Formation of CaCO3 deposits on OMS‐2 surface to synergistically promote peroxymonosulfate activation and organic dyes degradation

The development of green and efficient catalysts for peroxymonosulfate (PMS) activation and organic pollutants degradation has received widespread attention. In this study, the hybrid CaCO₃/OMS‐2 catalysts were prepared by a simple precipitation approach and characterized by X‐ray powder diffraction, N₂ adsorption–desorption, scanning electron microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy and cyclic voltammetry. It was found that deposition of CaCO₃ on OMS‐2 surface can weaken the Mn‐O bond by formation of Ca‐O‐Mn bond. The interactions between CaCO₃ and OMS‐2 significantly enhanced Acid Orange 7 degradation in the presence of PMS with a pseudo‐first‐order kinetic constant of 0.21 min^?1, which was much higher than those of OMS‐2 (0.026 min^?1) and CaCO₃ (0.021 min^?1). The CaCO₃/OMS catalysts were also much more efficient than other reported OMS‐2 hybrid catalysts, and could be performed over a wide solution pH and for other organic dyes degradation. Sulfate and hydroxyl radicals were formed from the oxidation of low valent manganese species by PMS as the active species in the system. This study can provide a simple method for the design of efficient manganese‐based hybrids for wastewater remediation via PMS activation.     

Innovative stability-indicating LC-Corona CAD method for simultaneous determination of assay in Artesunate and Mefloquine hydrochloride fixed-dose combination product

This work describes for the first time a stability-indicating HPLC-Corona CAD method for content determination of Artesunate (AS) and Mefloquine hydrochloride (MQ) in coated tablets 100 + 220 mg (ASMQ) developed by Farmanguinhos-Fiocruz. The chromatographic separation was carried out on two Promosil C18 columns in sequence. Chromatography was done using 0.05% formic acid/acetonitrile (80:20) in gradient at flow rate of 1 mL min^?1, flow 0.6 mL/min for the right pump, and 0.3 mL/min for the left pump (acetonitrile 100%). The temperature was set at 25 °C for the oven and the detection. The elution time of AS and MQ was found to be 40.5 ± 0.5 min and 10.5 ± 0.5, respectively. The method was validated for system suitability, selectivity, linearity, precision, accuracy, and robustness. The forced degradation studies indicated that AS instability is the major trigger for product degradation, especially under heat and oxidative conditions. In conclusion, the method validation was in agreement with ICH guideline Q2(R1) and AOAC acceptance criteria. Our findings prospected the Corona-CAD detector as a quality control solution regarding the challenges of stability-indicating methods for fixed-dose products.     

不同调理剂作用下的污泥生物干化有机质降解研究

为探讨不同调理剂作用下污泥生物干化过程中的有机质降解情况, 分别使用可循环调理剂(T1组)、负载TiO2的可循环调理剂(T2组)、陶粒(T3组)对污泥进行生物干化, 分析各阶段挥发分、E4/E6等常规理化指标, 探究了水解酶类和过氧化物酶活性, 以及相应降解底物蛋白质、脂肪酶、纤维素和木质素等的含量变化. 结果表明, 各组关键酶活性与相应底物降解率呈正相关, 在生物干化前期水解酶类发挥主导作用, 后期过氧化物酶活性逐渐增强. 经生物干化后, T1组木质素、碳水化合物降解程度最高, T2组蛋白质、纤维素降解程度最高, T3组脂肪降解程度最高. 因此, 可循环调理剂对有机质降解促进效果更好, 可作为污泥生物干化调理剂使用, 以促进污泥减量化.     

Temperature-dependent rate coefficients for the gas-phase OH + furan-2,5-dione (C4H2O3, maleic anhydride) reaction

Rate coefficients, k₁(T), for the gas-phase reaction of the OH radical with furan-2,5-dione (maleic anhydride (MA), C₄H₂O₃), a biomass burning related compound, were measured under pseudo–first-order conditions in OH using the pulsed laser photolysis–laser-induced fluorescence method over a range of temperature (283-374 K) and bath gas pressure (50-200 Torr; He or N₂). k₁(T) was found to be independent of pressure over this range with k₁(283-374 K) = (1.55 ± 0.20) × 10⁻¹² exp[(−410 ± 44)/T) cm³ molecule⁻¹ s⁻¹ and k₁(296 K) = (3.93 ± 0.28) × 10⁻¹³ cm³ molecule⁻¹ s⁻¹, where the uncertainties are 2σ and the preexponential term includes the estimated systematic error. The atmospheric lifetime of MA with respect to OH reactive loss is estimated to be ∼15 days. The present results are compared with a previous room temperature relative rate study of the OH + MA reaction, and the significant discrepancy between the studies is discussed; the present results are approximately a factor of 4 lower. It is also noteworthy that the experimentally measured k₁(296 K) value obtained in this work is nearly a factor of 110 less than estimated by a structure activity relationship based on trends in ionization potential. Based in part on a computational evaluation, an atmospheric degradation mechanism of MA is proposed.     

Mixed dye degradation by Bacillus pseudomycoides and Acinetobacter haemolyticus isolated from industrial effluents: A combined affirmation with wetlab and in silico studies

The environment-friendly bacterial strains are used for wastewater treatment due to their high degrading capability and cost-effectiveness. In the present study, we isolated, identified, characterized, and optimized culture condition ( Temperature 35 °C for both, time up to 96 h, pH 7 and 7.5 respectively) of two dye degrading bacteria from industrial effluents. Morphological, biochemical, and molecular identification confirmed those strains as Bacillus pseudomycoides and Acinetobacter haemolyticus. Spectrophotometric methods were used to investigate the dye degradation(single and mixed dye) capability of these two bacteria. These strains were the potential for degrading methylene green (MG), basic violet (BV) and acid blue (AB) dyes. In case of MG + BV, B. pseudomycoides, and A. haemolyticus showed a degradation rate of 74% and 75%, respectively. While degradation was found 75% and 82% for MG + AB combination, 73% and 73% for AB + BV combination, and 80% and 82% for MG + BV + AB combination respectively. Azoreductase enzymes from bacteria are essential for breaking down the azo bond in textile azo dyes. In molecular docking, the binding energy of three docking complexes (protein and MG, protein and BV, protein and AB) were ?6.3, ?6.6, and ?6.8 Kcal/mol, respectively. The binding stability of the docked complexes was ensured by the root mean square deviations (RMSD), solvent accessible surface area (SASA), radius of gyration (Rg) and hydrogen bond in a molecular dynamics simulation study, indicating strong and stable binding. This study revealed that both B. pseudomycoides and A. haemolyticus could decolorize single and mixed dyes efficiently. As a result, both the strains could be used in further research to apply their potentiality in large-scale dye degradation in the future.     

Evaluation of the pattern and kinetics of degradation of adalimumab using a stability‐indicating orthogonal testing protocol

Forced degradation studies are crucial for the evaluation of the stability and biosimilarity. Here, adalimumab was subjected to oxidation, pH, temperature, agitation and repeated freeze–thaw in order to generate all possible degradation products. An orthogonal stability‐indicating testing protocol comprising SE‐HPLC, RP‐HPLC, TapeStation gel electrophoresis, dynamic light scattering (DLS), and functional receptor binding assay was developed and validated. The assay protocol was used for the assessment of the pattern and kinetics of aggregation/degradation of adalimumab. SE‐HPLC and DLS were used to show the formation of aggregates/fragments of adalimumab under nondenaturing conditions. TapeStation electrophoresis was performed under denaturing conditions to reveal the nature of aggregates. Results of the receptor binding assay agreed to those of SE‐HPLC and DLS which indicated that it can be used as an activity‐indicating assay for adalimumab. RP‐HPLC demonstrated excellent selectivity for adalimumab in the presence of its oxidized forms. The kinetics of degradation was studied in each case and the results showed that it followed the first‐order reaction kinetics. Correlation between the results supported the quality assessment of the tested product in industrial and clinical settings. This orthogonal protocol is a useful tool in stability assessment of monoclonal antibodies and a key criterion for the biosimilarity assessment.     

Synthesis of TiO2 on different substrates by chemical vapor deposition for photocatalytic reduction of Cr(VI) in water

TiO₂ loaded on several substrates such as carbon fiber, aluminum plate, silica plate, and glass plate was prepared using the chemical vapor deposition (CVD) method for the photocatalytic reduction of Cr(VI) in water with the presence of ethanol under Ultraviolet (UV) illumination. As‐prepared samples were characterized by X‐Ray Diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), and scanning electron microscopy (SEM). The catalyst with TiO₂ loaded on carbon fiber possessed an extremely large surface area (1,463,91 m²/g), while the other catalysts possessed small surface areas (0.05–0.21 m²/g). The photocatalytic activity of TiO₂ loaded on carbon fiber, which was determined by the conversion of Cr(VI) and the degradation of chemical oxygen demand (COD), was much higher than that of other catalysts. The reusability of TiO₂ loaded on carbon fiber catalyst exhibited almost the same activity as the fresh catalyst. The results indicated that TiO₂ loaded on carbon fiber is feasible for practical application.     

Photo‐induced surface transformations of silica nanocomposites

The photo‐induced, physicochemical surface transformations to silica nanoparticle (SiNP) ‐ epoxy composites have been investigated. The silica nanocomposites (SiNCs) were prepared using a two‐part epoxy system with a 10% mass fraction of SiNPs and exposed to varying doses of high intensity, ultraviolet (UV) radiation at wavelengths representative of the solar spectrum at sea level (290 nm to 400 nm) under constant temperature and humidity. Visibly apparent physical modifications to the SiNC surface were imaged with scanning electron microscopy. Surface pitting and cracking became more apparent with increased UV exposure. Elemental and surface chemical characterization of the SiNCs was accomplished through X‐ray energy dispersive spectroscopy and X‐ray photoelectron spectroscopy, while attenuated total reflectance Fourier transform infrared spectroscopy revealed changes to the epoxy's structure. During short UV exposures, there was an increase in the epoxy's overall oxidation, which was accompanied by a slight rise in the silicon and oxygen components and a decrease in overall carbon content. The initial carbon components (e.g. aliphatic, aromatic and alcohol/ether functionalities) decreased and more highly oxidized functional groups increased until sufficiently long exposures at which point the surface composition became nearly constant. At long exposure times, the SiNC's silicon concentration increased to form a surface layer composed of approximately 75% silica (by mass). Published 2012. This article is a U.S. Government work and is in the public domain in the USA.     

Enzymatic‐ and light‐degradable hybrid nanogels: Crosslinking of polyacrylamide with acrylate‐functionalized Dextrans containing photocleavable linkers

Enzymatically cleavable and light‐degradable hybrid nanogels were prepared by free radical inverse miniemulsion copolymerization of acrylamide (AAm) with a newly synthesized functional dextran crosslinker containing acrylate moieties attached to the backbone via a photolabile linker, that is, dextran‐photolabile linker‐acrylate (Dex‐PL‐A). The Dex‐PL‐A/AAm feed ratio was systematically varied to investigate the influence of the particle composition on the gel properties. The resulting hydrogel nanoparticles were examined with regard to their degradation behavior upon the appliance of the two orthogonal stimuli by turbidity measurements in combination with dynamic light scattering. Although continuous photolytic cleavage of the photolabile linkers between polyacrylamide chains and dextran molecules was found to proceed fast and quantitatively yielding completely disintegrated networks, stepwise irradiation resulted in partial degradation of crosslinking points. Thus, nanogels of a desired specific degree of swelling (DGS) can be obtained by adjusting the irradiation time accordingly. Partial enzymatic cleavage of the dextran backbones of the Dex‐PL‐A crosslinking molecules resulted in an increase in the DGS of the nanogels up to a constant value. Subsequent irradiation of those swollen hydrogel particles was used to fully degrade the network structure in a second step. Hence, a two‐step degradation profile was realized by the combination of the two orthogonal stimuli. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012