Small Molecular Acids Research Articles

A facile “one-pot” synthesized CaAl MnO4 LDH with a high loading capacity of oxidants for the sustained oxidation of oxytetracycline in soil

This study aims to address previous issues such as low payload of sustained release materials and excessive consumption of oxidants by developing novel sustained-release oxidation agents. Through a one-pot synthesis method, MnO4- intercalated Ca-Al-layered double hydroxide (CaAl MnO4 LDH) was synthesized with an oxidant payload of 4.82 mmol/g, constituting 53.2 % of the total mass. MnO4- exists in the sustained-release material in two forms: 57 % in free state and 43 % intercalated. The free MnO4- rapidly degrades oxytetracycline (OTC), while the intercalated MnO4- is gradually released from the LDH interlayers through ion exchange and interface dissolution, continuously degrading OTC desorbed from the soil. Additionally, CaAl LDH readily releases Ca2+; the small molecular acids and CO2 generated after OTC degradation will re-fix Ca2+ to form CaCO3, achieving carbon sequestration and enhancing the utilization efficiency of Ca2+. In simulated OTC contaminated soil columns (50 mg/kg) treated with 0.5 wt% MnO4 LDH at a water flow rate of 0.04 ml/min, it was confirmed that the oxidant utilization efficiency of MnO4 LDH was 3.5 times higher than that of the KMnO4 system, removing 99.8 % of OTC within 40 days. This study provides new insights for the design of sustained-release materials and theoretical support for the remediation of organic pollutants.

Sunlight degradation of tetracycline by Z-type BiOI/g-C3N4 photocatalyst synthesized via a simple two-step process: Response surface methods, degradation pathways, toxicity evaluation

A method combining grinding and hydrothermal treatments was utilized to densely load three-dimensional BiOI onto two-dimensional g-C3N4, thereby preparing a BiOI/g-C3N4 photocatalyst with a Z-type heterojunction. Under varying climatic conditions throughout the year, 10%BiOI/g-C3N4 photocatalyst degraded 92.26 % of tetracycline (TC) under sunlight exposure in summer (sunny days) in 150 min, whereas it only degraded 47.33 % of TC under sunlight exposure in winter (cloudy days). The degradation parameters for TC by 10%BiOI/g-C3N4 were optimized using Response surface methods, establishing the optimal conditions for TC degradation (pollutant concentration of 10.94 mg/L, catalyst dosage of 31.34 mg, pH of 4.02), resulting in a degradation efficiency of 95.63 % for TC under the specified conditions. Employing HPLC-MS/MS and 3D EEM techniques, the degradation of TC primarily occurs due to the cleavage of its CC double bonds and CN bonds triggered by free radical attacks, and small molecular acids are produced during the degradation process. The impacts of TC solution treatment on plants were investigated, and the oxidative stress indicators MDA, SOD, POD, and CAT were assessed. The results demonstrated a decrease in all four indicators in plants cultured in TC degradation product solution, further affirming the applicability of 10%BiOI/g-C3N4 in practical scenarios.

Enhancing the photoelectrochemical hydrogen evolution activity of polyaniline through small molecular acid doping to introduce polariton-enhanced active sites

Development of organic polymer photoelectrodes with high surface activity is the key to efficient water splitting for hydrogen production. Polyaniline (PANI) prepared under alkaline conditions has semiconducting properties, but high reaction rates are difficult to achieve due to its poor surface activity. In this study, electrochemical doping was used to introduce small molecular acids (2,3-hydroxybutanedioic acid (TA), 2-hydroxybutanedioic acid (MA), and succinic acid (SA)) containing different numbers of hydroxyl groups into the PANI backbone to form polarizers, dipolarizers and active sites. Density Functional Theory (DFT) shows that small molecular acids interact with the imine (=N-) structure of the PANI backbone via electron cloud stacking to form complex active sites. Meanwhile, the transition from polarons to dipolarons under light conditions increases the polarity of the PANI molecular chain, which further improves the photoelectrocatalytic performance. This study will bring new ideas for efficient photoelectrocatalysis based on organic polymers.

Controllable Synthesis of Defective UiO-66 for Efficient Degradation and Detection of Ozone.

Metal-organic framework (MOF) structures have gained significant attention for their exceptional catalytic performance in ozone degradation, even under high humidity conditions, which is attributed to the presence of unsaturated metal sites (MOF defects). However, the correlation between MOF defects and catalytic ozone remains ambiguous, and a general approach for the controllable synthesis of high-performance MOF structures is currently lacking. Herein, different defective UiO-66 materials with cluster or ligand defects were obtained by precisely controlling small molecular acid modulators. Their catalytic performance can be analyzed in real time through the specific cataluminescence (CTL) signal of ozone at the interface. The presence of ligand defects was found to be crucial for both catalytic degradation and luminescence of ozone, and the CTL signal exhibited a positive correlation with the endogenous hydroxyl group content in the material (R2 = 0.982), while external humidity further supplemented internal water molecules within the material. Furthermore, theoretical calculations were conducted to compare the adsorption behaviors of ozone on the defective UiO-66 under dry/wet conditions, leading to the proposal of two potential reaction pathways. Subsequently, UiO-66-DA with superior catalytic performance was employed to develop a highly efficient CTL sensor capable of accurately detecting ozone (LOD = 23.3 ppb). This study held significant value in elucidating the reaction site of ozone on MOFs and achieving optimal catalytic effects through the careful selection of modulators and humidity levels.

Pyridine-bridged cobalt tetra-aminophthalocyanine to active peroxymonosulphate for efficient degrading carbamazepine

ABSTRACT In this study, each cobalt tetra-aminophthalocyanine (CoTAPc) molecule was immobilised with four isonicotinic acid (INA) molecules by amide bonding, a novel and highly efficient catalyst pyridine-bridged cobalt tetra-aminophthalocyanine (CoTAPc-TINA) was synthesised. The introduction of INA molecules promoted CoTAPc to expose more active sites, and increased the electron cloud density of cobalt ions promoting O–O bond homolysis of PMS to generate more active species, which significantly enhanced catalytic activity. With the pharmaceutical of carbamazepine (CBZ) as model pollutant, 0.1 g/L CoTAPc-TINA in dark in the presence of 0.4 mM PMS, 98.8% CBZ was removed within 10 min. However, under the same conditions the removed of CBZ was only 58.9% by CoTAPc/PMS system. Radical capture experiments combined electron paramagnetic resonance technology demonstrate that hydroxyl radicals, sulphate radicals, superoxide radicals and singlet oxygen are the main active species in the CoTAPc-TINA/PMS system. As the reaction proceeded, all aromatic intermediates were transformed to small molecular acids by these active species. This investigation provided a new insight for application of metal phthalocyanine in wastewater treatment.

Degradation of polyacrylamide (PAM) in aqueous solution by electron beam technology: Efficiency, viscosity reduction and correlation with microstructure of polymer molecules

In this paper, we present a systematic evaluation about degradation of partially hydrolyzed polyacrylamide (HPAM) in aqueous solution by ionizing radiation to find relationship between HPAM decomposition, viscosity reduction and microstructure of polymer molecules. The viscosity of the two HPAM solution declined rapidly from 5.2 to 3.0 mPa s to 1.4–1.2 mPa s with the adsorbed dose of 0.1 kGy, and then reached the level of pure water at 0.5 kGy. The molecular weight declined remarkably from 1.6 × 107 Da to 1.4 × 105 Da (HPAM1) and from 1.2 × 107 Da to 1.1 × 106 Da (HPAM2) at 0.1 kGy. The HPAM solution changed from pseudoplastic fluid behavior to Newtonian fluid after irradiation. Following ionizing radiation, the presence of anion Na+, Ca2+, Mg2+, anions HCO3- and SO42-(1000–5000 mg/L) and surfactant sodium dodecyl sulfate (SDS) (50–100 mg/L) respectively has slight effect on the rate and extent of viscosity reduction, while CO32- and surfactant petroleum sulfonate exhibit a great negative effect on reducing HPAM viscosity. Ionizing radiation is able to destroy the molecular structure and spatial structure of HPAM. Both the C-C backbones and pendant are attacked. It is proposed that the degradation products include ammonium, aliphatic hydrocarbon, small molecular acids and compounds with double-bond. With the absorbed dose of 0.1 kGy, the micelles-like aggregates are broken into small particles by direct microscope observation, while the stretched and coiled molecular strands shrink and curl to form an irregular network from AFM and SEM observation. The chains break into fragment scattered randomly as increasing dose to 1.0 kGy. Both the diameter size and dispersity of HPAM molecules decreased remarkably after irradiation.·OH is the major active species responsible for HPAM degradation and viscosity reduction. This study contributes to a multiscale understanding the mechanism of ionizing radiation-induced degradation of HPAM in aqueous solution.

Efficient elimination of carbamazepine using polyacrylonitrile-supported pyridine bridged iron phthalocyanine nanofibers by activating peroxymonosulfate in dark condition

The monoaminotrinitro iron phthalocyanine (FeMATNPc) is used to connect with isonicotinic acid (INA) for amide bonding and axial coordination to synthetic a unique catalyst FeMATNPc-INA, which is loaded in polyacrylonitrile (PAN) nanofibers by electrospinning. The introduction of INA destroys the π-π conjugated stack structure in phthalocyanine molecules and exposes more active sites. The FeMATNPc-INA structure is characterized by X-ray photoelectron spectroscopy and UV-visible absorption spectrum, and the FeMATNPc-INA/PAN structure is characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The FeMATNPc-INA/PAN can effectively activate peroxymonosulfate (PMS) to eliminate carbamazepine (CBZ) within 40 minutes (PMS 1.5 mmol/L) in the dark. The effects of catalyst dosage, PMS concentration, pH and inorganic anion on the degradation of CBZ are investigated. It has been confirmed by electron paramagnetic resonance, gas chromatography–mass spectroscopy and free radical capture experiments that the catalytic system is degraded by •OH, SO4•− and Fe (IV) = O are the major active species, the singlet oxygen (1O2) is the secondary active species. The degradation process of CBZ is analyzed by ultra-high performance liquid chromatography-mass spectrometry and the aromatic compounds have been degraded to small molecular acids.

Fenton-like reaction of glucose oxidase-glucose@Kaolin coupled with green rust: A framework triggering FeⅣ=O in refractory pollutants degradation

Fenton reaction has been widely applied with fast reaction speed and strong oxidation capacity, but it also has some noticeable defects of acid-alkali reagents over-consumption and strong tendency of H2O2 self-decomposition under high concentration. In order to overcome these shortcomings, this study proposed a green rust/Kaolin fixed glucose oxidase (GR/Glu-Kaolin@GOD) Fenton system. The production of H2O2 from Glu-GOD@Kaolin system was catalyzed by GR to generate oxidizing species and degrade aniline organic wastewater. Results showed that the enzymatic reaction could produce H2O2 at a gradual incremental pace in situ, avoiding active agent quenching and heightening its utilization rate. Furthermore, this system was proved to have an excellent removal effect under neutral and weak-acid conditions, which was superior to the traditional homogeneous Fenton with a narrow pH range. In this study, diversified active substances in the system were detected including hydroxyl radicals, FeIV=O and superoxide radicals, whose real-time degradation contribution changes were calculated and analyzed. On basis of the results, the roles of these active agents and the interactional principles among them were explored. Furthermore, the close correlation between Fe2+ in GR and GlcA and degradation mechanisms upon 3, 4-DMA were set forth in detail. Especially, in the middle and later stage of the reaction, the contribution of FeIV=O, generated through the complexes between Fe(Ⅱ) and GlcA, would continue to increase due to the gradually benign pH environment and FeIV=O gave full play to advantages in decarboxylating those intermediate products containing methyl, etc, which consequently enhanced both the oxidation efficiency and effluent biodegradability. In addition, the optimal operational conditions were determined through response surface data analysis. Moreover, the residual Glu and small molecular acids in the water could be fully exploited as suitable microbial carbon sources, and elevate the efficiency of the subsequent biological treatment.

Enhancing esterification of small molecular acids with alcohols by molten salt hydrates

A novel approach is reported for efficient esterifying low molecular acids with alcohols in molten salt hydrate (MSH) without additional catalyst. A series of MSHs (LiCl, CaCl2, ZnCl2 and ZnBr2) were evaluated for catalytic esterification of chloroacetic acid (CA) with methanol to methyl chloroacetate (MC). The effects of coordination water number also examined. It was found that appropriate coordination water number not only can promote the protonation of the reactant acids, but also enhance the activity of the protons as well as esterification equilibrium towards ester formation. A MC yield of 98.1% with concentration of 92.1% in the organic-phase could be readily achieved after reacting at 80 °C for 2.0 h in CaCl2·4H2O. MSH also demonstrated excellent performance in esterification of other acids (acetic, mercaptoacetic, propionic, n-butyric and levulinic acids) with alcohols (ethanol, n-propanol and n-butanol). After removing portion of the water from MSH, it can be reused without any difficulty. The promotion effects of MSH on the esterification reaction can be categorized to three aspects: (1) accelerating the reaction rate due to the enhanced protonation of the reactant acids and reduction in the hydration degree of the protons; (2) facilitating phase-splitting by virtue of the poor solubility in MSH and thus expelling the formed esters into organic-phase, as a result, boosting up esterification conversions; and (3) promoting the esterification reaction equilibrium owing to the strong hygroscopicity of MSH.Economic analysis shows, compared with the conventional esterification of CA with ethanol, in which organic solvents is used as the water-carrying agent, that esterification in MSH could not only accelerate the reaction rate and strengthen the equilibrium conversion, but also save energy input.

Quality changes and deterioration mechanisms in three parts (belly, dorsal and tail muscle) of tilapia fillets during partial freezing storage

The quality changes in tilapia belly muscle (BM), dorsal muscle (DM) and tail muscle (TM) were studied and the hypothesis of browning of the fillets was revealed during partial freezing. Compared with DM and TM groups, BM samples had higher thiobarbituric acid reactive substances (TBARS) (0.41 mg malondialdehyde eq/kg at 49 d) and K values (61.81% at 42 d) (P < 0.05). The microstructure of the BM group deteriorated most obviously during storage. Therefore, the BM group was considered to be the fastest to oxidize and deteriorate. In addition, 54 different micromolecular metabolites were identified from tilapia fillets by UHPLC-Q-TOF-MS analysis, and there were significant differences in the micromolecular metabolites in the three parts of tilapia. Therefore, proteins and lipids were degraded by the action of enzymes and microorganisms to produce some amines and small molecular acids, leading to the deterioration of the quality of tilapia fillets.

Metabolomics analysis of soymilk fermented by Bacillus subtilis BSNK-5 based on UHPLC-Triple-TOF-MS/MS

Soymilk is an ideal alternative to develop functional soybean foods, and fermentation can effectively enhance the digestibility and nutritional and functional properties of soymilk. In this study, the metabolites changes of soymilk fermented by Bacillus subtilis BSNK-5 were investigated through comparative metabolomics with UHPLC-Triple-TOF-MS/MS. The metabolites were gradually enriched with the extension of fermentation time and stabilized in the fermentation anaphase. In total, 289 differential metabolites were identified as the major chemical components, and they were distributed into 14 categories, mainly involving in three types of metabolites, peptides and amino acids, lipids, and flavonoids. Moreover, the fermented soymilk at 48 h exhibited the highest abundance of metabolites. Based on KEGG analysis, 14 pathways were enriched, associated with 14 specific metabolites, and mainly related to amino acid and lipid metabolism. Thus, BSNK-5 could effectively degrade the macromolecular substances of soymilk into small molecules, synthesize small peptides, small molecular acids, quinones, and isoflavone aglycones to affect the nutritional and functional properties of fermented soymilk. The in-depth analysis of metabolites in BSNK-5-fermented soymilk provides a theoretical foundation for the development of small molecule functional foods in later stages.

Removal of low-concentration nickel in electroplating wastewater via incomplete decomplexation by ozonation and subsequent resin adsorption

Effective removal of low-concentration chelated nickel in electroplating wastewater to meet the strictest discharge standard for nickel less than 0.1 mg/L has long been a challenging task. Herein, a method combining ozonation and resin adsorption was successfully used to remove the initial total Ni concentration of below 10 mg/L at ozone dosage of 8–38 mg/L. It is notable that the nickel complexation was destroyed by ozone while the co-existing organic matters were not completely mineralized. After ozonation, even the common cation-exchange resin can successfully remove the nickel. The fixed-bed adsorption experiment showed that the working capacity of cation-exchange resin for the ozonated wastewater was 1150 bed volume (BV) at the nickel breakthrough point of 0.1 mg/L, much higher than 5 BV without ozonation treatment. Three-dimensional fluorescence and HPLC-QTOF-MS were employed to characterize the change of Ni-complexes during the treatment process. The decomplexation mechanism of Ni-complexes by ozonation and removal mechanism by cation-exchange resins were proposed. After ozonation, the organic macromolecules were degraded into small molecular acids, which could chelate nickel with one carboxyl group and form positively charged complexes. These nickel complexes were readily adsorbed to the cation-exchange resin via cation exchange or complete complexation, enhancing the removal efficiency. Accordingly, ozone oxidation and subsequent resin adsorption are effective for the removal of low-concentration chelated nickel from electroplating wastewater.

Taping into the super power and magic appeal of ultrasound coupled with EDTA on degradation of 2,4,6-TCP by Fe0 based advanced oxidation processes

Chlorophenol is a widely used organic compound, and the environmental and health problems caused by it have being worsened in recent years. This study used 2,4,6-trichlorophenol (2,4,6-TCP) as the target pollutant, and employed ultrasound (US) enhanced zero-valent iron (Fe0)/EDTA/air system (FEA), namely US/FEA, to remove 2,4,6-TCP. The influence of single factor experimental conditions such as EDTA concentration, Fe0 dosage, US power, pH and pollutant concentration on the removal efficiency of 2,4,6-TCP was investigated, and the optimal reaction conditions were determined. The mechanism of reactive oxygen species (ROS) produced by US/FEA was explored. The degradation process and removal mechanism of 2,4,6-TCP in the US/FEA were discussed through the determination and analysis of intermediate products. The results showed that US could continuously activate and renew the Fe0 surface, accelerate its oxidation and corrosion process, and then continuously and stably produce sufficient amounts of Fe2+ and Fe3+. Ultrasonic cavitation effect could reduce the difficulty of O2 activation reaction, and promote the production of sufficient H2O2. The addition of EDTA made the system have a wide range of pH applications, and its performance under neutral and alkaline conditions was also superior. The ROS of US/FEA included ·OH, O2·- and Fe(IV), where Fe(IV) was the main contributor to the removal of 2,4,6-TCP. In addition, the degradation of 2,4,6-TCP had two processes including dechlorination and benzene ring opening. First, 2,4,6-TCP was dechlorinated and degraded into phenol. And then, phenol was degraded into small molecular acids by ring-opening, and finally it was mineralized into CO2 and H2O completely. US/FEA is a promising technology for high-efficiency degradation of organic matter and deep environmental purification.

Tolerance of photo-fermentative biohydrogen production system amended with biochar and nanoscale zero-valent iron to acidic environment

Anaerobic fermentation system is easy to become acidic due to the generation of small molecular acids, which will affect the metabolism of bacteria. Therefore, it is necessary to improve the acid resistance of system. In this work, the tolerance of photo-fermentative biohydrogen production system amended with biochar, nanoscale zero-valent iron (nZVI) and biochar + nZVI to acidic environment was studied. Results showed that additives improved the stability and performance of the photo fermentation. The best increment of biohydrogen from 0 to 286.83 ± 2.77 mL was obtained by adding biochar and nZVI together at the original pH of 4.5. The additive reduced the oxidation–reduction potential and promoted the consumption of acetate and butyrate. At initial pH of 5, 6 and 7, the highest biohydrogen yield of 361.02 ± 10.11, 419.36 ± 10.70 and 382.67 ± 25.08 mL was obtained by adding nZVI, respectively, representing 42%–44.45% increase compared with the control group under the same conditions.

Research on quinoline degradation in drinking water by a large volume strong ionization dielectric barrier discharge reaction system

Quinoline is widely used in the production of drugs as a highly effective insecticide, and its derivatives can also be used to produce dyes. It has a teratogenic carcinogen to wildlife and humans once entering into the aquatic environment. In this study, the degradation mechanism of quinoline in drinking water by a strong ionization dielectric barrier discharge (DBD) low-temperature plasma with large volume was explored. High concentration of hydroxyl radical (·OH) (0.74 mmol l−1) and ozone (O3) (58.2 mg l−1) produced by strongly ionized discharge DBD system were quantitatively analyzed based on the results of electron spin resonance and O3 measurements. The influencing reaction conditions of input voltages, initial pH value, ·OH inhibitors, initial concentration and inorganic ions on the removal efficiency of quinoline were systematically studied. The obtained results showed that the removal efficiency and TOC removal of quinoline achieved 94.8% and 32.2%, degradation kinetic constant was 0.050 min−1 at 3.8 kV and in a neutral pH (7.2). The proposed pathways of quinoline were suggested based on identified intermediates as hydroxy pyridine, fumaric acid, oxalic acid, and other small molecular acids by high-performance liquid chromatography/tandem mass spectrometry analysis. Moreover, the toxicity analysis on the intermediates demonstrated that its acute toxicity, bioaccumulation factor and mutagenicity were reduced. The overall findings provided theoretical and experimental basis for the application of a high capacity strong ionization DBD water treatment system in the removal of quinoline from drinking water.

Treatment of Ni-EDTA containing wastewater by electrochemical degradation using Ti3+ self-doped TiO2 nanotube arrays anode

Ethylene diamine tetraacetic acid (EDTA) could form stable complexes with nickel due to its strong chelation. Ni-EDTA has significant impacts on human health because of its acute toxicity and low biodegradability, thus some appropriate approaches are required for its removal. In this research, a Ti3+ self-doped TiO2 nanotube arrays electrode (ECR-TiO2 NTA) was prepared and employed in electrochemical degradation of Ni-EDTA. The oxygen evolution potential of ECR-TiO2 NTA was 2.6 V vs. SCE. More than 96% Ni-EDTA and 88% TOC was removed after reaction for 120 min at current density 2 mA cm−2 at pH 4.34. The degradation of Ni-EDTA was mainly through the cleavage of amine group within Ni-EDTA and furthermore decomposed it into small molecular acids and inorganic ions including NH4+and NO3−. The electro-deposition of nickel ions at cathode was confirmed by XPS and was greatly affected by the pH of solution. The effects of current density, initial Ni-EDTA concentration, initial pH of solution and HCO3− concentration on Ni-EDTA degradation were investigated. The results exhibited that the ECR-TiO2 NTA had excellent efficiencies in electrochemical degradation of Ni-EDTA. The LSV analysis suggested that Ni-EDTA oxidation on ECR-TiO2 NTA anode and the production of hydroxyl radical (·OH) on the anode played an important role in the removal of Ni-EDTA.

The effects of char and potassium on the fast pyrolysis behaviors of biomass in an infrared-heating condition

During the solar pyrolysis of biomass, the heat transfer of biomass is restrained due to uncontrolled heating area and accumulation effect. So the co-pyrolysis reaction behaviors of biomass and char, and the secondary pyrolysis reactions of biomass under co-pyrolysis situation are worth exploring. The effects of char and potassium on fast pyrolysis products distribution by fully mixing and extruding sample materials under various heating rates (5 °C/s, 20 °C/s, 100 °C/s) and pyrolysis temperature (350 °C, 425 °C, 500 °C) were discussed. The results showed that high temperature was favorable to the release of volatiles, and higher heating rate promoted decomposition of bio-oils into gaseous products. Higher heating rate contributed to the release of O element and the accumulation of C element in bio-char to some extent. The char enhanced the secondary pyrolysis reaction resulting further decomposition of small molecular acids and the conversion of guaiacyl-contained structure into simple phenols and CH4 by demethylation and demethoxylation reaction. The influences of potassium were concentrated in increasing the reactivity of biomass pyrolysis, which promoted the conversion of bio-oils into gas (especially CO2) and the demethylation reaction of guaiacyl at low temperature.

Iron-loaded carbon nanotube-microfibrous composite for catalytic wet peroxide oxidation of m-cresol in a fixed bed reactor.

A kind of novel iron-loaded carbon nanotube-microfibrous composite (Fe2O3-CNT-MF) catalyst is prepared and tested for fixed bed m-cresol catalytic wet peroxide oxidation (CWPO) reaction. Results show that the Fe2O3-CNT-MF can significantly decline the pressure drop of the fixed bed. Higher temperature, lower feed flow rate, higher catalyst bed height, and higher H2O2 dosage are beneficial to m-cresol degradation. Lower pH can also improve m-cresol degradation, but it will cause severe iron leaching. The highest m-cresol removal (over 99.5%) and total organic carbon (TOC) removal (53.6%) can be observed under condition of 2cm bed height, flow rate of 2mL/min, reaction temperature of 70°C, 6g/L H2O2, and initial pH = 1. Meanwhile, the Fe2O3-CNT-MF catalyst shows good stability with less than 10% decrease in m-cresol conversion and 7% decrease in TOC conversion after 24-h reaction and less than 2mg/L iron leaching is observed in all conditions except for strong acid condition. Two probable pathways of m-cresol degradation process are presented. Under most conditions, m-cresol will first be turned into methylhydroquinone, followed by oxidation to p-toluquinone. In basic condition, some m-cresol will first be changed into 4-methylpyrocatechol. These aromatic intermediates will then be oxidized into some small molecular acids and finally be mineralized to CO2 and H2O.

Selective Conversion of Hemicellulose in Macroalgae Enteromorpha prolifera to Rhamnose.

Direct hydrothermal conversion (HC) of macroalgae Enteromorpha prolifera was conducted over the temperature range of 140–240 °C. At 160 °C, monosaccharides and small molecular acids began to generate. A high yield (18.8%) of monosaccharides was obtained at 180 °C, whereas 29.6% of small molecular organic acids was attained at 200 °C. Formic acid (FA) was then employed as a catalyst, which could selectively catalyze the conversion of hemicellulose at low temperature (94.1%, 140 °C). Rhamnose (45.2%) based on the mass of carbohydrates in E. prolifera was produced by the catalysis of 0.7 mL of FA (160 °C, 60 min, 1 g of biomass loading). A low ratio of biomass amount to water was beneficial to the solution of water-soluble components of hemicellulose in E. prolifera to get high yields to monosaccharides. HC showed promise to be an applicable and efficient method in the treatment of E. prolifera with high conversion of carbohydrates.

Bioaugmentated activated sludge degradation of progesterone: Kinetics and mechanism

Progesterone (PGT) is not completely removed in conventional treatment plants, and the processing results may have adverse effects on aquatic organisms. In this study, an effective PGT-degradation bacterium, Rhodococcus sp. HYW, was newly isolated from the pharmaceutical plant and was used to augment degradation of PGT. When grown in a mineral medium (MM) containing a trace amount of PGT (500 μg/L) as the sole carbon and energy source, the results show that 99% of PGT was degraded within 1 h and followed the first-order reaction kinetics. Bioaugmentation of PGT-contaminated activated sludge greatly enhanced the PGT degradation rate (∼91%) and its derivatives degradation rate were also greatly improved (>83%). The process of PGT degradation in non-bioaugmented PGT-contaminated activated sludge (NBS) and bioaugmentation activated sludge with the bacterial consortium(BS) also conforms to the first-order kinetic model. Furthermore, 12 and 11 biodegradation products for PGT in the NBS and BS were identified using HPLC-LTQ-Orbitrap XL™, respectively. Based on these biodegradation products, two degradation pathways for PGT in NBS and BS were proposed, respectively. Comparing the degradation kinetics and metabolites, it was found that BS degrades PGT more rapidly and can further convert PGT to a small molecular acid. Finally, to reveal the probable cause for the differences in the PGT degradation efficiency and products in the NBS and BS.