Different Types Of Adsorbents Research Articles

Surface Characterization of the Adsorbent Derived from Activated East Kalimantan’s Low Rank Coal (LRC) Yuli Patmawati

Adsorption process has several applications today particularly for the treatment of wastewater. Consequently, the creation and enhancement of adsorbent materials is an important subject of research. When a novel adsorbent is offered, adequate material properties is necessary to understand its characteristics, encourage the utilization of it as well as comprehend Its effectiveness in the intended technique. The objective of this inquiry is to figure out the structure and surface area of the adsorbent derived from East Kalimantan’s activated LRC utilizing Brunauer Emmett Teller (BET) analyses. Before conducting BET analysis, the adsorbent is degassed and vacuumed. After that, it gets exposed to N2 gas at constant temperature of 77 Kelvin. From this paper reported an adsorbent derived from East Kalimantan's activated LRC has surface areas of 321.26 m2/g, many micropores with the average pore size of 1.41 nm and 0.23 cm3/g total volume of pore. Furthermore, based upon the isotherms of N2 gas adsorption and desorption, the adsorbent derived from East Kalimantan's activated low rank coal follows a combination of IUPAC types I and IV. It possesses microporous and mesoporous characteristics, as well as monolayer and multilayer adsorption processes. Identifying the surface characteristics of the adsorbent makes it feasible to evaluate the effectiveness of utilizing the adsorbent derived from East Kalimantan’s activated LRC in the adsorption process as compared to different types of adsorbents.

The Role of Biocomposites and Nanocomposites in Eliminating Organic Contaminants from Effluents

Many contaminants such as heavy metals, dyes and hydrocarbon compounds are annually generated by industrial activities and discharged into water sources. They have destructive impacts on the environment. To eliminate these toxic contaminants from aqueous media, sorption can be considered a proper and efficient process, as it has indicated high efficiency for removing organic contaminants. This paper entails a comprehensive evaluation of different organic pollutants, pros and cons of the sorption process in removing these pollutants, comparing different types of adsorbents and investigating the recyclability of different types of composites. Moreover, the sorption mechanism and kinetic behavior of organic contaminants are investigated using biocomposites and nanocomposites. Moreover, the future perspectives of biocomposites and nanocomposites in eliminating organic compounds are discussed. Based on investigations, a large number of nanocomposites have been utilized for removing organic contaminants with high performance so far, including SiO2/MnFe2O4/ZIF-8 MOF, magnetite/MWCNTs, nano zerovalent iron, barium/Cobalt/polyethylene glycol (PEG), graphene oxide/Fe3O4, kaolin/CuFe2O4 and Fe3O4@UiO-66. Moreover, polyaniline/sodium alginate/Oscillatoria filamentous cyanobacterium biomass, cow bones/zeolite/coconut biocomposite and AC derived from melamine and sucrose are excellent biocomposites in the removal of organic pollutants. Moreover, the reusability study shows that poly(N-isopropylacrylamide)/Fe3O4 and corn stalk biomass/chitosan/Fe3O4 biocomposites have significant stability compared to other composites in the elimination of organic pollutants.

Adsorbate Formation/Removal and Plasma‐Induced Evolution of Defects in Graphitic Materials

AbstractThe preparation of adsorbate‐free graphene with well‐defined layer numbers is a current challenge in materials and surface science and required to fabricate graphene‐based nanodevices, such as used in nanoelectromechanical systems. One strategy to tailor the layer number is oxygen‐plasma treatment of few‐layer graphene/graphite flakes. However, when graphitic materials are stored in air under ambient conditions, it is almost inevitable that adsorbates deposit on their surfaces. When precisely removing individual graphene layers from graphitic flakes by oxygen‐plasma treatment, the amount and type of adsorbates strongly affect the required plasma‐treatment process and duration. To examine the removal/etching mechanism involved in removing such layers, few‐layer graphene/graphite flakes, with areas of different layer numbers, are stored in ambient air and stepwise exposed to oxygen plasma in a shielded configuration. The flakes are then successively analyzed by multifrequency atomic force microscopy together with Raman spectroscopy, focusing on etching rate, and adsorbate and defect evolution. Combined in‐plane and out‐of‐plane tip–adsorbate–substrate interaction analysis facilitates discrimination of different types of adsorbates (water, polycyclic aromatic hydrocarbons, and linear alkanes) and their formation with time. The results demonstrate the potential regarding the development of an efficient method for cleaning of graphitic surfaces and ablation of individual graphene layers.

Effect of Filtration Methods of Various Types of Adsorbents on the Quality of Coconut Shell and Kusambi Liquid Smoke as Raw Materials for Processed Meat Smoking

In this study, there were two groups, namely liquid smoke of kusambi and liquid smoke of coconut shells with various treatments of adsorbent filtration with 3 replications. There are three kind of treatment for each liquid smoke groups, first is liquid smoke without filtration process with adsorbent, liquid smoke with zeolite adsorbent treatment, liquid smoke with silica adsorbent treatment, and liquid smoke with activated charcoal adsorbent treatment. Analysis of variance showed that different types of liquid smoke and different adsorbent filtration had a very significant effect (P0.01) on antioxidants, total acid, specific gravity, tar, phenol content, pH, salinity, TDS, total yield, L* and b* color, hedonic color and smokey scent in the resulting liquid smoke. Analysis of variance showed that the different types of liquid smoke had no significant effect (P0.05), but the filtration treatment with different adsorbents had a very significant effect (P0.01) on viscosity. And the analysis of variance also showed that the different types of liquid smoke and the filtration of different adsorbents had no significant effect (P0.05) on the color a* of the resulting liquid smoke. The differences in the types of liquid smoke and the treatment of liquid smoke filtration with adsorbents had a very significant effect (P0 .01) on antioxidant, total acid, specific gravity, tar, phenol content, pH, salinity, TDS, total yield, L* and b* color, hedonic color, and smoke aroma in the liquid smoke produced. However, the different types of liquid smoke did not have a significant effect on the resulting viscosity (P0.05) and the different types of adsorbents in the liquid smoke filtration process had a very significant effect on the viscosity (P0.01). Meanwhile, the different types of liquid smoke and the different types of adsorbents in the liquid smoke filtration process did not have a significant effect on the value of the color a* or the reddish color of the liquid smoke (P0.05).

Adsorptive decontamination of antibiotics from livestock wastewater by using alkaline-modified biochar

Efficient abatement of antibiotics from livestock wastewater is in urgent demand, but still challenging. In this study, alkaline-modified biochar with larger surface area (130.520 m2 g−1) and pore volume (0.128 cm3 g−1) was fabricated and explored for the adsorption of different types of antibiotics from livestock wastewater. Batch adsorption experiments demonstrated that the adsorption process was mainly determined by chemisorption and was heterogeneous, which could be moderately affected by the variations of solution pH (3–10). Furthermore, the computational analysis based on density functional theory (DFT) indicated that the –OH groups on biochar surface could serve as the dominant active sites for antibiotics adsorption due to the strongest adsorption energies between antibiotics and –OH groups. In addition, the antibiotics removal was also evaluated in multi-pollutants system, where biochar performed synergistic adsorption towards Zn2+/Cu2+ and antibiotics. Overall, these findings not only deepen our understandings on the adsorption mechanism between biochar and antibiotics, but also promote the application of biochar in the remediation of livestock wastewater.

Effects of Inorganic Minerals and Kerogen on the Adsorption of Crude Oil in Shale

Shale oil stored in the shale system occurs mainly in adsorbed and free states, and ascertaining the amount of adsorbed crude oil in shale is a method of ascertaining its free oil content, which determines the accuracy of shale oil resource evaluation. Both inorganic minerals and kerogen have the ability to adsorb crude oil, but there is controversy surrounding which plays the greatest part in doing so; clarifying this would be of great significance to shale oil resource evaluation. Therefore, in this study, the evolution states of inorganic minerals and kerogen in shale were changed using pyrolysis, and the adsorbents were prepared for crude oil adsorption experiments, to explore the effects of inorganic minerals and kerogen on the crude oil adsorption of shale. The results showed that the differences in kerogen’s structural units and content in organic-rich shale (TOC = 1.60–4.52%) had no obvious effects on its crude oil adsorption properties. On the contrary, inorganic minerals, as the main body of shale, played a dominant role in the adsorption of crude oil. The composition and evolution of the inorganic minerals controlled the surface properties of shale adsorbents, which is the main reason for the different crude oil adsorption properties of the different types of adsorbents. The results of this study are helpful in improving our understanding of the performance and mechanisms of shale in adsorbing crude oil and promoting the development of shale oil resource evaluation.

Polymeric Adsorbents: Innovative Materials for Water Treatments

Background: Removing heavy metal ions and various organic contaminants from water (surface water, groundwater, drinking water, and wastewater) using inexpensive and readily available adsorbents is essential in all environmental and human aspects. This study aims to explore the various adsorbents with a particular emphasis on polymeric adsorbents for their applications in the removal of heavy metal ions and emerging contaminants from water. Methods: A brief review as a perspective article on polymeric adsorbents with a particular emphasis on their applications in water treatment, consequences, challenges, and relevant issues/ perspectives that need to be resolved in the future is highlighted. Results: Due to the increasing global human population with rapid urbanization, industrialization, and environmental change, removing heavy metals and emerging contaminants from water fonts has become a primary environmental concern and a huge challenge to ensure safe water supplies. This directs an utmost demand to develop various water treatment and recycling methods. Different types of adsorbents, including polymeric adsorbents, have also been discussed. The study indicates the presence and structural behaviors (e.g., functional groups, degradation, adsorption, desorption), adsorption-desorption process, regeneration, safe removal and disposal procedure, and toxicity of the adsorbents are vital to use them safely for an extended period in the application of water treatment. Conclusion: A brief discussion on adsorption, methods, various types of polymeric adsorbents, and their applications for removing organic and/or heavy metal contaminants from water and wastewater is presented in this review as a perspective article. A better understanding of the preparation of polymers from inexpensive, readily available, natural sources and toxicity issues is still needed to be considered, particularly in the human-related exposure and relevant risk on the water and wastewater treatment.

Reuse of Magnesol® for Purification of Biodiesel

Purification of biodiesel with dry adsorbents is an alternative method, as it uses compounds that eliminate the need for water in the process without generating liquid effluent. Currently, there is little discussion about the reuse of different types of adsorbents and in this context, the present work presents an efficient method of purification and investigates the performance of the reuse of Magnesol® in the purification of biodiesel in order to generate less waste to the environment. Therefore, the Magnesol® used was washed with several solvents with different polarity characteristics. Among the solvents tested, THF is the best solvent for the purification of Magnesol® and, after optimizing the Magnesol® purification process, it was concluded the best conditions are three washes in solvent / adsorbent ratio 30:1 at room temperature, resulting in only 3.89% of the residual value of contaminants and being an alternative for biodiesel companies.

In-plane and out-of-plane interaction analysis of adsorbates on multilayer graphene and graphite by multifrequency atomic force microscopy

Graphene and graphite are generally considered as materials exhibiting friction anisotropy. However, it was demonstrated by friction force microscopy experiments that friction anisotropy most likely originates from adsorbates aligning in well-ordered stripes on graphitic surfaces. In this study, we analyzed the evolution of adsorbates on a few-layer graphene-/graphite-flake on top of a Si/SiO 2 -substrate after different times of storage using a multifrequency force microscopy approach. The method allows for the simultaneous in-plane and out-of-plane sample analysis as well as the discrimination of conservative and dissipative tip-sample interactions directed parallel and perpendicular to the surface and thus offers a myriad of complementary physical information. We found that friction anisotropy was observable at distinct areas of the graphene-/graphite-flake after 14 days of storage when exposed to air, albeit not throughout the whole flake, indicating different types of adsorbates. High-resolution imaging revealed that friction anisotropy occurred not only at positions where stripe-like structures were visible, but also on areas which were completely covered with adsorbates. Additionally, we demonstrated that after removal of the adsorbate material by oxygen-plasma treatment, no friction anisotropy was observable on the graphene-/graphite-flake, corroborating adsorbate driven nature of friction anisotropy on graphitic surfaces. • Combined in-plane and out-of-plane force microscopy for interpretation of ordered adsorbate formation on graphite/graphene. • Discrimination of different types of adsorbates by tip-sample interactions parallel and perpendicular to the surface. • 90° rotation of the graphene/graphite flake revealed that friction anisotropy is only caused by certain types of adsorbates.

Selectivity Tuning of Adsorbents for Ethane/Ethylene Separation: A Review

Ethylene is an important feedstock for the production of many key-valued compounds, especially polymers. About 60% of the total ethylene produced is utilized for the production of polyethylene, while ethylene is normally produced by steam cracking of naphtha along with traces of ethane, which is undesirable. Considering the energy-intensive nature of the current technology to obtain ultrapure ethylene, the development of novel materials for separating ethylene from ethane by adsorption is of great significance, yet it remains challenging owing to the close molecular sizes and physical properties of the two compounds. Both ethylene- and ethane-selective adsorbents are reviewed in this work. Yet, as the industrial feed is rich in ethylene with traces of ethane, in order to obtain polymer grade ethylene, multiple adsorption–desorption cycles are required, which is yet again energy-demanding. Thus, ethane-selective adsorbents are energetically favorable; hence, in this Review, we pay particular focus on ethane-selective adsorbents. The rationale behind reverse-selective adsorbents is critically reviewed and discussed. Most of the ethane-selective adsorbents have been reported to exhibit low selectivity compared to ethylene-selective ones, as reverse-selectivity is mostly based on weak van der Waals interactions. In addition, we focused on various reported mechanisms behind the adsorptive separation of ethane/ethylene mixtures, as well as modifications and surface functionalization techniques reported for different types of adsorbents investigated for this separation.

Nitrate contamination in water resources, human health risks and its remediation through adsorption: a focused review.

The level of nitrate in water has been increasing considerably all around the world due to vast application of inorganic nitrogen fertiliser and animal manure. Because of nitrate's high solubility in water, human beings are getting exposed to it mainly through various routes including water, food etc. Various regulations have been set for nitrate (45-50 mgNO3-/L) in drinking water to protect health of the infants from the methemoglobinemia, birth defects, thyroid disease, risk of specific cancers, i.e. colorectal, breast and bladder cancer caused due to nitrate poisoning. Different methods like ion exchange, adsorption, biological denitrification etc. have the ability to eliminate the nitrate from the aqueous medium. However, adsorption process got preference over the other approaches because of its simple design and satisfactory results especially with surface modified adsorbents or with mineral-based adsorbents. Different types of adsorbents have been used for this purpose; however, adsorbents derived from the biomass wastes have great adsorption capacities for nitrate such as tea waste-based adsorbents (136.43mg/g), carbon nanotube (142.86mg/g), chitosan beads (104mg/g) and cetyltrimethylammonium bromide modified rice husk (278mg/g). Therefore, a thorough literature survey has been carried out to formulate this review paper to understand various sources of nitrate pollution, route of exposure to the human beings, ill effects along with discussing the key developments as well as the new advancements reported in procuring low-cost efficient adsorbents for water purification.

Iron Sulfide Scale Inhibition in Carbonate Reservoirs.

Hydrocarbon production operations include water injection, varying stimulation approaches, and enhanced oil recovery techniques. These treatments often affect reservoir formation, production, and injection facilities. Such sorts of well operations cause the formation of organic and inorganic scales in the near-wellbore region and various production and injection structures. Downhole squeeze treatment is commonly used as a control measure to prevent scale precipitation. A scale inhibitor solution is introduced into a formation by applying a squeeze treatment. The method allows scale inhibitors to adsorb on the internal rock surface to avoid settling down the scale precipitates. Thus, the study of adsorption of different types of inhibitors to prevent scale formation on the reservoir rock through the execution of downhole squeeze treatment is becoming necessary. This study incorporated different experimental techniques, including dynamic adsorption experiments of chelating agents employing a coreflooding setup, inductively coupled plasma-optical emission spectrometry (ICP-OES) to inhibit the formation of iron-containing scales in limestone rocks, and ζ-potential measurements targeting determination of iron precipitation in varying pH environments on calcite minerals. The influence of the inhibitor soaking time and salt existence in the system on chelating agent adsorption was also evaluated in the coreflooding experiments. The findings based on the coreflooding tests reveal that the concentration of chelating agents plays a significant role in their adsorption on carbonate rocks. The treatments with 20 wt % ethylenediaminetetraacetic acid (EDTA) and 20 wt % diethylenetriaminepentaacetic acid produced the highest adsorption capacity in limestone rock samples by inhibiting 84 and 85% of iron(III) ions, respectively. Moreover, the presence of the salts (CaCl2 and MgCl2) considerably decreased the adsorption of 10 wt % EDTA to 56% (CaCl2) and 52% (MgCl2) and caused nearly 20% more permeability reduction, while more inhibitor soaking time resulted in comparably higher adsorption and lesser permeability diminution. The results of ζ-potential measurements showed that the pH environment controls iron(II) and (III) precipitation, and iron(III) starts to deposit from a low pH region, whereas iron(II) precipitates in increased pH environments in calcite minerals.

The analysis and evaluation of direct air capture adsorbents on the material characterization level

Direct air capture (DAC) of carbon dioxide has been identified as a necessary negative emission technology to limit global temperature rise to 2 °C by 2100. With the research progress in DAC, an increasing number of adsorbents have been developed and investigated. This brings about the questions that what makes good adsorbents for DAC and how to characterize and compare them with different natures. In this paper, the performance parameters of state-of-art DAC adsorbents were investigated, and it is found that because of the varying test conditions, the comparison of some parameters appears to be difficult. Therefore, it is recommended that for each performance parameter, it is best to determine relatively uniform test methods. To this end, this paper selected five benchmark adsorbents and used a set of test methods as a demonstration. Key performance parameters of the adsorbents were measured. On this basis, by comparing the results with that in existing research, the characteristics of different types of adsorbents were summarized and suggestions for future material development were provided.

A Review on Heavy Metal Ion Adsorption on Synthetic Microfiber Surface in Aquatic Environments

Synthetic microfibers (SMFs), tiny particles which gets fragmented from large fragments of large synthetic fibers having less than 10µm in diameter, have gathered ubiquitously in each and every corner of the earth. After their release into the aquatic environment, they remain there without natural degradation. Furthermore, it can be anticipated that floating units are transported along the food chain leading to bioaccumulation. It has been estimated that approximately 10-20 Mt of large fabric products as garbage enter into aquatic system per annum. Recently, these synthetic fragments have been investigated as transporters of heavy metal ions (HMs) showing different types of interactions. Yet, the underlying mechanism of these types of interaction is not known, especially the factors stimulating this process and how badly they affect biotic communities. Through this article, a detailed survey was carried out on the sources of microfibers and HMs into the aquatic environment, adsorption of different types of HMs on the SMF surface, mechanics favors these HM-MF interactions, particularly highlighting the significant roles of interaction on microbial biofilm formation. Their collaborative effects which possess harmful effects on aquatic as well as terrestrial organisms was also discussed. Lastly, the future investigations should focus on rigorous research in this field. This article to the best of our knowledge briefly describes the current research developments and emphasizes the vital function of the microorganisms on MFs-HMs interactions with the encouragement for rigorous research in this field to reveal accurate mechanisms and decrease the hazards related with MF presence.

Characteristics of ball-milled PET plastic char for the adsorption of different types of aromatic organic pollutants

Ball-milled plastic char (BMPC) was manufactured by ball-milling of native plastic char (PC) that was synthesized via slow pyrolysis of polyethylene terephthalate (PET) water bottle waste, and its adsorption characteristics of aqueous phenanthrene (PHE), phenol, and 2,4,6-trichlorophenol (2,4,6-TCP) and its possible mechanisms were investigated. With the increase of PC pyrolysis temperature, the specific surface area of BMPC increased obviously, forming larger functional groups compared to PC. Boehm titration showed that total acidic groups of BMPC decreased significantly with the increase of pyrolysis temperature. The sorption kinetics of three adsorbates was adequately simulated by pseudo-second-order model (R2 > 0.99). Langmuir model fitted well the adsorption isotherms of PHE and phenol, while Freundlich model simulated the adsorption isotherm of 2,4,6-TCP better. The adsorption amount of PHE, phenol, and 2,4,6-TCP increased significantly as the pyrolysis temperature increased. The maximum BMPC adsorption capacity reached 21.9mg·g-1 (for PHE), 106mg·g-1 (for phenol), and 303mg·g-1 (for 2,4,6-TCP) at 25°C in aqueous solution. FTIR analysis suggested that surface sorption-based π-π interaction was a dominant mechanism of PHE adsorption; meanwhile, H-bonding between O-containing groups on BMPC and hydroxyl groups of adsorbates was responsible for phenol and 2,4,6-TCP removal. This paper shows that BMPC can be used as adsorbent for treating aromatic compounds in aqueous environment and has an economic worth of application.

Synergistic Fluoride Adsorption by Composite Adsorbents Synthesized From Different Types of Materials—A Review

The reduction of fluoride concentrations in water is one of many concerns. Adsorption is the most widely used technology for fluoride removal and the center to development of adsorption technology is the improvement of adsorbents. This review classifies the typical fluoride removal adsorbents into four types: metal oxides/hydroxides, biopolymers, carbon-based, and other adsorbents. The exploitation of new materials and the synthesis of composite materials are two ways of developing new adsorbents. In comparison to the discovery of novel adsorbents for fluoride adsorption, research into the composite synthesis of different types of conventional adsorbents has proliferated in recent years. The traditional adsorbents used the earliest, metal oxides, can act as active centers in a wide range of applications for modifying and compounding with other types of adsorbents. This study emphasizes reviewing the research on fluoride removal by composite adsorbents synthesized from different types of metal-modified materials. Seven factors were compared in terms of material characterization, initial fluoride concentration, adsorbent dose, pH, temperature, reaction time, and maximum adsorption capacity. The modification of composite adsorbents is facile and the synergistic effect of the different types of adsorbents significantly improves fluoride adsorption capacity. Metal composite adsorbents are synthesized by facile coprecipitation, hydrothermal, or impregnation modification methods. The adsorption mechanisms involve electrostatic attraction, ion exchange, complexation, and hydrogen bonding. The fluoride adsorption capacity of composite adsorbents has generally improved, indicating that most modifications are successful and have application prospects. However, to achieve significant breakthroughs in practical applications, numerous issues such as cost, separation/regeneration performance, and safety still need to be considered.

On the evaluation of asphaltene adsorption onto dolomite surface: The roles of flow condition, composition of asphaltene, and dolomite size

Asphaltene precipitation/deposition is one of the main problems in petroleum industry at various stages. In this study, various controlling factors on the adsorption of different types of asphaltene on the surface of dolomite of different size, as one of the most abundant minerals in the reservoir is investigated. First, asphaltenes and adsorbents (dolomite) properties were analyzed via several analytical techniques. Then, adsorption of four asphaltene samples of various origins and chemical composition on dolomite at micron and nano size were carried out in both static and dynamic modes and results were examined following the adsorption process. Based on the static tests, the adsorption amount of asphaltenes on nano- and micro-dolomite was measured 3.52–11 mg/m2 and 0.82–2.74 mg/m2, respectively. The results revealed that the most significant parameters that would affect the asphaltene adsorption on dolomite as an adsorbent are the total nitrogen and sulfur (N + S) content and the aromaticity of the asphaltenes. Moreover, as the flow rate was increased three times in the dynamic experiments, a decrease of 15–25% in asphaltene adsorption was observed, which was attributed to physisorption of asphaltene on dolomite or due to higher flow velocities. Collectively, the findings of this study can enable us to better understand the mechanisms of asphaltene adsorption/precipitation on dolomite and lead to better management of oil production from dolomitic reservoirs.

A Review on Removal of Heavy Metals from Water by Adsorption

Substantial contamination of heavy metals in drinking water has been an issue to consumers since long. The persisting contamination level has been monitored by various agencies and researchers, which direct towards constant deterioration of water quality. The quality of water is degrading exponentially from rural to urban areas in a significant manner. Industrial effluents, sewage and agricultural waste are the prime sources of contamination of water resources. Various heavy metals such as nickel, chromium, lead, arsenic, cadmium, mercury and copper may be present in industrial effluents. Though different methods such as chemical precipitation, ion exchange, membrane filtration, coagulation – flocculation and electro dialysis are known, amongst which adsorption being the most versatile and economically viable has been extensively adopted by various researchers for trace level of concentrations. In this review, several low cost adsorbents are reported in the literature have been studied at length. Different types of adsorbents like nanosorbent, biosorbents, carbonaceous material and metal based adsorbents have been considered for the review paper. The review paper evaluates the possibilities of utilizing various adsorbents for efficient removal of different heavy metals from water. Study reflected towards remarkable adsorption capacity, efficiency and cost effectiveness of adsorbents utilized by researchers. The boundless use of low cost adsorbents for treatment of wastewater are strongly recommended due to their availability,

From Sampling to Analysis: How to Achieve the Best Sample Throughput via Sampling Optimization and Relevant Compound Analysis Using Sum of Ranking Differences Method?

The determination of an optimal volatile sampling procedure is always a key question in analytical chemistry. In this paper, we introduce the application of a novel non-parametric statistical method, the sum of ranking differences (SRD), for the quick and efficient determination of optimal sampling procedures. Different types of adsorbents (Porapak Q, HayeSep Q, and Carbotrap) and sampling times (1, 2, 4, and 6 h) were used for volatile collections of lettuce (Lactuca sativa) samples. SRD identified 6 h samplings as the optimal procedure. However, 1 or 4 h sampling with HayeSep Q and 2 h sampling with Carbotrap are still efficient enough if the aim is to reduce sampling time. Based on our results, SRD provides a novel way to not only highlight an optimal sampling procedure but also decrease evaluation time.

Dynamic characteristics of a prestressed micro-diaphragm in a fluid subjected to distributed mass loading

This paper studies the vibrational behaviors of a distributive mass-loaded microscale circular diaphragm submerged in a fluid. The vibration of the diaphragm involving loadings simultaneously induced by an acoustic field and the adhesion of distributive mass has been investigated. Two different types of adsorbates, namely, in the form of discrete particles (mass only) and a uniform layer (mass and rigidity), are considered and compared. Moreover, the pre-existing stress in the diaphragm has also been taken into consideration. Based on Lamb's hypotheses of the fluid-loaded structure in conjunction with the Rayleigh–Ritz theorem, an analytical solution for the dynamic characteristics of the coupling system, including the resonant frequency, mode shape, and the quality factor, is developed. The results have been compared with those of the finite element simulations, and a good agreement has been obtained. The results reveal that the adsorbate properties contribute differently to the dynamic response of the micro-diaphragm in the fluid, and the contribution may be intervened by tuning the pre-stress. The theoretical model and novel analytical solution are of interest in the design of micro-diaphragm-based biosensing devices.