Water Impurities Research Articles

Revealing the Role of Methylammonium Iodide Purity on the Vapor‐Phase Deposition Process of Perovskites

Vapor deposition processes, well established in the industry, are considered a cost‐effective manufacturing route for large‐area depositions of lead halide perovskites. However, the vapor deposition of perovskites is constrained by its low reproducibility, whereby in particular the evaporation of methylammonium iodide (MAI) is frequently reported as extremely challenging. Herein, the influence of impurities on the evaporation dynamics of MAI is analyzed. It is proved that MAI heated in a high vacuum, depending on the purity, either undergoes a sublimation with a subsequent desublimation or a chemical decomposition with a following reverse reaction, leading to solid MAI in both cases. In situ mass spectrometry enables us to show that low purity MAI containing water and methylammonium phosphite impurities mainly sublimes, which results in a directional and by crystal microbalances traceable evaporation. In contrast, high purity MAI sublimes at higher temperatures and tends to form decomposition products such as methylamine and hydrogen iodide, which omnidirectional diffuse and can react with lead iodide to perovskite. The findings reveal the reason for the reported challenges, serve as a guideline for future material selections, and can enhance the reproducibility of the evaporation process to achieve a more controlled solar cell fabrication.

TAJDĪD MAFHŪM AL-MĀ AL-MUṬLAQ FĪ AL-SIYĀQ AL-MU’ĀṢIR (DIRĀSAH MUQĀRANAH BAINA FUQĀHA AL-MAẒĀHIB WA AL-MU’ĀSHIR FI ḌAUI AL-TAṬHĪR BI AL-ISTIHĀLAH)

The development of science and technology at the present time in the treatment of water has affected the understanding of the meaning of water and the provisions of its use in jurisprudence, which led to a change in the meaning of absolute, pure and purified water. If the mazhab scholars discuss the status of water that consists of absolute water, used water, mixed water and impure water without any expansion of the return of the water status to the absolute state through unnatural processes, then contemporary scholars seek to expand the status of water to become absolute, pure and purified by an unnatural process. This research uses the library studies method with a comparison between the mazhab scholars and contemporary scholars in understanding absolute water, and uses an analytical framework based on the theory of Istihālah in the process of recycling or distilling water. The results of the study indicate that there are efforts to renew and expand the form of absolute water by contemporary scholars through the process of Istihālah, so that the water that was used, or impure water, sewage or waste, becomes absolutely pure and purified water again, if it goes through a hydrological process. The renewal and expansion of the meaning of the absolute is a creative effort and a kind of contemporary jurisprudence that goes in line with the spirit that jurisprudential rulings are constantly evolving within the framework of accommodating the development of science and technology.

CO2 Electroreduction in Organic Aprotic Solvents: A Mini Review

An annual increase of CO2 concentrations in the atmosphere causes global environmental problems, addressed by systematic research to develop effective technologies for capturing and utilizing carbon dioxide. Electrochemical catalytic reduction is one of the effective directions of CO2 conversion into valuable chemicals and fuels. The electrochemical conversion of CO2 at catalytically active electrodes in aqueous solutions is the most studied. However, the problems of low selectivity for target products and hydrogen evolution are unresolved. Literature sources on CO2 reduction at catalytically active cathodes in nonaqueous mediums, particularly in organic aprotic solvents, are analyzed in this article. Two directions of cathodic reduction of CO2 are considered—nonaqueous organic aprotic solvents and organic aprotic solvents containing water. The current interpretation of the cathodic conversion mechanism of carbon (IV) oxide into CO and organic products and the main factors influencing the rate of CO2 reduction, Faradaic efficiency of conversion products, and the ratio of direct cathodic reduction of CO2 are given. The influence of the nature of organic aprotic solvent is analyzed, including the topography of the catalytically active cathode, values of cathode potential, and temperature. Emphasis is placed on the role of water impurities in reducing CO2 electroreduction overpotentials and the formation of new CO2 conversion products, including formate and H2.

Assessment of mine water solid phase impact on section pumps performance in the development of kimberlite ores

Despite innovations in ALROSA’s (PJSC) mining and processing complexes under the updated strategy for economic development, practice shows that in recent few years the operating costs of the section pumps at the Udachny underground mine’s main drainage have increased significantly. Such an increase could be the result of a concentration of mechanical impurities in the mine water. This study is aimed at the integrated assessment of the impact of mechanical impurities concentration in mine water on the performance of the Udachny underground mine’s main drainage section pumps. It is also aimed at studying the feasibility of sinking additional inclined clarifying working-reservoirs. The target goal was achieved by means of visual, analytical, statistical, and other types of research in determining the impact of the concentration of mechanical impurities in mine water on the performance indicators of section pumps of the kimberlite mine’s underground drainage facilities. The integrated studies showed that the concentration of mechanical impurities in mine water is the key factor in determining the overhaul life and electricity demand of pumping equipment. The Udachny underground mine’s main drainage section pumps overhaul life can be calculated as a linear function of their delivery rates at the moment of taking-down for overhaul. This function is reliably described by empirical expression Q = –7.5X6 + 326.67, where X6 is the averaged mechanical impurities concentration in the mine water. Calculations showed that reducing the concentration of mechanical impurities in mine water from 17 to 4 g/l would decrease the annual operating costs of the Udachny underground mine’s main drainage section pumps by 100 million rubles.

Insights into the Origins of Minority Carrier Traps in Solution‐Processed Organic Semiconductors and Their Effects on Transistor Photostability

AbstractMinority carrier traps in the bandgap of organic semiconductors (OSCs) are pervasive and of vital importance in determining the performance and stability of the optoelectronic device. Understanding their origins is one critical issue at both the fundamental and applied levels. However, relevant research has rarely been performed due to the lack of an effective strategy for quantitatively assessing the minority carrier traps buried in OSCs. Here, organic field‐effect transistors (OFETs) operated under strong and long‐term light illumination can be used as a model device to assess the amount of minority carrier traps in solution‐processed OSCs, are proposed. Based on the experimental results and theoretical calculations, first identified hydrated impurities (water and oxygen) in the residual organic solvents primarily contribute to formation of minority carrier traps within the OSC bandgap, giving rise to photo‐induced electrical instability of OFETs. To address this problem, a molecular additive strategy is developed to improve the OFET photostability by releasing trapped electrons from the levels of minority carrier traps. This work not only elucidates the significant role of water and oxygen in the residual organic solvents in forming minority carrier traps but also provides guidelines for improving OFET photostability for practical applications.

Chemical Composition, Antioxidant and Antimicrobial Activity of Some Types of Honey from Banat Region, Romania.

Honey is a natural product with multiple health benefits. The paper presents the chemical characterization and the antioxidant and antimicrobial potential of ten types of honey (knotweed, linden, wild cherry, acacia, honeydew, oilseed rape, sunflower, phacelia, plain polyflora and hill polyflora) from the Banat region, Romania. We studied the water content, dry matter, impurities, acidity and pH of honey. We also determined the content of reducing sugar, minerals and flavonoids and the total phenolic content. All honey samples analysed showed good nutritional characteristics according to the standard codex for honey. From the analysis of the mineral content of the honey samples, we observed a variability in the macro and microminerals, influenced by the botanical origin, ranging between 0.25% (wild cherry honey) and 0.54% (honeydew). The toxic metals’ (Cd and Pb) levels met the standard for almost all samples analysed except for knotweed. The flavonoid content of the samples ranged from 9.29 mg QE/100 g for wild cherry honey to 263.86 mg QE/100 g for linden honey, and for polyphenols between 177.6 mgGAE/100 g for acacia honey and 1159.3 mgGAE/100 g for honeydew. The best antioxidant capacity was registered in the case of linden honey (79.89%) and honeydew (79.20%) and the weakest in acacia (41.88%) and wild cherries (50.4%). All studied honey samples showed antimicrobial activity, depending on the type of honey, concentration and strain analysed. The novelty of this study is given by the complex approach of the study of honey quality, both from the perspective of chemical attributes and the evaluation of the antimicrobial potential on specific strains in correlation with the botanical and geographical origin of the analyzed area.

ASSESSING THE PERFORMANCE OF UNITS FOR THE SYNTHESIS OF OLIGODYNAMIC SOLUTIONS FOR WATER TREATMENT

Introduction: Fresh water suitable for water supply has been depleted due to production activities. Thus, closed water supply cycles are required at civil infrastructure facilities. The quality of water must meet the requirements on its use for various purposes. It is common knowledge that water is essential in providing adequate health and sanitary conditions for the public. Therefore, issues of water treatment remain in the focus of researchers. Water disinfection is one of the mandatory methods used in water purification and treatment. Currently, chlorination is still the main technology for water disinfection. However, it is responsible for toxic, carcinogenic, and other types of negative effects on the human body. In this paper, we consider the use of oligodynamic solutions as a new, rapidly-developing direction in water treatment. In the course of our study, we addressed a method of swimming pool water disinfection using units of oligodynamic synthesis and examined the results of treated water quality analyses. Methods: The study was based on the statistical analysis of water quality indicators in pools with water treated with silver and copper ions. The analysis made it possible to determine the hygienic safety and reliability of products. To assess hygienic safety and reliability, we analyzed the composition and properties of the product (oligodynamic solution) as well as the composition and concentration of impurities in pool water and determined if the disinfecting properties of water are preserved and proper levels of copper and silver ions (not exceeding MAC) in pool water are maintained. Results: The paper provides a rationale for procedures to analyze and determine the safety and reliability of small-scale units producing disinfection solutions to ensure optimal swimming conditions in swimming pools. Discussion: The obtained results indicate that it is expedient to apply oligodynamic water treatment to ensure the hygienic safety and reliability of swimming pools. The technology suggested fully meets the requirements of sanitary regulations on water quality.

Evaluation of Two Methods of Extracting Essential Oils from Citrus maxima

Essential oil from Citrus maxima was extracted by steam distillation and solvent extraction. The organic solvent extraction method achieved a 28.5% increase in efficiency compared with the steam distillation method. TD1 essential oil had a strong smell, mixed with water and other impurities (wax, resin...). In contrast, TD2 essential oil was fragrant due to its high essential oil content. The chemical composition of TD2 was more than TD1. The main components of essential oils such as pinene, limonene, phellandrene, ocimene, linalool, anethole, eugenol, zingiberene, nerolidol, etc. were kept intact, not denatured, without impurities.
 Keywords: 
 Citrus maxima, Oil, steam distillation, solvent extraction, GC-MS.

THE SYSTEM OF PRELIMINARY DISCHARGE OF RESERVOIR WATER ON DEPOSITS

Abstract. Kazakhstan is one of the world's largest oil-producing regions. Among the explored and exploited deposits, the largest are Tengiz, Zhanazhol, Karachaganak, Uzen, Zhetybay, Kalamkas, Kumkol and a number of others. The extracted oils are very diverse in terms of their physical and chemical properties, the content of asphaltenes, resins and paraffins. Many of them contain significant amounts of carbon dioxide, sulfur and its compounds. Kazakhstan has extensive experience in the development, development and operation of such deposits and monitoring the associated environmental impact. It can be generalized and used in the further development of the industry. The composition of the products of all deposits is unique and is the determining element in the choice of technological schemes for its collection and preparation. Methods for increasing the depth of preparation, efficiency and reliability have been sufficiently studied, but due to changing requirements and existing achievements, the arrangement work is always creative in nature, and the technological solutions made are becoming more perfect. Water is the only component of well production that has natural contact with oil and must be returned to the natural environment. Waste waters include formation waters that are separated at almost all stages of oil treatment, and flushing waters introduced for desalting and final dehydration of oil. Before injection into the absorbing reservoir, they must be cleaned. To prevent the formation of stable emulsions, solid deposits and suspensions, a system of preliminary water discharge at the fields has been proposed. To intensify the processes of separating gas, water and mechanical impurities and gas from drained water, preserve the light, most valuable hydrocarbon components of oil, prevent oil and gas losses and environmental pollution, it is proposed to introduce a three-product multihydrocyclone into the system of preliminary formation water discharge at the fields. To intensify the processes of separating gas, water and mechanical impurities and gas from drained water, preserve the light, most valuable hydrocarbon components of oil, prevent oil and gas losses and environmental pollution, it is proposed to introduce a three-product multihydrocyclone into the system of preliminary formation water discharge at the fields. At the same time, the water quality improves to values suitable for injection into injection wells without additional treatment.. Keywords: oil and gas condensate field, reservoir water, emulsion, demulsifier, three-product multi-hydrocyclone, oil, gas, intensification, mechanical impurities, centrifugal pumps, water discharge, gravitational forces, desalination, dehydration, oil treatment.

To study the dfferent sorces of water and its qualities with health perspective

Water is a life. Drinking water is very important to stay healthy. In Ayurveda different sources of water are described, among them divya jal-rain water is considered as very pure. In India we consider river as a Goddess. Himalaya, Himalayan Rivers are considered as holy. Clean, pure, sweet, light, satisfying, tridosha balancing, strength giving water is considered as pure and holy. Water from late monsoon rain water, autumn rain water, big lakes, upper Himalaya river water, and fountain water is considered as pure. Impure water we can identify with our five sense organs. Sun rays, air, fire, are methods to purify water. Katak is a herb which purifies water by sedimentation of dirt.to flavor water different herbs and spices are used. Properties of water changes according to its origin, land, soil and season.

Impact of impurities on vivianite crystallization for phosphate recovery from process water of hydrothermal carbonization of kitchen waste

Crystallization of vivianite is a sustainable way to recover phosphate from process water of kitchen waste hydrothermal carbonization (HTC). This study investigated impact of organic and inorganic impurities in HTC process water on vivianite crystallization and approaches to reduce their negative impact. Results showed that acetate, bovine serum albumin and humic acid reduced the phosphate removal and inhibited the vivianite crystallization. Ca and Mg triggered competing precipitations and reduced the vivianite purity while carbonate reduced the phosphate removal and the vivianite purity. In addition, negative effects of furfural and suspended solids on vivianite crystallization could be ignored. Increasing Fe(II)/P ratio rather than increasing pH minimized the negative effects of impurities on vivianite crystallization in real process water. The phosphate removal reached 98.2% when the Fe(II)/P ratio increased to 2 at pH 6. Therefore, it is technical-feasible to recover phosphate from HTC process water through vivianite crystallization.

Knowledge, perceptions, and practices of deworming and parasitic disease control activities among peri-urban livestock keepers in Barishal district, Bangladesh

Background: Bangladeshi farmers are not getting optimum outcomes from livestock farming due to various obstacles in farming, including a lack of modern technological and scientific knowledge. Therefore, this research was aimed at comprehending the knowledge, perceptions, and practices of deworming and parasitic disease control activities among peri-urban livestock farmers in the Barishal district of Bangladesh. Methods: Data on the knowledge, perceptions, and practices of deworming and parasitic disease control activities of 207 peri-urban livestock farmers were collected randomly from different areas of the Barishal district. A pre-tested questionnaire was administered via a face-to-face interview between June 2020 and December 2020 to collect data. The frequencies were expressed in percentage (%) and the association between farmer’s education and knowledge of parasitic disease prevention, control, and deworming activities were evaluated by crosstab analysis in IBM SPSS software (version 25). Results: The study revealed that 27.5% of the farmers provided impure water to their animals. Almost 100.0% of farmers were found to wash their hands before and after contacting the animals. About 29.0% of farmers were not accustomed to cleaning the farms and excreta regularly. Only 18.8% of respondents permitted their animals to co-graze with other animals. Approximately 45% of participants used anthelmintics regularly, and 32.4% of participants were informed of the scheduled deworming practices for their animals. Surprisingly, 96.6% of respondents never participated in deworming and parasitic disease control training programs. However, 100% of farmers agreed that parasitic disease control is essential for profitable farming and increasing production. Conclusion: A large proportion of farmers rear their livestock without deworming practices, and they are not aware of helminthiasis control and prevention. Therefore, intensive extension work is needed to educate them on helminthiasis and deworming activities.

Insights into the formation mechanism of hard sludge on the secondary side of PWR steam generators

• Mixtures of alumina, silica and magnetite have been aged in hydrothermal conditions. • Kaolinite has been identified as a cement binding the magnetite particles. • In presence of metallic iron, iron silicate precipitates. In the secondary circuit of nuclear Pressurized Water Reactors, corrosion products and impurities lead to the formation of undesirable hard deposits, called hard sludge, on the tube sheet of steam generators. Theses deposits are mainly composed of iron (magnetite), alumina and silica. The formation of hard sludge piles is investigated by reproducing the reaction of precursor oxides in the conditions of the steam generator (275 °C, 58 bar). Mixtures of magnetite, γ-alumina and amorphous silica in binary or ternary systems in an alkaline ethanolamine-ammonia solution at pH 25°C = 9.6 are studied. Carbon steel was tested as an alternative source of iron. The analysis of the evolution of the suspensions, completed by the industrial feedback, allows to explain the process of hard sludge formation in the steam generators. The following sequence is proposed: sedimentation of magnetite/confinement of the interstitial fluid/concentration of aqueous species such as aqueous silica and alumina/sorption of Al on magnetite and/or growth of boehmite/reaction with aqueous silica to form kaolinite as a resistant cement. Once formed, the kaolinite cement tends to densify over time while magnetite is passive. The absence of Fe-phyllosilicates predicted by thermodynamics is explained by the low solubility of magnetite making unfavorable the precipitation of Fe-silicate. By contrast, metallic iron is not stable at contact with water and the continual production of divalent iron, whose solubility is much higher than that of magnetite, allows to overpass a threshold concentration what makes possible the precipitation of a berthierine layer at the surface of corroded steel. This layer constitutes the nucleation site for the further precipitation of other aluminosilicates.

ВПЛИВ ПАРАМЕТРІВ РУХУ ВОДИ НА ЕНЕРГОЕФЕКТИВНІСТЬ ЇЇ ОБРОБКИ ІМПУЛЬСНИМ БАР’ЄРНИМ РОЗРЯДОМ

A study of the energy efficiency of the pulsed barrier discharge during water treatment in the aerosol state depending on the energy of the pulses (21-72 mJ), their repetition rate (50-300 Hz), the concentration of organic impurities in water (50-100 mg / l) and water content (1.6−3.2%) in the water-air mixture. The discharge was generated by unipolar short pulses (~ 100 ns) in an electrode system with vertically arranged cylindrical electrodes with a diameter of 2 mm, the distance between which was 2 mm. The highest energy yield, which was obtained by decomposing the impurity by 90%, was 32 g / kWh. In order to determine the influence of water movement parameters on the energy efficiency of a pulsed barrier discharge under similar conditions, the energy efficiency of this type of discharge during water movement in film, drip and aerosol states was compared. It is concluded that water treatment should be carried out in the drip state on the submillimeter size of the drops. In the case of such water movement, the energy efficiency of the pulsed barrier discharge is ≈30% higher than in aerosol. References 15, figures 6, table 1.

Analisis Hubungan Antar Parameter Kualitas Crude Palm Oil di PT. Laguna Mandiri Rantau Factory

Analysis of the relationship between the quality parameters of crude palm oil (CPO) at PT. Laguna Mandiri Rantau Factory using a simple linear regression method and multiple linear regression has been carried out. This study was to determine the free fatty acid content, water content, and gross content of CPO and to compare the sample with company standards and SNI. The relationship between parameters was modeled with a simple linear regression mathematical model, Y = a + bx and multiple linear regression, Y = a + b1X1 + c2x2… + bnXn. The results showed that the average free fatty acid was 4.02%, the water content was 0.18%, and the impurities content was 0.018%. The fatty acid content has not met the company standard, while the water content and impurities have met the company and SNI. The relationship of water content (X) to free fatty acids (Y) in the equation Y = 3.328 + 3.804x. The relationship of free fatty acids (X) to water content (Y) in the equation Y = - 0.808 + 0.246x. The relationship between impurities (X) and free fatty acids (Y) in the equation Y = 3.569 + 25.399x. The relationship of free fatty acids (X) to the level of impurities (Y) in the equation Y = -0.124 + 0.035x. The relationship between dirt content (X) and water content (Y) in the equation Y = 0.070 + 6.315x. The relationship between water content (X) and dirt content (Y) in the equation Y = - 0.007 + 0.135x. The relationship of water content (X1) and dirt content (X2) to free fatty acids (Y) in the equation Y = 3.391 + 2.542 X1 + 9.344 X2. The relationship of impurities (X1) and free fatty acids (X2) to water content (Y) in the equation Y = - 0.737 + 0.572 X1 + 0.226X2. The relationship of free fatty acids (X1) and water content (X2) to the level of impurities (Y) in the equation Y = - 0.107 + 0.030X1 + 0.021X2.

Burst Pressure Prediction of Subsea Supercritical CO2 Pipelines.

To improve transportation efficiency, a supercritical CO2 pipeline is the best choice for large-scale and long-distance transportation inshore and offshore. However, corrosion of the pipe wall will occur as a result of the presence of free water and other impurities present during CO2 capture. Defects caused by corrosion can reduce pipe strength and result in pipe failure. In this paper, the burst pressure of subsea supercritical CO2 pipelines under high pressure is investigated. First, a mechanical model of corroded CO2 pipelines is established. Then, using the unified strength theory (UST), a new burst pressure equation for subsea supercritical CO2 pipelines is derived. Next, analysis of the material’s intermediate principal stress parameters is conducted. Lastly, the accuracy of the burst pressure equation of subsea supercritical CO2 pipelines is proven to meet the engineering requirement by experimental data. The results indicate that the parameter b of UST plays a significant role in determining burst pressure of pipelines. The study can provide a theoretical basis and reference for the design of subsea supercritical CO2 pipelines.

Moisture-Sensitive Ratiometric Color-Changing Response: a Useful Tool for Precision Farming

Anthra[1,2-d]imidazole-6,11-dione-based charge transfer probes have been developed for the detection of water impurities in a wide range of laboratory-used organic solvents. The deprotonated (anionic) forms of the probe molecules, obtained upon addition of basic anions such as fluoride, demonstrate a ratiometric color-changing response (blue to yellow in presence of F– and red to yellow with CN– ion) even in the presence of a trace amount of moisture (detection limit: 0.008 wt %). Considering their high sensitivity and “naked-eye” response, the anionic receptors are utilized for the quantification of moisture level or water impurity in a wide range of real-life samples, such as building raw materials, packaged food items, soil, plant leaves, and so on. Determination of the moisture level of plant leaves or soil samples is particularly important for precision farming as it helps the farmers to schedule the irrigation events. Finally, low-cost, reusable, and optical kit-based dye-coated paper strips were developed for rapid, on-location detection as well as quantification purposes. Since such a sustainable approach does not involve any sophisticated instruments or complex sample preparation steps, the general public with little knowledge of science or technology will be able to use it without much difficulty.

The Nuclear Magnetic Flowmeter for Monitoring the Consumption and Composition of Oil and Its Complex Mixtures in Real-Time

The necessity of increasing the efficiency of primary oil purification in a drilling station or an offshore platform has been substantiated. We consider the problems that arise during the primary processing of oil mixtures. Important conditions for increasing the efficiency of primary purification (separation) of oil mixtures include measuring the consumption and determining the content of various impurities (water, undissolved particles) and air in them, with an error of no more than 2%. We analyzed the possibilities of using various designs of flowmeters to measure the consumption of the oil mixture coming from a well. It is also necessary to use other measuring instruments to control the state of this mixture, which creates additional problems (searching for an appropriate locations to place them, providing the required operating conditions). Various designs of nuclear magnetic flowmeters–relaxometers were considered, making it possible to measure the consumption of a liquid medium and its times of longitudinal T1 and transverse T2 relaxation with one device. The measured values of T1 and T2 determine the state of the medium. The design of the industrial nuclear magnetic flowmeter–relaxometer M-Phase 5000, which is used to control the flow and quality of oil and oil products, was considered in more detail. Problems were identified that did not allow using this design of a nuclear magnetic flowmeter–relaxometer in a drilling rig or offshore platform. A new design of a nuclear magnetic flowmeter–relaxometer was developed, implementing the methods for measuring q, T1, and T2. These methods and various technical solutions make it possible to use this device at a drilling station or offshore platform. The measurement errors of the consumption q, T1, and T2 were determined. The results of various media studies are presented and compared with q, T1, and T2 measurements on other devices and measured volume (to confirm the adequacy of q measurements). The application scopes of the developed nuclear magnetic flowmeter–relaxometer were determined, in addition to the systems of primary oil processing.

Deactivation Mechanisms of Engineering Adsorbents for VOCs Adsorption and the Lifetime-Prolonging Strategy

Adsorption–desorption process has been considered as a promising way for both the removal and recovery of volatile organic compounds (VOCs) from waste gases. However, during the engineering applications of the adsorbents, they would be deactivated or deteriorated. Herein, the deactivation mechanisms of different engineering VOC adsorbents (activated carbons and silica gels) by different processes or parameters have been investigated. It is found that the deactivation of adsorbents is mainly attributed to the following reasons: accumulation of VOCs in the pores, breaking of the pore structures due to the frequent-changing of processing conditions, occupation of the pores by water or other impurities, and so forth. For the temperature swing adsorption (TSA) process, the performance of adsorbents would be deteriorated by (i) the accumulation of VOCs due to incomplete desorption or (ii) the collapse of the pore structure of adsorbents (e.g., activated carbons and microporous silica gel) due to frequent cooling and heating between adsorption and desorption, respectively, leading to the deactivation of adsorbents. This phenomenon could be weakened when the pores in the adsorbents increased (e.g., the mesoporous silica gel, SG B). For the vacuum swing adsorption (VSA) process, the pore structure of adsorbents was slightly influenced during the adsorption–desorption cycles. The decrease in the adsorption capacity of adsorbents was mainly ascribed to the accumulation of VOC chemicals in the pores. In addition, in the TSA or VSA process, when the water vapor was present, the adsorption performance of adsorbents will be significantly reduced due to the occupation of adsorption sites by the water, resulting in faster deactivation. Considering the processing cost and lifetime of adsorbents, the TSA and VSA are combined together herein. The results show that, compared with the single TSA and VSA, the combined VSA–TSA process could be applied to different VOCs and improve the desorption rate of the adsorbents greatly at lower energy consumption and longer lifetime.

Dialysis Water Quality and Its Impact on Maintenance for the Hemodialysis Community

The quality of water for hemodialysis (HD) is a concern for all dialysis centers because of its impact on the health of HD patients. There are guidelines by the Association for the Advancement of Medical Instrumentation (AAMI) for maximum limits for chemical contaminants, bacterial colony-forming units, and endotoxin limits. But some of the contaminants like fungus and algae are still missing from guidelines. Impurities in dialysis water can lead to many health issues among the HD community and it can increase the mortality rate as well. The present paper focuses on the different contaminants in dialysis water and their health impacts on the HD community.