Separation Speed Research Articles

Laser-structured superhydrophobic/superoleophilic aluminum surfaces for efficient oil/water separation.

The current demand for oil/water separation with an efficient, cost-effective, and environmentally friendly method is increasing. A laser-structured superhydrophobic/superoleophilic aluminum was prepared by using a nanosecond laser. The aluminum plate was used for oil/water separation without external force, which can replace the traditional porous materials. The effect of hole diameter and spacing on the effectiveness of oil/water separation is discussed. The results show that the aluminum plate with a hole size of 0.5 mm can be considered a more appropriate choice for the oil/water mixtures with large water content. In addition, complete separation of oil and water can be achieved in the hole spacing range of 1.0-3.0 mm. The oil separation speed can be increased without changing the water permeability by reducing the hole spacing, which is positively related to the hole spacing. Separation efficiencies were tested with various oil/water mixtures. The aluminum plate with a hole size of 0.5 mm can quickly separate the different oil mixtures with less than 50% oil content while achieving an oil separation efficiency of up to 99%. Due to the difference in dynamic viscosity of various oil phases, the separation efficiencies of the petrol, kerosene, and diesel are slightly different but can still be maintained above 99%. The laser-processed aluminum plate has several advantages of high porosity, high surface of superhydrophobic properties, and easy tunable structures. In practical applications, the hole size and the spacing should be appropriately adjusted according to specific conditions, such as different oils, the mixing ratios, etc., to obtain the best separation efficiency and speed.

Ship's compliance with a traffic separation scheme and speed limit in the Gulf of Panama and implications for the risk to humpback whales

To reduce the whale-vessel strike risk in the Gulf of Panama, the International Maritime Organization (IMO) adopted a Traffic Separation Scheme (TSS) with corresponding inshore traffic zones and seasonal (Aug–Nov) speed limits of ≤10 kn (Speed Over Ground, SOG) commencing December 2014. Here, we assessed compliance rates to these new regulations. Vessel traffic data in the area were obtained between 2014 (pre-TSS implementation) and 2016 using Automated Identification System (AIS) transponders. Most vessels (86.1 and 89.8% in 2015 and 2016, respectively) promptly adhered to the TSS. Significant differences were also detected in speed compliance rates among years, but overall speed compliance was low, i.e., only 19.0% of ships in 2015 and 9.7% in 2016 traveled at ≤10 kn. Compliance rates with the TSS and speed limits varied significantly by vessel type. These divergent compliance responses were likely due to inadequate communication to mariners and notes on printed and digital charts. Speed compliance could be enhanced, e.g. via education programs to raise awareness of endangered whales, along with collaborative initiatives between the maritime industry and port authorities, and law enforcement. In addition, continued monitoring of compliance with IMO regulations, as well as ship-related cetacean injuries/mortality by local environmental authorities should aid assessing the efficacy of these conservation measures and mitigating the whale-vessel strike risk in the Gulf of Panama. Above all though, authorities need to evaluate a mandatory speed regulation by the IMO or unilaterally, based on the newly modified and extended baseline for nation's internal waters.

Application of Рolyelectrolyte Сomplexes for the Removal of Suspended Particles in the Process of Water Treatment аnd Рurification

The possibility and efficiency of biflocсulation systems, including polymer electrolytes capable of interaction and polyelectrolyte complexes formation, usage in the processes of water treatment for the mineral particles separation, was studied. The influence of the nature, molecular weight of polyelectrolyte components and their ratio in the system on the efficiency and speed of the dispersed phase particles deposition process was considered. Sodium salt of carboxymethylcellulose, poly-N,N-dimethyl-N,N-diallylammonium chloride and polyanions and polycations polyacrylamide-based were used as polyelectrolytes. It was shown that application biflocсulation systems significantly increases the speed of the dispersed phase separation and allows to improve the clarification quality of the dispersion with a much lower (compared to monoflocculation systems) consumption of polymer electrolytes.

Turbulent Supercritical Fluid Chromatography in Open-Tubular Columns for High-Throughput Separations.

A method utilizing turbulent flow to perform ultrafast separations and screen chiral compounds in supercritical fluid chromatography (SFC) is described. Carbon dioxide at high flow rates (up to 4.0 mL/min) is delivered into gas chromatography (GC) open-tubular columns (OTC, 0.18 mm i.d., 20 m long, ∼0.2 μm stationary film thickness) to establish turbulent flow at Reynolds numbers (Re) as high as 9000. Postcolumn dispersion is eliminated by using a modified UV detector that takes measurements directly on column. Upon crossing the laminar-to-turbulent flow transition regime, a significant reduction in plate height is observed resulting in a nearly 3-fold increase in peak capacity from the laminar regime. This is explained by the massive reduction of the mass transfer resistance in the mobile phase due to a flatter flow profile and faster analyte dispersion across the open-tubular column (OTC) i.d.. Demonstrated in this work is a 9 s separation of four polycyclic aromatic hydrocarbons (PAHs) over a 2.2 s separation window using a poly(dimethylsiloxane-co-methylphenylsiloxane) coated OTC. Additionally, three chiral compounds and three chiral cyclodextrin-incorporated OTCs were evaluated at high temperatures (90-120 °C) and CO2 flow rates (3.3-3.7 mL/min) to demonstrate column stability and application of this method for rapid screening. Turbulent SFC provides a separation method for users desiring to achieve separation speeds above what is currently available with very high-pressure LC systems and do so without the resolution loss commonly observed at maximum allowable speed.

Interface Coassembly and Polymerization on Magnetic Colloids: Toward Core-Shell Functional Mesoporous Polymer Microspheres and Their Carbon Derivatives.

Core–shell structured magnetic mesoporous polymer or carbon‐based microspheres not only possess the combined merits of magnetic particles and stable mesoporous shell but also provide various organic functional groups for further modification and immobilization of active sites, thus opening up more possibility for various applications. Herein, a bottom‐up soft‐templating strategy is developed to controllably synthesize core–shell magnetic mesoporous polydopamine microspheres (MMP) and their derivative magnetic mesoporous carbon (MMC) microspheres via an amphiphilic block copolymer‐directed interface assembly and polymerization (denoted as abc‐DIAP) approach. The obtained uniform MMP microspheres have a well‐defined structure consisting of magnetic core, silica middle layer and mesoporous PDA shell, uniform mesopores of 11.9 nm, high specific surface areas (235.6 m2 g−1) and rich functional groups. They show fast magnetic separation speed and superior performance in selective adsorption of Cyt.C from complex biosample solutions. Moreover, they can be in situ converted into core–shell magnetic mesoporous carbon (MMC) for efficient in‐pore immobilization of ultrafine Au nanoparticles for high‐efficiency catalytic epoxidation of styrene with high conversion (88.6%) and selectivity (90.1%) toward styrene oxide.

Voltage program-based MEKC with LIF detection for rapid quantification of native capsaicin and dihydrocapsaicin in foods

Voltage program (VP)-based micellar electrokinetic chromatography (MEKC) with a laser-induced fluorescence (LIF) detector was developed for fast, high-sensitivity detection of native capsaicin (CAP) and dihydrocapsaicin (DHC) in various foods. The combination of mixed nonionic (Tween 20) and anionic (SDS) surfactants in a sodium borate running buffer showed excellent separation efficiency, selectivity, and speed without loss of resolving power (Rs > 2). Compared to conventional UV absorption, LIF showed enhanced detection sensitivity with detection limits at the pM level. In addition, the developed VP-based MEKC-LIF method was successfully applied for quantification of capsaicin in chili pepper, baechu, and kimchi at a 98% confidence level. CAP and DHC were also analyzed within a short time in extracts from real samples of gochujang, snacks (Swingchip®), black pepper, and ginger but were not detected in garlic.

Sifat Fisik Dan Mekanik Papan Komposit Dari Serat Tandan Kosong Kelapa Sawit (TKKS) Hasil Penguraian Secara Mekanis Dengan Perekat Gambir

Oil palm empty fruit bunches (OPEFB) are a solid waste product from the oil palm industry that are about 70% fiber. Previous research has indicated that this fiber can be used to produce composite board. Gambier can be used in an adhesive to produce these boards as it has strong adhesive properties. This research investigates the suitability of four types of OPEFB fiber resulting from different mechanical separation speeds and three adhesive made from differing concentrations of Gambier (12%, 14%, 16%) to produce high quality composite board. The results of the research suggest the type of the fiber and the concentration of the gambier used significantly influence the density of the resulting board and that there are interactions between these two variables. The water content of the board is significantly influenced by the type of OPEFB fibre but not by the concentration of gambier or any interaction between these variables. Thickness swelling, modulus of rupture (MOR) and modulus of elasticity (MOE) are all influenced by type of fiber and concentration of gambier without any significant interaction between these two factors. The best types of fiber was those labeled A and B. The best performing composite board was produced from the longer B fibers and 16% gambier adhesive. This board a had density of 0.86 g/cm3, MOR 251.3 kg/cm2 and strength parallel to the grain of 145.6 kg/cm2. This data suggests that the density, water content and MOR of the boards made with this combination of material meets standard SNI 03-2105-2006 however the thickness swelling of the board fails this standard.

Adaptive Speech Separation Based on Beamforming and Frequency Domain-Independent Component Analysis

Voice signals acquired by a microphone array often include considerable noise and mutual interference, seriously degrading the accuracy and speed of speech separation. Traditional beamforming is simple to implement, but its source interference suppression is not adequate. In contrast, independent component analysis (ICA) can improve separation, but imposes an iterative and time-consuming process to calculate the separation matrix. As a supporting method, principle component analysis (PCA) contributes to reduce the dimension, retrieve fast results, and disregard false sound sources. Considering the sparsity of frequency components in a mixed signal, we propose an adaptive fast speech separation algorithm based on multiple sound source localization as preprocessing to select between beamforming and frequency domain ICA according to different mixing conditions per frequency bin. First, a fast positioning algorithm allows calculating the maximum number of components per frequency bin of a mixed speech signal to prevent the occurrence of false sound sources. Then, PCA reduces the dimension to adaptively adjust the weight of beamforming and ICA for speech separation. Subsequently, the ICA separation matrix is initialized based on the sound source localization to notably reduce the iteration time and mitigate permutation ambiguity. Simulation and experimental results verify the effectiveness and speedup of the proposed algorithm.

A stimuli response, core-shell structured and surface molecularly imprinted polymers with specific pH for rapid and selective detection of sulfamethoxazole from milk sample

In this study, a novel kind of pH-responsive, magnetic and core-shell structured molecularly imprinted polymer (pH-MMIPs) was synthesized for the selective recognition of sulfamethoxazole (SMX). It was synthesized by way of surface imprinting and free radical polymerization. The composition and structure of pH-MMIPs has magnetic nanoparticles as its core, a thin imprinted polymer layer as its shell using 2-(Dimethylamino) ethyl methacrylate and 4-vinylphenylbronic acid as the pH-sensitive monomers, and SMX as template molecule. Interestingly, the pH-MMIPs could control the capture/release process in the selective recognition and detection of SMX by changing the pH value. Evaluation of the property of pH-MMIPs through series of adsorption experiments showed that it has an adsorption capacity of 25.41 mg·g−1 with a very rapid speed of magnetic separation. Additionally, it was successfully applied to selectively detect SMX in real milk samples, and the recoveries was in ranges of 89.7% and 98.2%. This study provides a new method and idea for the selective separation of SMX residue in food using molecularly imprinted polymers with pH- response and identification.

Polypropylene capillary-channeled polymer fiber column as the second dimension in a comprehensive two-dimensional RP × RP analysis of a mixture of intact proteins.

Online, comprehensive two-dimensional liquid chromatography (2D-LC) has become an attractive option for the analysis of complex samples of relevance in various fields (e.g., environmental, food, biology, and polymer sciences). In general, the second-dimension (2D) separation plays a more crucial role than the first (1D) in the total performance of LC × LC systems. Speed and efficiency of the 2D separation are of primary importance. These challenges are amplified in the case of protein separations where mass transfer limitations effect elution kinetics. The research presented here leverages the developments of capillary-channeled polymer (C-CP) fiber stationary phases directed at high-throughput and rapid protein separations, evaluating them as 2D material in comprehensive reversed-phase × reversed-phase (RP × RP) 2D-LC versus conventional, packed-bed columns as 2D. The ability to operate fiber columns at high linear velocities (> 75mms-1 at < 1000psi) without sacrifice in resolution is the first step towards potential 2D implementation, alleviating the need for ultrahigh-pressure pumping (i.e., UHPLC) in that stage. What must be realized are fast elution gradients and rapid re-equilibration to minimize cycling times (modulation periods). Different flow rates and gradient programs were evaluated. Rapid elution allows the use of shorter shift-gradient windows. At the optimized gradient recycling time on this instrument, 36s, there is no significant degradation in peak capacity. Finally, a graphic comparison of the separation efficiency between seven commercial reversed-phase columns and the polypropylene C-CP fiber column is presented for a synthetic, eleven-protein mixture using the recommended operating conditions for each of the 2D columns. The kinetic advantages of the fiber columns are clearly demonstrated.

Floating oil skimmer design using rotary disc method

Over the past few years there have been many oil accidents that have occurred in the sea. Oil accidents can occur due to oil spill, drilling processes at sea or due to pipeline leaks. The oil in the sea will float and if not remove will damage the surrounding ecosystem. Therefore, in this paper implements an oil skimmer system which can be used to remove and separate oil from the water. The oil skimmer system is composed of a rotary disc to take oil on the surface of the water and two propellers to move the oil skimmer. The rotary disc and propeller are driven by DC motor which is connected to the motor driver and Arduino Mega as a controller. The oil skimmer is also equipped with a joystick that is used to adjust the rotation speed of the rotary disc and control the movement of the oil skimmer. Based on the results of testing the oil skimmer has been able to take and separate oil on the surface of the water with separation speed of 620.28 ml/min at a speed of 18 rpm.

Online blind source separation method with adaptive step size in both time-invariant and time-varying cases

To effectively balance the convergence speed and steady-state error of online blind source separation, this paper develops an online blind source separation method with adaptive step size based on an equivariant adaptive separation via independence (EASI) algorithm. First, we construct a separation indicator from the convergence condition of EASI that can reveal the separation degree of mixed signals. Next, a new forgetting factor suitable for non-stationary cases is designed to reduce the error accumulation of previous data, and the separation indicator can be adaptively updated. To automatically adjust the step size according to separation degree, a nonlinear mapping between the separation indicator and step size is constructed. Finally, numerical and experimental case studies are provided to evaluate the performance of the proposed method, which comparison of results proves to be more effective. The results of numerical case studies show that the step size of the proposed method can be adaptively adjusted in the separation process and the proposed method can effectively balance convergence speed and steady-state error in both time-invariant and time-varying cases. The results of experimental case studies show that the proposed method has higher estimation accuracy.

Progress in application of functionalized magnetic nanomaterials for sample pretreatment

With the increasing complexity of the sample properties in analytical chemistry and the lower concentrations of the detected substances, it is imperative to develop accurate and efficient sample pretreatment processes before chromatography and mass spectrometry analyses. Magnetic solid-phase extraction (MSPE) can be regarded as an efficient sample pretreatment method due to the simple synthesis, convenient operation, and high extraction efficiency. In recent years, Fe3O4 magnetic nanomaterials have been widely used in separation and analysis due to their advantages such as high separation speed, good dispersion, and biocompatibility. Functionalized Fe3O4 magnetic nanomaterials are expected to show greatly improved physical and chemical stability, with superior adsorption and separation ability. In this paper, the preparation of magnetic nanomaterials functionalized with carbon-based nanomaterials, molecularly imprinted polymers, ionic liquids, boronate affinity ligands, metal organic frameworks, covalent organic frames, quantum dots, and metal oxides and their applications to sample pretreatment in the fields of biological, environmental, and food safety are reviewed. In addition, future research on sample pretreatment processes is prospected.

Optimization on Adhesive Stamp Mass-Transfer of Micro-LEDs With Support Vector Machine Model

In this work, the process of adhesive stamp mass-transfer of micro light-emitting diode (micro-LED) is optimized by a Support Vector Machine (SVM) model. The pick-up experiments have been performed repeatedly for hundreds of times from which the separation speed and the force between the stamp and the donor substrate are extracted as signal features. The SVM model with a Gaussian kernel function is designed to classify pick-up results into success and failure. In addition, the optimal cost parameter C as well as the Gaussian kernel function parameter gamma (γ) has been optimized, leading to the improvement of the classification by Particle Swarm Optimization (PSO) algorithm. Finally, an 85% classification accuracy is achieved based on the SVM model, implying that more sophisticated definition of signal features is demanded in future work.

Fully-automated and field-deployable blood leukocyte separation platform using multi-dimensional double spiral (MDDS) inertial microfluidics.

A fully-automated and portable leukocyte separation platform was developed based on a new type of inertial microfluidic device, multi-dimensional double spiral (MDDS) device, as an alternative to centrifugation. By combining key innovations in inertial microfluidic device designs and check-valve-based recirculation processes, highly purified and concentrated WBCs (up to >99.99% RBC removal, ∼80% WBC recovery, >85% WBC purity, and ∼12-fold concentrated WBCs compared to the input sample) were achieved in less than 5 minutes, with high reliability and repeatability (coefficient of variation, CV < 5%). Using this, one can harvest up to 0.4 million of intact WBCs from 50 μL of human peripheral blood (50 μL), without any cell damage or phenotypic changes in a fully-automated operation. Alternatively, hand-powered operation is demonstrated with comparable separation efficiency and speed, which eliminates the need for electricity altogether for truly field-friendly sample preparation. The proposed platform is therefore highly deployable for various point-of-care applications, including bedside assessment of the host immune response and blood sample processing in resource-limited environments.

Efficient separation of V(V) and Cr(VI) in aqua by microemulsion extraction

Separation of V(V) and Cr(VI) in aqua is intensively demanded in consideration of full resource utilization and environmental safety of vanadium extraction industry, which is however a challenge due to their highly similar chemical properties. In this work, chromium transformation is firstly conducted to convert Cr(VI) anions into Cr(III) cations that are differentiable from V(V) anions. Then, the microemulsion system of Aliquat 336/isoamyl alcohol/n-heptane/NaCl is utilized to selectively extract V(V) anions by method of microemulsion extraction and leave Cr(III) cations in the raffinate, leading to the separation of V and Cr. In optimal conditions of microemulsion extraction, the extraction efficiency of V is as high as 98.45% while that of Cr is only 4.44%, confirming the efficient separation of V and Cr in aqua. Extracted V is retrieved back to aqueous solution by stripping V-loaded microemulsion and simultaneously concentrated by 4 times with total recovery of 97.91%; Cr(III) left in the raffinate is environmentally safe and ready for direct precipitation recovery. The achieved separation of V(V) and Cr(VI) is thus not only efficient, but also beneficial to their subsequent recovery. This work has demonstrated a powerful separation method for V(V) and Cr(VI) with high separation capacity, efficiency and speed, which lays the essential foundation for the recovery and comprehensive utilization of V and Cr resources in vanadium metallurgy industry.

Construction of WS2/MoSe2 heterojunction for efficient photoelectrocatalytic hydrogen evolution

As a typical n-type semiconductor, MoSe2 is limited in the application of photoelectrocatalytic hydrogen evolution due to the rapid recombination of photo-generated electron-hole pairs. To solve this problem, in this work, a p-type WS2 is selected to design a WS2/MoSe2 hybrid semiconductor catalyst with a p-n heterojunction. The obtained samples were characterized by XRD, Raman, SEM, TEM, UV and XPS. Besides, the photoelectrocatalytic performances for hydrogen production were also evaluated. It was found that the WS2/MoSe2 hybrid catalyst with a loading of 20% WS2 (20W-M) showed the best photocatalytic performance with a photocurrent density of 35 μA cm-2 at -0.6 V (vs SCE), much larger than those of single MoSe2 (20 μA cm-2) and WS2 (3.5 μA cm-2). And the improved performances should be ascribed to the construction of p-n heterojunction, which leads to the change of photoelectron-hole transport mode, accelerates the separation speed of carriers and prolongs the carrier lifetime. This work demonstrates the promoting effect of WS2 as a cocatalyst and this strategy can be extended to other semiconductors.

Less than one minute low-pressure gas chromatography - mass spectrometry

Conventional gas chromatography - mass spectrometry (GC-MS) takes 20–40 min per sample, which is undesirably slow in any application if speed can be increased while still meeting analytical needs. In this study, we achieved reasonably good separations with full analysis cycle times of less than 1 min by combining for the first time low-pressure (LP) GC-MS with low thermal mass (LTM) resistive-heating for rapid temperature ramping and cooling of the capillary column. The analytical column is threaded into the LTM thin-walled metal tubing in an instrumental device known as “LTM Fast GC” that is mounted at the top of the gas chromatograph in a detector port. The column inlet and outlet are connected to the GC injector and MS transfer line as usual. For LPGC-MS, a 40 cm, 0.1 mm. i.d. uncoated flow restrictor capillary connected at the injector is coupled with a 2.6 m, 0.25 mm i.d., 0.25 µm film thickness analytical column leading to the MS. Thus, the inlet operates at normal GC pressures, but the analytical column is under vacuum, which increases the optimal helium carrier gas flow velocity thereby increasing speed of full range separations while maintaining acceptable quality of chromatography. This column configuration in LTM-LPGC-MS trades a 64-fold gain in speed of analysis vs. standard GC-MS for a 4-fold loss in chromatographic peak capacity, thereby converting analysis time from minutes into seconds in common applications. For example, jet fuel containing fatty acid methyl esters (akin to biofuel) was separated in 25 s with <1 min full analysis cycle time. An EPA Method 8270 mixture of 76 analytes was also analyzed in <1 min full cycle time by LTM-LPGC-MS. Other examples include very fast analysis of heroin in a street drug powder and elucidation of a new organic synthetic compound. In this report, we describe and discuss the several advantageous and practical features of LTM-LPGC-MS, as well as its trade-offs.

Novel produced water treatment using microemulsion systems to remove oil contents

Produced water (PW) is one of the main sources of oil pollution and it represents the most important environmental concern associated to the oil industry. In this work, microemulsion systems were used to remove dispersed oil from PW. The systems used in the experiments were composed by PW as aqueous phase; kerosene as oil phase; isoamyl alcohol as co-surfactant; and Dissolvan® or Lipesa® as surfactant. An experimental design was applied for process optimization. Experiments were performed according to Scheffé net and showed oil removal efficiencies (%RE) between 24–99%. The microemulsion extraction point used for the process optimization was composed by 60 wt% PW, 5 wt% kerosene, and 35 wt% co-surfactant/surfactant ratio (C/S ratio = 9). The effects of C/S ratio, microemulsion load capacity, oil removal kinetics, temperature, and speed of phase separation were evaluated. From these tests, it was possible to achieve 100% oil removal using C/S = 9, t =25 min, T = 50–60 °C, demonstrating the feasibility of the systems evaluated.

Development and validation of a supercritical fluid chromatography method for fast analysis of six flavonoids in Citri Reticulatae Pericarpium

The study is aimed to develop a rapid and efficient supercritical fluid chromatography coupled with diode-array detection (SFC-DAD) method for simultaneous quantification of six flavonoids in Citri Reticulatae Pericarpium (CRP). The chromatographic parameters including stationary phase, mobile phase composition, back pressure, temperature and flow rate, were systematically optimized with single-factor test. The results indicated that the six compounds were baseline separated on an Agilent Zorbax RX-SIL column using gradient elution within 10 min. The optimized mobile phase was constituted of carbon dioxide (CO2) and methanol. And the parameters were set as follows: backpressure, 95 bar; temperature, 45 °C; flow rate, 0.8 mL/min. The optimized method showed satisfactory retention and resolution for the analytes. The method was validated to demonstrate its selectivity, linearity, precision, accuracy and robustness. Thus, the verified SFC method was successfully applied to quantification of flavonoids present in CRP samples. The results indicated that SFC has the potential to become an excellent alternative for the analysis of flavonoids in herbal medicines, owning to its intrinsic features like high efficiency, separation speed and eco-friendly characteristics.