Solid Phase Adsorption Method Research Articles

Selection of the Second Adsorbent for Sampling Volatile Organic Compounds in the Biomass Gasification Tar Using Solid-Phase Adsorption.

The purpose of this study is to examine the effectiveness of a solid-phase adsorption method for measuring the concentrations of tar compounds in biomass. This method involves collecting tars on a column with an amino-phase sorbent. However, because biomass tar has a high concentration of volatile organic compounds, not all of them can be collected with just one column. Therefore, the researchers decided to add a second column with a different adsorbent to improve the accuracy of the measurement. They also chose to test three different sorbents (Carbopack B, Carbotrap, and activated coconut charcoal) in order to determine which one is the most effective for determining the concentration of volatile organic compounds. The desorption efficiency from various sorbents, the adsorption efficiency of the studied compounds on each sorbent depending on the sampled gas temperature, and the maximal amounts of compounds adsorbed on activated coconut charcoal were evaluated. The best results were obtained using activated coconut charcoal. A modified sampling device consisting of 500 mg of the amino-phase adsorbent and 100 mg of activated coconut charcoal was selected as the optimal choice for collecting tar, including its volatile organic compounds, from the synthesis gas generated during biomass gasification.

Dust collection efficiency of commercial gas collection tubes

Gas sampling tubes are essential tools for the evaluation of air quality in work environments. It adsorbs toxic gaseous matters onto the surface of various granular adsorbents, such as silica gel or activated carbon packed in a thin glass tube, for quantitative analysis by gas chromatography. Currently, most of the semi-volatile matters are evaluated via aerosol filtration or solid-phase gas adsorption depending on the main phase of the substances; however, only a few substances have a sampling protocol regarding both solid and gaseous phases. Therefore, semi-volatile components evaluated by the solid-phase adsorption may result in the underestimation of the component concentrations due to particulate components passing through and remaining in the adsorbent. To highlight issues on sampling of semi-volatile matters by the solid-phase adsorption method, the collection efficiency of aerosol particles by 17 commercial gas sampling tubes were measured via pressure drop. To measure the particle collection efficiency of the gas collection tubes, precise control and dilution of the aerosol particle monitors are essential. However, we cannot apply typical filter test methods at a lower filtration flow rate than that of the aerosol particles monitors. Therefore, we developed a new experimental method that considers flow adjustment between the aerosol monitors. By assuming two specific particle size distributions and five inlet conditions, the collection efficiencies of total mass particles are estimated. From the gas-particle partitioning ratio of 16 polycyclic aromatic hydrocarbons (PAHs) in a coal tar pitch manufacturing industry, the underestimation of the concentration of semi-volatile matters using the gas collection tubes has been discussed. The aerosol particles were collected in all kinds of layers in the gas sampling tubes, such as in the glass wool cap, gas adsorbent granular bed, and polyurethane foam. Furthermore, the collection efficiency curve of all 17 gas sampling tubes tested showed similar trends; a valley around particle sizes ranging from 0.2-0.3 μm between high collection zones below 0.1 μm and above 1 μm was observed. The observations suggested granular bed filters collection mechanisms such as inertial impaction, Brownian diffusion, gravity, and interception as same as air filters. Solid-phase collection can underestimate the concentrations of multi-phase matters. Thus, we wish to highlight the importance of solid-phase collection methods along with filtration collection methods to collect all phases of semi-volatile matters.

Selective isolation of hyaluronan by solid phase adsorption to silica

A solid phase adsorption method for selective isolation of hyaluronan (HA) from biological samples is presented. Following enzymatic degradation of protein, HA can be separated from sulfated glycosaminoglycans, other unsulfated glycosaminoglycans, nucleic acids, and proteolytic fragments by adsorption to amorphous silica at specific salt concentrations. The adsorbed HA can be released from silica using neutral and basic aqueous solutions. HA ranging in size from ∼9 kDa to MDa polymers has been purified by this method from human serum and conditioned medium of cultured cells.

Solid phase adsorption method for tar sampling – How post sampling treatment affects tar yields and volatile tar compounds?

The Solid Phase Adsorption (SPA) methodology is the method of choice for sampling tar from biomass gasifiers and pyrolysers. Reliable and robust tar measurement techniques are essential for having an efficient implementation of these thermochemical processes. This paper critically evaluates the SPA tar sampling method from the following perspectives: (i) the efficiency of tar extraction from the aminopropyl silica sorbent; (ii) the effect of transport and storage period on tar adsorbed on the SPA sorbents; (iii) off-line SPA vs. the on-line µGC method for quantitative determination of benzene and toluene. The present study showed that the tar extraction efficiency for aminopropyl silica sorbent SPA cartridges was typically 95% or higher. The 30% of tar was lost from these sorbent materials during the airfreight and 21.9% during 5 days of ambient storage, respectively. When two sorbents were employed into the SPA sampling device, the loss was reduced to 15%. The loss of SPA detectable tar was 16.4% when aminopropyl silica sorbents were stored in a freezer for 5 days prior to analysis. A significant portion of light tar compounds (benzene and toluene) was lost from the aminopropyl silica sorbent during the airfreight, while, under either ambient or frozen storage, these compounds were preserved relatively well. The best performance using the SPA method was achieved when tar was extracted from the sorbent immediately on-site. The study also demonstrated the superiority of on-line µGC measurement over the off-line SPA method for quantitative determination of light tar compounds. Light tar sampling efficiency, such as for benzene and toluene, was improved by introducing the second activated charcoal sorbent. Benzene yields measured by on-line µGC were up to 10.4 times higher than those extracted from the SPA aminopropyl silica sorbent solely, and, even when two sorbents were employed, they were up to 3.4 times higher. Regarding toluene yields, these values were 2.6 and 1.7 times higher.

Reinforcement of Quaternary Ammonium Modified Silica (QAMS) with Magnetite and its Application by Solid Phase Adsorption (SPA) to Adsorb Chromate Ions

Chromium (VI) in the form of chromate anions that have toxic properties needs to be overcome. This study aims to reinforce cationic sorbent quaternary amine-modified silica with magnetite (QAMS-Fe3O4) to adsorb chromate ions. QAMS prepared by reflux methylation ammine modified silica (AMS) obtained from destruction silicate from rice husk ash followed by the addition of 3-APTMS. Characterization QAMS-Fe3O4 by FT-IR showed successfully of methylation process indicated by disappearing absorbance at 1388 cm-1, and emerging absorbance at 2939 cm-1 in QAMS and QAMS-Fe3O4 indicated a transformation of N-H from -NH2 group to [-N+(CH3)3]. XRD analysis denotes 2θ = 30.15°, 35.53°, 43.12°, 57.22°, and 62.90° (JCPDS No. 00-033-0664) fathomed as a characteristic peak of magnetite. SEM-EDX reveals the homogenous topological spherical form with an average particle size 0.006 µm that is dominated by Si element (52.81%) with magnetic moment value = 34.1 emu/g. The stability test shows that this material stable in an acid condition. The adsorption of chromate ions was conducted by the SPA method. Optimal pH obtained by pH range 4-7 with more than 90% adsorbed chromate ions. Variation of increasing series flow rate from 0.05 to 1.5 mL min-1 resulted in decreased adsorbed chromate ions. The use of SPA methods offered simpler and easier handling than the batch method without overriding the adsorption process effectiveness.

Rapid and efficient ultrasonic assisted adsorption of diethyl phthalate onto FeIIFe2IIIO4@GO: ANN-GA and RSM-DF modeling, isotherm, kinetic and mechanism study

Herein, an ultrasonic assisted dispersive magnetic solid-phase adsorption method along with a high-performance liquid chromatography system for the diethyl phthalate (DEP) removal was developed. In this regard, magnetic iron oxide/graphene oxide (MGO) nanocomposites were prepared by a simple and effective chemical co-precipitation method, followed by nucleation and growth of nanoparticles. The structure and morphology of MGO was identified by Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) spectroscopy X-ray diffraction (XRD), Vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and N2 adsorption-desorption techniques. The interactive and main effect of parameters such as pH, adsorbent dosage, sonication time and concentration of DEP involved in the adsorption process were set within the ranges 3.0–11.0, 0.10–0.50 g L−1, 1–5 min, 5–10 mg/L, respectively. Root means square error (RMSE), mean absolute error (MAE), absolute average deviation (AAD), and coefficient of determination (R2) was employed to examine the applicability of the response surface methodology (RSM) and artificial neural network (ANN) models for the description of experimental data. Compared to RSM, the ANN showed a more accurate performance for modeling the process of DEP adsorption. Using genetic algorithm-ANN, optimum conditions were set to 5.38, 334.7 mg/L, 3.723 min and 4.21 mg/L for pH, adsorbent dose, sonication time and concentration of DEP, respectively. Under the optimized conditions, the maximum adsorption capacity and adsorption factors were 116.933 mg/g and 100%, respectively, while the relative standard deviations (RSDs) was <1.6% (N = 5). The isotherm models display that the Langmuir has the best fit with the equilibrium data, and adsorption kinetics followed the pseudo-second-order model. The thermodynamic results confirmed that the sorption was endothermic and occurred spontaneously. The results exhibited that MGO has excellent potential as an adsorbent for the removal of phthalates from the contaminated water.

Air Pollution Method: A new method based on ionic liquid passed on mesoporous silica nanoparticles for removal of manganese dust in the workplace air

Chronic effect of manganese exposure to humans caused the dysfunction of nervous system. An applied sorbent based on hydrophobic ionic liquid passed on mesoporous silica nanoparticles was used for adsorption/removal of manganese dust (Mn) from workplace air by solid phase adsorption method. In bench scale set up, 5 mL of standard solution of nitrate and oxide of Mn (0.2-5 mg L-1) was used for generation of manganese dust in pure air by drying procedure, and then was passed through column of IL/MSNPs by SKC pump with flow rate of 200-500 mL min-1 by SKC pump. The Mn particles separated from column of IL/MSNPs by irrigation of nitric acid solution before determined by F-AAS/ET-AAS. In optimized conditions, the adsorption capacity of MSNPs and IL/MSNPs for Mn removal from air in batch system (1 Li) was obtained 118.5 mg g-1 and 216.2 mg g-1, respectively.

Tar from pilot scale co-pyrolysis of biological dairy sludge and spruce wood chips

A pilot scale investigation of co-pyrolysis of biological dairy sludge and spruce wood chips and pyrolysis of spruce wood chips solely was carried out. Pyrolysis was tested as a waste treatment method aiming to reduce the volume of dairy sludge while producing a pyrolysis gas suitable for an internal combustion engine. Pyrolysis tests were carried out in a continuously fed, pilot scale rotating retort type of facility in the temperature range between 700 and 770 °C. Feedstock feeding rates were between 40.9 – 68.6 kgd.a.f. h-1. Tar yields and composition was measured by means of the solid phase adsorption method in order to assess gas quality with regard to the specified tar limits given for downstream applications. The yields of total gas chromatography detectable tar produced from the dairy sludge and spruce wood chips blend was in the range between 7.25 - 10.98 gtotal tar Nm-3dry raw gas, while spruce wood chips solely produced yields between 11.18 - 13.31 gtotal tar Nm-3dry raw gas. Composition wise, the main difference was a number of nitrogen-containing tar compounds reflecting the high nitrogen content in dairy sludge feedstock with 2-butenenitrile, pyridine and 1H-pyrrole being the most abundant nitrogen-containing tar compounds. Raw pyrolysis gas from the two feedstocks tested did not meet the requirements regarding tar limits given in the manufacturer’s specification for their internal combustion engine. The raw pyrolysis gas contained excessive amounts of 3 and 4+ aromatic ring tars. Therefore tar removal is required prior to combustion in the engine. The proposed tar removal strategy includes a thermal tar reformer using air as a reforming agent followed by adsorption using wood chips, or in-process generated bio-char, or torrefied biomass as a viable adsorbent.

Experimental comparison of solid phase adsorption (SPA), activated carbon test tubes and tar protocol (DIN CEN/TS 15439) for tar analysis of biomass derived syngas

The quantification of aromatic higher hydrocarbons, so called tar compounds, is crucial for the assessment of gasification processes. The presented work compares three different sampling methods: solid phase adsorption (SPA), adsorption on activated carbon test tubes and DIN CEN/TS 15439 (‘tar-protocol’). Two different groups of operators have been sampling simultaneously in the raw syngas from a fixed-bed stratified upstream biomass gasifier in steady state operation The gathered analysis results offer the possibility to investigate the influence of sampling method, sampling equipment and operators collecting the samples. In total, 79 samples by adsorption and four wet absorption samples by DIN CEN/TS 15439 have been collected and analyzed in one single laboratory by gravimetrical analysis as well as gas chromatographic analysis of 22 tar species. In general, the gravimetric analysis of the wet samples showed much higher tar concentrations in comparison to the sum of GC calibrated species. The BTX concentration obtained by means of adsorption with activated carbon test tubes did neither match values from SPA nor DIN CEN/TS 15439 analysis. Moreover, the upper limit of the third quartile of a boxplot of SPA values coincides well with the arithmetic average of the DIN CEN/TS 15439 analysis. This underlines that SPA method offers potential for tar analysis in a similar manner as DIN CEN/TS 15439.

Tars from Fluidized Bed Gasification of Raw and Torrefied Miscanthus x giganteus

The current study investigates the effect of temperature, equivalence ratio, and biomass composition on tar yields and composition. Torrefied and raw Miscanthus x giganteus (M×G) were used as biomass feedstocks in an atmospheric bubbling fluidized bed gasifier for experiments undertaken between 660 and 850 °C and equivalence ratios from 0.18 to 0.32. Tar was sampled according to the solid phase adsorption method and analyzed by gas chromatography. There is an indication that torrefied M×G produces higher amounts of total GC-detectable tar as well as higher yields of 20 individually quantified tar compounds compared with those of raw M×G. Under similar gasification conditions (800 °C and an equivalence ratio of 0.21), the total GC-detectable tar for torrefied M×G is approximately 42% higher than that for raw M×G. Higher tar yields are observed to be related to higher lignin and lower moisture content of torrefied M×G. The effect of temperature on tar yields is in good agreement with the literature. The hig...

Exploration of silver oxide nanoparticles as a pointer of lanthanum for environmental applications

Solid phase extraction technique is a promising advancement in the fundamental science and has vital role in the environmental and health monitoring. A huge number of solid phase materials have been studied but the prospective for industrial development as an environmental supplement is still limited. Therefore, silver oxide (Ag2O) nanoparticles have been prepared and applied as a selective adsorbent for the adsorption and determination of lanthanum ion using simple eco-friendly solid phase adsorption method. Pure Ag2O nanoparticles powders were illustrated by field emission scanning electron microscopy (FEEM), X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The analytical potential of Ag2O nanoparticles was studied for a selective extraction of nickel prior to its determination by inductively coupled plasma-optical emission spectrometry. The selectivity of Ag2O nanoparticles was investigated toward different metal ions, including Cd(II), Cu(II), Hg(II), La(III), Mn(II), Pb(II), Pd(II) and Y(III). Data obtained from the selectivity study showed that the selectivity of Ag2O nanoparticles was the most toward La(III). The uptake capacity for La(III) was experimentally calculated to be 94.30mg/g. Moreover, adsorption isotherm data of La(III) on Ag2O nanoparticles, were well fit with the Langmuir adsorption isotherm, strongly supporting that the adsorption process was mainly monolayer on homogeneous adsorbent surfaces. Kinetic study revealed that the adsorption of La(III) on Ag2O nanoparticles followed the pseudo-second-order kinetic model.

Assessment of the Solid-Phase Adsorption Method for Sampling Biomass-Derived Tar in Industrial Environments

Low-temperature gasification of biomass is a primary process step for production of biofuels or electricity using gas-fired engines or turbines. In addition to the desired product gas, the raw gas produced through gasification inevitably contains condensable hydrocarbons, known collectively as tar. The amount and composition of the tar have relevance for the efficiencies of the downstream processes. Tar can be measured using both online and off-line methods. However, many of these methods currently lack information regarding their implementation and accuracy levels for large-scale systems. In this work, the Solid-Phase Adsorption (SPA) method for measuring tar in industrial applications is evaluated. The individual steps of the method were examined for their effects on the overall performance of the analysis. Sample collection was found to be the most prominent source of error, and this was mainly due to human factors. Omitting to determine the temperature and pressure of the sampled gas contributed to this error, as the sampled volume of gas under normal conditions could not be correctly calculated. Inconsistencies in the treatment and storage of the collected samples were shown to affect the more volatile species with boiling points similar to that of benzene. The gas chromatography (GC) analysis was performed with satisfying accuracy. However, the reliability of the estimations of the average composition and dew-point of the tar mixture were dependent upon the amount of the identified species. The current implementation of the SPA method yields values with a relative standard deviation within 10% for the majority of the compounds in a given sample. However, in line with the result of previous studies, the tar species with boiling points between those of benzene and xylene (i.e., the BTX compounds) were measured with a lower accuracy than those of heavier tars.

Comparison of efficiency of two methods for tar sampling in the syngas

In the present work, a cold solvent trapping (CST) and solid-phase adsorption (SPA) methods for determining concentration of tar compounds have been chosen for comparison. When the cold solvent trapping method is used, the producer gas flows through a series of impingers containing 2-propanol, whereas in a solid-phase adsorption method it passes through two adsorbent cartridges loaded with 500mg of aminopropyl-bonded silica, and 100mg of activated coconut charcoal. During the experiment, 52 compounds were identified by the cold solvent trapping method and 48 compounds by the solid-phase adsorption method. The SPA method is more accurate than those using impingers, especially for determining such volatile organic compounds as benzene, toluene, and xylenes, due to the use of a second sorbent, activated coconut charcoal. By contrast, the CST method proves to be more accurate for determining components of heavy tar due to a much larger volume of the sampled gas.

Use of two different adsorbents for sampling tar in gas obtained from peat gasification

Gasification is one of the most promising techniques proposed for the production of energy from biomass. Gasification for producing synthesis gas is regarded as one of the most reasonable options for utilising biomass. Gasification of biomass produces a raw gas mixture containing tar, among other components. Traditional methods for tar sampling are based on cold solvent-trapping coupled with solvent absorption in impingers. The present work focusses on a solid-phase adsorption method for determining the concentration of tar compounds. A modified sampling device consisting of 500 mg of amino-phase sorbent and 100 mg of activated coconut charcoal was chosen as optimal for sampling tar (including its volatile organic compounds) in synthesis gas produced by biomass gasification. For research in a real life context, the circulating fluidised bed (CFB) gasifier situated in eastern Latvia (Rēzekne region) was used. Varying volumes of product gas were drawn through the adsorbents, and the total amount of tar was then compared to the number of its individual component compounds. With an increase of the volume of product gas drawn through the adsorbents, a persistently larger amount of benzene and toluene passes through the amino-phase adsorbent and is collected on the activated coconut charcoal. An increased volume of the product gas leads to a growing number of compounds detected and identified on the amino-phase adsorbent.

A solid-phase adsorption method for PEGylation of human serum albumin and staphylokinase: preparation, purification and biochemical characterization

A solid-phase adsorption method was developed to circumvent the disadvantage of the conventional liquid-phase PEGylation, i.e. the heterogeneity of the PEGylated products. The model proteins, human serum albumin (HSA) and staphylokinase (SAK), were adsorbed on the ion exchange chromatography media, followed by PEGylation with succinimidyl carbonate (SC)-mPEG5K and salt elution. Since PEGylation with SC-PEG5K alters the positive charge of the proteins, Q-Sepharose Big Beads and DEAE Sepharose Fast Flow were used for adsorption of HSA and SAK, respectively. Size exclusion chromatography and SDS-PAGE studies demonstrated that solid-phase PEGylation of proteins generate monoPEGylated proteins with the yield of 35-47%. Circular dichroism and intrinsic fluorescence studies showed that solid-phase PEGylation led to little conformational change of the proteins. Solid-phase PEGylation resulted in 35% loss in the biological activity of SAK, which is lower than the liquid-phase PEGylation (70%).

Sampling of benzene in tar matrices from biomass gasification using two different solid-phase sorbents

Biomass tar mainly consists of stable aromatic compounds such as benzene and polyaromatic hydrocarbons, benzene being the biggest tar component in real biomass gasification gas. For the analysis of individual tar compounds, the solid-phase adsorption method was chosen. According to this method, tar samples are collected on a column with an amino-phase sorbent. With a high benzene concentration in biomass tar, some of the benzene will not be collected on the amino-phase sorbent. To get over this situation, we have installed another column with activated charcoal which is intended for collection of volatile organic compounds, including benzene, after the column with the amino-phase sorbent. The study of maximal adsorption amounts of various compounds on both adsorbents while testing different sampling volumes led to the conclusion that benzene is a limiting compound. The research proved that the use of two sorbents (500 mg + 100 mg) connected in series allows for assessment of tar in synthesis gas with a tar concentration up to 30-40 g m(-3), which corresponds to the requirements of most gasifiers.

Preparation and characterization of dimeric bovine hemoglobin tetramers.

Dimeric bovine hemoglobin (Hb) tetramers were prepared by a one-step solid phase adsorption method. Briefly, Hb was absorbed by the solid phase, Q Sepharose Fast Flow media, followed by reaction with the glutaraldehyde and elution procedure. Then, dimeric bovine Hb tetramers were formed and purified from Hb tetramers by anion-exchange chromatography based on Protein-Pak DEAE 8HR. The dimeric Hb tetramer showed a P50 value of 15.9 mm Hg, oxygen transporting efficiency of 14.2%, and Hill coefficient of 1.72. The number of Bohr protons released for dimeric Hb tetramers was 0.59 H/tetramer, which was 39% of that of native bovine Hb. The number of chloride ions released on oxygenation was 0.60/tetramer for dimeric Hb tetramers, which was 46% of that of native bovine Hb.

A solid phase adsorption method for preparation of bovine serum albumin–bovine hemoglobin conjugate

A solid phase adsorption method was proposed to prepare well-defined bovine serum albumin–bovine hemoglobin (Hb) conjugate. After adsorption by the solid phase, Q Sepharose Fast Flow media, bovine serum albumin (BSA) molecules were allowed to react with glutaraldehyde. The spacing out of BSA molecules on the solid phase was assumed to limit polymerization of BSA molecules, except some molecules bound closely on the solid phase resulting in minor dimer formation. Following the elution procedure, the activated monomeric BSA was separated from the dimers by gel filtration chromatography on Superdex 200 and then reacted with bovine Hb at 4 °C and pH 9.5. The 1:1 (BSA:Hb) conjugate was obtained with the yield of 64%. The P 50 values of the conjugates, prepared under anaerobic and aerobic conditions, were 19.1 and 14.2 mmHg, respectively. The dependence of the P 50 on chloride ions for the conjugate was slightly diminished, presumably due to covalent attachment of BSA to bovine Hb.

Catalytic tar decomposition of biomass pyrolysis gas with a combination of dolomite and silica

In this study the catalytic effects of dolomite and silica on biomass tar decomposition were investigated. The concentration of naphthalene is of particular interest since it is the most difficult compound to decompose when dolomite is used as catalyst. The two catalysts were tested in different combinations to see whether synergetic effects on the cracking of naphthalene could be found. Thermal and catalytic cracking were carried out at 700–900°C under ambient pressure in a fixed bed reactor using a tar-rich gas obtained from pyrolysis of different biomass materials. Characterisation of light components of tars using the solid phase adsorption method was also performed. Experimental results indicate that when a pure silica is placed in a layer above the dolomite, considerably less naphthalene and total light tar remains after cracking.

Tar evolution profiles obtained from gasification of biomass and coal

The tar content of the product gases from gasification of biomass is one of the major factors affecting the subsequent process stages. In this work, evolution profiles of the main tar constituents, i.e. benzene, toluene, indene, naphthalene and phenol were obtained during about 1 h gasification runs of biomass and coal in a pressurised fluidised-bed at 700 and 900°C, 0.4 MPa. Sampling and analysis was achieved, using the solid-phase adsorption (SPA) method, previously developed in our laboratory. Our main objectives were: (1) to illustrate the usefulness of the SPA method; (2) to shed new light on the main factors governing tar evolution. It was found that temperature and the type of feedstock used mainly affected tar yields. For both biomass and coal the concentration of tar products decreased with increasing run time at a rate that was fastest initially. This behaviour, which was much more pronounced for coal, provides evidence that char catalytically affects tar evolution. Accordingly, char accumulates in the bed to a various extent depending on fuel and gradually approaching steady state. Biomass char, contrary to coal char, is readily oxidised during gasification, and thus only small steady-state amounts are available to catalyse tar cracking reactions.