume. PC-1 demonstrated enhanced adsorption capacity in cement, improved initial dispersibility of cement slurry, and a reduction in slurry yield stress of more than 27.8%. LC, with its higher C2S content and smaller specific surface area compared to RC, could decrease the formation of flocculated structures, resulting in a reduction in slurry yield stress of over 57.5% and displaying favorable fluidity in cement slurry. PC-1 had a greater retarding effect on the hydration induction period of cement compared to PC-2. RC, which had a higher C3S content, could adsorb more PCE, leading to a greater retarding effect on the hydration induction period compared to LC. LC and PC-2, on the other hand, exhibited inhibition during the hydration acceleration period. The addition of PCE with different structures did not significantly affect the morphology of hydration products in the later stage, which was consistent with the trend of KD variation. This indicates that the analysis of hydration kinetics can better reflect the final hydration morphology.

Fabrication and Evaluation of a Total Organic Carbon Analyzer Using Photocatalysis

Fabrication and Evaluation of a Total Organic Carbon Analyzer Using Photocatalysis

Upper maastrichtian palynology and paleoenvironment of the Urucutuca Formation, Almada basin (BA), Brazil

Hydrocarbon exploration involving the Urucutuca Formation is taking place in several basins located mainly in the central segment of the eastern Brazilian margin, including the Almada Basin. Relatively rich accumulations of organic material and promising prospects, especially for gas, have been discovered. The Brazilian National Petroleum Agency (ANP) considers the Urucutuca Formation as a speculative play exploratory (Urucutuca-Urucutuca) in deep and ultra-deep areas of the Almada Basin, including others.The focus was on improving the understanding of the sediments of the Urucutuca Formation and establishing a palynostratigraphic outline for the upper cretaceous strata, which still need to be updated. Therefore, integrated palynological, palynofaciological, and organic-geochemical (total organic carbon -TOC) investigation methods were carried out. For this purpose, 250 m of well 1-SST-01, drilled in the onshore part of the Almada Basin in Bahia State, were analyzed using 26 core samples along the Urucutuca Formation.By typifying palynofaciological variations based on organic matter content in conjunction with palynological and geochemical data, it was possible to distinguish three palynofacies with different characteristics of the marine influence environment. Palynofacies 1, the amorphous organic matter (AOM) group, predominates with proportions up to 54.1 and a TOC of 0.75%. The high phytoclasts percentage (70%) and a TOC content of 1% characterize the Palynofacies 2. Palynofacies 3, on the other hand, has the highest content of marine palynomorphs (40%).The analysis of total organic carbon yielded values ranging from 0.04% to 1.85%, which were heterogeneously distributed throughout the borehole.The palynological succession showed a dominance of representatives of continental origin. However, marine elements (dinoflagellates and microforaminiferal inner tests) are present throughout the section.Two expressive occurrences of dinoflagellate cysts are evident throughout the section. In the basal and middle portions, quantity and diversity suggest transgressive events or at least sea-level fluctuations. Biostratigraphically, the unit could be placed in the Tricornites elongatus (P-470) Biozone of the Crassitricolporites brasiliensis (P-450) Superzone and assigned to the Eomaastrichtian. These biostratigraphic units are consistent with the proposed zonation for other basins of the Brazilian Atlantic margin.Palynofacies and palynological data allowed the observation of variations in a predominantly platform paleoenvironment, sometimes distal and sometimes more proximal, with possible transgressions.

Mineralogy and phase transition mechanisms of atmospheric mineral particles: Migration paths, sources, and volatile organic compounds

Inorganic mineral particles play an important role in the formation of atmospheric aerosols in the Sichuan Basin. Atmospheric haze formation is accompanied by the phase transition of mineral particles under high humidity and stable climatic conditions. Backward trajectory analysis was used in this study to determine the migration trajectory of atmospheric mineral particles. Furthermore, Positive matrix factorization (PMF) was used to analyze the sources of atmospheric mineral particles. The phase transition mechanisms of atmospheric mineral particles were studied using ion chromatography, inductively coupled plasma emission spectrometry, total organic carbon analysis, X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy coupled with energy dispersive spectrometry, and grand canonical Monte Carlo methods. Three migration and phase transition paths were identified for the mineral particles. Sources of atmospheric mineral particles included combustion, vehicle emissions, industrial emissions, agricultural sources, and mineral dust. The main mineral phases in atmospheric particles, calcite and dolomite, were transformed into gypsum, and muscovite may be transformed into kaolinite. The phase transition of mineral particles seriously affects the formation of aerosols and worsens haze. Typically, along the Nanchong-Suining-Neijiang-Zigong-Yibin path, calcite is converted into gypsum under the influence of man-made inorganic pollution gases, which worsen the haze conditions and cause slight air pollution for 3–5 days. However, along the Guangyuan-Mianyang-Deyang-Chengdu-Meishan-Ya'an path, anthropogenic volatile organic compounds (VOCs) hindered gypsum formation from dolomite. Furthermore, dolomite and VOCs formed stable adsorption systems (system energies from −0.41 to −4.76 eV, long bonds from 0.20 to 0.24 nm). The adsorption system of dolomite and m/p-xylene, with low system energy (−1.46 eV/−1.33 eV) and significant correlation (r2 = 0.991, p < 0.01), was the main cause of haze formation. Consequently, calcite gypsification and dolomite–-VOC synergism exacerbated regional haze conditions. This study provides a theoretical reference for the mechanism of aerosol formation in basin climates.

Photocatalytic degradation of aqueous methylene blue using ca-alginate supported ZnO nanoparticles: point of zero charge role in adsorption and photodegradation.

A novel insoluble Ca-Alginate created from soluble Na-Alginate was used as a support substrate for ZnO nanoparticles producing ZnO@Ca-Alginate composite photocatalyst. Fourier Transform Infrared (FT-IR), Ultraviolet-Visible (UV-Vis), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), and X-ray Diffraction (XRD) analysis techniques were used in the characterization of the prepared ZnO@Ca-Alginate. The ZnO@Ca-Alginate was tested for its potential use in the photodegradation of Methylene Blue (MB) from an aqueous solution under solar-simulated light. This composite photocatalyst efficiency in MB removal was compared with naked ZnO potential considering different conditions and parameters (e.g. pH, MB concentration, amount of photocatalyst, and irradiation time). The MB concentrations were identified using UV-vis spectrophotometric methods. While, high-performance liquid chromatography (HPLC), Total organic carbon (TOC) analysis, and other elemental analyses were used to confirm the MB complete mineralization. The MB photodegradation results were performed by using UV-vis analysis., the results showed that up to 95% of MB (40 mL, 40 ppm) was removed within 30 min of irradiation using either ZnO@Ca-Alginate or naked ZnO. The pH and the zero-charge point (Pzc) values play a main role in the adsorption and photodegradation results. The Pzc values for Ca-Alginate, ZnO, and Zn@Ca-Alginate were 6.5, 8.8, and 6.8 respectively. The prepared composite catalyst showed a maximum adsorption and photodegradation in a basic to slightly basic medium, the MB completely removed at pH of 7.7 within an hour of irradiation. The complete miniralzation of MB at the end of the photodegrdation process was confirmed. Here it is proved that the ZnO@Ca-Alginate photocatalyst can be recovered and reused without any significant decrease in its effectiveness.