Maximum Degradation Rate Research Articles

Peroxydisulfate activation by CuFe2S3 nanocrystal doped C/N catalyst for phenanthrene degradation: Experimental, mechanism, and density functional theory calculation

In Fenton-like reactions, metal-doped catalysts generally have high catalytic activity, but their active sites are always randomly distributed, yielding electron transfer mechanisms between orbitals are difficult to explain. Herein, a CuFe2S3-C/N catalyst was synthesized to activate peroxydisulfate (PDS) for phenanthrene (PHE) degradation. The periodic structure of CuFe2S3 nanocrystals embedded in the C/N skeleton facilitated the cooperation of Fe, Cu, and S, resulting in a more effective degradation of PHE [i.e., maximum degradation rate of up to 93.5% (Initial PHE concentration: 1 mg/L)]. A phenanthrene degradation pathway was then proposed, and the dominant reactive oxygen species were proven to be •OH, SO4•-, 1O2 and O2•-. This pathway was elucidated using density functional theory (DFT) methods, and the negative adsorption energy (-2.05 eV) of S2O82- corresponding to a spontaneous adsorption process. The CuFe2S3 surface stretched the O-O bond from 1.306 to 1.433 Å, and the loss of electrons from the 2p bonding orbital of O atoms led to a lower energy barrier for O-O bond cleavage. Additionally, the electrons were transferred from part of the 3d orbitals of Cu and Fe atoms to the 2p orbital of O atoms in S2O82- and the electron donating capacity of the Cu atom was 3–7 times higher than that of the Fe atom, indicating that the Cu atoms dominated the PDS activation. This study expands on approaches that can be used to modify metal-doped materials to degrade phenanthrene and it contributes towards a clearer understanding of electron transfer mechanisms underlying PDS activation.

Effect of dibutyl itaconate on plasticization efficiency of a REX processed polylactide with peroxides

This work reports the effect of a reactive extrusion (REX) process on polylactide (PLA) based formulations plasticized with dibutyl itaconate (DBI). As DBI contains a carbon-carbon double bond, it is suitable for reactive extrusion. REX was carried out in a co-rotating twin extruder with the addition of two different organic peroxides. The main aim of using REX during the blending of the DBI plasticizer with PLA is to improve the interaction between them so the obtained final properties of the formulations could be improved. Plasticization process allowed to improve the ductile properties of PLA, by using REX, an improvement on the tensile strength was obtained with a no remarkable change in ductility. The thermal characterization also revealed that the glass transition temperature Tg was reduced for all formulations including DBI. REX with DBI provided a slight increase in Tg and this effect was also evident in thermomechanical properties. Regarding the thermal degradation behaviour, the plasticizer reduced the onset degradation and the maximum degradation rate, while a slight improvement on thermal stability was observed by using REX with organic peroxides. Finally, plasticizer migration in water was observed in conventional extruded PLA/DBI formulations, while REX provided improved behaviour against migration.

A Series of Polymer-Supported Polyoxometalates as Heterogeneous Photocatalysts for Degradation of Organic Dye.

Photocatalytic degradation technology has developed rapidly in the treatment of organic pollutants due to its high efficiency, mild reaction conditions and easy control. In this paper, a series of heterogeneous photocatalysts, BWZ-en-R (BWZ = [BW11Z(H2O)O39]7-, Z = Zn, Cd, Mn, en = ethylenediamine, R = Merrifield resin), were prepared by using ethanediamine as a linker to immobilize Keggin-type transition elements substituting tungstoborates on Merrifield resin and characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The photocatalytic properties of BWZ-en-R (Z = Zn, Cd, Mn) for the degradation of methyl red (MR) were investigated. The results show that the BWZ-en-R (Z = Zn, Cd, Mn) photocatalysts exhibited high photodegradation ability for MR under the irradiation of ultraviolet light, and were easily separated from the reaction media. The maximum degradation rate (%) of MR (40 mL, 25 μM, pH = 2) reached 96.4% for the BWMn-en-R photocatalyst (40 mg) after being irradiated for 30 min, making this a promising photocatalyst candidate for dye degradation. Moreover, the influences of some factors, such as the Z-substituted elements in the BWZ, the BWZ-en-R dosage and the MR initial concentration, on the photocatalytic degradation rate of MR were also examined.

Fabrication of mixed matrix nanofibers with electrospraying and electrospinning techniques and their application to gas toluene removal

This study describes the fabrication and characterization of mixed matrix nanofiber air filters having adsorptive and photocatalytic properties. Two fabrication techniques were applied as (i) single electrospinning (SE) and (ii) successive electrospinning and electrospraying (SEE) for doping of photocatalyst (TiO2) in nanofiber structure. Polyacrylonitrile (PAN) was used as main polymer, the nanoclay (NC) was used with ratios of 0.5%, 1.0% and 2.0% (w/w) as nanoadsorbent and TiO2 was used as photocatalytic oxidation agent. TiO2 was integrated to the nanofiber structure with two doping methods (blended in solution and sprayed) providing as same TiO2 mass (0.2 g TiO2/g PAN) in unit area of final nanofiber structure. The water vapor transmission rate (WVTR) values showed a decreasing trend with the addition of NC and varies between 80 and 150 g/m2h. The presence of NC played a critical role in increasing of toluene adsorption capacity of nanofiber from 15% to 40% with increasing of NC amount. The maximum toluene degradation rates of mixed matrix nanofiber were found as 0.09 ppm/min for the NC2.0-TiO2-S coded nanofiber and 0.05 ppm/min for the NC2.0-TiO2 coded nanofiber. The integration of TiO2 to nanofibers with SEE was found as more effective for toluene oxidation than SE. With the electrosprayed TiO2, the contact area of nanofiber is further increased and the UVA light more easily activates TiO2 onto nanofiber. Among all nanofibers, NC2.0-TiO2-S coded nanofiber (doped TiO2 with SEE) is promising for air filter considering its filtration properties in general, as it has high toluene adsorption and oxidation efficiency, good air permeability, 93% particulate matter filtration efficiency and low pressure drop.

Pyrolytic conversion of human hair to fuel: performance evaluation and kinetic modelling.

There are several environmental and human health impacts if human hair waste is not adequately disposed of. In this study, pyrolysis of discarded human hair was carried out. This research focused on the pyrolysis of discarded human hair under controlled environmental conditions. The effects of the mass of discarded human hair and temperature on bio-oil yield were studied. The proximate and ultimate analyses and calorific values of disposed of human hair, bio-oil, and biochar were determined. Further, chemical compounds of bio-oil were analyzed using a gas chromatograph and a mass spectrometer. Finally, the kinetic modeling and behavior of the pyrolysis process were characterized through FT-IR spectroscopy and thermal analysis. Based on the optimized mass of disposed of human hair, 250g had a better bio-oil yield of 97% in the temperature range of 210-300°C. The different parameters of bio-oil were: pH (2.87), specific gravity (1.17), moisture content (19%), heating value (19.34MJ/kg), and viscosity (50 CP). C (56.4%), H (6.1%), N (0.16%), S (0.01%), O (38.4%), and Ash (0.1%) were discovered to be the elemental chemical composition of bio-oil (on a dry basis). During breakdown, the release of different compounds like hydrocarbons, aldehydes, ketones, acids, and alcohols takes place. According to the GC-MS results, several amino acids were discovered in the bio-oil, 12 abundant in the discarded human hair. The FTIR and thermal analysis found different concluding temperatures and wave numbers for functional groups. Two main stages are partially separated at about 305°C, with maximum degradation rates at about 293oC and 400-4140°C, respectively. The mass loss was 30% at 293 0C and 82% at temperatures above 293 0C. When the temperature reached 4100C, the entire bio-oil from discarded human hair was distilled or thermally decomposed.

Study on kinetics of spent FCC catalyst applied to the living waste plastics

AbstractThe thermochemical method is one of the most potential ways to treat waste plastics. In order to reduce the energy consumption of pyrolysis, this study selected spent fluid catalytic cracking (FCC) catalyst as a catalyst for pyrolysis of waste plastics to explore the pyrolysis process of mixed waste plastics (polypropylene (PP)/polyethylene (PE)/polystyrene (PS)). The kinetic calculations show that there was a positive synergistic effect in the co‐pyrolysis of mixed plastics, which was beneficial to the reduction of activation energy. However, the participation of spent FCC catalysts can further reduce the pyrolysis temperature and activation energy of plastics, and increase the thermal degradation rate. Compared with non‐catalytic pyrolysis, the pyrolysis temperature corresponding to the maximum weight loss rate during catalytic pyrolysis was about 12 K earlier, the maximum degradation rate was about 41% higher, and the average activation energy decreased by about 22 kJ/mol. In order to further improve the catalytic efficiency of spent FCC catalysts, the spent FCC catalysts were modified by ball milling or ultrasonic method and then used for plastic pyrolysis. It was found that the modification effect of ball milling method was better than that of the ultrasonic method. Through thermodynamic analysis, it was found that the endothermic reaction occurred in the process of plastic pyrolysis and could not proceed spontaneously. The formed pyrolysis products reduced the disorder of a microscopic system. Combined with the experimental results of this paper, it can provide theoretical support for the catalytic pyrolysis of spent FCC catalysts for mixed waste plastics.

Significant enhancement of photocatalytic activity of g-C3N4/vermiculite composite by the introduction of nitrogen defects

Nitrogen-defect g-C3N4/vermiculite composites (gCVx, x = 0.1, 1, 3, 4) with high efficient photocatalytic performance were constructed by a wet chemical method cooperating with the calcination process, as well as using the pre-expanded vermiculite and the melamine pre-treated by hydrochloric acid solutions of 0.1, 1, 3, 4 mol/L, respectively. Micron-sized g-C3N4 sheets with nitrogen defects were synthesized and uniformly distributed in the gCVx composites. Photocatalytic performance was evaluated by degrading Rhodamine B (RhB) aqueous solution. The results indicated that photocatalytic activities of gCVx increased firstly and then dropped down gradually with the increase of HCl concentration. gCV3 achieved the maximum degradation rate of 97.90 % for RhB after photocatalysis for 20 min, whose degradation rate constant was 14.9 times than that of bulk g-C3N4. gCV3 also exhibited the highest photocatalytic activity toward degrading the tetracycline and phenol solutions. The excellent photocatalytic performance was ascribed to the enhanced amounts of active sites, increased specific surface area, improved visible light absorption ability, accelerated charge transfer and separation efficiency of photogenerated-carriers, which resulted from the synergistic effect between vermiculite and nitrogen defects in g-C3N4, as well as the mutual electrostatic repulsion between the negative-charged vermiculite and the photo-induced electron from the nitrogen-defect g-C3N4.

Microwave irradiation: Reduction of higher alcohols in wine and the effect mechanism by employing model wine

Reduction of higher alcohols contributed more to the aromatic characteristics of wine. In this paper, response surface methodology was used to optimize the parameters of microwave time, temperature, and power to obtain optimal microwave processing conditions for the maximum degradation rate of higher alcohols in model wine solution, and the maximum degradation rate of higher alcohol was 11.21% under optimized microwave conditions of 100 W, 50 °C and 3 min. The possible mechanism of microwave reducing on the higher alcohols was studied at optimized microwave conditions, the results showed that high concentrations of tartaric acid, glyoxylic acid, and ferrous ions could obviously decrease the content of higher alcohols; the content of higher alcohols in low concentrations ethanol and cupric ions was obviously lower than that in high concentration of ethanol and cupric ions; the appropriate (+)-catechin concentration had more obvious effect on higher alcohols content; the mannitol inhibited the degradation of higher alcohols and its subsequent reactions by scavenging free radicals in model wine solution. In summary, all these results could help understand the influence of improvement effect of microwave irradiation on the aromatic characteristics in wine by reducing the contents of higher alcohols.

Aeolian dust distribution, elemental concentration, characteristics and its effects on the conversion efficiency of crystalline silicon solar cells

Exposure of PV modules to ambient environmental conditions like dust deposits, has some deleterious effects on peak power (Pmax) and overall conversion efficiency (η). This study investigates the effect of module height, tilt, and orientation on the rate of dust deposition on the surfaces of PV modules. Consequently, the effect of different dust categories on Pmax and η are investigated. North facing module surfaces are observed to exhibit higher deposition rates in southerly winds. A significant decrease in conversion efficiency of 1.30%, 1.74%, 4.05%, 2.74% and 1.38% after a fortnight are observed in modules installed in five randomly selected study sites. A higher decrease in efficiency on average after a fortnight is observed in sites having traces of anthropogenic particles on dust samples collected from the PV surfaces with minimal effects observed in sites having biogenic and geogenic particles. Abundance of anthropogenic dust particles coupled with mild tilt and leeward orientation led to a higher maximum power and efficiency degradation rate.

Enhanced degradation of tetracycline under natural sunlight through the synergistic effect of Ag3PO4/MIL-101(Fe) photocatalysis and Fenton catalysis: Mechanism, pathway, and toxicity assessment

Here, we show that the adverse environmental and health effects of tetracycline (TC) can be efficiently reduced by encapsulating Ag3PO4 into MIL-101(Fe) to construct a Ag3PO4/MIL-101(Fe) heterojunction composite through advanced oxidation processes, such as Fenton catalysis, photocatalysis, and photo-Fenton catalysis. Notably, the reaction can be driven by natural sunlight and does not require any artificial energy source. Remarkably, the optimal degradation of TC can be achieved under different compositions of the composite system through photocatalysis and photo-Fenton catalysis. For photo-Fenton catalysis, the maximum degradation rate of TC (2.5730 min−1) is achieved when the mass ratio of MIL-101(Fe) to Ag3PO4 in the composite is 5:1, which is 31.65- and 3.12-fold of that in the Ag3PO4 + PDS + Sunlight and MIL-101(Fe) + PDS+ Sunlight catalyst systems, respectively. Moreover, the internal conversion of matrix during photocatalysis and Fenton catalysis processes inhibits the photocorrosion of Ag3PO4 and improves the reusability of the composite. Furthermore, it is found that both radical and non-radical species participate in the TC degradation. Besides, the degradation products and catalytic mechanism of Ag3PO4 and Ag3PO4/MIL-101(Fe) systems are explored. The toxicity evaluation results suggest that the intermediates produced during Ag3PO4/MIL-101(Fe) catalysis have a lower biotoxicity than those produced during Ag3PO4 catalysis. Overall, this work provides an effective strategy to inhibit the inherent photocorrosion of Ag3PO4 and establishes an efficient catalytic system for the treatment of organic-contaminated wastewater under natural sunlight conditions.

Effects of Fe-Co@N-BC anode on degradation of sulfamethoxazole (SMX) in microbial fuel cells

Sulfamethoxazole (SMX), a common antibiotic, is commonly used to treat urinary tract infections and intestine infections caused by sensitive bacteria. Water pollution is exacerbated as a result of its abuse and discharge. The feasibility and advantage of using microbial fuel cells (MFC) to degrade sulfamethoxazole have been proved. However, MFC is limited in wastewater treatment due to low bioelectric catalytic efficacy and expensive electrode costs. In this research, high performance Fe-Co@N/BC anode materials were prepared by bimetal and N doping to improve the electrochemical performance and biocompatibility of the electrodes, and Fe-Co@N/BC anode MFC was applied to the degradation of SMX. The results show that the MFC of Fe-Co@N/BC anode has the lowest internal resistance (144.46 Ω), greatly improves the electrical performance, and the maximum degradation rate of SMX reaches 89.1 %, which is 2.1 times that of a conventional anaerobic reactor. The results show that Fe-Co@N/BC anode has good physicochemical properties and the Fe-Co@N/BC anode MFC reactor can effectively degrade SMX.

Growth of Ag/g-C3N4 nanocomposites on nickel foam to enhance photocatalytic degradation of formaldehyde under visible light

Formaldehyde is a pollutant that significantly affects the indoor air quality. However, conventional remediation approaches can be challenging to deal with low-concentration formaldehyde in an indoor environment. In this study, Photocatalysts of Ag/graphitic carbon nitride (g-C3N4)/Ni with 3D reticulated coral structure were prepared by thermal polymerization and liquid phase photo-deposition, using nickel foam (NF) as the carrier. Experiments demonstrated that when the Ag concentration was 3%, and the relative humidity was 60%, the Ni/Ag/g-C3N4 showed the maximum degradation rate of formaldehyde at 90.19% under visible light irradiation, and the formaldehyde concentration after degradation was lower than the Hygienic standard stated by the Chinese Government. The porous structure of Ni/Ag/g-C3N4 and the formation of Schottky junctions promoted the Adsorption efficiency and degradation of formaldehyde, while the nickel foam carrier effectively promoted the desorption of degradation products. Meanwhile, the degradation rate was only reduced by 3.4% after 16 recycles, the three-dimensional porous structure extended the lifetime of the photocatalyst. This study provides a new strategy for the degradation of indoor formaldehyde at low concentrations.

Sucralose biodegradation and enriched degrading consortia revealed by combining Illumina and Nanopore sequencing

Sucralose has been regarded as an emerging pollutant with growing concerns owing to its environmental persistence and potential risks to ecosystems and human health. However, limited information is currently available regarding its biodegradability and degradation pathway in the environment. In this study, complete and efficient sucralose biodegradation was achieved by enriched consortia seeded with activated sludge. In the enrichments with sucralose as the sole carbon source, 73 % of the total organic carbon was removed with a maximum degradation rate of 3.87 mg sucralose/g VSS·h−1, coupling with the release of three chloride ions of sucralose. Additionally, five biotransformation products, namely TP-409N, TP-373N, TP-357N, TP-455N, and TP-393N, were determined by UPLC-QTOF-MS, and an aerobic sucralose-degrading pathway was proposed. Then, Illumina and Nanopore sequencing were employed to provide a genome-centric resolution of microbial communities, demonstrating that the enriched consortia were dominated by Proteobacteria, Bacteroidota, Chloroflexota, and Planctomycetota. At the species level, over half of metagenome-assembled genomes were potentially affiliated with new lineages, implying that the function of sucralose biodegradation was driven by some novel species (at the genus level). Combined with the network analysis, species from UBA11579 and Polyangiaceae were suspected to be involved in the biodegradation of sucralose. This research evidenced the bacterial biodegradability of sucralose and first demonstrated the sucralose-biodegrading pathway and microbial communities, providing novel insights into sucralose biodegradation in the environment.

Hybrid persulfate/sonocatalysis for degradation of acid orange 7 in the presence of Ag2O/CuWO4 composite: Operating parameters and sonocatalytic mechanism

A series of Ag2O/CuWO4 composite catalysts were constructed and the effects, parameters and mechanisms of their sonocatalytic degradation of acid orange 7 (AO7) and hybrid persulfate/sonocatalysis for degradation of AO7 were studied. Ag2O/CuWO4 composite catalysts were constructed by coprecipitation method. The crystal characteristics, surface element composition, valence state and electrochemical characteristics, etc. of the composite were characterized by relevant instruments. The sonocatalytic process of Ag2O/CuWO4 composite catalyst was studied and optimized. Under the condition of ultrasonic power of 500 W, AO7 solution with initial concentration of 15 mg/L was sonocatalytic degraded for 1 h by Ag2O/CuWO4 (1:10) composite catalyst (adding amount of 1 g/L), and the degradation effect was the best, with the maximum degradation rate of 84.97 ± 2.23%. When persulfate was combined with sonocatalysis, the degradation rate of AO7 continued to increase to 99.01 ± 0.04% after 15 min of reaction. Compared with the single action, it not only improved the efficiency but also improved the effect. The trapping experiment showed that the active substances generated during the sonocatalytic degradation of AO7 by Ag2O/CuWO4 included hydroxyl radical, holes and superoxide anion radical. Based on this, the mechanism of sonocatalytic degradation was proposed. At the same time, Ag2O/CuWO4 composite catalyst showed good stability and reusability for recycling, which has the potential for further industrial development and application.

Hypolipidemic mechanism of Pleurotus eryngii polysaccharides in high-fat diet-induced obese mice based on metabolomics.

In this study, the structure of Pleurotus eryngii polysaccharides (PEPs) was characterized, and the mechanism of PEP on obesity and hyperlipidemia induced by high-fat diet was evaluated by metabonomic analysis. The structure of PEPs were characterized by monosaccharide composition, Fourier transform infrared spectroscopy and thermogravimetry. In animal experiments, H&E staining was used to observe the morphological difference of epididymal adipose tissue of mice in each group. Ultrahigh performance liquid chromatography (UHPLC)-(QE) HFX -mass spectrometry (MS) was used to analyze the difference of metabolites in serum of mice in each group and the related metabolic pathways. The PEPs contained nine monosaccharides: 1.05% fucose, 0.30% arabinose, 17.94% galactose, 53.49% glucose, 1.24% xylose, 23.32% mannose, 1.30% ribose, 0.21%galacturonic acid, and 1.17% glucuronic acid. The PEPs began to degrade at 251°C (T0), while the maximum thermal degradation rate temperature (Tm) appeared at 300°C. The results histopathological observation demonstrated that the PEPs had signifificant hypolipidemic activities. After PEPs intervention, the metabolic profile of mice changed significantly. A total of 29 different metabolites were selected as adjunctive therapy to PEPs, for treatment of obesity and hyperlipidemia-related complications caused by a high-fat diet. These metabolites include amino acids, unsaturated fatty acids, choline, glycerol phospholipids, and other endogenous compounds, which can prevent and treat obesity and hyperlipidemia caused by a high-fat diet by regulating amino acid metabolism, fatty acid metabolism, and changes in metabolic pathways such as that involved in the citric cycle (TCA cycle). The presented results indicate that PEPs treatment can alleviate the obesity and hyperlipidemia caused by a high-fat diet and, thus, may be used as a functional food adjuvant, providing a theoretical basis and technical guidance for the prevention and treatment of high-fat diet-induced obesity and hyperlipidemia.

Investigation of Thermochemical Properties and Pyrolysis of Barley Waste as a Source for Renewable Energy

Energy consumption is rising dramatically at the price of depleting fossil fuel supplies and rising greenhouse gas emissions. To resolve this crisis, barley waste, which is hazardous for the environment and landfill, was studied through thermochemical characterization and pyrolysis to use it as a feedstock as a source of renewable energy. According to proximate analysis, the concentrations of ash, volatile matter, fixed carbon, and moisture were 5.43%, 73.41%, 18.15%, and 3.01%, consecutively. The ultimate analysis revealed that the composition included an acceptable H/C, O/C, and (N+O)/C atomic ratio, with the carbon, hydrogen, nitrogen, sulfur, and oxygen amounts being 46.04%, 6.84%, 3.895%, and 0.91%, respectively. The higher and lower heating values of 20.06 MJ/kg and 18.44 MJ/kg correspondingly demonstrate the appropriateness and promise for the generation of biofuel effectively. The results of the morphological study of biomass are promising for renewable energy sources. Using Fourier transform infrared spectroscopy, the main link between carbon, hydrogen, and oxygen was discovered, which is also important for bioenergy production. The maximum degradation rate was found by thermogravimetric analysis and derivative thermogravimetry to be 4.27% per minute for pyrolysis conditions at a temperature of 366 °C and 5.41% per minute for combustion conditions at a temperature of 298 °C. The maximum yields of biochar (38.57%), bio-oil (36.79%), and syngas (40.14%) in the pyrolysis procedure were obtained at 400, 500, and 600 °C, respectively. With the basic characterization and pyrolysis yields of the raw materials, it can be concluded that barley waste can be a valuable source of renewable energy. Further analysis of the pyrolyzed products is recommended to apply in the specific energy fields.

Thermogravimetric analysis of face mask waste: Kinetic analysis via iso-conversional methods

The surge of face mask waste in response to the global pandemic has proven to be a liability to the environment. Microfibers from plastic constituents of the face mask would cause microplastic pollution in the water bodies. Fortunately, these waste could be converted into renewable source of energy via thermochemical method, i.e. pyrolysis. However, the studies on the thermal decomposition of face masks and their kinetic mechanisms are not well-established. The aim of this paper focuses on the prospects of pyrolysis at low to high heating rates ranging from 10 °C min -1 to 100 °C min -1 , to cater for the slow pyrolysis and fast pyrolysis modes. Following this, the thermal degradation behaviour of the face mask waste was studied via thermogravimetric analysis which determined the single peak temperature degradation range at 218 to 424 °C at 10 °C min -1 , and maximum degradation rate was determined at 172.51 wt.% min -1 at 520 °C, with heating rate of 100 °C min -1 . Flynn-Wall-Ozawa (FWO) and Starink method was employed to determine the average activation energy and average pre-exponential factor of the pyrolysis process of face mask waste. i.e., 41.31 kJ mol -1 and 0.9965, 10.43 kJ mol -1 and 0.9901 for FWO and Starink method, respectively.

SDS-degrading Bacterium Isolated from a Paddy Field

A bacterium capable of degrading sodium dodecyl sulphate (SDS) isolated from a paddy field water is characterized. In this report, we showed that almost complete degradation of SDS was observed in 6 to 10 days when the bacterium was grown on medium supplemented with SDS ranging from 0.75 to 1.75 g/L while higher concentrations showed partial degradation with no degradation was observed at concentrations higher than 2.0 g/L. The SDS-degrading bacterium was partially identified and provisionally named Pseudomonas sp. strain Maninjau1. We also showed that the presence of metal ions such as silver, copper, cadmium, chromium, lead and mercury inhibit the ability of the bacterium to degrade SDS by 50%. Growth kinetic studies show a correlation coefficient value of 0.99 for the Haldane model indicates it fits the curve while a low correlation coefficient value of 0.67 for the Monod model indicates poor fitting. The specific growth rate μ was discovered to rise as the substrate concentration was increased but it reached a peak value followed by a slow decrease indicating substrate inhibition. The calculated qmax or maximum degradation rate was 0.917 h-1 (95% confidence interval or C.I. from 0.664 to 1.171) while the saturation constant Ks or half velocity constant was 0.178 g/L SDS (95% C.I. from 0.089 to 0.266). The inhibition constant Ki was 0.605 g/L SDS (95% C.I. from 0.358 to 0.941). The very high maximum degradation rate obtained in this study indicates that this bacterium can be an efficient agent for bioremediation of SDS especially in soils.

Visible-light-enhanced photocatalytic activity of BaTiO3/γ-Al2O3 composite photocatalysts for photodegradation of tetracycline hydrochloride

A polyacrylamide gel method combined with low temperature sintering technology was developed for fabrication of BaTiO3/γ-Al2O3 composite photocatalysts, which exhibits excellent photocatalytic activity for the degradation of tetracycline hydrochloride (TC-HCl) under simulated sunlight irradiation. The effects of BaTiO3/γ-Al2O3 mass percentages, drug concentrations and pH values on the photocatalytic activity of BaTiO3/γ-Al2O3 composite photocatalysts were investigated. The optimum BaTiO3/γ-Al2O3 mass percentage, drug concentration and pH value are 5 wt%, 50 mg/L, and 6.77, respectively. The maximum photocatalytic degradation rate of BaTiO3/(5 wt%) γ-Al2O3 composite photocatalysts for the degradation of TC-HCl was approximately 16.81 times that of γ-Al2O3. The trapping experiments and reactive oxygen species production experiments proved that reactive hole and hydroxyl radical played major role in drug degradation. The photocatalytic activity enhancement of the BaTiO3/γ-Al2O3 composite photocatalysts came from the defect states in alumina and the interfacial defects between barium titanate and alumina and the high charge transfer and separation efficiency, which resulted from the type II band arrangement structure of BaTiO3/γ-Al2O3. The above results reveal that there is a significant potential application for the BaTiO3/γ-Al2O3 composite as a photocatalyst in the photo-degradation of drugs under simulated sunlight irradiation.

Efficient ZnCr LDH/monoclinic‐WO3 composites for Degradation of Tetracycline under Visible Light

AbstractRecently, efficient removal of antibiotics like Tetracycline (TC) from wastewater is emerging as a crucial problem. However, low adsorption capacity and high cost of photocatalysts limit their utility. In this context, monoclinic tungsten trioxide (WO3) loaded ZnCr layered double hydroxide (LDH) composites (ZnCr‐xWO3 x=10 and 20 %) are prepared by co‐precipitation method and characterized by several techniques viz. X‐Ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman, Photoluminescence (PL), Field‐Emission Scanning Electron Microscopy (FE‐SEM), Brunauer Emmett Teller (BET), Diffuse Reflectance Spectroscopy (DRS) and Dynamic Light Scattering (DLS). The XRD pattern confirms the formation of ZnCr LDH and its composites with monoclinic‐WO3. Bond vibrations and phase transitions were explored with the help of FTIR and Raman spectra. The BET analysis for ZnCr LDH and ZnCr‐10WO3 composite shows surface area as 27.439 m2/g and 47.691 m2/g. The higher photocatalytic performance of the composites formed is due to enhanced specific surface area and better separation efficiency of photo‐generated electrons and holes through conventional class II hetero junction between ZnCr LDH and monoclinic‐WO3. The kinetics studies performed shows better fit for pseudo first order reaction with maximum degradation efficiency and rate constant for ZnCr‐10WO3 (i. e., 86.7 % and 1.5×10−2 min−1).