Degradation Of Ring Research Articles

Olefin metathesis-crosslinked, bulky imidazolium-based anion exchange membranes with excellent base stability and mechanical properties

To improve the mechanical properties of anion exchange membranes (AEMs) with bulky imidazolium cations, a series of anion-conductive poly(2,6-dimethyl-phenylene oxide)s (PPO)s with crosslinkable terminal double bonds were synthesized by the Menshutkin reaction. Following crosslinking via olefin metathesis at room temperature catalyzed by a Grubb's second generation catalyst, tough, transparent, and flexible PPO-based AEMs were obtained. The crosslinked AEMs exhibited good mechanical properties (tensile strength at maximum load of 20.8–49.9 MPa and values of elongation at break of 1.5–3.0%) though their bulky imidazolium cation groups which could destroy the film-forming ability of polymer. And the obtained mechanical properties were considerably better than those of the non-crosslinked AEMs with a similar architecture, which broke into small pieces during the process of membrane fabrication using solvent casting. Furthermore, the crosslinked AEMs exhibited an extremely low water uptake (up to 13.9 wt% at 80 °C) and minimal swelling (<7% at 80 °C), attributed to the high-density crosslinking network. A high bromide conductivity (22.9 mS/cm at 80 °C) was achieved despite the low water uptake for the crosslinked AEM. Moreover, long-term alkaline stability testing in 1 M NaOH at 80 °C, no obvious degradation of the imidazolium ring was observed, with the conductivity of aged crosslinked membranes remaining at ~100% after 960 h. It was assumed that the bulky substituents at the C2, C4, and C5 positions of imidazolium cations and the crosslinked architecture prevented H2O and/or OH− from attacking the cationic center. Moreover, the AEM fuel cell performance and durability was further explored for the membrane electrode assembly (MEA) with crosslinked and uncrosslinked bulky imidazolium-based ionomers in catalyst layers. An optimistic cell performance (a peak power density of 173 mW/cm2 at 410 mA/cm2) and improved short-term durability at a constant current density of 200 mA/cm2 were obtained for the crosslinked ionomers, and its lifetime was ca. 3 times longer than that of benzyltrimethylammonium functionalized PPO ionomer.

Survey reactivity of 5-substituted tetrazoles toward pentafluoropyridine

Reactivity of some 5-substituted tetrazoles with pentafluoropyridine under basic conditions in acetonitrile was investigated. The reaction of pentafluoropyridine with tetrazoles regioselectively occurs at the 4-position of pyridine ring by N2 in the tetrazole ring. Tetrazoles with substituents at the position 5 such as Ph, 4-NO2C6H4, 4-CF3CONHC6H4, 4-ClC6H4CH2, EtOOCCH2, and 5-tetrazolyl−CH2 gave products containing unchanged tetrazole moiety. In contrast, tetrazole with substituents at the position 5 such as 3-(5-tetrazolyl)C6H4, 4-MeOC6H4, and 3-CF3CONHC6H4, gave hydrazide products via degradation of tetrazole ring.

Removal of Tetrachloroethylene from Aqueous Media by Means of Adsorption or Degradation of Growth Ring of Water Distribution Network

AbstractIn this study, the composition of actual pipeline sediment, the growth ring, was analyzed. According to this, we prepared and characterized a simulated growth ring. Adsorption or degradatio...

Energy level mediation of (BiO)2CO3via Br doping for efficient molecular oxygen activation and ciprofloxacin photodegradation

Solar-driven molecular oxygen activation is of great importance for reactive oxygen species (ROS) production in environmental remediation. In this work, a convenient bromine doping strategy was developed to mediate the energy level of Bi2O2CO3 for molecular oxygen activation. The band structure and DFT calculation demonstrate that the Fermi level of Bi2O2CO3 elevates after bromine doping, which promotes the molecular oxygen activation and ROS production. The Br-doped Bi2O2CO3 exhibits remarkably enhanced photocatalytic ability and could degrade 95% of the ciprofloxacin within 30 min. Moreover, HPLC-MS analysis elucidates that the pyrrolidone ring degradation process is the dominate pathway in ciprofloxacin degradation over Br-doped Bi2O2CO3, resulting in the decrease of antimicrobial activity of the degradation products and the risk of drug-resistance. This work not only provides a molecular oxygen activation strategy via energy level mediation, but also helps us to further understand the relationship between the elemental doping and molecular oxygen activation.

Effects of different scrap iron as anode in Fe-C micro-electrolysis system for textile wastewater degradation.

The degradation of organic contaminants in actual textile wastewater was carried out by iron carbon (Fe-C) micro-electrolysis. Different Fe-C micro-electrolysis systems (SIPA and SISA) were established by using scrap iron particle (SIP) and scrap iron shaving (SIS) as anode materials. The optimal condition of both systems was obtained at the initial pH of 3.0, dosage of 30g/L and Fe/C mass ratio of 1:1. Commercial spherical Fe-C micro-electrolysis material (SFC) was used for comparison under the same condition. The results indicated that total organic carbon (TOC) and chroma removal efficiencies of SIPA and SISA were superior to that of SFC. Total iron concentration in solution and XRD analysis of electrode materials revealed that the former showed relatively high iron corrosion intensity and the physicochemical properties of scrap iron indeed affected the treatment capability. The UV-vis and 3DEEM analysis suggested that the pollutants degradation was mainly attributed to the combination of reduction and oxidation. Furthermore, the potential degradation pathways of actual textile wastewater were illustrated through the GC-MS analysis. Massive dyes, aliphatic acids, and textile auxiliaries were effectively degraded, and the SIPA and SISA exhibited higher performance on the degradation of benzene ring and dechlorination than that by SFC. In addition, SIPA and SISA exhibited high stability and excellent reusability at low cost. Graphical abstract.

Facile HPTLC-densitometric determination of ertapenem and paracetamol in pharmaceuticals and rabbit plasma with pharmacokinetic insights

Simultaneous chromatographic determination of both ertapenem (ERP) and paracetamol (PCL) was achieved for the first time via a new HPTLC-densitometric method. The developed method relied on a simple planar chromatographic separation by mixture of acetonitrile and water (35:15, v/v) and dual-wavelength detection at λmax of both drugs (294 and 247 nm for ERP and PCL, respectively). The Rf values were 0.74 ± 0.05 and 0.88 ± 0.05 for ERP and PCL, respectively. Under the optimized conditions, the linearity range was 40.0–600.0 and 15.0–200.0 ng band−1 for ERP and PCL, respectively with good correlation coefficients (0.9997 and 0.9998 for ERP and PCL, respectively). The LOD were 13.08 and 3.65 ng band−1 for ERP and PCL, respectively. The method validation parameters were in compliance with the international standards. The developed method was enough sensitive and selective for the determination of ERP in the presence of its open beta-lactam ring degradation product, which makes it a suitable stability-indicating method. Consequently, it was successfully applied for pharmaceutical formulation, spiked and real plasma samples of healthy rabbits for real pharmacokinetic studies of ERP and PCL.

Poly (bromocresol green) flakes-decorated pencil graphite electrode for selective electrochemical sensing applications and pharmacokinetic studies

A square wave voltammetric method for selective determination of meropenem (MRP) and ertapenem (ERP) was developed using pencil graphite electrode modified with poly (bromocresol green) (PGE/PBCG). The modified electrode film was characterized by scanning electron microscopy and electro-chemical impedance spectroscopy. Under the optimized conditions, the prepared electrode has good linearity over concentration range 1.0–60.0 and 0.3.0–75.0 μM for MRP and ERP, respectively. The developed method was validated according to ICH guidelines. In addition, the diffusion co-efficients of MRP and ERP were estimated to be 1.24 × 10−6 and 9.09 × 10−6 cm2 s−1, respectively using chronoamperometric technique. The developed method was highly sensitive and selective for the determination of MRP or ERP in the presence of their corresponding open beta-lactam ring degradation products. Consequently, it was successfully utilized for in-vitro and in-vivo applications in spiked and real plasma samples of healthy rabbits for their pharmacokinetic studies. Furthermore, the method was applied for the assay of the available dosage forms of both drugs.

Unraveling the Fate of Lignin from Eucalyptus and Poplar during Integrated Delignification and Bleaching.

Efficient deconstruction of lignocellulose is vitally important for the biorefinery industry because lignin structures play a crucial role in the high value-added conversion of lignin. In this study, an integrated process based on hydrothermal pretreatment (HTP) and Kraft delignification was proposed to deconstruct lignocellulosic biomass. It was found that the HTP not only facilitated the production of xylo-oligosaccharides but also reduced the chemicals dosage of the following delignification. The structural characteristics of lignin obtained from the integrated process were investigated by NMR spectroscopy and gel-permeation chromatography. Additionally, double enzymatic lignins (DELs) isolated from different feedstocks were used as "model lignin" to delineate the structural transformations of lignin during H2 O2 , ClO2 , and O3 bleaching. Significant changes of the lignin structure were observed during the ClO2 bleaching process, including degradation of aromatic rings, enrichment in p-hydroxyphenyl units, and increase of carboxylic groups. A comparison of the structural characteristics of the bleached lignins indicated that HTP benefited the subsequent bleaching process. Enhanced knowledge of lignin chemistry during deconstruction and delignification could provide valuable insight into the current lignocellulose biorefinery.

A New Synthetic Method for Tetraazatricyclic Derivatives and Evaluation of Their Biological Properties

AbstractA new method for the synthesis of tetraazatricyclic compounds by a reaction of benzoyl isothiocyanates with 2‐aminobenzimidazole is presented and a possible mechanism proposed. The new base‐catalyzed degradation of the tetraazatricyclic ring has been carried out. A reaction of benzoyl isothiocyanate with 2‐aminobenzoxazole, however, resulted in the formation of 3‐benzoyl‐1‐(2‐hydroxyphenyl)urea while a reaction with 2‐aminobenzothiazole gave 3‐(1,3‐benzothiazol‐2‐yl)‐1‐(benzoyl)thiourea. Density functional theory computed reaction mechanism for the formation of tetraazaatricyclic compounds is discussed. Biological screening of the compounds against Plasmodium falciparium and HIV‐1 protease showed very little activity but they were moderately active against Trypanosoma brucei with an IC50 of 19.71 μM for 11‐(3‐methoxyphenyl)‐1,8,0,12‐tetraazatricyclo [7.4.0.02,7]trideca‐2(7),3,5,9,11‐pentaene‐13‐thione (4).

Catalytic Oxidative Cracking of Benzene Rings in Water

Efficient degradation of harmful benzene rings in water is indispensable for achieving a clean water environment. We report herein unprecedented catalytic oxidative benzene cracking (OBC) in water ...

Crossflow electrochemical filtration for elimination of ibuprofen and bisphenol a from pure and competing electrolytic solution conditions.

For the first time, a crossflow electrochemical filtration system containing multiwalled carbon nanotubes (MWNTs) blended with buckypaper as a flat sheet dual membrane electrode was investigated for the removal of two contaminants of emerging concern, Ibuprofen and Bisphenol A. Breakthrough experiments revealed that a crossflow configuration could be highly efficient in eliminating both contaminants at applied DC potentials of 2 and 3 V over an extended period, from pure salt electrolyte as well as from synthetic secondary wastewater effluent. The shear flow provided consistent surface coverage resulting in excellent sorption performance. The long residence time of the two contaminants within the membrane (18.3 s) was sufficient enough to allow for almost complete degradation of phenolic aromatic products and quinoid rings and the resulting formation of aliphatic carboxylic acids, which was more evident at a higher applied potential (3 V). The formation of the non-toxic aliphatic carboxylic acids is a clear indication of the superior electrochemical performance of the crossflow mode over the dead-end flow-through system. Moreover, this study provides an in-depth understanding of different factors such as filter surface area and residence time that can greatly affect the removal of the contaminants considered.

Biodegradation of triphenylmethane dye crystal violet by Cedecea davisae.

The present study focuses on the biodegradation of triphenylmethane dye crystal violet (CV) by Cedecea davisae. The degradation of CV was evaluated via ultraviolet absorbance at 254 nm (UV254) and chemical oxygen demand (COD) removal, and the kinetics was used to evaluate the degradation efficiency. Intermediate products were analyzed via UV-vis spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), and high-performance liquid chromatography (HPLC). Results showed that C. davisae was able to decolorize the CV, and the maximum decolorization ratio reached 97%. COD reduction was observed after decolorization, with average removal rates of >90% after 48 h. Moreover, 50% of UV254 can be removed after 14 h. The removal efficiency of CV by C. davisae followed first- and second-order reaction kinetics at temperature ranged from 20 °C to 40 °C and pH 4.0 to 6.0, respectively. By using UV, the peak representing the CV disappeared 14 h after CV decolorization, and the degradation of aromatic and naphthalene rings was attributed to the formation of a new metabolite. The FTIR spectra of metabolites showed that a new functional group of OH, CH, CH2, CH3, NH, CN, CN, or CO was produced. The chromatograms of HPLC recorded at 589 nm at retention time decreased and were not detected following incubation for 8 h by C. davisae.

The Radiostability of Meropenem Trihydrate in Solid State.

The influence of ionising radiation on the physicochemical properties of meropenem trihydrate in solid state was studied for doses of e-beam radiation: 25 kGy and 400 kGy. In the first part of our studies, we evaluated the possibility of applying radiosterilization to obtain sterile meropenem. No changes for meropenem irradiated with a dose of 25 kGy, the dose required to attain sterility, was confirmed in the results of spectroscopic (FT-IR), thermal (DSC, TGA) and X-ray powder diffraction (XRPD) studies. The radiation dose of 25 kGy produces no more than about 1500 ppm of radical defects. The chromatographic studies of irradiated meropenem in solutions did not show any chemical degradation. Moreover, the antimicrobial activity of meropenem irradiated with the dose of 25 kGy was unchanged. Based on the received results, we can conclude that radiostelization is a promising, alternative method for obtaining sterile meropenem. In the second part of the research, meropenem was exposed to e-beam radiation at the 400 kGy dose rate. It was confirmed, that reducing of antimicrobial activity could be connected with the degradation of β-lactam ring and changes in the trans-hydroxyethyl group. Apart from chemical changes, changes in the physical stability of irradiated meropenem (400 kGy) was also observed.

Spectroscopic (IR, Raman, UV\u2013Vis) study and thermal analysis of 3d-metal complexes with 4-imidazolecarboxylic acid

In this work, the spectroscopic (IR, Raman, UV–Vis) and thermal properties of 3d metal complexes with 4-imidazolecarboxylic acid were studied in order to determine the effect of 3d metals [i.e., Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II)] on the electronic structure and physicochemical properties of the ligand. The spectroscopic studies showed that the 3d-transition metals stabilize the electronic system of 4-imidazolecarboxylic acid. Similar results were obtained previously for benzoic and pyridinecarboxylic acids. The complexes synthesized in an aqueous medium were hydrated, as determined by the elemental and thermogravimetric analysis. The complexes of 4-imidazolecarboxylic acid have the general formula: M(C3N2H3COO)x·nH2O where M = Mn, Fe, Co, Ni, Cu, Zn, x = 3 for iron complex, x = 2 for other complex and n = 0–3. Thermogravimetric analysis conducted in oxygen atmosphere showed that the complexes decompose to metal oxides. During the thermal decomposition process carbon monoxide, carbon dioxide and imidazole ring degradation products are released.

Separation of 1,4-Dihydropyridine Derivative and Its Oxidized Form

Derivatives of 1,4-dihydropyridine (DHP) still play an important role in treatment of cardiovascular diseases. Typical degradation of the DHP ring is aromatization to pyridine ring which occurs both chemically and biochemically. It is, therefore, important to have a reliable and robust analytical method for separation of DHPs from their oxidized counterparts. Separation of closely-related substances possessing similar hydrophobicity, such as DHP and its oxidized form, can be challenging on conventional alkyl-bonded sorbents. In this study, an impact of reversed-phase (RP) liquid chromatography conditions on separation of the DHP/Ox pair has been investigated. Initially, a systematic study has been performed on 33 commercial RP columns with mobile phase acetonitrile/water for separation of foridone and its corresponding oxidized form. The retention and selectivity are discussed in view of the hydrophobic-subtraction model. Best separation was found replacing conventional C18 sorbents with ones containing an embedded polar group due to polar interactions. Similarly, application of cyano columns resulted in efficient separation of analytes. Organic modifier of mobile phase (methanol vs. acetonitrile) contributed significantly to separation of foridone from its oxidized counterpart. Separation of six chemically diverse DHPs from corresponding oxidized forms was studied on seven RP columns (traditional C18 sorbent, alkyl sorbent with polar embedded group, two different aromatic phases, pentafluorophenylpropyl sorbent and sorbent with straight chain perfluorohexyl ligand). Both acetonitrile and methanol were applied as organic modifier. It was found that application of alkyl sorbent with an embedded polar group (column Zorbax Bonus RP) or cyano sorbent (column ACE CN) yields clear separation of chemically diverse DHPs from their oxidized forms.

Functional Characterization of Three Specific Acyl-Coenzyme A Synthetases Involved in Anaerobic Cholesterol Degradation in Sterolibacterium denitrificans Chol1S.

The denitrifying betaproteobacterium Sterolibacterium denitrificans Chol1S catabolizes steroids such as cholesterol via an oxygen-independent pathway. It involves enzyme reaction sequences described for aerobic cholesterol and bile acid degradation as well as enzymes uniquely found in anaerobic steroid-degrading bacteria. Recent studies provided evidence that in S. denitrificans, the cholest-4-en-3-one intermediate is oxygen-independently oxidized to Δ4-dafachronic acid (C26-oic acid), which is subsequently activated by a substrate-specific acyl-coenzyme A (acyl-CoA) synthetase (ACS). Further degradation was suggested to proceed via unconventional β-oxidation, where aldolases, aldehyde dehydrogenases, and additional ACSs substitute for classical β-hydroxyacyl-CoA dehydrogenases and thiolases. Here, we heterologously expressed three cholesterol-induced genes that putatively code for AMP-forming ACSs and characterized two of the products as specific 3β-hydroxy-Δ5-cholenoyl-CoA (C24-oic acid)- and pregn-4-en-3-one-22-oyl-CoA (C22-oic acid)-forming ACSs, respectively. A third heterologously produced ATP-dependent ACS was inactive with C26-, C24-, or C22-oic-acids but activated 3aα-H-4α-(3'propanoate)-7aβ-methylhexahydro-1,5-indanedione (HIP) to HIP-CoA, a rather late intermediate of aerobic cholesterol degradation that still contains the CD rings of the sterane skeleton. This work provides experimental evidence that anaerobic steroid degradation proceeds via numerous alternate CoA-ester-dependent or -independent enzymatic reaction sequences as a result of aldolytic side chain and hydrolytic sterane ring C-C bond cleavages. The aldolytic side chain degradation pathway comprising highly exergonic ACSs and aldehyde dehydrogenases is considered to be essential for driving the unfavorable oxygen-independent C26 hydroxylation forward.IMPORTANCE The biological degradation of ubiquitously abundant steroids is hampered by their low solubility and the presence of two quaternary carbon atoms. The degradation of cholesterol by aerobic Actinobacteria has been studied in detail for more than 30 years and involves a number of oxygenase-dependent reactions. In contrast, much less is known about the oxygen-independent degradation of steroids in denitrifying bacteria. In the cholesterol-degrading anaerobic model organism Sterolibacterium denitrificans Chol1S, initial evidence has been obtained that steroid degradation proceeds via numerous alternate coenzyme A (CoA)-ester-dependent/independent reaction sequences. Here, we describe the heterologous expression of three highly specific and characteristic acyl-CoA synthetases, two of which play key roles in the degradation of the side chain, whereas a third one is specifically involved in the B ring degradation. The results obtained shed light into oxygen-independent steroid degradation comprising more than 40 enzymatic reactions.

Green catalytic processing of native and organosolv lignins

Two ways of catalytic depolymerization of native and isolated wood lignins are described: the peroxide delignification of hardwood (aspen, birch) and softwood (abies) in the medium of acetic acid – water over TiO2 catalyst and the thermal dissolution of organosolv lignins (ethanol-lignin and acetone-lignin) in supercritical alcohols (ethanol and butanol) over solid Ni-containing catalysts.The catalyst TiO2 in rutile modification has the higher activity in wood peroxide delignification at 100 °C as compared to TiO2 in anatase modification. The results of kinetic studies and optimization of the processes of peroxide depolymerization of hardwood (aspen, birch) and softwood (abies) lignins in the medium of acetic acid – water over catalyst TiO2 (rutile) at mild conditions (≤100 °C, atmospheric pressure) are compared. The catalyst TiO2 initiates the formation of OH and OOH radicals from H2O2 which promote the oxidative fragmentation of wood lignin. In this case, the peroxide depolymerization of softwood lignin, constructed from phenylpropane units of guaiacyl-type proceeds more difficult than the hardwood lignins, mainly containing syringyl-type units.The solid and soluble products of peroxide catalytic delignification of wood under the optimized conditions were studied by FTIR, XRD, GC–MS and chemical methods. Regardless of the nature of wood the cellulosic products have a structure similar to microcrystalline cellulose. The soluble products mainly consist of monosaccharides and organic acids. Aromatic compounds are present only in a low amount which indicates the oxidative degradation of aromatic rings of lignin phenylpropane units under the used conditions of wood catalytic delignification.The processes of thermal dissolution of acetone-lignin and ethanol-lignin from aspen-wood in supercritical ethanol and butanol over Ni-containing catalyst (NiCu/SiO2, NiCuMo/SiO2) are compared. The composition, structure and thermal properties of organosolv lignins were studied with the use of FTIR, GPC, 1H – 13C HSQC NMR, DTA and elemental analysis.The influence of a composition of Ni-containing catalyst on the thermal conversion in supercritical butanol and ethanol of ethanol-lignin and acetone-lignin was established. The highest conversion of lignins (to 93% wt.) in supercritical alcohols and the highest yield of liquid products (to 90% wt.) were achieved at 300 °C in the presence of catalyst NiCuMo/SiO2.Scheme of green biorefinery of wood based on the use of non-toxic and low-toxic reagents (H2O2, H2O, acetic acid, ethanol, butanol) and solid catalysts (TiO2, NiCuMo/SiO2) is suggested.

A patchwork pathway for oxygenase-independent degradation of side chain containing steroids.

The denitrifying betaproteobacterium Sterolibacterium denitrificans serves as model organism for studying the oxygen-independent degradation of cholesterol. Here, we demonstrate its capability of degrading various globally abundant side chain containing zoo-, phyto- and mycosterols. We provide the complete genome that empowered an integrated genomics/proteomics/metabolomics approach, accompanied by the characterization of a characteristic enzyme of steroid side chain degradation. The results indicate that individual molybdopterin-containing steroid dehydrogenases are involved in C25-hydroxylations of steroids with different isoprenoid side chains, followed by the unusual conversion to C26-oic acids. Side chain degradation to androsta-1,4-diene-3,17-dione (ADD) via aldolytic C-C bond cleavages involves acyl-CoA synthetases/dehydrogenases specific for the respective 26-, 24- and 22-oic acids/-oyl-CoAs and promiscuous MaoC-like enoyl-CoA hydratases, aldolases and aldehyde dehydrogenases. Degradation of rings A and B depends on gene products uniquely found in anaerobic steroid degraders, which after hydrolytic cleavage of ring A, again involves CoA-ester intermediates. The degradation of the remaining CD rings via hydrolytic cleavage appears to be highly similar in aerobic and anaerobic bacteria. Anaerobic cholesterol degradation employs a composite repertoire of more than 40 genes partially known from aerobic degradation in gammaproteobacteria/actinobacteria, supplemented by unique genes that are required to circumvent oxygenase-dependent reactions.

The identification and analytical characterization of 2,2'-difluorofentanyl.

New psychoactive substances (NPS) have expanded their distribution and become widely available in the global market in recent years. The illicit use of fentanyl and its analogs has become an important worldwide concern linked to their high potency and risk of fatal overdose. This study describes the analytical characterization of a new fentanyl derivative N-(1-(2-fluorophenethyl)-4-piperidinyl)-N-(2-fluorophenyl)propionamide (2,2'-difluorofentanyl). Identification was based on ultra-high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UHPLC-QTOF-MS), gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. To our knowledge, this study is the first to report on analytical data for this compound. The most abundant fragment ion in the electrospray ionization (ESI) mass spectrum under collision-induced dissociation (CID) mode was formed by the cleavage between the piperidine ring and the N-phenyl-amide moiety of the protonated molecule. Two diagnostic ions in the electron ionization (EI) mass spectrum were formed by the loss of a tropylium ion (M-91), and by the degradation of the piperidine ring and dissociate of the COC2 H5 moiety altogether, respectively.

Oxidative degradation of benzene rings using iron sulfide activated by hydrogen peroxide/ozone

Mineral pyrites—metal sulfides abundant in the earth's crust—exhibit oxidative ability when exposed to water. This oxidizing ability makes mineral pyrites suitable for the natural and enhanced remediation of environmentally hazardous materials. Herein, we evaluate the benzene ring degradation ability of iron bisulfide activated by H2O2 and O3 and elucidate the corresponding reaction pathways. A set of control experiments was conducted to optimize the reaction conditions, i.e., the FeS2/H2O ratio under aerobic conditions and the H2O2 and/or O3 dosages. Benzene ring was successfully decomposed to CO2 via organic acids even by the simplest FeS2/H2O combination. This process was accelerated by the addition of both O3 and H2O2. The extent of degradation to CO2 increased in the presence of O3, while oxalic acid generation increased in the presence of H2O2. The reaction proceeded via the radicals generated on FeS2/H2O, which is enhanced by O3, and a Fenton-like reaction using the iron obtained from FeS2 dissolution.