Effect Of Different Treatment Processes Research Articles

Effects of different treatment processes on microstructure and tensile fracture behaviour of selected laser melting TC17 titanium alloy

It is essential to study the tensile fracture mechanism of additively manufactured materials and develop the effective process treatment techniques to improve their fracture resistance. In this paper, the effects of different treatment processes on the microstructure and tensile fracture properties of TC17 titanium alloy melted by laser selective zone melting were investigated. The static tensile fracture morphological characteristics were observed by combining SEM and EDS. The metallographic microstructure after chemical corrosion was observed optically. And the tensile fracture morphology of the three states of TC17 titanium alloy samples at room temperature conditions was investigated. The results show that the metallographic matrix microstructure of TC17 titanium alloy after HT, HIP and HIP-HT treatments was a bimodal structure with α+β phases, i.e., β phase was in the form of a net basket, and α phase was in the form of a coarse bar. The grain sizes of the samples treated by different processes were different, but the difference in grain size of the HT-treated tissues was small, and the difference in grain size of the HIP-HT-treated tissues was large. And the coarse α-phase segregation could be seen at the edge of the samples. The 3D-printed materials had complex changes in anisotropic properties affected by the printing structure and tissue. The printed tissues were brittle and had high internal stresses. These problems were partly improved at high temperatures, but they still existed. The HIP-HT-treated materials had a large α+β-phase bimodal structure. The HT-treated material had coarse grains and precipitation phases, poor room temperature plasticity, and improved high temperature plasticity. After HT treatment, the original printing microstructure changed, the strength and plasticity were significantly improved, but the macroscopic printing structure still had a slight influence on the fracture morphology. When HIP treatment temperature was higher, the influence of macroscopic printing structure basically disappeared, but the grain and microstructure grew up, and the strength and plasticity were slightly lower than that of the HT treatment. HIP process basically eliminated the unfused defects of the three-dimensional morphology, and the local weak bonding zone formed.

Physical Simulation of Medium and Low Temperature Rolling of Mg-Li Alloy Sheet

In this paper, LZ91 magnesium-lithium alloy was taken as the research object. At the rolling temperature of room temperature and 453 K, the plane strain compression physical simulation experiment was carried out on the sample with one pass reduction of 15 % and three passes total reduction of 45 %. After each pass of rolling, the sample was annealed at 503 K for 30 min. Then the effects of different treatment processes on the microstructure of LZ91 magnesium-lithium alloy were studied by metallographic microscope, X-ray diffractometer and scanning electron microscope. The results show that under the same strain, the stress of room temperature rolling is larger than that of 453 K rolling; with the increase of annealing passes, the effect of work hardening gradually weakened. With the increase of rolling amount, the original mechanically mixed ' α ' phase and ' β ' phase will deform along the deformation direction, showing a streamline shape. Rolling at 453 K, the diffraction peak of the sample with 45 % total reduction of three passes changes the most.

Abundance, characteristics, and removal of microplastics in different wastewater treatment plants in a Yangtze River Delta city of China

Microplastics (MPs) have become emerging environmental pollutants worldwide. Wastewater treatment plants (WWTPs) are considered to be the major source and sink of MPs in the terrestrial and aquatic environment. The present study has been carried out for Nanjing, a typical Yangtze River Delta city in China. In this work, the abundance and characteristics of MPs were investigated in the influent of four WWTPs, and the removal effect of different treatment processes was studied in the two advanced tertiary treatment WWTPs. In the influent, the abundance of MPs of industrial WWTPs (IWWTPs) was higher than that of municipal WWTPs (MWWTPs), with a dominant size of 38–63 μm. MP shapes were mainly distributed in fragments and fibers, with polymer species of polypropylene (PP) and polyethylene (PE). In the final effluent, MPs were removed by 93.81 % in IWWTPs versus 88.10 % in MWWTPs, which were mainly influenced by the tertiary treatment technology. The tertiary treatment showed significant differences with the removal efficiency of 61.58 % in IWWTPs, equipped with a high-density sediment tank, and 30.40 % in MWWTPs, equipped with a denitrification filter. This study provides comprehensive information about the MPs' characteristics and fate contained in different sewage of WWTPs and analyzes the tertiary treatment effect of MPs, expecting to provide constructive support for the improvement of management strategies in WWTPs technologies.

Migration of rare and abundant species, assembly mechanisms, and ecological networks of microbiomes in drinking water treatment plants: Effects of different treatment processes

Microorganisms play an important role in the degradation of pollutants. However, they also cause problems in drinking water distribution systems, such as pipe corrosion and biofilm growth. The microbial assembly mechanisms and molecular ecological networks associated with different drinking water treatment processes have not yet been clearly analyzed. Therefore, this study investigated the microbiomes of three processes (coal filtration–activated carbon, ozone–activated carbon and UV, and ozone–activated carbon) during different seasons. The results showed that the microbial composition and diversity among the different processes and during different seasons. Water treatment processes had deterministic effects on the microbial assembly process and significantly changed the composition of rare and abundant species, altering the size and modules of molecular ecology networks. Rare species considered as keystone species play important roles in microbial ecology and microbial community construction. Ozone–activated carbon and UV/chlorination decreased the bacterial concentration, increased the deterministic process of microbial assembly, and significantly reduced the size of the network, which is of great significance to microbial control in drinking water. This research broadens our perspectives on the microbial assembly associated with drinking water treatment processes and contributes to ensuring the safe supply of drinking water.

Recovery in oxidation behavior of damaged SiC[sbnd]ZrB2/SiC coating of carbon/carbon composites

Polysiloxane (PSO) was adopted as the matrix of the repair agents, and SiCZrB2 powder was used as the filler, to repair the prefabricated defects on the SiCZrB2/SiC (SZS) coating of carbon/carbon (C/C) composites. The repair agents were brushed on the defect areas and then underwent preoxidation (PR) or heat-treatment (HR) in a vacuum. The effects of different treatment processes on the chemical composition, microstructure of the repair agents, and the oxidation resistance behavior of the repaired coating were investigated. The repaired agents after both processes were pyrolyzed and generated SiOC ceramics, and they were well combined with the original coating. The thermal stability of PSO after preoxidation is poorer than that after heat-treatment, resulting in a weight loss rate of 5.88% after oxidation at 1 500 °C for 270 min, while that of the HR coating is only −0.87%, yet both have been great improvement compared with the unrepaired coating. This work provides an effective and simple approach to repairing damaged coatings for high-temperature applications.

Effects of different treatment processes in four municipal wastewater treatment plants on the transport and fate of microplastics

The behavior of microplastics in wastewater treatment plants has been investigated, but specific effects of treatment process on microplastics' fate are still unclear due to varied analysis methods and regional differences. In this study, four wastewater treatment plants in Ningbo of southeastern China with different treatment processes were selected to investigate transport and fate of microplastics. Based on number of microplastic particles, fibers and fragments were the main microplastics types in wastewater, while synthetic cellulose represented the largest fraction. The dominance of fibers (76.7%–90.0%) and small particle sizes (<2.0 mm, 62.5%–81.5%) in effluents suggested that they escaped easily from the wastewater treatment plants. The abundance of microplastics particles decreased from 78.0 ± 2.9 items/L in influent to 6.0 ± 2.8 items/L in effluent for anaerobic-anoxic-oxic process, 100.0 ± 3.1 items/L to 4.3 ± 3.4 items/L for sequencing batch reactor activated sludge process, 105.0 ± 5.3 items/L to 3.5 ± 2.6 items/L for cyclic activated sludge technology, 65.0 ± 4.3 items/L to 3.0 ± 1.6 items/L for oxidation ditch process. The microplastics removal capacity of primary and secondary treatment processes for four wastewater treatment plants ranged from 83.7% to 96.3%. Application of different tertiary treatment processes (coagulation/flocculation, membrane related technology and disinfection) enhanced microplastics removal to achieve overall removal rate of 92.3%–96.7%. The removed microplastics from the wastewater treatment plants were mainly transferred to sludge (226.1 ± 95.7–896.0 ± 144.0 items/g dry weight). The biological treatment unit played an important role in microplastics removal with rates varying between 86.9%–95.2%, while tertiary treatment reduced daily microplastics emission 1.4 × 108–2.3 × 108 items/day. This study suggests that proper selection of wastewater treatment unit could significantly reduce the emission number of microplastics, which supports an efficient control strategy of microplastics in wastewater treatment plants.

Effect of eco-friendly chemical sodium bicarbonate treatment on the mechanical properties of flax fibres: Weibull statistics

In this work, a chemical treatment with different concentrations of NaHCO3 (sodium bicarbonate) of 5%, 10% and 20% on the surface of the flax fibre for a period of 120 h at room temperature is achieved. The purpose of this study is to observe the effect of different treatment processes on flax fibres, which is to say on its mechanical properties such as strength and strain at fracture and Young’s modulus. An important campaign of the test of more than 480 tests is carried out. Due to the variability of plant fibres, more than 120 samples were tested for each group at a gauge length (GL = 20 mm). The tensile mechanical property values of the flax fibres present a large dispersion of results; this is typical for natural fibres, hence the need for a statistical study. This dispersion has been studied and carried out by means and statistical tools such as the distribution of Weibull at two and three parameters by applying a prediction model to a confidence level at 95% CI and one-way ANOVA analysis of variance.

Impact of Surface Treatment of Flax Fibers on Tensile Mechanical Properties Accompanied by A Statistical Study

In this work, a surface treatment with sodium bicarbonate (NaHCO3) at different concentrations of 4 and 8% is applied to the surface of the flax fiber for a period of 80 hours at room temperature. The purpose of this study is to observe the effect of different treatment processes on the flax fiber, i.e. on its mechanical properties such as: stress and strain at break and Young's modulus. A major test campaign of more than 240 tests is carried out. Due to the variability of the plant fibers, more than 80 samples were tested for each group at a gauge length (GL = 10 mm). The results of the quasi-static tensile tests have a large dispersion which makes it possible to measure the degree of variability in the stress and strain deformation and the Young's modulus of the fiber. This degree of variability has been studied by means and statistical tools such as the Weibull distribution at two.

Ultrasound-assisted adsorption of phenol from aqueous solution by using spent black tea leaves.

This study is conducted to examine the removal of phenol using spent black tea leaves (SBTL) by the process of ultrasound-assisted adsorption. The effect of different treatment processes, i.e., sonolysis, adsorption, and ultrasound-assisted adsorption, was investigated. The morphology of SBTL was studied using a scanning electron microscope (SEM), and the porous structure of the SBTL was identified before phenol was adsorbed onto the adsorbent. FTIR analysis of SBTL after adsorption showed the presence of an aliphatic band of carboxylic acids which depict degradation of the phenol molecule due to ultrasound-assisted adsorption. The experimental results showed that the hybrid process was found more effective for phenol removal (85%) as determined by a spectrophotometer. The optimum conditions of the reaction parameters were found as: phenol conc. = 25mgL-1, pH = 3.5, time = 60min, adsorbent dosage = 800mgL-1, ultrasound power = 80W, and operating temperature = 30 ± 2°C. Chemical oxygen demand (COD) and total organic carbon (TOC) were found to be 78 and 39%, respectively. HPLC studies suggest nonselective oxidation of phenol resulting in by-products such as catechol and hydroquinone and finally carboxylic acids and CO2. In order to find reaction kinetics, different kinetic models, viz. pseudo-first- and pseudo-second-order models, were studied. The best fit to the isotherm models, i.e., Langmuir and Freundlich, was determined. It is concluded that phenol removal by the hybrid process follows the pseudo-second-order reaction kinetics and Langmuir isotherm model. In addition, thermodynamic studies revealed the nonspontaneous and exothermic nature of the phenol adsorption process.

Removal and transformation of effluent organic matter (EfOM) in biotreated textile wastewater by GAC/O3 pre-oxidation and enhanced coagulation

GAC/O3 (ozonation in the presence of granular activated carbon) combined with enhanced coagulation was employed to process biotreated textile wastewater for possible reuse. The doses of ozone, GAC and coagulant were the variables studied for optimization. The effects of different treatment processes on effluent organic matter (EfOM) characteristics, including biodegradability, hydrophobic and hydrophilic nature, and apparent molecular weight (AMW) distribution were also investigated. Compared with ozonation, GAC/O3 not only presented a higher pre-oxidation efficiency, but also improved the treatability of hydrophobic and high molecular weight compounds by enhanced coagulation. After treatment by GAC/O3 pre-oxidation (0.6 mg O3·mg−1 COD and 20 g·L−1 GAC) and enhanced coagulation (25 mg·L−1 Al3+ at pH 5.5), the removal efficiencies of chemical oxygen demand (COD), dissolved organic carbon (DOC) and colour were higher than those for coagulation alone by 17.3%, 12.0% and 25.6%, respectively. Residual organic matter consisted mainly of hydrophobic acids and hydrophilic compounds of AMW<1 kDa, which were colourless and of limited biological availability. The combination of GAC/O3 and enhanced coagulation was proved to be a simple and effective treatment strategy for removing EfOM from biotreated textile wastewater.

Effect of Different Treatment Processes and Preservation Methods on the Quality of Truffles: I. Conventional Methods (Drying/Freezing)

Truffles are one of the major food ingredients of many favorite traditional dishes in the Middle East. Because of their short shelf life, truffles are considered a perishable commodity. Two varieties of local truffles were blanched in 2 or 4% boiling salt (NaCl) solutions for 2 or 4 min or by dry salting and or spraying with 5% vinegar. The treated samples were dried in an oven at 110C or were immediately frozen at -18C and were stored for 1 year. In conclusion, color, texture and flavor were best preserved by blanching in 4% boiling NaCl solution for 4 min. Freezing was superior to dehydration as a preservation method.

The effect of different treatment processes on estimates of radionuclide distribution coefficients in freshwater sediments

Concentrations of several major ions in pore waters, extracted by centrifugation after manipulation in air, were significantly lower than those obtained after similar treatment under a nitrogen atmosphere. These differences are probably due to the oxidation of ferrous sulphide in air, which increases SO 4 in solution. The corresponding reduction in Fe 2+ reduces competition for sorption sites on the solids so that more major cations are sorbed. Even more determinands (major ions and nutrients) showed significantly higher concentrations in samples frozen under air compared to unfrozen samples manipulated in air. In frozen samples, cell rupture probably released additional CO 2 into solution which resulted in higher Ca and alkalinity concentrations. The higher Ca concentrations increased competition for sorption sites with consequent increases in other cations in solution. Frozen and unfrozen samples manipulated under nitrogen showed no significant differences in major ion chemistry due to the large variability between samples. The latter probably results from a variable re-equilibration of CO 2 with CO 2-free nitrogen compared with air containing CO 2. In the samples studied here, k d Sr in frozen samples is likely to be a factor of 2 lower than in unfrozen samples. For Cs, k d Cs could be up to an order of magnitude lower in frozen samples, due to release of ammonia. Hence separation of pore water by freeze-thawing is not a reliable method for in situ k d estimation.