Complete Total Organic Carbon Research Articles

Photocatalytic Activity and Reusability of F, Sm3+ Co-Doped TiO2/MWCNTs Hybrid Heterostructure for Efficient Photocatalytic Degradation of Brilliant Black Bis-Azo Dye

A global freshwater pollution catastrophe is looming due to pollutants of emerging concern (PECs). Conventional water treatment methods are limited in removing PECs such as pharmaceuticals and dye house effluent from aquatic systems. This study provides an effective potential solution by developing an innovative wastewater treatment method based on solar-light-responsive semiconductor-based photocatalysts. A sol-gel synthesis technique was used to produce Fluorine-Sm3+ co-doped TiO2 (0.6% Sm3+) (FST3) photocatalysts. This was followed by loading multi-walled carbon nanotubes (MWCNTs) in the range of 0.25 to 1 wt% into the FST3 matrix. Solid state UV-visible spectroscopy measurements showed a bathochromic shift into the visible light region after the co-doping of TiO2, whereas XRD analysis confirmed the presence of predominantly anatase polymorphs of TiO2. The FT-IR and EDX results confirmed the presence of the F and Sm3+ dopants in the synthesised photocatalysts. XRD and TEM measurements confirmed that the crystallite sizes of all synthesised photocatalysts ranged from 12–19 nm. The resultant photocatalysts were evaluated for photocatalytic degradation of Brilliant Black BN bis-azo dye in aqueous solution under simulated solar irradiation. FST3 completely degraded the dye after 3 h, with a high apparent rate constant (Ka) value (2.73 × 10−2 min−1). The degree of mineralisation was evaluated using the total organic carbon (TOC) technique, which revealed high TOC removal (82%) after 3 h and complete TOC removal after 4 h. The incorporation of F improved the optical properties and the surface chemistry of TiO2, whereas Sm3+ improved the quantum efficiency and the optical properties. These synergistic effects led to significantly improved photocatalytic efficiency. Furthermore, incorporating MWCNTs into the F and Sm3+ co-doped TiO2 (0.6% Sm3+) improved the reaction kinetics of the FST3, effectively reducing the reaction time by over 30%. Recyclability studies showed that after 5 cycles of use, the FST3/C1 degradation efficiency dropped by 7.1%, whereas TiO2 degradation efficiency dropped by 33.4% after the same number of cycles. Overall, this work demonstrates a sustainable and efficient dye-removal technique.

Influencing factors of venlafaxine degradation at boron-doped diamond anode

Degradation of the antidepressant venlafaxine by an effective electrocatalytic process, boron-doped diamond (BDD) electrode, was study. The BDD electrode was selected as the anode, and the degradation efficiency of venlafaxine under different influencing factors was systematically investigated. The preliminary grasp of the degradation law of venlafaxine by anodic electro-degradation using BDD electrode was obtained. The experimental results showed that the electrochemical oxidation technology using BDD anode can effectively degrade venlafaxine and remove total organic carbon (TOC) from the solution, complete venlafaxine degradation and TOC elimination could be achieved within 30 and 120 min of BDD oxidation process, respectively, and it has good stability and reusability. Increasing the electrolyte concentration (≤0.1 mol/L) and current density (≤100 mA/cm 2 ) within a certain range could accelerate the degradation of venlafaxine. HCO 3 – and PO 4 3− could inhibit the degradation efficiency of venlafaxine through of competing for free radicals. It is interesting that the presence of Cl − significantly promoted the degradation efficiency of venlafaxine. The results of this study suggest that the Electro-degradation treatment may provide a promising way to treat venlafaxine contaminated water.

Ozonation of Amoxicillin and Ciprofloxacin in Model Hospital Wastewater to Increase Biotreatability.

Amoxicillin (AMX) and Ciprofloxacin (CIP) are antibiotics commonly used in human medicine with high environmental toxicity and poor biodegradability. They have been found in various hospital effluents and groundwater, and their environmental impact is still not fully understood. In this work, we investigated the possibility of treating model wastewaters containing the antibiotics AMX and CIP using ozonation, with the addition of H2O2 under various conditions, including different pH values, H2O2, and ozone dosages. The quantification of and treatment efficacy for antibiotic removal were determined via solid phase extraction followed by chromatographic separation by liquid chromatography coupled with tandem triple quadrupole mass spectrometry (LC/MS/MS). This analytical system is quite efficient for the detection of all major antibiotic classes, even if they are present at very low concentrations. The efficiency of ozonation was determined by measuring the TOC (Total Organic Carbon) changes after ozonation of the model wastewater and by measuring the concentration of the two antibiotics. In a sequential activated sludge process of ozone-treated model wastewater, almost complete TOC removal and an overwhelming decrease in antibiotic concentrations (up to 99%) were observed. Ozonation resulted in complete removal of AMX and CIP in less than 30 and 120 min, respectively. The results of this work indicate that ozonation could be a suitable pretreatment method to reduce the toxicity of contaminants (AMX and CIP) and improve the biodegradability of hospital wastewater.

In Situ-Formed PdFe Nanoalloy and Carbon Defects in Cathode for Synergic Reduction–Oxidation of Chlorinated Pollutants in Electro-Fenton Process

Complete dechlorination and mineralization of chlorophenols via the reduction-oxidation-mediated electro-Fenton process with a composite bulk cathode is first proposed. The in situ formation of a PdFe nanoalloy and carbon defects as key active sites is mutually induced during the formation of a carbon aerogel-based electrode. Specifically, the PdFe nanoalloy promotes the generation of [H]ads as reduction sites and improves the electron transfer via an electrical circuit, while the carbon defects selectively favor the 2e- oxygen reduction pathway. Notably, this work implies a novel electrocatalytic model for the formation of ·OH via (2 + 1)e- oxygen reduction by a consecutive reaction with carbon defects and a PdFe nanoalloy. Complete total organic carbon removal and dechlorination of 3-chlorophenol were performed after 6 h. The kinetic rate constant for removing haloacetamides (HAMs) in drinking water was 0.21-0.41 h-1, and the degradation efficiency was self-enhanced after electrolysis for 2 h because of the increased concentration of [H+]. The specific energy consumption was ∼0.55 W·h·g-1 at 100% removal of some HAMs, corresponding to a power consumption of 0.6-1.1 kW·h for complete dehalogenation per ton of drinking water in waterworks. Moreover, the PdFe alloy/CA exhibited extreme mechanical and electrochemical stability with limited iron (∼0.07 ppm) and palladium (0.02 ppm) leaching during the actual application.

Electroanalytical techniques applied to monitoring the electro-Fenton degradation of aromatic imidazolium-based ionic liquids

In this study, the degradation of the ionic liquid (IL) 1,3-dicyclohexylbenzimidazolium chloride ([DCy6bim][Cl]) was carried out by applying an heterogeneous electro-Fenton (HEF) treatment using iron alginate spheres (FeAS) as catalyst. Initial trials were performed at current between 50 and 250 mA, different FeAS dosages (1–5 g), and [DCy6bim][Cl] concentrations (70–280 mg L−1) as key parameters for the characterization of the HEF process. Comparative experiments suggest that high current, low FeAS dosage and low [DCy6bim][Cl] concentration are the best conditions to yield near complete total organic carbon decay after 4 h. In order to evaluate the catalyst behaviour and iron leaching during the degradation of [DCy6bim][Cl], differential pulse voltammetry (DPV), a sensitive and selective electroanalytical technique, was used to monitor the IL degradation, by-products and iron evolution into the solution at high concentration levels. The profile of the voltammetric curves obtained by DPV suggests almost complete cleavage of the cation structure of [DCy6bim][Cl] during the first 120 min. At longer treatment times, DPV revealed the generation of iron complex with chloride and carboxylic acids. Finally, chromatographic analysis of these carboxylic acids and inorganic anions permitted to validate the results obtained by DPV and demonstrated the feasibility of the HEF process for IL degradation.

Electrooxidation of cardanol on mixed metal oxide (RuO2-TiO2 and IrO2-RuO2-TiO2) coated titanium anodes: insights into recalcitrant phenolic compounds

In Brazil, the cashew-nut industry has an important role in national economy, but the lack of suitable treatment of the residues generated by this activity represents a serious risk to the environment and biodiversity. Cardanol (CDN) is a highly toxic and recalcitrant phenolic compound, and it is the major component from this activity. This work evaluated, for first time, the performance of mixed metal oxide DSA®-type anodes (Ti/TiO2-RuO2 and Ti/TiO2-RuO2-IrO2) to develop a suitable electrochemical treatment for the cashew-nut industry residues, using CDN as model molecule. Results clearly showed that for both Ti/TiO2-RuO2 and Ti/TiO2-RuO2-IrO2 active anodes, an increase on the current densities (j) enhanced the percentage of total organic carbon (TOC) removal as a function of the electrolysis time (t). The complete TOC removal was efficiently achieved with Ti/TiO2-RuO2 (j≥40mAcm−2 and t≥5.0h) at 25°C, although Ti/TiO2-RuO2-IrO2 ternary anode has also showed suitable performance for this purpose (j=60mAcm−2 and t≥4.0h). UV-visible spectrophotometric data showed similarity between the CDN electrooxidation kinetics for both anodes, independently of the applied current density. Analyses performed by gas chromatography coupled to mass spectrometry confirmed the complete mineralization of CDN and its intermediates, mainly at higher densities. A positive effect in the degradation performances was achieved when an increase on the temperature was attained, at both anodes; despite the satisfactory results achieved at 25°C, favor an affordable cost.

Ultrasound-enhanced electrochemical mineralization of perfluorooctanoic acid in aqueous solutions: Assessed by response surface methodology

Aims: The sonoelectrochemical mineralization of the synthetic aqueous solution of the perfluorooctanoic acid (PFOA) on Ti/PbO 2 anode was investigated using the response surface methodology based on a central composite design (CCD). Materials and Methods: The CCD was performed using three different variables such as current density (CD) (mA/cm 2 ), pH, and supporting electrolyte (EL) concentration (mM). The total organic carbon (TOC) removal was determined as an indicator of PFOA mineralization. A Shimadzu TOC analyzer was used to measure the TOC of the samples. The Ti/PbO 2 electrode was prepared using the electrochemical deposition method. In order to enhance the electrochemical mineralization, ultrasonic (US) radiation was used. The US frequency was 20 kHz. Results: The optimum conditions for PFOA mineralization in synthetic solution were EL concentration of 94 mM, pH of 2, and CD of 83.64 mA/cm 2 , which resulted in complete TOC removal. The results indicated that the most effective factor for PFOA mineralization was CD. Besides, the TOC removal efficiency significantly increased with increasing CD. Conclusions: Under optimum conditions, the mineralization of PFOA was almost completed after 90 min of sonoelectrolysis. Therefore, sonoelectrolysis was found to be a more effective technique for mineralization of an environmentally persistent compound.

Electro-peroxone treatment of the antidepressant venlafaxine: Operational parameters and mechanism

Degradation of the antidepressant venlafaxine by a novel electrocatalytic ozonation process, electro-peroxone (E-peroxone), was studied. The E-peroxone treatment involves sparging ozone generator effluent (O2 and O3 gas mixture) into an electrolysis reactor that is equipped with a carbon-polytetrafluoroethylene cathode to electrocatalytically transform O2 in the bubbled gas to H2O2. The in-situ generate H2O2 then reacts with the bubbled O3 to yield OH, which can non-selectively degrade organic compounds rapidly in the solution. Thanks to the significant OH production, the E-peroxone treatment greatly enhanced both venlafaxine degradation and total organic carbon (TOC) removal as compared to ozonation and electrolysis alone. Under optimal reaction conditions, complete venlafaxine degradation and TOC elimination could be achieved within 3 and 120min of E-peroxone process, respectively. Based on the by-products (e.g., hydroxylated venlafaxine, phenolics, and carboxylic acids) identified by UPLC–UV and UPLC/Q-TOF-mass spectrometry, plausible reaction pathways were proposed for venlafaxine mineralization by the E-peroxone process. The results of this study suggest that the E-peroxone treatment may provide a promising way to treat venlafaxine contaminated water.

Routes for the electrochemical degradation of the artificial food azo-colour Ponceau 4R by advanced oxidation processes

The performance of three electrochemical advanced oxidation processes, namely electro-oxidation with electrogenerated H2O2 (EO–H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF) for the treatment of aqueous solutions of the food azo dye Ponceau 4R in an undivided cell with a BDD anode and an air-diffusion cathode was compared in terms of colour, dye concentration and total organic carbon (TOC) removals. PEF treatments in ultrapure water with Na2SO4 were performed to assess the effect of current density, as well as supporting electrolyte and dye concentrations. At 100mAcm−2, solutions of 130mL of 254mgL−1 of the dye in 0.05M Na2SO4 became colourless and totally mineralized after 50 and 240min, respectively, which can be explained by the synergistic action of BDD(OH) at the anode surface and homogeneous OH formed in the bulk from Fenton’s reaction promoted in the presence of Fe2+ catalyst. Furthermore, UVA photons induced the continuous Fe2+ regeneration and photolytic decomposition of refractory intermediate complexes. In that aqueous matrix, the cleavage of the dye molecules proceeded through several reaction routes to yield N-containing and non-N-containing derivatives with one or two aromatic rings, short-chain aliphatic carboxylic acids and inorganic ions. Oxalic and oxamic acids and sulfate ions were accumulated at different rates in EO–H2O2, EF and PEF. The three methods allowed the progressive decontamination of Ponceau 4R solutions in a real water matrix even without the addition of electrolyte, although complete TOC abatement after 360min at 33.3mAcm−2 was only ensured by the iron-catalyzed PEF process.

Heterogeneous Fenton-like degradation of 4-chlorophenol using a novel FeIII-containing polyoxometalate as the catalyst

Fenton-like degradation of 4-chlorophenol (4-CP) in aqueous solution was studied over a novel FeIII-containing polyoxometalate (POM) as heterogeneous catalyst. The POM, assigned as FeIIIAspPW12, was synthesized via precipitation reaction of phosphotungstic acid (PW12) with the complex of ferric ion and aspartic acid (Asp) in aqueous solution. The catalyst displays high activity and good reusability for oxidation of 4-CP by hydrogen peroxide in the range from acidic to circumneutral pH values. The enhanced oxidation of 4-CP was observed when the reaction system was irradiated by a high pressure mercury lamp. Under the conditions of H2O2 20mM, FeIIIAspPW12 0.2g/L, temperature 25±2°C and pH 6.5, the complete total organic carbon (TOC) removal for 100mg/L 4-CP solution could be achieved in both dark and irradiation systems within 120 and 60min, with H2O2 utilization of 77% and 83% respectively. It is speculated that the catalysis may possibly undergo the redox cycles of FeIII⇌FeII and POM⇌POM− on the surface of FeIIIAspPW12, accompanied by hydroxyl radical formation from H2O2, and the oxidation of 4-CP consequently.

Comparison of sulfate and hydroxyl radical based advanced oxidation of phenol

UV-C photo-assisted persulfate (PS), hydrogen peroxide (H2O2) and peroxymonosulfate (PMS) oxidation processes were evaluated and compared for aqueous phenol degradation. The effect of initial oxidant concentration on PS/UV-C, H2O2/UV-C and PMS/UV-C treatment efficiencies was examined on the basis of phenol and total organic carbon (TOC) removals. Complete phenol degradation could be achieved under all examined reaction conditions with apparent phenol degradation rate constants varying between 0.069±0.002–0.382±0.003min−1 accompanied with complete TOC removals (⩾97%) under optimized PS (20mM), H2O2 (30mM) and PMS (20mM) concentrations. Hydroquinone, catechol and benzoquinone were quantified during H2O2/UV-C and PMS/UV-C treatment of phenol verifying a HO-dominated oxidation pathway. During PS/UV-C oxidation, the identification of benzoquinone and 3-phenoxyphenol verified the hydroxycyclohexadienyl radical and phenoxyl radical pathways in SO4- mediated phenol oxidation.

Comparative efficiencies of the decolourisation of leather dyes by enzymatic and electrochemical treatments

Leather dyes are important chemical pollutants of industrial origin. The society demand for colour-free waste discharge to receiving waters has made decolourisation of industrial wastes a top priority. Due to their complex chemical structures, the decolourisation of these wastes is a challenging task. In this study, the decolourisation and degradation efficiency of six leather dyes by enzymatic and electrochemical treatments were studied. In the presence of salts, all dyes were totally decolourised by electrochemical treatment in 4 h. Though it has showed appreciable ability of enzymatic degradation, it was observed that the salts present in tannery effluents cause inhibition problems that significantly affected the dye degradation. In addition, enzymatic and electrochemical treatments with a mixture of the six dyes were carried out. Once again, the electrochemical treatment shows better results and after 4 h the obtained decolourisation was total which is squared with a complete total organic carbon (TOC) reduction. Besides, the degradation of this mixture was carried out successfully in a continuous electrochemical bubble reactor. Therefore, the results provide fundamental knowledge for the treatment of a leather wastewater stream.

Investigation of photocatalytic ozonation treatment of water over WO3 under visible light irradiation

The aim of this study is to develop a highly efficient and environmentally friendly water treatment technique. Water treatment by photocatalytic ozonation over bare WO3 under visible light irradiation (O3/vis/WO3) system was performed under different experimental conditions using a phenol aqueous solution as model wastewater. The effects of parameters such as the initial phenol concentration, water temperature, and initial solution pH on the total organic carbon (TOC) removal efficiency in the O3/vis/WO3 system were investigated. The results suggest that the TOC removal process consists of three stages, and the combined effect of photocatalysis and ozonation, which is important for complete TOC removal, became dominant in the third stage. Furthermore, the TOC removal efficiency increased with increasing water temperature in the O3/vis/WO3 system.

Microbial Conversion of Olive Oil Mill Wastewaters into Lipids Suitable for Biodiesel Production

Lipomyces starkey were able to survive and proliferate in the presence of olive oil mill wastewaters (OMW), a medium difficult to process by biological treatments, due to the antimicrobial activities of their phenolic components. The microorganisms were grown in the presence of undiluted OMW, without external organic supplements, producing a significant reduction of both the total organic carbon (TOC) and the total phenols content. The OMW treated by L. starkey showed a significant increase of the germination index. The preliminary dilution of OMW enhanced the reduction of polluting components of OMW, leading to a complete TOC removal, as well as to lower levels of residual phenols. The activities of extracellular lipases and esterases significantly increased in the course of the OMW fermentation. A significant increase in lipid yield was observed in L. starkey in the course of the OMW treatment, particularly enhanced when the feedstock was preliminarily diluted. The fatty acid distribution showed a prevalence of oleic acid, demonstrating the potential of L. starkeyi as a source of lipids to be used as a feedstock for the synthesis of II generation biodiesel.

On the kinetics and mechanisms of photolytic/TiO2-photocatalytic degradation of substituted pyridines in aqueous solutions

Pyridine and pyridine derivatives are extensively used for the production of pesticides, medicinal drugs, industrial solvents, dyes, rubber chemicals etc. They are encountered in their wastewaters and due to their hazardous effects on ecosystems and human health, their removal is imperative. However, the methods for their treatment need to be improved or replaced by more effective alternatives. With this in mind and following our previous work on photolytic treatment of 2-halogenated pyridines (2-HalPys), the combined photolytic/photocatalytic (TiO2 P-25) at 254nm degradation and mineralisation of 2-chloropyridine (2-CPY), 2-fluoropyridine (2-FPY) and 2-hydroxypyridine (2-HPY), a major photolytic product of all 2-HalPys but 2-FPY are studied in a range of conditions. In order to probe into the mechanisms and factors affecting their degradation, the effects of pH, radical scavenger tert-butanol and inorganic ions, were examined. The former had a substantial impact on 2-CPY photocatalytic removal rate, which, however, remained practically unaffected by the latter. 2-CPY photocatalytic removal was faster at near neutral pH. 2-HPY degradation was faster in the presence of TiO2, low pH and in the presence of F− or SO42− anions. On the contrary, Cl− anions or the presence of tert-butanol had a pronouncedly detrimental effect on 2-HPY degradation rate. Main reaction by-products accompanying the purely photocatalytic destruction of 2-CPY and 2-FPY were identified. Complete total organic carbon removal was achieved in all cases.

2-Hydroxypyridine photolytic degradation by 254 nm UV irradiation at different conditions

The degradation and mineralisation of (400 mL, 3.15 mM) aqueous solutions of 2-hydroxypyridine (2-HPY), a primary intermediate formed during the photolytic degradation of 2-chloropyridine (2-CPY), 2-bromopyridine (2-BPY) and 2-iodopyridine (2-IPY), was studied at 50 °C, under 254 nm UV irradiation in a range of conditions. The rate of 2-HPY disappearance was found to heavily depend on agitation, dissolved oxygen, pH and hydroxyl radical scavenger presence. pH has a pronounced effect on the phototreatment of 2-HPY, i.e. 2-HPY removal is faster at lower pH, but except for their influence on the solution pH, Cl − or F − do not appear to affect 2-HPY rate of removal or mineralisation. 2-HPY removal rate increases with dissolved oxygen, thus indicating a prominent 2-HPY photooxidation pathway. Helium purging of the solution before and during the measurement reduced 2-HPY removal rate, thus supporting the existence of a photooxidation pathway. Pure photolytic 2-HPY removal, i.e. when photooxidation is limited, fits pseudo-first order kinetics, and a kinetic model was developed for 2-HPY formation and removal during 2-CPY, 2-BPY and 2-IPY photolytic degradation under laminar flow. The addition of radical scavenger ( tert-butanol) had a detrimental effect on the photolytic degradation of 2-HPY. Complete total organic carbon removal was achieved.

Photolytic removal and mineralisation of 2-halogenated pyridines

The photolytic destruction and mineralisation of 2-halogenated pyridines (2-HalPYs) was studied in a range of conditions by means of ultraviolet irradiation at 254 nm. In all cases pseudo-first order kinetics satisfactorily describe the degradation process. Key decomposition products were identified and primary reaction pathways are proposed. 2-HalPYs were rapidly dehalogenated with a subsequent sharp pH drop. Complete Total Organic Carbon (TOC) removal was achieved. Their photolytic removal rate is not affected by pH or aeration. The fastest TOC removal was observed in 2-fluoropyridine (2-FPY) photolysis. 2-Hydroxypyridine (2-HPY) was identified as the primary intermediate formed by destruction of 2-chloropyridine (2-CPY), 2-bromopyridine (2-BPY) and 2-iodopyridine (2-IPY). 2-HPY is further destructed to form Dewar pyridinone. 2-FPY only marginally reacted to form 2-HPY. Instead, its major intermediate product is Dewar pyridinone. 2-IPY results in a, most likely aliphatic, photostable product, the production of which appears to increase at low pH and high 2-HPY concentration.

Catalytic wet air oxidation of olive mill wastewater

The objective of this work was to study the suitability of catalytic wet air oxidation (CWAO) for the treatment of olive mill wastewater (OMW). Experiments were performed in a high pressure reactor at 100 and 200 °C under an oxygen partial pressure of 6.9 bar, using carbon supported platinum (1 wt.% Pt) and iridium (5 wt.% Ir) catalysts prepared by incipient wetness impregnation. At 100 °C, refractory organic compounds persisted even after prolonged reaction time (8 h). At 200 °C, complete total organic carbon and colour removal was obtained with the Pt/C catalyst after 8 h of reaction. A kinetic model was developed taking into account catalytic and non-catalytic reactions, formation of refractory compounds and catalyst deactivation. Very good agreement between the proposed model and CWAO experimental data at 200 °C was found. The results obtained in this work indicate that Pt/C is a promising catalyst for the CWAO of OMW.

Bisphenol A Mineralization by Integrated Ultrasound-UV-Iron (II) Treatment

Bisphenol A (BPA), an organic compound largely used in the plastic industry as a monomer for production of epoxy resins and polycarbonate, is an emerging contaminant that is released in the environmentfrom bottles and packaging. BPA degradation (118 micromol L(-1)) under sonochemical conditions was investigated in this study, using a 300 kHz frequency, with a 80 W electrical power. Under these conditions, BPA was eliminated by the ultrasound process (-90 min). However, even after long ultrasound irradiation periods (10 h), more than 50% of chemical oxygen demand (COD) and 80% of total organic carbon (TOC) remained in the solution, indicating that most BPA intermediates are recalcitrant toward ultrasonic action. Accumulation of hydrogen peroxide from *OH and *OOH radical recombination was also observed. To increase the efficiency of BPA treatment, experiments combined ultrasound with Fe2+ (100 micromol L(-1)) and/or UV radiation (254 nm): Ultrasound/UV; Ultrasound/Fe2+; Ultrasound/UV/ Fe2+. Both UV and Fe2+ induced hydrogen peroxide dissociation, leading to additional *OH radicals and complete COD and TOC removal. Thus difficulties in obtaining mineralization of micropollutants like BPA through ultrasonic action alone, can be overcome by the Ultrasound/UV/ Fe2+ combination. Moreover, this technique was found to be the most cost-effective one. So, the integrated ultrasound-UV-iron(ll) process was shown to be of interest for the treatment of wastewaters contaminated with BPA.

Preservation of carbohydrates through sulfurization in a Jurassic euxinic shelf sea: Examination of the Blackstone Band TOC cycle in the Kimmeridge Clay Formation, UK

A complete total organic carbon (TOC) cycle in the Upper Jurassic Kimmeridge Clay Formation (KCF) comprising the extremely TOC-rich (34%) Blackstone Band was studied to investigate the controlling factors on TOC accumulation. Compared with the under- and overlying strata, TOC in the Blackstone Band was enriched by a factor of six and, concomitantly, the δ 13C TOC shows a ∼4‰ enrichment. Al-normalized TOC values indicated that the enhanced TOC values were probably caused by increased TOC accumulation and not by a decreased dilution with inorganic matter. The amounts of short chain alkylated thiophenes and the sulfur-rich unresolved complex mixture (UCM) in the kerogen pyrolysates, as well as the TOC/Al ratios, correlated linearly with δ 13C TOC for sediments with TOC/Al ratios >1.7. The alkylated thiophenes and sulfur-rich UCM both originate from sulfurized carbohydrate carbon (C carb), suggesting that the primary cause of the TOC maximum is the enhanced contribution of C carb to TOC. Since carbohydrates can be substantially 13C-enriched over lipids in biomass, the enhanced contribution of C carb explains the enriched δ 13C TOC values. Compound specific isotope data showed that primary productivity during deposition of the KCF TOC cycle varied little, while a two member isotopic mixing model showed that the preservation of C carb relative to that of the lipid carbon may have increased by a factor of >10 in the Blackstone Band. The enhanced preservation of C carb was most likely caused by more frequent or longer lasting events of photic zone euxinia, as revealed by the concentration of isorenieratene derivatives. Enhanced contributions of C carb have also been observed in other KCF cycles, suggesting that enhanced preservation of C carb, rather than an increase in primary production, exerted direct control on the TOC cycles of the KCF.