Total Organic Carbon Measurements Research Articles

Visible light assisted photocatalytic degradation of Indigo Carmine dye and NO2 removal by Fe doped TiO2 nanoparticles

A simple sol-gel method was employed to synthesize Fe doped TiO2 nanoparticles with a controlled mole percentage of Fe. Synthesized nanoparticles were characterized by several standard analytical techniques. X-ray diffraction patterns (XRD) of pure and Fe doped TiO2 nanoparticles confirm the anatase phase, which is further confirmed by Raman analysis. The change in the morphology and structural modification of the material by doping concentration of Fe in TiO2 is confirmed by Scanning Electron Microscopic (SEM) images and FTIR study respectively. The size and shape of nanoparticles were determined by High-Resolution Transmission Electron Microscopy (HRTEM). The energy bandgap and recombination rate of charge carriers were studied by Optical absorption and Photoluminescence (PL) measurements respectively. Photocatalytic activity of the prepared nanoparticles was investigated through degradation of Indigo Carmine (IC) dye under visible light illumination. Total Organic Carbon (TOC) measurement was done to determine the degree of mineralization of IC-dye on photodegradation. In addition, the Photocatalytic performance of FeT_2 photocatalyst for nitrogen dioxide gas (NO2) removal was evaluated under visible light irradiation and found to be very effective for NO2 removal.

Aqueous chemical bleaching of 4-nitrophenol brown carbon by hydroxyl radicals; products, mechanism, and light absorption

Abstract. The reaction of hydroxyl radicals (OH) with 4-nitrophenol (4NP) in an aqueous solution was investigated at pH = 2 and 9. The molar yield of the phenolic products quantified was ca. 0.2 at pH = 2 and 0.4 at pH = 9. The yield of 4-nitrocatechol (4NC) was higher at pH = 9. At the same time, a lower number of phenolic products was observed at pH = 9 due to irreversible reactions of some phenols formed at pH > 7. Mineralization investigated with a total organic carbon (TOC) analyzer showed that after 4NP was completely consumed, approximately 85 % of the organic carbon remained in the aqueous solution. Moreover, as inferred from the TOC measurements and the molar yields of the phenols formed, 65 % of the organic carbon that remained in the aqueous solution was attributed to the non-aromatic products. The light absorption of the reaction solution between 250 and 600 nm decreased as a result of the OH reaction with 4NP. However, the 4NP solution showed a noticeable resistance to the chemical bleaching reaction investigated due to the formation of light-absorbing by-products. This phenomenon effectively prolongs the timescales of the chemical bleaching of 4NP by OH by a factor of 3–1.5 at pH 2 and 9, respectively. The experimental data acquired indicated that both photolysis and the reaction with OH can be important processes for the removal of light-absorbing organic compounds from cloud water particles containing 4NP.

A New Setup for the Measurement of Total Organic Carbon in Ultrapure Water Systems.

With the increasing demand for ultrapure water in the pharmaceutical and semiconductor industry, the need for precise measuring instruments for those applications is also growing. One critical parameter of water quality is the amount of total organic carbon (TOC). This work presents a system that uses the advantage of the increased oxidation power achieved with UV/O3 advanced oxidation process (AOP) for TOC measurement in combination with a significant miniaturization compared to the state of the art. The miniaturization is achieved by using polymer-electrolyte membrane (PEM) electrolysis cells for ozone generation in combination with UV-LEDs for irradiation of the measuring solution, as both components are significantly smaller than standard equipment. Conductivity measurement after oxidation is the measuring principle and measurements were carried out in the TOC range between 10 and 1000 ppb TOC. The suitability of the system for TOC measurement is demonstrated using the oxidation by ozonation combined with UV irradiation of defined concentrations of isopropyl alcohol (IPA).

Deciphering CaO-induced peroxydisulfate activation for destruction of halogenated organic pollutants in a low energy vibrational mill

• CaO-PDS features high reactivity in low energy vibrational mill. • The CaO addition much enhances 2,4-DCP dechlorination and mineralization. • PDS is activated via electron transfer, base activation, and energy transfer. • CaO both activates PDS and transforms SO 4 •− surf to •OH surf. • CaO-PDS enables destruction of persistent halogenated organic pollutants. Mechanochemical (MC) treatment utilizing calcium oxide (CaO) and peroxydisulfate (PDS) for halogenated organic pollutants (HOPs) has been developed for pure substance degradation and contaminated soil remediation. However, the role of CaO and the mechanism of PDS activation in solid phase reaction remain unclear. This study was dedicated to decipher CaO-induced PDS activation for destruction of typical HOPs such as 2,4-dichlorophenol (2,4-DCP), in a low energy single-cylinder horizontal vibrational mill. With mass ratio of CaO:PDS:2,4-DCP = 6.3:6.7:1, CaO-PDS as co-milling agents destructs 2,4-DCP with much higher degradation and dechlorination rate than CaO (about 13.9- and 121.2-fold) or PDS (about 2.5- and 9.4-fold) only. According to detection of intermediates and measurement of total organic carbon, the CaO addition shifts the degradation pathway into dechlorination and ring-open routes, and increase mineralization efficiency from 64% (PDS only) to 96%. Quenching test suggests •OH surf is the dominant oxidative species with CaO-PDS as co-milling agents, which enables complete oxidative destruction. PDS in such MC system is activated mainly via electron transfer (∼50.6%), followed by base activation (∼40.5%) and energy transfer (＜ 8.9%). CaO plays a dual role in activating PDS and transforming SO 4 •− surf to •OH surf . Finally, CaO-PDS shows high reactivity in destructing persistent HOPs like polybrominated phenols and polychlorinated benzenes, which expands its potential in practical application. This study may guide the selection of effective oxidative co-milling agents for mineralization of solid HOPs by mechanochemistry, facilitating safe disposal of obsolete HOPs.

Behavior of matrix parameters and their correlation to micro-pollutant degradation during treatment of real wastewater by carrier-bound photocatalytic ozonation.

Immobilized titanium dioxide catalysts were used within a photocatalytic immersion rotary body reactor, which was connected to a substream ozonation unit to remove micro-pollutants from wastewater. Within this work data on the behavior of cumulative parameters during treatment of wastewater by photocatalysis and photocatalytic ozonation are provided. The investigated parameters are spectral absorption coefficient at 254 nm (SAC254), total organic carbon (TOC) and chemical oxygen demand (COD). All experiments were carried out using secondary effluent from the same wastewater treatment plant. For the parameter SAC254, consistent concentration curves and dependencies to operational parameters of the experimental system could be measured. The measurements of the parameters TOC and COD showed greater uncertainties, although basic trends could nonetheless be observed. A good linear correlation (R2 < 0.85) between the reduction of SAC254 and 8 micro-pollutants for photocatalysis and photocatalytic ozonation was found. This confirms the suitability of the SAC254 as a control parameter for a large-scale application of a photocatalytic 4th treatment stage. A linear correlation between measured TOC and COD degradation rates was possible with a coefficient of determination of 0.58-0.86. The simultaneous decrease of TOC and COD is an indicator for a mineralization of the treated wastewater matrix.

Reversible Adsorption of Polycarboxylates on Silica Fume in High pH, High Ionic Strength Environments for Control of Concrete Fluidity.

Polycarboxylate-based superplasticizers are essential for production of ultrahigh-performance concrete (UHPC), facilitating particle dispersion through electrostatic repulsion and steric hindrance. This study examines for the first time the effect of changes in pH, ionic strength, and charge on the adsorption/desorption behavior of a polycarboxylate-based superplasticizer on silica fume in aqueous chemistries common in low-CO2 UHPC. Data from total organic carbon measurements, Fourier transform infrared and nuclear magnetic resonance spectroscopy, and zeta potential measurements reveal the silica surface chemistry and electrokinetic properties in simulated UHPC. Addition of divalent cations (Ca2+) results in polycarboxylate adsorption on silica fume via (i) adsorption of Ca2+ ions on the silica surface and a negative zeta potential of lower magnitude on the silica surface and (ii) reduction of polycarboxylate anionic charge density due to complexation with Ca2+ ions and counter-ion condensation. Addition of OH– ions results in polycarboxylate desorption via deprotonation of silanol groups and a negative zeta potential of greater magnitude on the silica surface. Simultaneous addition of both Ca2+ and OH– results in rapid polycarboxylate desorption via (i) formation of an electric double layer and negative zeta potential on the silica surface and (ii) an increase in polycarboxylate anionic charge density due to deprotonation of the carboxylate groups in the polymer backbone, complexation with Ca2+ ions, and counter-ion condensation. This provides an explanation for the remarkable fluidizing effect observed upon addition of small amounts (1.0 wt %) of a solid, powdered Ca source to fresh, low-CO2, UHPC, which exhibits significantly higher fresh state pH (>13) than those based on Portland cement (pH 11).

Enhanced separation of base metal sulfides in flotation systems using Chitosan-grafted-Polyacrylamides

• Chitosan-grafted-Polyacrylamide (Chi-g-PAM) was prepared and characterized. • Adsorption studies of Chi-g-PAM on metal sulfide surfaces were conducted. • Chi-g-PAM was tested as pyrite’s depressant in metal sulfide flotation. • Chi-g-PAM outperformed other depressants at producing less pyrite-diluted products. In this study, chitosan-grafted-polyacrylamide (Chi-g-PAM), a synthetic biocompatible polymer was investigated as a selective depressant of iron sulfide minerals [i.e., pyrite (FeS 2 )] in the flotation process of base metal sulfide minerals [i.e., galena (PbS), chalcopyrite (CuFeS 2 ), and sphalerite (ZnS)]. Chi-g-PAM was successfully synthesized by grafting polyacrylamide chains onto chitosan backbone. The synthesized polymer was characterized using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), and X-ray Powder Diffraction (XRD) analysis. Adsorption studies of Chi-g-PAM on mineral surfaces were conducted using zeta potential, contact angle, and total organic carbon (TOC) measurements in addition to X-ray Photoelectron Spectroscopy (XPS). Adsorption tests showed that Chi-g-PAM was most selective to pyrite as compared to the base metal sulfides indicating that this polymer may have the potential to be used as pyrite’s depressant in the flotation of base metal sulfides under specific conditions. XPS studies suggested that the depression of pyrite by Chi-g-PAM was due to chemisorption of the amine, amide, and hydroxyl groups of Chi-g-PAM at pyrite-water interface. The impact of Chi-g-PAM on the flotation response of sulfide minerals was investigated in both microflotation and batch flotation systems using model minerals and real sulfide ore, respectively. In microflotation tests of model minerals, the best separation efficiencies between valuable base metal sulfides and pyrite were achieved at pH 7. In batch flotation tests of complex sulfide ore of Mississippi Valley type (MVT) at natural pH (7.8), a separation efficiency of 61% was achieved between galena and pyrite when Chi-g-PAM was used compared to 35% with sodium cyanide (NaCN), the depressant that is commonly applied for this type of ore. However, the separation efficiency between chalcopyrite and pyrite was 15% and 21% with Chi-g-PAM and NaCN, respectively. Comparative studies indicated that Chi-g-PAM outperformed other depressants at producing less pyrite-diluted flotation concentrates.

Rapid removal of fungicide thiram in aqueous medium by electro-Fenton process with Pt and BDD anodes

• Advanced oxidation processes (AOP) are effective for the wastewater treatment. • These processes are based to the production of power oxidizing hydroxyl radicals ( • OH). • Electro-Fenton (EF) process is one of the AOP widely used to treat water polluted by pesticides. • Constant rate for oxidation of thiram by • OH was found to be 5.54 × 10 9 M −1 s −1 . • Almost complete mineralization of thiram was reached by electro-Fenton with BDD anode. The electro-Fenton (EF) process was used to assess the electrochemical degradation of the fungicide thiram and its complete removal from water using an undivided electrolytic cell equipped with Pt or BDD anode and carbon felt cathode. Hydroxyl radicals, produced homogeneously in bulk solution from electrochemically generated Fenton's reagent ( • OH) and heterogeneously on the anode surface (M( • OH)) from oxidation of water, reacted with thiram leading to its fast oxidation. Oxidative degradation and mineralization kinetics were monitored by chromatographic analysis (HPLC) and total organic carbon (TOC) measurements. The electrochemical degradation of thiram by hydroxyl radicals followed a pseudo-first-order reaction kinetics with an absolute rate constant k abs(Thir) of 5.54 (±0.03) × 10 9 M −1 s −1 , determined by competition kinetics method. The TOC removal rate values were found significantly higher with BDD anode than Pt anode. Thus, almost complete mineralization (92%) of thiram solution was obtained when using BDD anode. These results highlight the major role of heterogeneous BDD( • OH) formed in the mineralization of thiram. The contribution of homogeneous • OH in mineralization of thiram was found relatively low due to its specific aliphatic structure. The efficiency of the EF process was evaluated by determining mineralization current efficiency and energy consumption per gram of TOC removed. Degradation by-products and inorganic ions, such as nitrate (NO 3 − ), nitrite (NO 2 − ), ammonium (NH 4 + ) and sulfate (SO 4 2 − ) formed during mineralization process, were identified by GC–MS and ionic chromatography analyses and a plausible mineralization pathway was proposed.

Bulk petroleum geochemistry of shales from the onshore Rio del Rey Basin, Cameroon

Petroleum production in the Rio del Rey Basin, which is an extension of the Niger Delta of Nigeria into Cameroon, has been limited to the Tertiary offshore portion since the late 1970s. Owing to declining reserves in this offshore portion, the onshore Cretaceous portion of the basin attracted significant attention in the last decade. In the present study, shales from outcrops in the onshore portion of the basin were analyzed to evaluate their potential as source rocks, assess hydrocarbon generation, and highlight their significance for exploration. Outcrop observations, total organic carbon (TOC) measurements, and Rock-Eval pyrolysis were used to generate data for these investigations. Rock-eval S2 values (0.42–3 mg HC/g rock) based on measured present-day TOC values (0.58–2.44 wt%) of the shales studied signify poor to fair source rock potentials, whereas calculated S2 values (1.74–8.19 mg HC/g rock) based on estimated original TOC values (0.67–2.87 wt%) produced fair to good source rocks containing Type Ⅱ/III kerogen, which were transformed by maturity to the present-day Type Ⅲ/Ⅳ kerogen. Maturity of the samples based on Tmax values varying between 439 and 471 °C are equivalent to maturity values ranging between 0.74% Rr and 1.32% Rr, and these represent the peak oil to condensate/wet gas zones of hydrocarbon generation. These results demonstrate that mature source rocks are present in the onshore part of the Rio del Rey Basin, and thus, it is suitable for petroleum exploration.

Experimental investigation of the influence of sequential water-rock reactions on the mineral alterations and porosity evolution of shale

Because shale is widely used as a building material, it is critical to accurately determine its mineral alteration and porosity evolution during deterioration processes. When fluids flow through shale’s porosity spaces, their chemical properties gradually change because of the products produced by the water–rock reactions. These changes may lead to different water–rock reaction rates in the rock’s interior and on the rock’s surface, which are manifest as a “sequential” process. In this study, a self-designed reaction device was used to simulate sequential reaction conditions, and three disk-shaped shale samples were arranged in a series to represent the shale at different locations in a larger block. Deionized water was made to flow through the samples in sequence and to react for different periods of time (2, 4, and 6 months). Through X-ray diffraction (XRD) analysis, total organic carbon (TOC) measurements, nitrogen absorption tests, and scanning electron microscopy (SEM) observations, the alterations of the mineral composition and porosity characteristics of the shale specimens were investigated. The results revealed that the mineral alterations mainly involved decreases in the amount of pyrite and the TOC and an increase in the total amount of clay minerals, while the porosity changes included increases in both the specific surface area and the pore volume. These changes were greater for longer reaction times and were greater in the specimens in the later part of the sequence than in those at the beginning of the sequence. The microscopic observations were consistent with the mineral and porosity changes. For the reacted solution, the aqueous pH decreased and the electrical conductivity (EC) increased after the reactions, and these effects were magnified by the sequential water–rock reactions. These results suggest the conclusions that follow. i) The self-designed reaction system can represent sequential water–rock reactions well. ii) The sequential water–rock reactions accelerated the mineral alterations and porosity evolution in the latter part of the sequence compared to the beginning of the sequence. iii) Along the direction of the water flow, the shale deterioration increased successively, which can be primarily attributed to the accumulation of soluble protons during the sequential water–rock reactions.

Designing intimate porous Al2O3 decorated 2D CdO nano-heterojunction as enhanced white light driven photocatalyst and antibacterial agent

The mesoporous network of γ-Al2O3 ceramic support was coupled with the two dimensional (2D) hexagonal CdO nanoplates by ultrasonic assisted method. The fabricated photocatalyst was analyzed for its structural, morphological and optoelectrical properties by employing X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), photoluminescence, electron spin resonance (ESR) analysis and electrochemical impedance spectroscopy (EIS). The X-ray powder diffraction (XRD) result supports the good crystallinity of the fabricated nanohybrid with co-existence of pure phases of γ-Al2O3 and CdO nanoparticles (NPs). The nanohybrid was tailored to narrow down the bandgap to visible-light region. The bandgap energy obtained by UV–visible diffuse reflectance spectroscopy (DRS) for CdO/Al2O3 nanocomposite (NCs) was 2.95 eV. The Brunauer-Emmett-Teller (BET) surface area analysis shows porosity of material with high surface area. During photocatalysis, e- from CdO migrates to defect levels of Al2O3 that facilitated charge separation. The kinetic rate of degradation of methylene blue (MB) by NCs was 3.5 and 14 times higher than CdO and Al2O3 respectively. The performance was optimized and it showed good reusability. In addition, the multiple applications of the CdO/Al2O3 were evaluated by testing the bactericidal activity. The nanohybrid posed high growth inhibition activity towards both gram positive and negative bacterial strains. The maximum colour removal (97.3%) and high mineralization (87%) was verified by UV–visible and total organic carbon (TOC) measurements. This promotes the nanohybrid to act as a better candidate for environmental remediation and disinfectant applications.

Atomic sheets of silver ferrite with universal microwave catalytic behavior

Prompt degradation of organic pollutants renders microwave (MW) catalysis technology extremely lucrative; ideal microwave catalysts are therefore being hunted with an unprecedented urgency. Ideal functional microwave catalyst should be highly crystalline, room temperature ferromagnetic (for magnetic retrieval), highly dielectric (for sufficient microwave absorption) apart from being structurally stable at high temperature. The potential of silver ferrite 2D sheets (2D AFO) synthesized using a novel microwave technique as a microwave catalyst for the degradation of a variety of organic dyes and antibiotics was investigated in this article. While organic dyes like malachite green (MG), brilliant green (BG) and nile blue A (NB) achieved 99.2%, 98.8% and 95.2%, respectively; antibiotic tetracycline hydrochloride (TCH) molecule resulted in 75.8% degradation efficiency. Total organic carbon (TOC) measurements yielded 76%, 59.1%, 49.1% and 47.6% of carbon content for MG, BG, NB and TCH, respectively. The reaction pathway via intermediates and subsequent degradation to CO2 and H2O is revealed by liquid chromatography-mass spectrometry (LCMS). Both superoxide and hydroxyl radicals are participating in the process, according to scavenger tests. The evolution of silver ferrite as a new 2D material and its demonstration as an ideal microwave catalyst will lead to a new beginning in catalysis science and technology.

Evaluating iron-based nanoparticles for ciprofloxacin removal: Date seed extract as a biostabilizing and a bioreducing agent

Iron-based nanoparticles (FeNPs) are promising materials for the removal of pharmaceutical pollutants. In this study, the following FeNPs were evaluated for ciprofloxacin (CIP) removal: (a) nanoscale zerovalent iron (nZVI) prepared using chemical reduction method (b) nZVI coated with extracts from Phoenix dactylifera/date palm seeds (ds-coated-nZVI) (c) iron-sulfide nanoparticles prepared using date seed extract in a green synthesis approach (ds-FeS). The successful use of date seed extract as a biostabilizer and as a bioreductant was evaluated through multiple characterization techniques to determine nanoparticle morphologies, sizes, and surface chemistry. Batch experiments were used to assess CIP removal capacities and rates by nZVI, ds-coated-nZVI and ds-FeS. Among the three isotherm models investigated (i.e., Langmuir, Freundlich and Hill), the Hill model provided the best fit with maximum removal capacities (qm) of 196 mg g−1 for nZVI, 92 mg g−1 for ds-coated-nZVI and 100 mg g−1 for ds-FeS. The CIP removal kinetics was better represented by the pseudo-second-order model compared to pseudo-first-order and showed concentration dependent enhancements and decreases depending on the FeNP. While nZVI outperformed ds-coated-nZVI and ds-FeS particles in terms of removal rates and extents at higher CIP concentrations (>10 mg/L), the removal performance was similar for the three FeNPs at lower CIP concentrations. Liquid chromatography mass spectrometry and total organic carbon measurements indicated the involvement of both sorption and degradative transformation of CIP. Overall, results from this study suggest the strong capability of FeNPs for CIP removal and also indicate the potential of employing comparatively eco-friendly FeNP alternatives at lower environmentally relevant CIP concentrations.

Geological parameters controlling the bedding-parallel vein distribution in Vaca Muerta Formation core data, Neuquén Basin, Argentina

It is important to understand the occurrence of bedding-parallel veins in the Vaca Muerta Formation because this helps to predict their presence away from well controls so that they can ultimately be incorporated in reservoir simulators and hydraulic fracturing modelers. Given that their occurrence has a significant impact on the propagation of hydraulic fractures, their spatial distribution will help to select sweet spots for unconventional resource development. In this study, we try to identify the key parameters that control bedding-parallel veins. Therefore, detailed sedimentological core descriptions were performed on 10 different wells, including total organic carbon measurements at a spacing of 0.5 cm and several degrees of maturity ranging from 0.7% to 1.8% vitrinite reflectance. Through a comparison between bedding-parallel vein localization and sedimentological descriptions, we built a statistical method to identify key parameters controlling the localization of such veins within the Vaca Muerta Formation. We show that bedding-parallel veins are primarily located at facies boundaries (70%) rather than in homogeneous facies (30%). The major rheological discontinuities, such as ashbeds and calcitic concretion boundaries, as well as organic-rich facies have a significant impact on the localization of both bedding-parallel veins. The total organic carbon seems to influence the generation of bedding-parallel veins by locating these fractures in organic-rich areas with more than 2 wt. % in total organic carbon. We also found a correlation between the degree of maturity of the source rock within a same sequence stratigraphy and the (1) number of bedding-parallel veins and (2) thickness of the bedding-parallel vein, suggesting a strong link between the generation of hydrocarbons during the burial of the rock with the generation and distribution of bedding-parallel veins.

Experimental method and thermodynamic model for competitive adsorption between polycarboxylate comb copolymers

This study presents a method that establishes the existence of competitive adsorption between polycarboxylate ether (PCE) molecules with different molecular architecture. By combining well-established total organic carbon measurements with UV–Visible absorption, competition between PCEs of different structures could be quantified.Results are interpreted by deriving a fundamental thermodynamic model describing the PCE competition as a dynamic equilibrium between adsorbed and dissolved PCE molecules with different architectures. The model rationalizes the effect of dispersity in charge and backbone length on the adsorption behavior of PCEs and contributes to a fundamental understanding of the PCE working mechanism on the molecular level.

Laboratory Measurements of Total Organic Carbon (TOC) and Petrophysical Properties of Drilled Core Samples

Laboratory Measurements of Total Organic Carbon (TOC) and Petrophysical Properties of Drilled Core Samples

Isolating Detrital and Diagenetic Signals in Magnetic Susceptibility Records From Methane‐Bearing Marine Sediments

AbstractVolume‐dependent magnetic susceptibility (κ) is commonly used for paleoenvironmental reconstructions in both terrestrial and marine sedimentary environments where it reflects a mixed signal between primary deposition and secondary diagenesis. In the marine environment, κ is strongly influenced by the abundance of ferrimagnetic minerals regulated by sediment transport processes. Post‐depositional alteration by H2S, however, can dissolve titanomagnetite, releasing reactive Fe that promotes pyritization and subsequently decreases κ. Here, we provide a new approach for isolating the detrital signal in κ and identifying intervals of diagenetic alteration of κ driven by organoclastic sulfate reduction (OSR) and the anaerobic oxidation of methane (AOM) in methane‐bearing marine sediments offshore India. Using the correlation of a heavy mineral proxy from X‐ray fluorescence data (Zr/Rb) and κ in unaltered sediments, we predict the primary detrital κ signal and identify intervals of decreased κ, which correspond to increased total sulfur content. Our approach is a rapid, high‐resolution method that can identify overprinted κ resulting from pyritization of titanomagnetite due to H2S production in marine sediments. In addition, total organic carbon, total sulfur, and authigenic carbonate δ13C measurements indicate that both OSR and AOM can drive the observed κ loss, but AOM drives the greatest decreases in κ. Overall, our approach can enhance paleoenvironmental reconstructions and provide insight into paleo‐positions of the sulfate‐methane transition zone, past enhancements of OSR or paleo‐methane seepage, and the role of detrital iron oxide minerals on the marine sediment sulfur sink, with consequences influencing the development of chemosynthetic biological communities at methane seeps.

Evaluation of sono-assisted solar/Fenton process for indigo carmine degradation over magnetic ZnO-Fe3O4 supported Tunisian kaolinite clay

This study reports a novel ZnO-Fe3O4 supported natural Tunisian kaolinite clay as a photocatalyst (denoted herein as ZnO-Fe3O4/Kal) magnetic separation. The ZnO-Fe3O4/Kal was prepared using the hydro-thermal following by sol-gel methods. This material was assayed in the degradation of Indigo Carmine in an aqueous solution, as a model of organic dye, using sono-Fenton under solar irradiation. The effect of pH, catalyst amount, H2O2 concentration, initial IC concentration, and the presence of inorganic ions were studied and then optimized. Under optimum experimental, the complete degradation of IC (50 mg/L) was achieved in 100 min of irradiation time. By applying the combination of ultrasonic waves and US irradiation, a synergistic effect was observed in the presence of ZnO-Fe3O4/Kal, and the synergy value was found to 53.84%. UV-vis and total organic carbon (TOC) measurements indicated required longer reaction times were for achieving IC mineralization 97.45%. The importance of this work is that a simple external magnetic field can easily separate the ZnO-Fe3O4/Kal. This material also has a strong catalytic activity after five successive uses.

Sustainable Removal of Microplastics and Natural Organic Matter from Water by Coagulation-Flocculation with Protein Amyloid Fibrils.

Water contamination is a global threat due to its damaging effects on the environment and human health. Water pollution by microplastics (MPs), dissolved natural organic matter (NOM), and other turbid particles is ubiquitous in water treatment. Here, we introduce lysozyme amyloid fibrils as a novel natural bio-flocculant and explore their ability to flocculate and precipitate the abovementioned undesired colloidal objects. Thanks to their positively charged surface in a very broad range of pH, lysozyme amyloid fibrils show an excellent turbidity removal efficiency of 98.2 and 97.9% for dispersed polystyrene MPs and humic acid (HA), respectively. Additionally, total organic carbon measurements confirm these results by exhibiting removal efficiencies of 93.4 and 61.9% for purifying water from dispersed MPs and dissolved HA, respectively. The comparison among amyloid fibrils, commercial flocculants (FeCl3 and polyaluminumchloride), and native lysozyme monomers points to the superiority of amyloid fibrils at the same dosage and sedimentation time. Furthermore, the turbidity of pristine and MP-spiked wastewater and lake water decreased after the treatment by amyloid fibrils, validating their coagulation-flocculation performance under natural conditions. All these results demonstrate lysozyme amyloid fibrils as an appropriate natural bio-flocculant for removing dispersed MPs, NOM, and turbid particles from water.

Microwave synthesized strontium hexaferrite 2D sheets as versatile and efficient microwave catalysts for degradation of organic dyes and antibiotics

Microwave catalysis is extremely lucrative due to prompt mineralization and superior efficiency. Ideal microwave catalysts should possess crystalline nature, large surface area, room temperature ferromagnetic, high dielectric properties apart from structural stability at elevated temperature. In the present article, the candidature of microwave synthesized strontium hexaferrite 2D sheets (2D SFO) has been explored as microwave catalysts for the degradation of a host of organic dyes and antibiotics. Malachite green (MG) and nile blue A (NB) in particular exhibited 99.8% and 97.6% degradation, respectively. Degradation reaction is established to follow pseudo-second-order kinetics. Total organic carbon (TOC) measurements hint at 52% and 60% mineralization for MG and NB, respectively. Liquid chromatography-mass spectroscopy (LCMS) measurements indicate the reaction pathways via intermediates and eventual mineralization to CO2 and H2O. Mott-Schottky measurements along with scavenger tests hint that both hydroxyl and superoxide radicals participate in the reaction. Having superior efficiency apart from the versatile nature of the 2D SFO microwave catalyst, the present research will guide to the emergence of microwave catalysis as a new technology.