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Considering the ever-increasing need for efficient wastewater treatment, this study focused on the development of new kraft lignin-based carbon xerogel/zinc oxide (XCL/ZnO w) photocatalysts. The inclusion of the carbon xerogel is expected to cause an improvement in charge transfer throughout the photoactivation process, consequently enhancing its overall photocatalytic efficiency. Characterization shows that the materials developed are composed of both zinc oxide and carbon xerogel. The addition of the lignin-based carbon xerogel caused a significant morphological modification to the composite materials, resulting in a greater specific surface area. Regarding the photocatalytic efficiency, the optimized composite (XCL/ZnO 1.0) displayed superior efficiency to the pure zinc oxide, especially when calcined at 700 °C, with an increase of 20% in the overall photodegradation capacity for the 4-chlorophenol (4CP) molecule. The XCL/ZnO 1.0 also displayed better performance than its tannin counterpart, previously reported in the literature, obtaining a 60% increase in the apparent reaction rate constant. The XCL/ZnO 1.0 also displayed better performance for the simultaneous hexavalent chrome (Cr (VI)) reduction/4CP oxidation reaction. Salinity and system pH had a significant influence on the efficiency of the 4CP photodegradation, as higher values of salinity and lower pHs caused a decrease in the overall efficiency of the process. At last, chronoamperometry and open-circuit potential tests confirmed the superiority of the XCL/ZnO 1.0 over the pure ZnO, highlighting the beneficial impact of the carbon xerogel on the charge transport dynamics of the composite.

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Introducción: Uno de los derivados de los clorofenoles más utilizado en Estomatología, lo constituye el p-clorofenol (4-clorofenol), empleado como agente antibacteriano en la desinfección del conducto radicular durante el tratamiento pulporradicular. Son escasos los reportes científicos sobre sus efectos en la musculatura lisa vascular arterial y la regulación del flujo sanguíneo local. Objetivo: Determinar el efecto del 4-clorofenol sobre el músculo liso vascular de aorta abdominal de ratas Wistar. Material y Métodos: Se realizó una investigación experimental preclínica, utilizando 30 anillos de aorta abdominal (porción superior) obtenidos de ratas Wistar adultas. Las preparaciones de unos 5 mm se colocaron en baño de órganos, registrándose la tensión desarrollada por el músculo liso vascular tras la adición de 4-clorofenol en diferentes concentraciones y durante diferentes intervalos de tiempo. Resultados: El 4-clorofenol, tras la preactivación del musculo liso vascular de anillos de aorta abdominal, indujo relajación del vaso, la que se incrementó durante todo el tiempo de estudio y al aumento de la concentración del medicamento. Existieron diferencias significativas entre los valores de tensión promedios registrados en los diferentes intervalos de tiempo con los de la tensión base inicial. Conclusiones: El p-clorofenol indujo in vitro, relajación del músculo liso vascular de aorta abdominal de ratas Wistar(AU)

Introduction: In Dentistry, p-chlorophenol (4-chlorophenol) is one of the most widely used derivatives of chlorophenols. It is used as an antibacterial agent in root canal disinfection during pulp-radicular treatment. There are few scientific reports on its effects on vascular smooth musculature and the regulation of local blood flow. Objective: To determine the effect of 4-chlorophenol on vascular smooth muscle of abdominal aorta from Wistar rats. Material and Methods: A preclinical experimental research was carried out using 30 abdominal aortic rings (upper portion) obtained from adult Wistar rats. The preparations of about 5 mm were placed in an organ bath, recording the tension developed by the vascular smooth muscle after the addition of 4-chlorophenol at different concentrations and during different time intervals. Results: The results demonstrate that 4-Chlorophenol induced vasorelaxation after the preactivation of the vascular smooth muscle of the abdominal aortic rings, which increased during the entire study time and with increased drug concentration. There were significant differences among average tension values registered at different intervals of time in relation to the initial base tension. Conclusions: It is concluded that in vitro, p-chlorophenol induced relaxation of abdominal aorta vascular smooth muscle in Wistar rats(AU)

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The treatment of industrial waste and harmful bacteria is an important topic due to the release of toxins from the industrial pollutants that damage the water resources. These harmful sources frighten the life of every organism which was later developed as the carcinogenic and mutagenic agents. Therefore, the current study focuses on the breakdown or degradation of 4-chlorophenol and the antibacterial activity against Escherichia coli (E. coli). As a well-known catalyst, pure titanium-di-oxide (TiO2) had not shown the photocatalytic activity in the visible light region. Hence, band position of TiO2 need to be shifted to bring out the absorption in the visible light region. For this purpose, the n-type TiO2 nanocrystalline material's band gap got varied by adding different ratios of p-type CuO. The result had appeared in the formation of p (CuO) - n (TiO2) junction synthesized from sol-gel followed by chemical precipitation methods. The optical band gap value was determined by Kubelka-Munk (K-M) plot through UV-Vis diffusive reflectance spectroscopy (DRS). Further, the comprehensive mechanism and the results of photocatalytic and antibacterial activities were discussed in detail. These investigations are made for tuning the TiO2 catalyst towards improving or eliminating the existing various environmental damages.

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V-doped TiO2 materials (0.01, 0.05, 0.10, and 1.00 nominal atomic %) were synthesized by the sol-gel method and characterized by X-ray diffraction, Raman spectroscopy, UV-visible diffuse reflectance spectroscopy, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and H2-temperature programmed reduction. Two vanadium precursors (vanadyl acetylacetonate and ammonium metavanadate) and three calcination temperatures (400, 500, and 600 °C, with and without air circulation) were assayed. The efficiency of the materials as photocatalysts was studied by the degradation of phenol with UV and visible lamps. The photocatalyst prepared from vanadium acetylacetonate, with a vanadium content of 0.01 nominal atomic %, calcination at 400 °C without air circulation (0.01VTi-400), showed the best performance, reaching 100% and 30% degradation of phenol (50 µM) by irradiation with UV lamps (3 h) and visible lamps (5 h), respectively. To evaluate the efficiency of this catalyst in the degradation of other structurally related compounds, two substituted phenols were selected: 4-chlorophenol and 4-nitrophenol. The 0.01VTi-400 photocatalyst showed to be applicable to the degradation of phenolic compounds when the substituent was an activating group or a weakly deactivating group (for electrophilic reactions). Additionally, the selectivity of 0.01VTi-400 for phenol degradation in the presence of Aldrich humic acid was tested: phenol degradation reached 68% (3 h, UV lamps). The performance of 0.01VTi-400 indicated that it is a promising material for further applications.

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Chlorophenols are inhibitory compounds that can be biodegraded by aerobic granules in discontinuous processes. Many industrial wastewaters are characterized by transient pH variation over time. These pH changes could affect the overall granule structure and microbial activity during the chlorophenol biodegradation. The objective of this research was to evaluate the effects of transient pH variation on the specific degradation rate (q), granule integrity coefficient (IC), and size in sequencing batch reactors treating 4-chlorophenol (4-CP). First, aerobic granules were acclimated for efficient 4-CP degradation (>99%). The acclimated granules consisted of 55.7% of the phyla Proteobacteria and 40.6% of Bacteroidetes. The main bacteria belong to the order Sphingobacteriales (24%), as well as Amaricoccus, Acidovorax, Shinella, Rhizobium, and Flavobacterium, some of which are new genera reported in acclimated granules degrading 4-CP. Then, pH changes were applied to the acclimated aerobic granules, observing that acid pHs decreased to a greater extent the specific degradation rate (67% to 99%) than basic pHs (34% to 80%). These pH changes caused the granule disaggregation but with lower effects on the IC. The effects of pH change were mainly on the microbial activity more than the physical characteristics of aerobic granules degrading 4-CP.

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The aim of this study was to analyze the mechanisms, stoichiometry, and stability of 4-chlorophenol (4CP) biodegradation kinetics by phenol-acclimated activated sludge using open respirometry. While the removal of 4CP was higher than 98%, the removal of chemical oxygen demand (COD) ranged between 69 and 79% due to the accumulation of an intermediate metabolite. The value obtained from respirometric profiles for the stoichiometric ratio of O2 to 4CP (YO2/4CP) was 1.95 ± 0.04 mol of oxygen consumed per mol of 4CP removed. This YO2/4CP value reflected the action of the oxygenases responsible for the first steps of the aerobic oxidation of 4CP. The 4CP degradation activity decreased noticeably when successive pulses of 4CP were added to the respirometer. A mathematical model was developed to represent the aerobic biodegradation of 4CP. The fitted model adequately predicted the oxygen consumption rate, total phenols, and soluble COD concentrations as a function of time. The results presented could help to predict the dynamic of biodegradation of chlorophenols in a biological wastewater treatment system.

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