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A UV-assisted heterogeneous photo-Fenton process based on powder activated carbon (PAC)/Fe3O4 catalyst was investigated to degrade metronidazole (MTZ). Successful uniform synthesis of PAC/Fe3O4 has confirmed by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-Ray spectroscopy mapping (EDX-mapping), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR) techniques. The interaction of five independent variables in the MTZ degradation in the UV + P A C / Fe 3 O 4 + H 2 O 2 photo-Fenton system was optimized by a three-level full-face-centered central composite design (CCD). Proposed model proved to have adequacy and validity in prediction of MTZ degradation (P value < 0.0001 and R2 = 0.9512). Although the desirable pH for MTZ degradation was 3, Fenton-like reaction was ongoing over a wide range of pH. However, at alkaline pH, the process efficiency was more affected by MTZ concentration than acidic pH. MTZ degradation by UV+ P A C / Fe 3 O 4 + H 2 O 2 heterogeneous Fenton system followed the pseudo-first-order model (R2 > 0.95). High stability, reusability, and separation capability of PAC/Fe3O4 were confirmed by EDX and VSM analyses and iron leach investigation. This process could represent the MTZ degradation, DOC, and COD removal efficiencies of 96.12%, 93.67, and 94.87%, respectively. Also, increasing of the AOS value from -0.422 to 0.437 and increasing of the COS value from -0.422 to 3.773 indicate that the MTZ has been highly mineralized and the solution biodegradability has been improved. MTZ degradation intermediates, mechanism, and pathways were proposed. The abundancy of intermediates with m/z < 70 confirmed the strong degradation of MTZ in the photo-Fenton system. [ABSTRACT FROM AUTHOR]

In this paper we find a generalization of the snake lemma and Schanuel's lemma in Hv-modules. We define the isomorph sequences and determine the conditions to split the exact sequences in Hv-modules. Some interesting results on these concepts are given. [ABSTRACT FROM AUTHOR]

The largest class of multivalued systems satisfying the module-like axioms are the Hv -modules. The main tools concerning the class of Hv -modules with the ordinary modules are the fundamental relations. Based on the relation ε* , exact sequences in Hv -modules are defined. In this paper, we introduce the Hv -module M[A] and determine its heart and the connection between equivalence relations ε* M[A] and ε* A . Moreover, we define the M[-] and -[M] functors and investigate the exactness and some concepts related to them. Finally, we prove the five short lemma in Hv -modules. [ABSTRACT FROM AUTHOR]

The use of chemical pesticides in agriculture to increase the quantity and quality of crops ultimately leads to pollution of water and soil resources. The evaluation of parameters that can affect the efficiency of three-dimensional sono-electro-Fenton (3D/SEF) with PAC/Fe 3 O 4 particle electrodes using and SS316/β-PbO 2 anode in 2,4-D degradation, and those parameters were optimized by Taguchi design technique. Different analyses (i.e., Field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), energy-dispersive X-ray spectroscopy mapping (EDX-mapping), vibrating sample magnetometer (VSM), and Fourier Transform Infrared Spectroscopy (FTIR) could approve the fruitful synthesis of PAC/Fe 3 O 4 and SS316/β-PbO 2 anode. By employing LC-MS analysis, the intermediates generated from pollutant degradation were spotted, and degradation pathways was proposed. The pH of the solution (with percentage contribution of up to 39.52%) was as the most effective independent variable on system response. The optimal conditions for removal of 2,4-D were determined to be as follows: 2,4-D concentration = 50 mβL, pH = 3; FeSO 4 = 0.08 mg/250 mL, electrolysis time = 60 min, H 2 O 2 concentration = 0.2 mL/L, current density = 5 mA/cm2, catalyst dose = 5 g/L, and Na 2 SO 4 concentration = 0.3 g/250 mL; in these conditions, removal efficiencies of the 2,4-D, COD and TOC were 96.2%, 92.31% and 86.5%, respectively. Moreover, significant reduction was detected in the biological toxicity of the outlet effluent from the 3D/SEF process. Finally, 2,4-D herbicide was completely degraded using hydroxyl radicals produced by the electrocatalytic process and converted into CO 2 and H 2 O products. Considering obtained results, the wastewater containing pesticides such as 2,4-D herbicide can effectively treated by 3D/SEF process, and it could offer acceptable results. [Display omitted] [ABSTRACT FROM AUTHOR]