Papers by Keyword: Degradation

Abstract: This paper addresses the study of hydraulic oil degradation, the increase in the number of wear metals, and contaminants in the monitored oil sample during 6 months of operation of an agricultural tractor. In a closed hydraulic circuit, the oil undergoes gradual degradation due to operational influences, which is caused not only by contamination from external impurities but also by the mixing of operational fluids from other attachment devices. Chemical analysis, water content measurements, and ferography were conducted on a sample of HARVELLA TX 10W40 hydraulic oil, which was compared with a sample of new, uncontaminated oil. The condition of operational fluids affects the proper functioning and lifespan of hydraulic circuit components and is one of the diagnostic indicators of their wear. During the operation of the equipment, the mixing of hydraulic oil from the main device and attachment devices occurs, resulting in changes to the operational properties of the fluid. The study compared the state and contamination of the mixed fluid in the tractor's internal hydraulic circuit with the hydraulic fluid applied by the manufacturer in new equipment. The measurement results indicated that during the experiment, no significant contamination of the oil occurred from pollutant elements present in the external environment, and the physicochemical properties of the monitored fluid were not significantly reduced.

Abstract: One of the important issues and tasks to be solved today is how to reduce the negative effects of plastic use on the environment. This study examines the applicability of polyketone with an aliphatic structure, which can be classified in the group of technical plastics, after mechanical recycling. Samples were reprocessed once and five times under identical injection molding conditions to assess degradation and chemical changes. After recycling, UV radiation tests were performed on both virgin and repeatedly reprocessed samples, along with melt flow index measurements. The effects of UV radiation on polymers range from physical changes, such as discoloration, to chemical modifications, including photooxidative degradation. In some cases, both phenomena must be considered during processing. The aim of the study is to detect the changes that have occurred in the unfilled aliphatic polyketone under the influence of UV radiation. Standard injection-molded specimens were stored in a UV chamber for durations equivalent to one to five years of radiation. The resulting changes, including new chemical bond formation, oxidative degradation, and crosslinking, were analyzed using FT-IR spectroscopy and melt flow index measurements.

Abstract: This article investigated the properties and applicability of a composite containing thermoplastic starch (TPS), coffee and straw fiber. Plastics are indispensable in everyday life because these materials are used very widely, e.g. industrial and agricultural use, food packaging, cables, car parts, mattresses, medical devices, household appliances, etc. Although the use of plastics has many advantages, an environmentally conscious approach is increasingly important in modern society and therefore the disadvantageous properties of plastics have also become an issue. On the one hand, they are petroleum derivatives, which are a finite resource, and on the other hand, the life cycle of packaging materials is short. Multiple recycling is also a problem due to the deteriorating quality during recycling. The above two negative properties can be eliminated by using biopolymers, as biopolymers effectively replace single-use petroleum-based packaging products, for which recycling is difficult or impossible from environmental and economic perspectives. The aim of the pilot program was to produce a mixture of biodegradable biopolymers, including starch-based TPS polymers, coffee grounds and straw fiber, and to investigate one of the main indicators of degradable polymer composites, the degradation process by reacting in different pH matrixes (4 different water and 3 different soil-based matrixes) during a period of 0-2 months. The degradation process was analyzed by following mass and shape changes and FT-IR measurements. The applicability of the biopolymer composite was verified, as the decomposition process was proven in an aqueous medium at 72h. We were able to detect the conversion of some chemical bonds through the change of absorbance of carbonyl and CH₂ groups, CH₃ umbrella vibration. The produced mixture is planned to be used in agricultural areas as a raw material for seedling pots, which could reduce the generation of additional waste and, by using fillers, the use of the composite also provides protection against pests.

Abstract: Crude palm oil (CPO) is commonly utilised in processed food items, including cooking oil. Cooking oil is made by heating it at high temperatures and refining it with bleaching earth to remove the sap and brown-red hue. As a result, it can remove β-carotene from CPO, which is no longer physiologically beneficial for human metabolism. This study seeks to eliminate sap and contaminants in CPO by assessing optimal degumming operation model with response surface methodology (RSM) to gain degummed red palm oil (DRPO) at high retaining β-carotene content. The results show that the optimal factors are 70°C heating temperature and 0.4% (v/v) of phosphoric acid concentration, with a β-carotene value was 455.892 ppm. After the degumming process, the physicochemical properties of palm oil remained relatively constant. Group bonds were unchanged since the primary triglyceride component contains C-H and C=O group bonds. The predicted degradation β-carotene model was y = 451.94 - 53.8(X) - 10.99(Y) + 3.61(XY) - 17.23(X²) - 18.56(Y²) by lack of fit 3.47%, X is temperature range, and Y volume range. This quadratic model has function for further degummed reactor design, on range operation variable.

Abstract: The photoactive nanocomposites TiO₂/Sn⁴⁺ with various ratios of Sn⁴⁺ were prepared by a sol-gel method. Their morphology and crystal structure were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The effect of various parameters such as amount of doped Sn⁴⁺ ions, catalyst loading, initial pollutant concentration, pH value, H₂O₂ concentration on photocatalytic degradation performance were analyzed and optimized. The optimal experimental conditions obtained through orthogonal experiments that highest value was obtained at 3%-Sn⁴⁺ doping amount, catalyst dosage 1.5 g/L, initial chemical oxygen demand(COD) concentration 600 mg/L, initial ammonia nitrogen(NH₄⁺-N) concentration 50 mg/L, H₂O₂ 3%, and pH = 8. The photocatalytic degradation rates of NH₄⁺-N and COD reached 87.54% and 75.32%, respectively.

Abstract: This article presents a study of the mechanical behavior of tuffeau, a porous building limestone. Previous studies were focused on using strain gauges for mechanical monitoring with some limited success due to the size and the local nature of the measurement. The Digital Image Correlation (DIC) method has proven to be a valuable tool for noncontact, full-field strain measurements in various materials, including rocks which are natural and heterogeneous materials. After a prior phase of optimization involving texture acquisition and lighting conditions, this paper compares several DIC software programs to achieve consistent results on soft limestone specimens. Once the DIC program is chosen, a focus is made on detecting heterogeneities in the stone specimens. The occurrence of such heterogeneities explains why strain gauge measurement sometimes fails when applied to soft and natural materials.

Abstract: The effect of electrical and thermal treatment on silver nanowire (AgNW) network morphology and its impact on ultraviolet-visible (UV/Vis) and luminescence spectra is reported. The results exhibit that the conductivity enhancing welding of the single AgNWs at connection points changes the network morphology towards an increased proportion of spherical like structures. This inhomogeneity which is particularly noticeable for joule heated films not only gives rise to an inhomogeneous line broadening in absorption and luminescence spectra but also causes a red shift of the surface plasmon resonances in comparison to a non post-treated AgNW network. With increasing inhomogeneity either due to welding or beginning degradation the d-sp interband excitation pathway is especially efficient for the decay of surface plasmons and shows the strong coupling of the corresponding exciting and emitting photons to the surface plasmon excitation.

Abstract: SrTiO_3, or STO, is an intriguing candidate and has been extensively studied for photocatalytic degradation because of its outstanding features. This study purposed to compare and determine the effects of low Mn doping (x= 1% and 3%) on the phase, structural property, and photocatalytic activity of Mn-doped STO (SrTi_1-xMn_xO₃) as a photocatalyst for degrading MB dye. The synthesis performed the co-precipitation method with a sintering temperature of 1000°C for 4 h holding time. The phase and structural properties of the powder samples were characterized using X-Ray Diffraction (XRD) and Fourier Transform Infra-Red (FTIR) instruments. The XRD and FTIR data validated that all Mn-doped STO samples had been successfully fabricated. The photocatalytic activity of STO:Mn 1% and STO:Mn 3% was confirmed by Methylene Blue (MB) dye degradation under UV light. It revealed that the STO:Mn 1% showed better photocatalytic activity than STO:Mn 3%, with the highest degradation percentage of 58.01% at 6 h irradiation.

Abstract: Following the growing interest in monitoring the status, behavior and impact of micropollutants in the environment, a significant area of concern revolves around the degradation of plastics, which is closely associated with a range of environmental risks. The long-term goal is to investigate the degradation process of plastics in an aqueous environment within controlled laboratory settings and analyze the status of degraded particles over a specific period. The proposed methodology, which is the subject of this paper, aims to achieve this objective. Over the period of one year, both conventional and biodegradable plastics are subjected to the combined effects of UV radiation and water motion. This paper presents the design of laboratory setting and experimental setup for conducting the degradation process. Based on its implementation, the degradation process is evaluated including weight loss and conducting microscopic and FTIR analysis of microplastic particles (MP). By gaining a better comprehension of these processes, we expect to be able to effectively mitigate the adverse environmental consequences caused by plastics.

Abstract: Microplastic is the most problematic persistent pollutants in the environment despite of its unique properties for various life application. The objective is to investigate the feasibility and practicability of the nanostructured TiO₂ coupling with noble metal in removal polypropylene (PP) microplastics. The TiO₂ nanowires (NWs) were synthesized by thermal oxidation of Ti foil under various mixed oxidation environments. TiO₂ NWs were successfully grown uniformly and with full coverage over the foil under the condition of ramping in KOH mist and soaking in water vapour at 700 °C for 120 minutes. Heterojunction photocatalyst of Ag/TiO₂ NWs was formed using wet impregnation method. Small quantity of Ag nanoparticles (NPs) was attached onto the TiO₂ nanowires. The photocatalytic efficiency of the synthesized Ag/TiO₂ NWs photocatalyst was tested upon removal of PP microplastic from non-static water bodies under UV irradiation. Coupling Ag NPs with TiO₂ NWs have better photocatalytic performance than those without Ag NPs from the reduction of weight loss and the possibility of presence of carbonyl group.